It cannot be pointed out too often that by far the most extensive period of human history is prehistory. In the past it was possible to evade this fact and its problematic consequences for conventional historiography, because prehistory could be safely set aside as not being history at all. The subsequent rise of scientific historiography, which allows us to read texts other than written language — geological texts, genetic texts, the texts of material culture uncovered by archaeologists, and so on — have been progressively chipping away at the facile distinction between history and prehistory, so that boundary between the two can no longer be maintained and any distinction between history and prehistory must be merely conventional, such as the convention of identifying history sensu stricto with the advent of written language.

The evolutionary psychology of human beings carries the imprint of this long past until recently unknown to us, lost to us, its loss during the earliest period of civilization being a function of history effaced as the events of more recent history wipe clean the slate of the earlier history that preceded it. Scientific historiography provides us with the ability to recover lost histories once effaced, and, like a recovered memory, we recognize ourselves in this recovered past because it is true to what we are, still today.

From the perspective of illuminating contemporary human society, we may begin with the historical recovery of relatively complex societies that emerged from the Upper Paleolithic, which communities were the context from which the Neolithic Agricultural Revolution emerged. But from the perspective of the evolutionary psychology that shaped our minds, we must go back to the origins of the brain in natural history, and follow it forward in time, for each stage in the evolution of the brain left its traces in our behavior. The brainstem that we share with reptiles governs autonomous functions and the most rudimentary drives, the limbic system that we share with other mammals and which is implicated in our sentience-rich biosphere is responsible for our emotions and a higher grade of consciousness than the brainstem alone can support, and the cerebral cortex enables more advanced cognitive functions that include reflexive self-awareness and historical consciousness (awareness of the past and the future in relation to the immediacy of the present).

Each of these developments in terrestrial brain evolution carries with it its own suite of behaviors, with each new set of behaviors superimposed on previous behaviors much as each new layer of the brain is superimposed upon older layers. Over the longue durée of evolution these developments in brain evolution were also coupled with the evolution of our bodies, which enact the behaviors in question. As we descended from the trees and hunted and killed for food, our stomachs shrank and our brains grew. We have the record of this transition preserved in the bones of our ancestors; we can still see today the cone-shaped ribcage of a gorilla, over the large stomach of a species that has remained primarily vegetarian; we can see in almost every other mammal, almost every other vertebrate, the flat skull with nothing above the eyes, compared to which the domed cranium of hominids seems strange and out of place.

As I wrote in Survival Beyond the EEA, “Evolution means that human beings are (or were) optimized for survival and reproduction in the Environment of Evolutionary Adaptedness (EEA).” (Also on the EEA cf. Existential Threat Narratives) The long history of the formation of our cognitive abilities has refined and modified survival and reproduction behaviors, but it has not replaced them. Our hunter-gatherer ancestors of the Upper Paleolithic were already endowed with the full cognitive power that we continue to enjoy today, though admittedly without the concepts we have formulated over the past hundred thousand years, which have allowed us to make better use of our cognitive endowment in the context of civilization. Everything essential to the human mind was in place long before the advent of civilization, and civilization has not endured for a period of time sufficient to make any essential change to the constitution of the human mind.

The most difficult aspects of the human point of view to grasp objectively are those that have been perfectly consistent and unchanging over the history of our species. And so it is that we do not know ourselves as dwellers on the surface of a planet, shaped by the perspective afforded by a planetary surface, looking up to the stars through the distorting lens of the atmosphere, and held tight to the ground beneath our feet by gravity. At least, we have not known ourselves as such until very recently, and this knowledge has endured for a much shorter period of time than civilization, and hence has had even less impact on the constitution of our minds than has civilization, however much impact it has had upon our thoughts. Our conceptualization of ourselves as beings situated in the universe as understood by contemporary cosmology takes place against the background of the EEA, which is a product of our evolutionary psychology.

To understand ourselves aright, then, we need to understand ourselves as beings with the minds of hunter-gatherers who have come into a wealth of scientific knowledge and technological power over an historically insignificant period of time. How did hunter-gatherers conceive and experience their world? What was the Weltanschauung of hunter-gatherers? Or, if you prefer, what was the worldview of hunter-gatherers?

Living in nature as a part of nature, only differentiated in the slightest degree from the condition of prehuman prehistory, the hunter-gatherer lives always in the presence of the sublime, overwhelmed by an environment of a scale that early human beings had no concepts to articulate. And yet the hunter-gatherer learns to bring down sublimely large game — an empowering experience that must have contributed to a belief in human efficacy and agency in spite of vulnerability to a variable food supply, not yet under human control. Always passing through this sublime setting for early human life, moving on to find water, to locate game, to gather nuts and berries, or to escape the depredations of some other band of hunter-gatherers, our ancestor’s way of life was rooted in the landscape without being settled. The hunter-gatherer is rewarded for his curiosity, which occasionally reveals new sources of food, as he is rewarded for his technological innovations that allow him to more easily hunt or to build a fire. The band never has more children than can be carried by the adults, until the children can themselves escape, by running or hiding, the many dangers the band faces.

As settled agriculturalism began to displace hunter-gatherers, first from the fertile lowlands and river valleys were riparian civilizations emerged, new behaviors emerged that were entirely dependent upon the historical consciousness enabled by the cerebral cortex (that is to say, enabled by the ability to explicitly remember the past and to plan for the future). Here we find fatalism in the vulnerability of agriculture to the weather, humanism in this new found power over life, a conscious of human power in its the command of productive forces, and the emergence of soteriology and eschatology, the propitiation of fickle gods, as human compensations for the insecurity inherent in the unknowns and uncertainties of integrating human life cycles with the life cycles of domesticated plants and animals and the establishment of cities, with their social differentiation and political hierarchies, all unprecedented in the history of the world.

The Weltanschauung of hunter-gatherers, which laid the foundations for the emergence of agrarian and pastoral civilizations, I call the homeworld effect in contradistinction to what Frank White has called the overview effect. The homeworld effect is our understanding of ourselves and of our world before we have experienced the overview effect, and before the overview effect has transformed our understanding of ourselves and our world, as it surely will if human beings are able to realize a spacefaring civilization.

The homeworld effect — that our species emerged on a planetary surface and knows the cosmos initially only from this standpoint — allows us to assert the uniqueness of the overview effect for human beings. The overview effect is an unprecedented historical event that cannot be repeated in the history of a civilization. (If a civilization disappears and all memory of its having attained the overview effect is effaced, then the overview effect can be repeated for a species, but only in the context of a distinct civilization.) A corollary of this is that each and every intelligent species originating on a planetary surface (which I assume fulfills the principle of mediocrity for intelligent species during the Stelliferous Era) experiences a unique overview effect upon the advent of spacefaring, should the cohort of emergent complexities on the planet in question include a technologically competent civilization.

The homeworld effect is a consequence of planetary surfaces being a locus of material resources and energy flows where emergent complexities can appear during the Stelliferous Era (this is an idea I have been exploring in my series on planetary endemism, on which cf. Part I, Part II, Part III, Part IV, and Part V). We can say that the homeworld effect follows from this planetary standpoint of intelligent beings emerging on the surface of a planet, subject to planetary constraints, just as the overview effect follows from an extraterrestrial standpoint.

We can generalize from this observation and arrive at the principle that an effect such as the overview effect or the homeworld effect is contingent upon the experience of some standpoint (or, if you prefer, some perspective) that an embodied being experiences in the first person (and in virtue of being embodied). This first level of generalization makes it obvious that there are many standpoints and many effects that result from standpoints. Standing on the surface of a planet is a standpoint, and it yields the homeworld effect, which when formulated theoretically becomes something like Ptolemaic cosmology — A Weltanschauung or worldview that was implicit and informal for our hunter-gatherer ancestors, but which was explicitly formulated and formalized after the advent of civilization. A standpoint in orbit yields a planetary overview effect, with the standpoint being the conditio sine qua non of the effect, and this converges upon a generalization of Copernican cosmology — what Frank White has called the Copernican Perspective. (We could, in which same spirit, posit a Terrestrial Perspective that is an outgrowth of the homeworld effect.) If a demographically significant population attains a particular standpoint and experiences an effect as a result of this standpoint, and the perspective becomes the perspective of a community, a worldview emerges from the community.

Further extrapolation yields classes of standpoints, classes of effects, classes of perspectives, and classes of worldviews, each member of a class possessing an essential property in common. The classes of planetary worldviews and spacefaring worldviews will be different in detail, but all will share important properties. Civilization(s) emerging on planetary surfaces at the bottom of a gravity well constitute a class of homeworld standpoints. Although each homeworld is different in detail, the homeworld effect and the perspective it engenders will be essentially the same. Initial spacefaring efforts by any civilization will yield a class of orbital standpoints, again, each different in detail, but yielding an overview effect and a Copernican perspective. Further overview effects will eventually (if a civilization does not stagnate or collapse) converge upon a worldview of a spacefaring civilization, but this has yet to take shape for human civilization.

A distinctive aspect of the overview effect, which follows from an orbital standpoint, is the suddenness of the revelation. It takes a rocket only a few minutes to travel from the surface of Earth, the home of our species since its inception, into orbit, which no human being saw until the advent of spacefaring. The suddenness of the revelation not only furnishes a visceral counter-example to what our senses have been telling us all throughout our lives, but also stands in stark contrast to the slow and gradual accumulation of knowledge that today makes it possible to understand our position in the universe before we experience this position viscerally by having attained an orbital standpoint, i.e., an extraterrestrial perspective on all things terrestrial.

With the sudden emergence in history of the overview effect (no less suddenly than it emerges in the experience of the individual), we find ourselves faced with a novel sublime, the sublime represented by the cosmos primeval, a wilderness on a far grander scale than any wilderness we once faced on our planet, and, once again, as with our ancestors before the vastness of the world, the thundering thousands of game animals on the hoof, oceans that could not be crossed and horizons that could not be reached, we lack the conceptual infrastructure at present to fully make sense of what we have seen. The experience is sublime, it moves us, precisely because we do not fully understand it. The human experience of the homeworld effect eventually culminated in the emergence of scientific civilization, which in turn made it possible for human beings to understand their world, if not fully, at least adequately. Further extrapolation suggests that the human experience of the overview effect could someday culminate in an adequate understanding of the cosmos, as our hunter-gatherer drives for locating and exploiting resources wherever they can be found, and the reward for technological innovations that serve this end, continue to serve us as a spacefaring species.

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I am indebted to my recent correspondence with Frank White and David Beaver, which has influenced the development and formulation of the ideas above. Much of the material above appeared first in this correspondence.

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Grand Strategy Annex

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Depiction of a mammoth from Roufignac, France, painted by our distant ancestors.

Depiction of a mammoth from Roufignac, France, painted by our distant ancestors.

Between the advent of cognitive modernity, perhaps seventy thousand years ago (more or less), and the advent of settled agricultural civilization, about ten thousand years ago, there is a period of fifty thousand years or more of human history — an order of magnitude of history beyond the historical period, sensu stricto, i.e., the period of written records formerly presumed coextensive with civilization — that we have only recently begun to recover by the methods of scientific historiography. This pre-Holocene world was a world of the “ice age” and of “cave men.” These ideas have become so confused in popular culture that I must put them in scare quotes, but in some senses they are accurate, if occasionally misleading.

This graph shows the alternation of cold glacial periods with warmer interglacial periods over a little more than a half million years of the recent past.

This graph shows the alternation of cold glacial periods with warmer interglacial periods over a little more than a half million years of the recent past.

One way in which the idea of an “Ice Age” is misleading is that it implies that our warmer climate today is the norm and an ice age is a passing exception to that norm. This is the reverse of the case. For the past two and a half million years the planet has been passing through the Quaternary Period, which mostly consists of long (about 100,000 year) periods of glaciation punctuated by shorter (about 10,000 year) interglacial periods (also called warming periods) during which the global climate warms and the polar ice sheets retreat. I have pointed out elsewhere that, although human ancestors have been present throughout the entire Quaternary, and so have therefore experienced several cycles of glaciation and interglacials, the present interglacial (the Holocene) is the first warming period since cognitive modernity, and we find the beginnings of civilization as soon as this present warming period begins. Thus the Holocene Epoch is dominated, from an anthropocentric perspective, by civilization; the Quaternary Period before the Holocene Epoch is, again from an anthropocentric perspective, human history before civilization: history before history.


We should remind ourselves that this very alien world and its inhabitants is the precursor to our world and the inhabitants are our direct ancestors. In other words, this is us. This is our history, even if we have only recently become accustomed to thinking of prehistory as history no less than the historical period sensu stricto. The Upper Paleolithic, with its ice age, cave bears, cave men, painted animals seen in flickering torchlight, and thousands upon thousands of years of a winter that does not end was a human world — the human world of the Upper Paleolithic — that we can only with effort recover as our own and come to feel its formative power to shape what we have become. The technical term is that his human world of the Upper Paleolithic was our environment of evolutionary adaptedness (EEA). It is this world that made us what we are today.

Cave bear 1

One website has this very evocative passage describing the world of the Upper Paleolithic:

“The longest war ever fought by humans was not fought against other humans, but against another species — Ursus spelaeus, the Cave Bear. For several hundred thousand years our stone age ancestors fought pitched and bloody battles with these denizens of the most precious commodity on earth — habitable caves. Without these shelters homo sapiens would have had little chance of surviving the Ice Ages, the winter storms, and the myriad of predators that lurked in the dark.”

While there isn’t direct scientific evidence for this compellingly dramatic way of thinking about the Upper Paleolithic (though I was very tempted to title this post “The 100,000 Year War”), it can accurately be said that human/cave bear interactions did occur during the most recent glacial maximum, that both human beings and cave bears are warm-blooded mammals and caves would have provided a measure of protection and warmth that would have endured literally for thousands or tens of thousands of years during this climatological “bottleneck” for mammals, whereas no human-built shelter could have survived these conditions for this period of time. Another species as ill-suited for cold weather as homo sapiens would have simply moved on or gone extinct, but we had our big brains by this time, and this made it possible for early man to fight tenaciously for keep a grip on life even in an environment in which they have to fight cave bears for the few available shelters.


Human beings would have survived elsewhere on the planet in any event, because the equatorial belt was still plenty warm at the time, but the fact that some human beings survived in caves in glaciated Europe is a testament both to their cognitive modernity and their stubbornness. It becomes a little easier to understand how and why early human beings squeezed into caves by passages that cause contemporary archaeologists to experience not a little claustrophobia, when we understand that human beings were routinely inhabiting caves, and probably had to explore them in some depth to make sure they wouldn’t have any unpleasant surprises when a cave bear woke up from its hibernation in the spring.

An elegant rendering of a cave bear by one of our ancestors, in Chavet cave.

An elegant rendering of a cave bear by one of our ancestors, in Chavet cave.

Unlike human beings, cave bears probably could not have survived elsewhere — they were a species endemic to a particular climate and a particular range and did not have the powers of behavioral adaptation possessed by human beings. The caves of ice age Eurasia were their world, and they spent enough time in these shelters that the walls of caves have a distinctive sheen that is called “Bärenschliffe”:

The “Bärenschliffe” are smooth, polished and often shining surfaces, thought to be caused by passing bears, rubbing their fur along the walls. These surfaces do not only occur in narrow passages, where the bear would come into contact with the walls, but also at corners or rocks in wider passages.

“Trace fossils from bears in caves of Germany and Austria” by Wilfried Rosendahl and Doris Döppes, Scientific Annals, School of Geology Aristotle University of Thessaloniki, Special volume 98, p. 241-249, Thessaloniki, 2006.

Some of these caves are said to be polished “like marble” (I haven’t visited any of these caves myself, so I am reporting what I have read in the literature), so that one must imagine cave bears passing through the narrow passages of their caves for thousands of years, brushing against the wall with their fur until the rough stone is made smooth. The human beings who later took over these caves would have run their hand along these smooth walls, noted the niches where the bears hibernated, and wondered if another bear would come to claim the cave they had claimed.

drachenloch skull vault

There is a particularly interesting cave in Switzerland, Drachenloch (which means “dragon’s lair,” as cave bear skulls were once thought to have been the skulls of dragons), in which early human beings seem to have stacked cave bear skulls in a stone “vault” in the floor of the cave. Certainly these two mammal species — ursus spelaeus and homo sapiens — would have known each other by all their shared signs of cave habitation. Indeed, they would have smelled each other.

Entrance to Drachenloch cave.

Entrance to Drachenloch cave.

Mythology scholar Joseph Campbell many times pointed out the fundamental mythological differences between hunter-gatherer peoples and settled agricultural peoples; in the case of the Upper Paleolithic, we have hunter-gatherers and only hunter-gatherers — that is to say, tens of thousands of years of a belief system emergent from a hunting culture with virtually no alternatives. Given the tendency of hunting peoples to animism, and of viewing other species as spiritually significant — metaphysical peers, as it were — one would expect that hunters who fought and killed cave bears in order to take over their shelters would have revered these animals in a religious sense, and this religious reverence for the slain foe (of any species) could explain the prevalence of apparent cave bear altars in caves inhabited by human beings during the Upper Paleolithic.

Perhaps the most permanent action that any human being has accomplished in the history of our species is when one of our ancestors placed this cave bear skull on a rock, where still it sits, tens of thousands of years later.

Perhaps the most permanent action that any human being has accomplished in the history of our species is when one of our ancestors placed this cave bear skull on a rock, where still it sits, tens of thousands of years later.

The human world of the Upper Paleolithic would also have been a world shared with other hominid species — an experience we do not have today, being the sole surviving hominid (perhaps as the result of being a genocidal species) — and most especially shared with Neanderthals. Recent genetic research has demonstrated that there was limited interbreeding between homo sapiens and Neanderthals (cf., e.g., Neanderthals had outsize effect on human biology), but it is likely that these communities were mostly separate. If we reflect on the still powerful effect of in-group bias in our cosmopolitan world, how much stronger must in-group bias have been among these small communities of homo sapiens, homo neanderthalensis, and Denisova hominins? One suspects that strong taboos were associated with other species, and rivals in hunting.


It is likely that Neanderthals evolved in the Levant or Europe from human ancestors who left Africa prior to the speciation of Homo sapiens. The Neanderthal were specifically adapted to life in the cold climates of Eurasia during the last glacial maximum. However, such is the power of intelligence as an adaptive tool that the modern human beings who left Africa were able displace Neanderthals in their own environment, much as homo sapiens displaced a great many other species (and much as they displaced cave bears from their caves). While Neanderthals had larger brains than Homo sapiens, they made tools and they wore clothing after a fashion, Neanderthals did not pass through a selective filter that (would have) resulted in the Neanderthal equivalent of cognitive modernity.

neanderthal tree

Homo sapiens made better tools and better clothing, and, in the depths of the last glacial maximum, better tools and better clothing constituted the margin between survival and extinction. Perhaps the most significant invention in hominid history after the control of fire was the bone needle, that allowed for the sewing of form-fitting clothing. With form-fitting clothing our prehistoric ancestors were able to make their way through the world of the last glacial maximum and the occupy every biome and every continent on the planet (with the exception of Antarctica).

The bone needle: key to human survival and expansion during the last glacial maxiumum (eyed needles from the Solutrean, dating to MIS 2, at Grotte de Jouclas, France, redrawn from White 1986, p. 78).

The bone needle: key to human survival and expansion during the last glacial maxiumum (eyed needles from the Solutrean, dating to MIS 2, at Grotte de Jouclas, France, redrawn from White 1986, p. 78).

While “lost worlds” and inexplicable mysteries are a favorite feature of historical popularization, the lost human world of the Upper Paleolithic is being recovered for us by scientific historiography. We are, as a result, reclaiming a part of our identity lost for the ten thousand years of civilization since the advent of the Holocene. The mystery of human origins is gradually becoming less mysterious, and will become less more, the more that we learn.

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Grand Strategy Annex

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filter layers

In my recent post Is encephalization the Great Filter? I quoted Robin Hansen’s paper that gave the original formulation of the Great Filter. Again, Hanson wrote:

“Consider our best-guess evolutionary path to an explosion which leads to visible colonization of most of the visible universe… The Great Silence implies that one or more of these steps are very improbable; there is a ‘Great Filter’ along the path between simple dead stuff and explosive life. The vast vast majority of stuff that starts along this path never makes it. In fact, so far nothing among the billion trillion stars in our whole past universe has made it all the way along this path. (There may of course be such explosions outside our past light cone [Wesson 90].)”

Robin Hanson, The Great Filter — Are We Almost Past It? 15 Sept. 1998

In filtration technology, the “steps” between the input and the output of a filter are called “elements,” “layers,” or “media.” I will here speak of “elements” of the Great Filter, and I will here take seriously the idea that, “…one or more of these [elements] are very improbable.” In other words, the Great Filter may be one or many, and we do not yet know which one of these alternatives is the case. Most formulations of the Great Filter reduce it to a single factor, but I want to here explicitly consider the Great Filter as many.

What is the Great Filter filtering? Presumably, the higher forms of complexity that are represented by the successive terms of the Drake equation, and which Big History recognizes (according to a slightly different schema) as levels of emergent complexity. The highest forms of complexity of which we are aware seem to be very rare in the universe, whereas the relatively low level of complexity — like hydrogen atoms — seems to be very common in the universe. Somewhere between plentiful hydrogen atoms and scarce civilizations the Great Filter interposes. And there may yet be forms of complexity not yet emergent, and therefore a filter through which we have not yet passed.

Hanson mentions visible colonization of the visible universe — this is a different and a much stronger standard to overcome than that of mere intelligence or civilization. Our own civilization does not constitute visible colonization of the universe, in so far as visible colonization means the consequences of intelligent colonization of the universe are obvious in the visible spectrum, but there is a sense in which we are highly visible in the EM spectrum. Thus the scope of the “visibility” of a civilization can be construed narrowly or broadly.

Construed broadly, the “visible” colonization of the universe would mean that the effects of colonization of the universe would be somewhere obvious along some portion of the EM spectrum. We can imagine several such scenarios. It might have been that, as soon as human beings put up the first radio telescope, we would have immediately detected a universe crowded with intelligent radio signals. We might have rapidly come to a science of analyzing the classifying the variety of signals and signatures of exocivilizations in the way that we now routinely classify kinds of stars and galaxies and now, increasingly, exoplanets. Or it might have been that, as soon as we thought to look for the infrared signatures of Dyson civilizations, we would have found many of these signatures. Neither of these things did, in fact, happen, but we can entertain them as counterfactuals and we easily visualize how either could have been the case.

The difference between a universe that is visibly colonized and one that is not is like the difference between coming over the ridge of hill and seeing a vast forest spread out below — i.e., a natural landscape that came about without the intervention of intelligence — and coming over the ridge of a hill and seeing an equally vast landscape of a city spread out below, with roads and building and lights and so on — i.e., an obvious built environment that did not come about naturally — out of reach from a distance, but no less obvious for being out of reach. At present, when we look out into the cosmos we see the cosmological equivalent of the forest primeval — call it the cosmos primeval, if you will (with a nod to Longfellow’s Evangeline).

In the illustration below the Great Filter is everything that stands between an empty universe and a universe filled with visible colonization by intelligent agents and their civilization. The Great Filter is then broken down into seven (7) diminutive filters, each a filter “element” of the Great Filter, which correspond to the terms of the Drake Equation. We could choose other elements for the Great Filter than the terms of the Drake equation, but this is a familiar and accessible formalism so I will employ it without insisting that it is exhaustive or even the best breakdown of the elements of the Great Filter. The reader is free to substitute any other appropriate formalism as an expression of the Great Filter, with any number of elements.

drake equation 1

In this illustration the lower case letters along the left margin that correspond to arrows each stopped by an element of the Great Filter are to be understood as follows:

a – failure of stars to form

b – failure of planets to form

c – failure of planets to be consistent with the emergence of a biosphere

d – failure of planets consistent with the emergence of a biosphere to produce a biosphere

e – failure of a biosphere to produce intelligent life and civilization

f – failure of a civilization to produce technically detectable signatures

g – failure of a technologically detectable civilization to survive a period of time sufficient to communicate

h – a civilization on a trajectory toward visible colonization of the universe

Given a Great Filter constructed from a series of lesser filters, relations between the elements of the Great Filter (the individual lesser filters) describe possible permutations in the overall structure of the Great Filter, as I have attempted to illustrate in the image below.

great filter elements

In this illustration the pathways marked by arrows are to be understood as curves, the X axis of which is the difficulty of passing through an element of the Great Filter, and the Y axis of which marks the gradual emergence of complexity strung out in time, as follows:

A – An inverse logarithmic Great Filter in which successive elements of the filter are easier to pass through by an order of magnitude with each element

B – An inverse linear gradient Great Filter in which successive elements of the filter are easier to pass through by degrees defined by the gradient

C – A constant Great Filter in which each element is equally easy, or equally difficult, to pass

D – A linear gradient Great Filter in which successive elements of the filter are progressively more difficult to pass through, with the change in the degree of difficulty between any two elements defined by the gradient (call it Δe, for change in difficulty of passage through an element)

E – A logarithmic Great Filter in which successive elements of the filter are each progressively more difficult to pass through by an order of magnitude for each element (my drawings are, or course, inexact, so I appeal to the leniency of the reader to get my general drift).

In the case of a Great Filter of an inverse logarithmic scale, the first filter element is by far the most difficult to pass through, and every subsequent element is an order of magnitude easier to pass. Once given the universe, then, intelligence and civilization are nearly inevitable. While such a filter seems counter-intuitive (most filters begin with coarse filtration elements and proceed in steps to finer filtration elements), something like may be unconsciously in mind in the accounts of the universe as a place teaming not only with life, but with civilizations — what I have elsewhere called an intelligence-rich galactic habitable zone (IRGHZ) — and I note that such visions of an IRGHZ often invoke the idea of inevitability in relation to life and intelligence.

However, this is not the problem that the universe presents to us. We do not find ourselves in the position of having to explain the prolixity of civilization in the universe; rather, we find ourselves in the predicament of having to explain the silentium universi.

The above analysis ought to make it clear that, not only do we not know what the Great Filter is — i.e., we do not know if there is one factor, one element among others, that is the stumbling block to the broadly-based emergence of higher complexity — but also that we do not know the overall structure of the Great Filter. Even if I am right that encephalization could be singled out at the Great Filter (as I postulated in Is encephalization the Great Filter?), and the one especially difficult element of the Great Filter to pass beyond, there are still further filters that could prevent our civilization from developing into the kind of civilization that Hanson describes as visibly colonizing the universe, that is to say, a cosmologically visible civilization.

encephalization filter

We can easily project a universe with a spacefaring civilization so pervasive that the stars in their courses are diverted from any trajectory that would be based on natural forces, that the constellations would have an obviously artificial character, and that use of energy on a cosmological scale leaves unambiguous infrared traces due to waste heat. A universe that was home to such a civilization would have passed beyond a filtration element that we have not yet passed beyond.

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Grand Strategy Annex

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Hominid encephalization reveals an exponential growth curve.

Hominid encephalization reveals an exponential growth curve.

The idea of the great filter was formulated by Robin Hanson. In the exposition below Hanson also names a number of steps (acknowledged to be non-exhaustive) in the development of explosively expanding life:

“Consider our best-guess evolutionary path to an explosion which leads to visible colonization of most of the visible universe… The Great Silence implies that one or more of these steps are very improbable; there is a ‘Great Filter’ along the path between simple dead stuff and explosive life. The vast vast majority of stuff that starts along this path never makes it. In fact, so far nothing among the billion trillion stars in our whole past universe has made it all the way along this path. (There may of course be such explosions outside our past light cone [Wesson 90].)”

Robin Hanson, The Great Filter — Are We Almost Past It? 15 Sept. 1998

Discussion of the Great Filter has focused on singling out one factor and identifying this one factor as the Great Filter, although Hanson is explicit that, “one or more of these steps are very improbable.” In the event that several steps in the development of explosively expanding life rather than some one single step is unlikely, the Great Filter may consist of several elements. I think that this is an important qualification to make, but at present I will adopt the conventional presumption that one step in the development of advanced civilization is improbable (or especially improbable) and constitutes the Great Filter.

Graph of the encephalization quotient of several mammals.

Graph of the encephalization quotient of several mammals.

What we know about the cosmos is consistent with it being rich in life, but poor in technologically advanced civilization. The more that we learn about exoplanetary systems (living, as we do, in the Golden Age of exoplanet discovery), the more our scientific understanding of the universe points toward a superfluity of habitable worlds (or, at least, potentially habitable worlds), even while no trace of intelligence has yet been seen or heard beyond Earth. Some of this may have to do with the amount of research funding that is channeled into astronomy and astrophysics in comparison to SETI research, which has received relatively little to date. This is about to change. A “Breakthrough Initiative” will be funneling a large amount of money into SETI — Breakthrough Listen — but there is no reason as yet to suppose that this effort will be any more successful than past efforts, though I would be quite pleased to be proved wrong.

Brain to body mass ratio is distinct from encephalization quotient (EQ).

Brain to body mass ratio is distinct from encephalization quotient (EQ).

The point that I made some time ago in SETI as a Process of Elimination still holds good: as our scientific instrumentation improves with each generation of technology, and our research methods become more sophisticated, we are able to exclude (and, correlatively, to include) an increasing number of possibilities and instances. In other words, progress in science comes about by falsifying certain hypotheses, as would be expected from a philosophy of science derived from the Popper-Lakatos axis. (It is often discussed in relation to SETI research that investigators are hesitant to publish negative results; perhaps if they better understood the crucial role of falsification in the methodology of the scientific research program that is SETI they would be more inspired to publish negative results.)

Comparative brain sizes of several mammals.

Comparative brain sizes of several mammals.

When, in the coming decades, we are able to obtain spectroscopic analyses of exoplanet atmospheres, our knowledge of what is going on on exoplanets — as opposed to merely knowing about their existence, location, size, orbital period, and so on, which is the kind of scientific knowledge we have only recently come into — will improve by an order of magnitude. At this point in time we will move from ne in the Drake equation (number of planets, per solar system, with an environment suitable for life) to fl (fraction of suitable planets on which life actually appears) and possibly also fc (fraction of civilizations that develop a technology that releases detectable signs of their existence into space, from which we can infer fi, fraction of life bearing planets on which intelligent life emerges) if exoplanet atmospheric signatures reveal signs of unambiguous industrial activity.

Frank Drake

We do not know the prevalence of life in our galaxy, much less in the universe at large — i.e., whether or not we live in a biota-rich GHZ, or even CHZ (cosmic habitable zone) — but we may soon be able to estimate the presence of life in the cosmos as we can now estimate the number of planets in the cosmos. It is entirely possible that the universe is teaming with life, even advanced life that is as sophisticated as the life of the terrestrial biosphere. I have written elsewhere that we may live in a “universe of stromatolites” (cf. A Needle in the Cosmic Haystack), but we may also be living in the universe rich in the ecological equivalents of sharks, koalas, and penguins. With one exception: the emergence of the cognitive capacity that makes abstract intelligence possible as well as the civilization that is predicated upon it.

Do we live in a universe of stromatolites?

Do we live in a universe of stromatolites?

In an earlier post, A Note on the Great Filter, I suggested that we are the Great Filter. I would now like to refine this: if I were to identify a “Great Filter” (i.e., a single element constituting the Great Filter) somewhere between plentiful life and absent advanced technological civilizations, I would put my finger on hominid encephalization. It was the rapid encephalization of our hominid ancestors that made what we recognize as intelligence and civilization possible. While there are many other large brains in the animal kingdom — the whale brain and the elephant brain are significantly larger than the human brain — and other mammals have brains as convoluted as the human brain — meaning more of the neocortex, which makes up the outer layer of gray matter — the encephalization quotient of the human brain is significantly greater than any other animal.


Brain size in absolute terms may have to exceed a certain threshold before intelligence of the sort we seek to measure can be said to be present. Neurons are of a nearly constant size, so the minimal neuronal structure necessary to control bodily functions take up about the same space in a mouse and an elephant. Factors other than sheer brain size are relevant to brain function, as, for example, the portion of the brain made up by the cerebral cortex and the amount of convolutions (therefore outer surface area, and the cerebral cortex is outer layer). Hence the introduction of encephalization quotient: encephalization quotient is not simply a ratio of brain mass to body mass, but is also based on the expected brain size for a given body plan — this introduces an admitted interpretive element into EQ, but that does not vitiate the measure. When, in the distant future, we can compare EQs over many different species from many different biospheres, we can firm up these numbers. Someday this will be the work of astroneurology.

The 'WOW!' signal -- fugitive signature of intelligence in an otherwise lonely universe? Perhaps astroneurology will someday study neural architecture across biospheres and arrive at a non-anthropocentric measure of intelligence that could account for something like the 'WOW!' signal.

The ‘WOW!’ signal — fugitive signature of intelligence in an otherwise lonely universe? Perhaps astroneurology will someday study neural architecture across biospheres and arrive at a non-anthropocentric measure of intelligence that could account for something like the ‘WOW!’ signal.

The human brain (with its distinctive and even disproportionate EQ) has not changed since anatomical modernity — at least a hundred thousand years, and maybe as much as three hundred thousand years — and human thought has probably not greatly changed since the advent of cognitive modernity, perhaps seventy thousand years ago. We must continually remind ourselves that even the earliest anatomically modern human beings had a brain structurally indistinguishable from the human brain today. With the blindingly rapid gains of technological civilization over the past hundred years it is increasingly difficult to maintain a sense of connection to the past, not to mention the distant past. But when the human brain appeared in its modern form, it was unprecedented in its cognitive capacity — it was and still is an extreme outlier. There was nothing else like it on the planet, and from this brain followed control of fire, language, technology, art, and eventually civilization.

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brain outline

Evolutionary Psychology in an Astrobiological Context

Recently I was reading about evolutionary biology and it struck me how it might be possible to place evolutionary psychology in an astrobiological context and thereby formulate a much more comprehensive conception of astrobiology that goes beyond biology narrowly conceived (as well as a much more comprehensive conception of evolutionary psychology). Evolutionary biology itself has gone beyond the strictly biological in the form of evolutionary psychology, which applies the theoretical framework of evolutionary biology to elucidate human nature, human behavior, and human thought. Evolutionary biology has also gone beyond the terrestrial in the form of astrobiology, which applies the theoretical framework of evolutionary biology to elucidate life on Earth in a cosmological context. To join together these extrapolations of biology in an even larger synthesis would provide a impressive point of view.

I cannot mention evolutionary psychology without pausing to acknowledge the controversy of this discipline, and evolutionary biology today has the (nearly) unique status of being disparaged by both the political left and the political right, but my readers will already have guessed where I am likely to stand on this controversy, especially if they have read my Against Natural History, Right and Left. That the tender sensibilities of the politically motivated are offended by the harsh insights of evolutionary psychology ought to be counted in its favor. Here I am reminded of something Foucault said:

“I think I have in fact been situated in most of the squares on the political checkerboard, one after another and sometimes simultaneously: as anarchist, leftist, ostentatious or disguised Marxist, nihilist, explicit or secret anti-Marxist, technocrat in the service of Gaullism, new liberal and so on. An American professor complained that a crypto-Marxist like me was invited in the USA, and I was denounced by the press in Eastern European countries for being an accomplice of the dissidents. None of these descriptions is important by itself; taken together, on the other hand, they mean something. And I must admit that I rather like what they mean.”

Foucault, Michel, “Polemics, Politics and Problematizations,” in Essential Works of Foucault, edited by Paul Rabinow, Vol. 1, “Ethics,” The New Press, 1998.

Being politically denounced in this way from all possible points of view is an admission that the existing framework of thought does not yet have a convenient pigeonhole in which a person or an idea can be placed and then forgotten.

Evolutionary psychology in the context of astrobiology becomes something even more difficult to place than it is at present, although it seems to me like the logical extrapolation of astrobiology placing biology in a cosmological context. I’m not the only one who has been thinking in these terms. About the same time that I started thinking about evolutionary psychology and astrobiology together, I happened across the work of Pauli Laine, who characterizes himself as a cognitive astrobiologist. Laine spoke at the 2013 and 2014 100YSS conferences (I spoke at the 2011 and 2012 100YSS conferences, so we didn’t cross paths).

The psychology of an organism that attains to consciousness will be constrained by the evolutionary history of that organism long before it made the breakthrough the consciousness. (However, it does not follow that the conscious mind is wholly determined by biological processes; this is a distinct thesis and must be separately defended.) The biology of the organism and its species is, in turn, constrained by the biosphere in which that organism evolved. The biosphere is, in turn, constrained by the planet upon which the biosphere emerged; the parameters of the planet are constrained by the protoplanetary disk from which it and its star formed, this protoplanetary disk is in turn constrained by the galactic ecology of its local galaxy, and the galaxy is constrained by the parameters of the universe. We need not assert determinism at any level in this sequence (i.e., we need not assert that any one level of emergent complexity is wholly and exhaustively determined by the preceding level of emergent complexity) in order to acknowledge the role of an earlier state of the universe in constraining a later state of the universe.

Following the above nesting of local constraints within global constraints, the consciousness and psychology of the individual is ultimately constrained by the parameters of the universe. However, these global constraints are relatively weak in comparison to the local constraints, such as the evolutionary history of the species to which the individual organism belongs.

The next step would be to begin the above nested sequence of transitive constraints with civilization, such that civilization is constrained by the minds that produce it, the minds that produce civilization are constrained by the evolutionary history of that organism long before it made the breakthrough the consciousness, and so on. This doesn’t work so neatly, as we can intuitively see that, while civilization is a product of mind, mind is in turn influenced by the civilization it creates, so that mind and civilization are coevolutionary. This is true of the other instances of transitive constraints mentioned. For example, evolutionary biology is constrained by the biosphere, but the biosphere is in its turn influenced by the organisms that emerge within it. This added complexity does not falsify the point I am trying to make, it just means that we have to take more factors into account. It also means that mind may ultimately play a role in the universe that ultimately constrains it, and if civilization expands throughout the cosmos it is easy to see how this could happen.

Elsewhere I have suggested that astrocivilization is civilization understood in a cosmological context, as astrobiology is biology understood in a cosmological context. I have cited the NASA definition of astrobiology as, “…the study of the origin, evolution, distribution, and future of life in the universe,” which invites the parallel formulation of astrocivilization as the study of the origin, evolution, distribution, and future of civilization in the universe. Astrocivilization is the extended conception of civilization that follows from transcending our native geocentrism and formulating a concept of civilization free from anthropocentrism and terrestrial bias (and one way to do this is to follow the Husserlian methodology of thought experiments).

Ultimately, our civilization is constructed gradually and piecemeal from countless individual decisions made by countless individuals, each following the promptings of a mind shaped by a long evolutionary history. This evolutionary history may be pushed back in time to the origins of the universe, and when science is capable of taking us beyond this point, the same evolutionary history will be pushed back even further in time to the antecedents of the observable universe. Somewhat more narrowly, given what I call the Principle of Civilization-Intelligence Covariance, the nature of astrocivilization follows from the nature of evolutionary psychology in a cosmological context.

I could have titled this post, “From Astrophysics to Astrocivilization” rather than “From Astrobiology to Astrocivilization,” because we can employ an even more comprehensive framework than that of astrobiology, according to which astrobiology is derived from astrophysics, and particular examples of evolution, ecology, and selection are local and limited instances of what on the largest scale is galactic ecology. But we still have much work to do in placing evolutionary psychology in an astrobiological context. We can think of this synthesis of evolutionary psychology and astrobiology (or, employing Laine’s term, cognitive astrobiology) as a higher form of naturalism, where “nature” is not our planet alone, but the whole of the cosmos. Naturalism in this sense is something like cosmologism. This would then answer the question, “What comes after naturalism?” That is to say, once contemporary philosophy has exhausted naturalism, what comes next? What comes next is the universe entire, and, after that, the universe beyond the scope of contemporary science.

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This Island Earth

Some time ago (on Twitter) I observed that astrobiology is island biogeography writ large. I return to this idea regularly, but have not yet adequately fleshed it out. I touched on this again in From an Astrobiological Point of View, but it would take considerable exposition to do justice to the idea. This post is an unsatisfactory response to my return to an idea that deserves to be studied in his own right and at some length.

Chart of the Galápagos Islands

Chart of the Galápagos Islands

Island biogeography has its origins in the origins of Darwin’s Origin of Species. As we all know, Darwin visited the Galápagos Islands during the voyage of the Beagle that Darwin recounted in The Voyage of the Beagle. Decades of thought and gestation followed, but it was in part the peculiar mix of species in the Galápagos that was crucial for Darwin’s breakthrough to the idea of natural selection. I have myself visited the Galápagos Islands (I wrote about this in Happy Birthday Charles Darwin!) and it is a spectacular lesson in natural history that I cannot recommend highly enough.

theory of island biogeography

Although island biogeography begins with Darwin, it was brought to explicit formulation and theoretical maturity by E. O. Wilson and Robert H. MacArthur in The Theory of Island Biogeography. There the authors say in their opening remarks:

“By studying clusters of islands, biologists view a simpler microcosm of the seemingly infinite complexity of continental and oceanic biogeography. Islands offer an additional advantage in being more numerous than continents and oceans. By their very multiplicity, and variation in shape, size, degree of isolation, and ecology, islands provide the necessary replications in natural ‘experiments’ by which evolutionary hypotheses can be tested.”

Robert H. MacArthur and Edward O. Wilson, The Theory of Island Biogeography, Princeton: Princeton University Press, 1967, Chap. 1, p. 3

Much of this remains valid when translated, mutatis mutandis, into astrobiology. The key, however, is how one goes about arriving at the mutatis mutandis. How can all other things remain equal when we are translating from terrestrial ecosystems in miniature, thus a bit easier to understand than the whole of the terrestrial biosphere, or some major division such as a biome, into worlds entire isolated in the blackness of interplanetary and interstellar space? The analogy is not perfect, but it is suggestive of parallel avenues of approach.

How do you quantify the life of an entire world? Higher biological taxa. This graph shows families rather than species.

How do you quantify the life of an entire world? Higher biological taxa. This graph shows families rather than species.

Scaling up biogeography

While the flora and fauna of islands are sufficiently restricted in scope to make it possible to do a detailed count not only of species present (already in The Voyage of the Beagle we see Darwin noting the number of genera and species present on various islands), but sometimes also of individuals. Obviously we are not going to be able to count species, much less individuals, for entire worlds. We must draw back, look at the big picture, and employ the kind of metrics we see in studies of mass extinctions. In detailing the loss of biodiversity of mass extinctions it is not merely species or even genera that go extinct; sometimes entire families, orders, and classes go extinct. These we can count; in fact, we could reasonably expect to count higher taxa for entire worlds.

taxnomic rank

The reformulation of island biogeographical ideas for astrobiology will be the labor of the production of a new science. The scaling up of our scope to higher biological taxa is only one among many scaling changes in our thought we must pursue in order to develop concepts adequate to the fate of life in the context of galactic ecology.

galactic ecology

Flight and its Technological Equivalents

Geologically young islands — as with the well-known example of the Galápagos Islands, mentioned above — are primarily populated by birds and marine animals. Birds bring with them a variety of plant life; moreover, many plants can float, and are brought to islands by ocean currents. Least common to arrive and to survive are those terrestrial species that find themselves on islands due to sweepstakes dispersal routes, i.e., somewhat unusual circumstances in which a breeding pair of terrestrial animals are able to ride a floating log or mass of vegetation to an otherwise isolated island and can there reproduce, like the marine iguanas on the Galápagos, who have learned to feed by diving into the ocean and forage on inter- and subtidal algae. That is to say, the least common colonists are life forms that cannot swim or fly; being able to traverse planetary distances is a limiting factor in the distribution of a life form.

Darwin Greenhouse

Darwin conducted a simple yet ingenious ecological experiment in island biogeography that he recounted in The Origin of Species:

“I have before mentioned that earth occasionally, though rarely, adheres in some quantity to the feet and beaks of birds. Wading birds, which frequent the muddy edges of ponds, if suddenly flushed, would be the most likely to have muddy feet. Birds of this order I can show are the greatest wanderers, and are occasionally found on the most remote and barren islands in the open ocean; they would not be likely to alight on the surface of the sea, so that the dirt would not be washed off their feet; when making land, they would be sure to fly to their natural fresh-water haunts. I do not believe that botanists are aware how charged the mud of ponds is with seeds: I have tried several little experiments, but will here give only the most striking case: I took in February three table-spoonfuls of mud from three different points, beneath water, on the edge of a little pond; this mud when dry weighed only 6¾ ounces; I kept it covered up in my study for six months, pulling up and counting each plant as it grew; the plants were of many kinds, and were altogether 537 in number; and yet the viscid mud was all contained in a breakfast cup! Considering these facts, I think it would be an inexplicable circumstance if water-birds did not transport the seeds of fresh-water plants to vast distances, and if consequently the range of these plants was not very great. The same agency may have come into play with the eggs of some of the smaller fresh-water animals.”

Charles Darwin, On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life, London: John Murray, 1st edition, 1859, GEOGRAPHICAL DISTRIBUTION. CHAP. XII., pp. 386-387

Such is the power of flight to widely disperse species over the surface of Earth. Flight has a value beyond the differential survival and reproduction advantage that it confers upon those species so endowed; it also plays a co-evolutionary role at the largest scale of planetary ecology. That flight should develop within a biosphere is perhaps not inevitable, but we could say instead that a biosphere in which flight emerges is likely to achieve much higher levels of biodiversity, and hence prove a more robust ecosystem. A robust ecosystem, in turn, is more likely to survive existential threats (such as the mass extinctions that have repeatedly punctuated the evolution of life on Earth), so that planetary biospheres of a given longevity are more likely to have flight than not.

convergent flight

Natural selection found several different solutions to the problem of flight. Some small plant seeds, and some very small animals (e.g., spiders), are light enough to be carried by the wind. Some animals fly by gliding (flying squirrels), and some animals employ wings for flight. Wings have emerged separately among insects, dinosaurs, birds, and mammals. Flying fish might also be said to have wings. Given a biosphere not disrupted by the anthropocene, flying fish might eventually transition to a fully flying way of life; this may yet happen in the distant future.



The problem of flight at the level that concerns astrobiology is potentially as diverse as the solutions to the problem of flight in a planetary biosphere. We are only just beginning to understand the complexity of the universe in which we live, and we are continually discovering capacities of nature and of life that previously would have strained our credulity. Just last week on the second episode of The Unseen Podcast, host Paul Carr noted that, with all the exchange of material between the inner planets of the solar system, we would not be surprised to find that all this life comes to the same root, while we probably would be surprised, if found like the oceans of the moons of Jupiter and Saturn, if it came from the same root. That far out in the solar system, we would expect a second genesis if there is any life at all.

If there is life in the subsurface ocean of Europa, we expect that life to be the result of a second genesis.

If there is life in the subsurface ocean of Europa, we expect that life to be the result of a second genesis.

That perspective on the likelihood the relations of life within the confines of a single solar system may change as we learn more about astrobiology. But so far this discussion is primarily a matter of naturally occurring dispersal vectors for species. We must consider astrobiology both before and after technologically-driven dispersal vectors, as well as in regard to terrestrial and to extraterrestrial dispersal vectors. Just as technological dispersal vectors have began to play a major role in our planetary biosphere, especially in relation to the distribution and introduction of invasive species, we would expect a mixture of both natural and technical dispersal vectors in astrobiology.


Spaceflight is to astrobiology as flight is to biogeography.

Given the continuity of natural history and civilization, that spaceflight is to astrobiology as flight is to biogeography follows naturally in the strict sense of “naturally.” In other words, there is a continuity from flight as the result of biology and flight as the result of technology; there is idea diffusion (or idea flow) from nature to civilization: we observe the existence proof of powered, heavier-than-air flight in nature, and we seek to reverse engineer this development and to reproduce it with technology. Thus, in a sense, technology is the pursuit of biology by other means. Thus spaceflight, as the technological equivalent of biological flight, will play a co-evolutionary role at the largest scale of galactic ecology.

flight 2

It may be worth noting in this context that the cluster of developments dependent upon human activity — intelligence, technology, language, and civilization among them — could be said to represent a solution to the problem of survival, but it is a “solution” that we find no where else in nature except in ourselves. Now, in referring to “nature” in the previous sentence I here mean “in the terrestrial biosphere.” This is significant, because a viable solution to the problem of survival (as we can see from the example of flight, or I might also use the example of vision) tends to be repeatedly emergent in nature, so that we find multiple instances of homology and convergent evolution. We do not find this in regard to the human solution to the problem of survival.

If this is a solution to the problem of survival as posed by the terrestrial environment, why did no other species exploit this strategy?

If this is a solution to the problem of survival as posed by the terrestrial environment, why did no other species exploit this strategy?

On a larger scale, a scale at which “nature” does not mean the terrestrial biosphere but rather means the whole of the universe, we may well yet see the cohort of complexities associated with human beings repeated elsewhere, though we have to scale up our perspective, just as with scaling up island biography until it coincides with astrobiology. Metrics appropriate to human activity in a terrestrial context will not be sufficient for human (or, more generally, intelligent) activity in an extraterrestrial context. Another way to understand this is that, confined to the surface of Earth, distinctions that would be significant to civilization are conflated by contingent circumstances; raised off the surface of the Earth, and given energy and resources almost without limit, previously conflated properties of civilization manifest themselves in an extraterrestrial context and eventually become obvious as spacefaring civilizations undergo rapid adaptive radiation and come to exemplify different civilizational properties.

Terrestrial civilizations from an extraterrestrial perspective appear homogenous, but this may be a function of their being subject in common to specific terrestrial selection pressures.

Terrestrial civilizations from an extraterrestrial perspective appear homogenous, but this may be a function of their being subject in common to specific terrestrial selection pressures.

But to return to the idea that technology is the pursuit of biology by other means, as I observed in my Centauri Dreams post, How We Get There Matters, existential ends are not indifferent to technological means. In the particular case of the pursuit of biological ends by technological means, this provides a context for thinking about astrobiology in an age of spacefaring civilizations.

starship classes

Many metrics have been proposed for spacefaring civilization. I mentioned some of these in my last post, Thinking about Civilization, including metrics that I have myself attempted to work out. In that post I did not mention the metric that I proposed in my Centuari Dreams post How We Get There Matters (and which I followed with SETI Under Conditions of Constraint for Spacefaring Civilization), which concerned classes of starships. This is a metric immediately relevant to the question of spaceflight understood as the development of a continuum that begins with the first wind-blown distribution of seeds and spores, and which might some day mean the greening of the galaxy.

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Fred Adams and Greg Laughlin's five ages of the universe

Fred Adams and Greg Laughlin’s five ages of the universe

Introduction: Periodization in Cosmology

Recently Paul Gilster has posted my Who will read the Encyclopedia Galactica? on his Centauri Dreams blog. In this post I employ the framework of Fred Adams and Greg Laughlin from their book The Five Ages of the Universe: Inside the Physics of Eternity, who distinguish the Primordial Era, before stars have formed, the Stelliferous Era, which is populated by stars, the Degenerate Era, when only the degenerate remains of stars are to be found, the Black Hole Era, when only black holes remain, and finally the Dark Era, when even black holes have evaporated. These major divisions of cosmological history allow us to partition the vast stretches of cosmological time, but it also invites us to subdivide each era into smaller increments (such is the historian’s passion for periodization).

The Stelliferous Era is the most important to us, because we find ourselves living in the Stelliferous Era, and moreover everything that we understand in terms of life and civilization is contingent upon a biosphere on the surface of a planet warmed by a star. When stellar formation has ceased and the last star in the universe burns out, planets will go dark (unless artificially lighted by advanced civilizations) and any remaining biospheres will cease to function. Life and civilization as we know it will be over. I have called this the End-Stelliferous Mass Extinction Event.

It will be a long time before the end of the Stelliferous Era — in human terms, unimaginably long. Even in scientific terms, the time scale of cosmology is long. It would make sense for us, then, to break up the Stelliferous Era into smaller periodizations that can be dealt with each in turn. Adams and Laughlin constructed a logarithmic time scale based on powers of ten, calling each of these powers of ten a “cosmological decade.” The Stelliferous Era comprises cosmological decades 7 to 15, so we can further break down the Stelliferous Era into three divisions of three cosmological decades each, so cosmological decades 7-9 will be the Early Stelliferous, cosmological decades 10-12 will be the Middle Stelliferous, and cosmological decades 13-15 will be the late Stelliferous.

Early Stelliferous

The Early Stelliferous

Another Big History periodization that has been employed other than that of Adams of Laughlin is Eric Chaisson’s tripartite distinction between the Energy Era, the Matter Era, and the Life Era. The Primordial Era and the Energy Era coincide until the transition point (or, if you like, the phase transition) when the energies released by the big bang coalesce into matter. This phase transition is the transition from the Energy Era to the Matter Era in Chaisson; for Adams and Laughlin this transition is wholly contained within the Primordial Era and may be considered one of the major events of the Primorial Era. This phase transition occurs at about the fifth cosmological decade, so that there is one cosmological decade of matter prior to that matter forming stars.

At the beginning of the Early Stelliferous the first stars coalesce from matter, which has now cooled to the point that this becomes possible for the first time in cosmological history. The only matter available at this time to form stars is hydrogen and helium produced by the big bang. The first generation of stars to light up after the big bang are called Population III stars, and their existence can only be hypothesized because no certain observations exist of Population III stars. The oldest known star, HD 140283, sometimes called the Methuselah Star, is believed to be a Population II star, and is said to be metal poor, or of low metallicity. To an astrophysicist, any element other than hydrogen or helium is a “metal,” and the spectra of stars are examined for the “metals” present to determine their order of appearance in galactic ecology.

The youngest stars, like our sun and other stars in the spiral arms of the Milky Way, are Population I stars and are rich in metals. The whole history of the universe up to the present is necessary to produce the high metallicity younger stars, and these younger stars form from dust and gas that coalesce into a protoplanetary disk surrounding the young star of similarly high metal content. We can think of the stages of Population III, Population II, and Population I stars as the evolutionary stages of galactic ecology that have produced structures of greater complexity. Repeated cycles of stellar nucleosynthesis, catastrophic supernovae, and new star formation from these remnants have produced the later, younger stars of high metallcity.

It is the high relative proportion of heavier elements that makes possible the formulation of small rocky planets in the habitable zone of a stable star. The minerals that form these rocky planets are the result of what Robert Hazen calls minerological evolution, which we may consider to be an extension of galactic ecology on a smaller scale. These planets, in turn, have heavier elements distributed throughout their crust, which, in the case of Earth, human civilization has dug out of the crust and put to work manufacturing the implements of industrial-technological civilization. If Population II and Population III stars had planets (this is an open area of research in planet formation and without a definite answer as yet), it is conceivable that these planets might have harbored life, but the life on such worlds would not have had access to heavier elements, so any civilization that resulted would have had a difficult time of it creating an industrial or electrical technology.

Middle Stelliferous

The Middle Stelliferous

In the Middle Stelliferous, the processes of galactic ecology that produced and which now sustain the Stelliferous Era have come to maturity. There is a wide range of galaxies consisting of a wide range of stars, running the gamut of the Hertzsprung–Russell diagram. It is a time of both galactic and stellar prolixity, diversity, and fecundity. But even as the processes of galactic ecology reach their maturity, they begin to reveal the dissipation and dissolution that will characterize the Late Stelliferous Era and even the Degenerate Era to follow.

The Milky Way, which is a very old galaxy, carries with it the traces of the smaller galaxies that it has already absorbed in its earlier history — as, for example, the Helmi Stream — and for the residents of the Milky Way and Andromeda galaxies one of the most spectacular events of the Middle Stelliferous Era will be the merging of these two galaxies in a slow-motion collision taking place over millions of years, throwing some star systems entirely clear of the newly merged galaxies, and eventually resulting in the merging of the supermassive black holes that anchor the centers of each of these elegant spiral galaxies. The result is likely to be an elliptical galaxy not clearly resembling either predecessor (and sometimes called the Milkomeda).

Eventually the Triangulum galaxy — the other large spiral galaxy in the local group — will also be absorbed into this swollen mass of stars. In terms of the cosmological time scales here under consideration, all of this happens rather quickly, as does also the isolation of each of these merged local groups which persist as lone galaxies, suspended like a island universe with no other galaxies available to observational cosmology. The vast majority of the history of the universe will take place after these events have transpired and are left in the long distant past — hopefully not forgotten, but possibly lost and unrecoverable.

tenth decade

The Tenth Decade

The tenth cosmological decade, comprising the years between 1010 to 1011 (10,000,000,000 to 100,000,000,000 years, or 10 Ga. to 100 Ga.) since the big bang, is especially interesting to us, like the Stelliferous Era on the whole, because this is where we find ourselves. Because of this we are subject to observation selection effects, and we must be particularly on guard for cognitive biases that grow out of the observational selection effects we experience. Just as it seems, when we look out into the universe, that we are in the center of everything, and all the galaxies are racing away from us as the universe expands, so too it seems that we are situated in the center of time, with a vast eternity preceding us and a vast eternity following us.

Almost everything that seems of interest to us in the cosmos occurs within the tenth decade. It is arguable (though not definitive) that no advanced intelligence or technological civilization could have evolved prior to the tenth decade. This is in part due to the need to synthesize the heavier elements — we could not have developed nuclear technology had it not been for naturally occurring uranium, and it is radioactive decay of uranium in Earth’s crust that contributes significantly to the temperature of Earth’s core and hence to Earth being a geologically active planet. By the end of the tenth decade, all galaxies will have become isolated as “island universes” (once upon a time the cosmological model for our universe today) and the “end of cosmology” (as Krauss and Sherrer put it) will be upon us because observational cosmology will no longer be able to study the large scale structures of the universe.

The tenth decade, thus, is not only when it becomes possible for an intelligent species to evolve, to establish an industrial-technological civilization on the basis of heavier elements built up through nucleosynthesis and supernova explosions, and to employ these resources to launch itself as a spacefaring civilization, but also this is the only period in the history of the universe when such a spacefaring civilization can gain a true foothold in the cosmos to establish an intergalactic civilization. After local galactic groups coalesce into enormous single galaxies, and all other similarly coalesced galaxies have passed beyond the cosmological horizon and can no longer be observed, an intergalactic civilization is no longer possible on principles of science and technology as we understand them today.

It is sometimes said that, for astronomers, galaxies are the basic building blocks of the universe. The uniqueness of the tenth decade, then, can be expressed as being the only time in cosmological history during which a spacefaring civilization can emerge and then can go on to assimilate and unify the basic building blocks of the universe. It may well happen that, by the time of million year old supercivilizations and even billion year old supercivilizations, sciences and technologies will have been developed far beyond our understanding that is possible today, and some form of intergalactic relationship may continue after the end of observational cosmology, but, if this is the case, the continued intergalactic organization must be on principles not known to us today.

Late Stelliferous

The Late Stelliferous

In the Late Stelliferous Era, after the end of the cosmology, each isolated local galactic group, now merged into a single giant assemblage of stars, will continue its processes of star formation and evolution, ever so slowly using up all the hydrogen produced in the big bang. The Late Stelliferous Era is a universe having passed “Peak Hydrogen” and which can therefore only look forward to the running down of the processes of galactic ecology that have sustained the universe up to this time.

The end of cosmology will mean a changed structure of galactic ecology. Even if civilizations can find a way around their cosmological isolation through advanced technology, the processes of nature will still be bound by familiar laws of nature, which, being highly rigid, will not have changed appreciably even over billions of years of cosmological evolution. Where light cannot travel, matter cannot travel either, and so any tenuous material connection between galactic groups will cease to play any role in galactic ecology.

The largest scale structures that we know of in the universe today — superclusters and filaments — will continue to expand and cool and to dissipate. We can imagine a bird’s eye view of the future universe (if only a bird could fly over the universe entire), with its large scale structures no longer in touch with one another but still constituting the structure, rarified by expansion, stretched by gravity, and subject to the evolutionary processes of the universe. This future universe (which we may have to stop calling the universe, as it is lost its unity) stands in relation to its current structure as the isolated and strung out continents of Earth today stand in relation to earlier continental structures (such as the last supercontinent, Pangaea), preceding the present disposition of continents (though keep in mind that there have been at least five supercontinent cycles since the formation of Earth and the initiation of its tectonic processes).

Near the end of the Stelliferous Era, there is no longer any free hydrogen to be gathered together by gravity into new suns. Star formation ceases. At this point, the fate of the brilliantly shining universe of stars and galaxies is sealed; the Stelliferous Era has arrived at functional extinction, i.e., the population of late Stelliferous Era stars continues to shine but is no longer viable. Galactic ecology has shut down. Once star formation ceases, it is only a matter of time before the last of the stars to form burn themselves out. Stars can be very large, very bright and short lived, or very small, scarcely a star at all, very dim, cool, and consequently very long lived. Red dwarf stars will continue to burn dimly long after all the main sequence stars like the sun have burned themselves out, but eventually even the dwarf stars, burning through their available fuel at a miserly rate, will burn out also.

The Post-Stelliferous Era

After the Stelliferous Era comes the Degenerate Era, with the two eras separated by what I have called the Post-Stelliferous Mass Extinction Event. What the prospects are for continued life and intelligence in the Degenerate Era is something that I have considered in Who will read the Encyclopedia Galactica? and Addendum on Degenerate Era civilization, inter alia.

Our enormous and isolated galaxy will not be immediately plunged into absolute darkness. Adams and Laughlin (referred to above) estimate that our galaxy may have about a hundred small stars shining — the result of the collision of two or more brown dwarfs. Brown dwarf stars, at this point in the history of the cosmos, contain what little hydrogen remains, since brown dwarf stars were not large enough to initiate fusion during the Stelliferous Era. However, if two or more brown dwarfs collide — a rare event, but in the vast stretches of time in the future of the universe rare events will happen eventually — they may form a new small star that will light up like a dim candle in a dark room. There is a certain melancholy grandeur in attempting to imagine a hundred or so dim stars strewn through the galaxy, providing a dim glow by which to view this strange and unfamiliar world.

Our ability even to outline the large scale structures — spatial, temporal, biological, technological, intellectual, etc. — of the extremely distant future is severely constrained by our paucity of knowledge. However, if terrestrial industrial-technological civilization successfully makes the transition to being a viable spacefaring civilization (what I might call extraterrestrial-spacefaring civilization) our scientific knowledge of the universe is likely to experience an exponential inflection point surpassing the scientific revolution of the early modern period.

An exponential improvement in scientific knowledge (supported on an industrial-technological base broader than the surface of a single planet) will help to bring the extremely distant future into better focus and will give to our existential risk mitigation efforts both the knowledge that such efforts requires and the technological capability needed to ensure the perpetual ongoing extrapolation of complexity driven by intelligent, conscious, and purposeful intervention in the world. And if not us, if not terrestrial civilization, then some other civilization will take over the mantle and the far future will belong to them.

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Grand Strategy Annex

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The Genocidal Species

15 March 2014



Homo sapiens is the genocidal species. I have long had it on my mind to write about this. I have the idea incorporated in an unpublished manuscript, but I don’t know if it will ever see the light of day, so I will give a brief exposition here. What does it mean to say that Homo sapiens is the genocidal species (or, if you prefer, a genocidal animal)?

Early human history is a source of controversy that exceeds the controversy over the scientific issues at stake. It is not difficult to understand why this is the case. Controversies over human origins are about us, what we are as a species, notwithstanding the obvious fact that we are in no way limited by our past, and we may become many things that have no precedent in our long history. Moreover, the kind of evidence that we have of human origins is not such as to provide us with the kind of narrative that we would like to have of our early ancestors. We have the evidence of scientific historiography, but no poignant human interest stories. In so far as our personal experience of life paradoxically provides the big picture narrative by which we understand the world (a point I tried to make in Kierkegaard and Futurism), the absence of a personal account of our origins is an ellipsis of great consequence.

To assert that humanity is a genocidal species is obviously a tendentious, if not controversial, claim to make. I make this claim partly because it is controversial, because we have seen the human past treated with excessive care and caution, because, as I said above, it is about us. We don’t like to think of ourselves has intrinsically genocidal in virtue of our biology. Indeed, when a controversial claim such as this is made, one can count on such a claim being dismissed not on grounds of evidence, or the lack thereof, but because it is taken to imply biological determinism. According to this reasoning, an essentialist reading of our history shows us that we are genocidal, therefore we cannot be anything other than genocidal. Apart from being logically flawed, this response misses the point and fails to engage the issue.

Yet, in saying that man is a genocidal species, I obviously making an implicit reference to a long tradition of pronouncing humanity to be this or that, as when Plato said that man is a featherless biped. This is, by the way, a rare moment providing a glimpse into Plato’s naturalism, which is a rare thing. There is a story that, hearing this definition, Diogenes of Sinope plucked a chicken and brought it to Plato’s Academy, saying, “Here is Plato’s man.” (Perhaps he should have said, “Ecce homo!”) This, in turn, reveals Diogenes’ non-naturalism (as uncharacteristic as Plato’s naturalism). Plato is supposed to have responded by adding to his definition, “with broad, flat nails.”

Aristotle, most famously of all, said that man is by nature a political animal. This has been variously translated from the Greek as, “Man is by nature an animal that lives in a polis,” and, “Man is by nature a social animal.” This I do not dispute. However, once we recognize that homo sapiens is a social or political animal (and Aristotle, as the Father of the Occidental sciences, would have enthusiastically approved of the transition from “man” to “homo sapiens”), we must then take the next step and ask what exactly is the nature of human sociability, or human political society. What does it mean for homo sapiens to be a political animal?

If Clausewitz was right, political action is one pole of a smoothly graduated continuum, the other pole of which is war, because, according to Clausewitz, war is the continuation of policy by other means (cf. The Clausewitzean Continuum). This claim is equivalent to the claim that politics is the continuation of war by other means (the Foucauldian inversion of Clausewitz). Thus war and politics are substitutable salve veritate, so that homo sapiens the political animal is also homo sapiens the military animal.

I don’t know if anyone has ever said, man is a military animal, but Freud came close to this in a powerful passage that I have quoted previously (in A Note on Social Contract Theory):

“…men are not gentle creatures who want to be loved, and who at the most can defend themselves if they are attack; they are, on the contrary, creatures among whose instinctual endowments is to be reckoned a powerful share of aggressiveness. As a result, their neighbor is for them not only a potential helper or sexual object, but also someone who tempts them to satisfy their aggressiveness on him, to exploit his capacity for work without compensation, to use him sexually without his consent, to seize his possessions, to humiliate him, to cause him pain, to torture and to kill him. Homo homini lupus. Who, in the face of all his experience of life and of history, will have the courage to dispute this assertion? As a rule this cruel aggressiveness waits for some provocation or puts itself at the service of some other purpose, whose goal might also have been reached by milder measures. In circumstances that are favorable to it, when the mental counter-forces which ordinarily inhibit it are out of action, it also manifests itself spontaneously and reveals man as a savage beast to whom consideration towards his own kind is something alien.”

Is it unimaginable that it is this aggressive instinct, at least in part, that made in possible for homo sapiens to out-compete every other branch of the hominid tree, and to leave itself as the only remaining hominid species? We are, existentially speaking, El último hombre — the last man standing.

What was the nature of the competition by which homo sapiens drove every other hominid to extinction? Over the multi-million year history of hominids on Earth, it seems likely that the competition among hominids likely assumed every possible form at one time or another. Some anthropologists that observed a differential reproductive success rate only marginally more fertile than other hominid species would have, over time, guaranteed our demographic dominance. This gives the comforting picture of a peaceful and very slow pace of one hominid species supplanting another. No doubt some of homo sapiens’ triumphs were of this nature, but there must have also been, at some time in the deep time of our past, violent and brutal episodes when we actively drove our fellow hominids into extinction — much as throughout the later history of homo sapiens one community frequently massacred another.

A recent book on genocide, The Specter of Genocide: Mass Murder in Historical Persepctive (edited by ROBERT GELLATELY, Clark University, and BEN KIEMAN Yale University), is limited in its “historical perspective” to the twentieth century. I think we must go much deeper into our history. In an even larger evolutionary framework than that employed above, if we take the conception of humanity as a genocidal species in the context of Peter Ward’s Medea Hypothesis, according to which life itself is biocidal, then humanity’s genocidal instincts are merely a particular case (with the added element of conscious agency) of a universal biological imperative. Here is how Ward defines his Medea Hypothesis:

Habitability of the Earth has been affected by the presence of life, but the overall effect of life has been and will be to reduce the longevity of the Earth as a habitable planet. Life itself, because it is inherently Darwinian, is biocidal, suicidal, and creates a series of positive feedbacks to Earth systems (such as global temperature and atmospheric carbon dioxide and methane content) that harm later generations. Thus it is life that will cause the end of itself, on this or any planet inhabited by Darwinian life, through perturbation and changes of either temperature, atmospheric gas composition, or elemental cycles to values inimical to life.

Ward, Peter, The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive? Princeton and Oxford: Princeton University Press, 2009, p. 35

Ward goes on to elaborate his Medea Hypothesis in greater detail in the following four hypotheses:

1. All species increase in population not only to the carrying capacity as defined by some or a number of limiting factors, but to levels beyond that capacity, thus causing a death rate higher than would otherwise have been dictated by limiting resources.

2. Life is self-poisoning in closed systems. The byproduct of species metabolism is usually toxic unless dispersed away. Animals pro- duce carbon dioxide and liquid and solid waste. In closed spaces this material can build up to levels lethal either through direct poisoning or by allowing other kinds of organisms living at low levels (such as the microbes living in animal guts and carried along with fecal wastes) to bloom into populations that also produce toxins from their own metabolisms.

3. In ecosystems with more than a single species there will be competition for resources, ultimately leading to extinction or emigration of some of the original species.

4. Life produces a variety of feedbacks in Earth systems. The majority are positive, however.

Ward, Peter, The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive? Princeton and Oxford: Princeton University Press, 2009, pp. 35-36

The experience of industrial-technological civilization has added a new dimension to hypothesis 2 above, as industrial processes and their wastes have been added to biological processes and their wastes, leading to forms of poisoning that do not occur unless facilitated by civilization. Moreover, a corollary to hypothesis 3 above (call is 3a, if you like) might be formulated such that those species within an ecosystem that seek to fill the same niche (i.e., that feed off the same trophic level) will be in more direct competition that those species feeding off distinct trophic levels. In this way, multiple hominid species that found themselves in the same ecosystem would be trying to fill the same niche, leading to extinction or emigration. Once homo sapiens achieved extensive totality in the distribution of the species range, however, there is nowhere else for competitors to emigrate, so if they are out-competed, they simply go extinct.

Ward was not the first to focus on the destructive aspects of life. I have previously quoted the great biologist Ernst Haeckel, who defined ecology as the science of the struggle for existence (cf. Metaphysical Ecology Reformulated), and of course in the same vein there is the whole tradition of nature red in tooth and claw. Such visions of nature no longer hold the attraction that they exercised in the nineteenth century, and such phrases have been criticized, but it may be that these expressions of the deadly face of nature did not go far enough.

There is a sense in which all life if genocidal, and this is the Medean Hypothesis; what distinguishes human beings is that we have made genocide planned, purposeful, systematic, and conscious. The genocidal campaigns that have punctuated modern history, and especially those of the twentieth century, represent the conscious implementation of Medean life. We knowingly engage in genocide. Genocide is now a policy option for political societies, and in so far as we are political animals all policy options are “on the table” so to speak. It is this that makes us the uniquely genocidal species.

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Grand Strategy Annex

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Third Time’s a Charm

8 February 2014


geological eras of life

The Three Eras of Life on Earth

The Earth, it would seem, has been regularly reduced to biological penury throughout its long history, which has been punctuated by mass extinctions that have very nearly reduced biodiversity to zero. It is possible that, in the earliest history of life on Earth, when our planet was regularly bombarded by objects from space, and exposed to especially harsh conditions, life may have emerged multiple times, only to be wiped out again in short order. There would have been plenty of time for this to occur during the 550 million years prior to the emergence of the earliest life known to be continuous with our own.

The repeated denudation of the planet by mass extinctions constituted a kind of ecological succession on a grand scale. Each time life had to recover anew, and, in recovering, the surviving species (the “weeds” that were the most robust and which went on to colonize the denuded landscape and seascape) underwent dramatic periods of adaptive radiation until, in the global climax ecosystems prior to a mass extinction event, almost every niche for life has been filled — possibly several times over, leading to contested niches where multiple species compete for the same limited resources.

The history of life is such a reliable indicator of geological time that there is an entire discipline — biostratigraphy — given over to the dating of rocks by the fossils they contain. Once life becomes sufficiently complex to leave a record of itself in the rocks of our planet, the development of life is a sure guide to the age of the rocks that contain traces of this past life. Contemporary scientific geology largely got its start through biostratigraphy in the work of William Smith (called “strata Smith” by his contemporaries), whom I have previously mentioned in The Transplanetary Perspective.

Three of the major divisions of geological time are named for the eras of life that they comprise: Paleozoic (old life), Mesozoic (middle life), and Cenozoic (common, or recent, life). These divisions of geological time give a “big picture” view of the history of life on Earth. The mass extinction events at the end of the Permian and at the K-T boundary were so catastrophic that the Earth in the case of the end Permian extinction came perilously close to being sterilized, and while the K-T event (now known as the Cretaceous–Paleogene or K–Pg extinction event) was not as disastrous, it ended the dominion of the dinosaurs over most ecological niches and thereby gave mammals the opportunity to experience an explosive adaptive radiation.

cosmos 06

Million Year Old Civilizations

We know that intelligent life on Earth arose in the late Cenozoic era, but how clement were these earlier eras of life on Earth to intelligent life? If intelligent life had arisen in the Paleozoic, founded a civilization, and survived to the present, that civilization would be in excess of 250 million years old. If, again, intelligent life had arisen in the Mesozoic, founded a civilization, and survived to the present, that civilization would be in excess of 65 million years old. However, both of these counterfactual civilizations that did not happen would have almost certainly have been destroyed by the catastrophic mass extinctions that separated these eras of terrestrial life (unless they had taken adequate measures to mitigate existential risk, which would seem to be a necessary condition for any truly long-lived civilization).

The idea of a civilization a million or more years old was a theme discussed by Carl Sagan on several occasions. Here is an explicit formulation of the million-year-old civilization theme from Chapter XII, “Encyclopedia Galacitca,” from Sagan’s book Cosmos:

“What does it mean for a civilization to be a million years old? We have had radio telescopes and spaceships for a few decades; our technical civilization is a few hundred years old, scientific ideas of a modern cast a few thousand, civilization in general a few tens of thousands of years; human beings evolved on this planet only a few million years ago. At anything like our present rate of technical progress, an advanced civilization millions of years old is as much beyond us as we are beyond a bush baby or a macaque. Would we even recognize its presence? Would a society a million years in advance of us be interested in colonization or interstellar spaceflight? People have a finite lifespan for a reason. Enormous progress in the biological and medical sciences might uncover that reason and lead to suitable remedies. Could it be that we are so interested in spaceflight because it is a way of perpetuating ourselves beyond our own lifetimes? Might a civilization composed of essentially immortal beings consider interstellar exploration fundamentally childish?”

Carl Sagan, Cosmos, Chapter XII, “Encyclopaedia Galactica”

Human civilization could be considered as being more than ten thousand years old if we date the advent of civilization to the Neolithic Agricultural Revolution. This is an atypical way to think about civilization, but I have seen it in a few sources (Jacob Bronowski, I think, takes this view, more or less), and it is how I myself think about civilization. A civilization ten thousand years old or more is nothing to dismiss; persisting for ten thousand years is a non-trivial accomplishment. Yet the history of terrestrial civilization may be compared to the history of terrestrial life: there is a long period that is nearly stagnant, with painfully slow innovations, and then an event occurs — the Cambrian explosion for life, the industrial revolution for civilization — and what it means to be “alive” or “civilized” is radically altered.

Dating to the Neolithic Agricultural revolution is consistent with my recent suggestion in From Biocentric Civilization to Post-biological Post-Civilization that civilization could be minimally defined as a coevolutionary cohort of species. However, our industrial-technological civilization is barely more than two hundred years old. To consider the geologically insignificant period of time of one hundred years is to contemplate a period of time half again as long as the entire history of industrial-technological civilization. The kind of technological gains that industrial-technological civilization could experience over a period of a hundred years can be quite remarkable, as our experience of the past hundred years suggests.

This year, 2014, we experience the one hundred year anniversary of global industrialized warfare. Not long after, we will experience the hundred year anniversaries of digital computers, jet propulsion, rocketry, and nuclear technology. Some of these technologies have improved by orders of magnitude. Some have improved very little. If the coming century brings commensurate technological innovations (not to mention innovations in science that would drive these technological innovations), even if not all these developments experience exponential development, and many languish in a state of stagnation, our world and our understanding of the world will nevertheless be repeatedly revolutionized.

Given what we know about the rapidity of technological change — bequeathed to our industrial-technological civilization as a consequence of the STEM cycle — we ought to conclude that we can know almost nothing about what a million year civilization would be like, except in so far as we might be able to imagine only the most stagnant aspects of such a civilization. It would be beyond our ability to understand advanced technologies ten thousand years hence, just as our ancestors, only beginning to lay the foundations of agrarian-ecclesiastical civilization ten thousand years ago, could have understood our advanced technologies today. Understanding across these orders of developmental magnitude lie beyond the human zone of proximal development.

Octopus evolution

Counterfactual Civilizations

I have written previously that there is an earliest bound in the history of our universe for life, for intelligent life, and for civilization. It would not be possible to produce an industrial-technological civilization as we know it (i.e., a peer civilization) without heavier metallic elements, so that the emergence of industrial-technological civilization must minimally wait for the formation of Population I stars and their planetary systems. That being said, many population I stars have been around for billions of years, and there have consequently been billions of years for industrial-technological civilizations to emerge and to attain great age.

Are there other constraints upon the emergence of life, intelligence, and civilization that move the boundary for the earliest possible emergence of these phenomena nearer to the present? Is there any reason to suppose, from our knowledge of the natural history of Earth and the complexity of the human brain, that intelligent life and civilization could not have arisen in earlier eras of life — Paleozoic intelligent life or Mesozoic intelligent life, which would, in turn, according to Civilization-Intelligence Covariance, give rise to Paleozoic civilization or Mesozoic civilization? Or, if not here on Earth, why not some other planet orbiting a population I star where life begins 550 million years after the formation of the planet?

Octopi, cuttlefish, and other cephalopods with large brains and highly sophisticated nervous systems — it takes a lot of raw neural processing power to do what some cephalopods do with their skin color — would seem to be ideal candidates for early terrestrial intelligent life. Octopi date back to the Devonian Period, more than 360 million years ago, during the Paleolithic Era, so that ancestors of this life form survived both the End Permian extinction and the K-T extinction (cf. Fossil Octopuses). Why didn’t cephalopods establish a counterfactual civilization during the Permian? There was certainly time enough to do so before the End Permian extinction.

Is a backbone, or something that can serve a similar function like an exoskeleton, a necessary condition for intelligence to issue in the production of civilization? Multicellular life forms without a backbone, or confined to an aquatic environment, might well develop intelligence, but would have a difficult time building a technological civilization — difficult, but not impossible. This is a question I considered previously in The Place of Bilaterial Symmetry in the History of Life and Counterfactuals Implicit in Naturalism.

If we should find life in the oceans below the icy surface of Europa, or any of the other moons in our solar system internally heated by gravitational forces, it would consist of life forms peculiarly constrained by their environment, i.e., possibly more constrained than terrestrial conditions, and therefore more likely to favor extremophiles. Oceanic lifeforms beneath a crust of ice many kilometers thick would not only have the technological disadvantage faced by any intelligent aquatic species, but would face the additional disadvantage of being cut off from the stars. Unable to physically see their place in the universe, such lifeforms might have an even more difficult time that we had in coming to understand the world. The mythology of such a life form would have to be very different from the mythologies created by early human societies, in which the stars typically played a prominent role. Any civilization that might be conjoined with such a mythology might constitute an extremophile civilization.


Inside the Charmed Circle

Many of the questions that I have posed above are variations on ancient themes of anthropocentrism, and from within the charmed circle of anthropocentrism it is difficult for us to see outside that circle. Our minds are quite literally defined by that circle, being the product of human biology, and our imagination is largely circumscribed by the limitations of our minds. But our minds are also capable, with effort, of passing beyond the charmed circle of anthropocentrism, identifying anthropic bias as such and transcending it.

For us, the third time life got a chance on Earth was the charm. Paleozoic life came and (largely) went without producing intelligence or civilization, as did Mesozoic life. It was not until Cenozoic life that intelligence and civilization emerged. But was this the result of mere contingency, or a function of some operative constraint — possibly even a constraint no one has even noticed because of its pervasive presence — that prevented intelligence and civilization from arising in earlier geological eras?

While there might be reason to believe that other forms of life will have something like a DNA structure, or that something like the transition from prokaryotic cells to eukaryotic cells will have taken place, but there is no particular reason to believe that the large scale structure of life on other worlds would have the terrestrial tripartite structure, since this big picture view of life on Earth was a result of particular mass extinction events that seem too contingent to characterize any possible emergence of life. However, there is reason to believe that there will be some mass extinction events afflicting life on other worlds, and at least some of these mass extinction events will result from large scale cosmological events. If solar systems form elsewhere in a process like the formation of our solar system, life elsewhere would also be exposed to asteroid impacts, comets, solar flares, and the like. This is one of the lessons of astrobiology.

That there will be constraints and contingencies that bear upon life we can be certain; but we cannot (yet) know exactly what these constraints and contingencies will be. This is a non-constructive observation: invoking the existence of constraints and contingencies without saying what they will be. What would a constructive approach to life’s constraints and contingencies look like? Is it necessary to adopt a non-constructive perspective where our knowledge is so lacking? As knowledge of the conditions of astrobiology and astrocivilization grows, may we yet adopt a constructive conception of them?

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Grand Strategy Annex

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What is astrobiology?

I suppose that “astrobiology” could be called one of those “ten dollar” words, but despite being a long word of six syllables and a dozen letters, it can be defined quite simply.

Astrobiology has been called, “The study of life in space” (Mix, Life in Space: Astrobiology for Everyone, 2009) and that, “Astrobiology… removes the distinction between life on our planet and life elsewhere.” (Plaxco and Gross, Astrobiology: A Brief Introduction, 2006). Taking these sententious formulations of astrobiology as the study of life in space, which removes the distinction between life on our planet and life elsewhere, together gives us a new perspective with which to view life on Earth (and beyond).

There are, of course, longer and more detailed definitions of astrobiology. There are two in particular that I have cited in previous posts:

“The study of the living universe. This field provides a scientific foundation for a multidisciplinary study of (1) the origin and distribution of life in the universe, (2) an understanding of the role of gravity in living systems, and (3) the study of the Earth’s atmospheres and ecosystems.”

from the NASA strategic plan of 1996, quoted in Steven J. Dick and James E. Strick, The Living Universe: NASA and the Development of Astrobiology, 2005


“Astrobiology is the study of the origin, evolution, distribution, and future of life in the universe. This multidisciplinary field encompasses the search for habitable environments in our Solar System and habitable planets outside our Solar System, the search for evidence of prebiotic chemistry and life on Mars and other bodies in our Solar System, laboratory and field research into the origins and early evolution of life on Earth, and studies of the potential for life to adapt to challenges on Earth and in space.”

from the NASA astrobiology website

I cited these two definitions of astrobiology from NASA in Eo-, Eso-, Exo-, Astro- and other posts in which I used parallel formulations to define astrocivilization.

Learning to take the astrobiological point of view

I‘ve posted a couple remarks about astrobiology on Twitter that I would like to repeat here to set the tone for what follows. More than two years ago I posted this on Twitter:

Astrobiology is island biogeography writ large.

This is one of the few “tweets” I’ve written that was “re-tweeted” multiple times (I’m not very popular on Twitter.) After I wrote this I began a more extensive blog post on this theme, but didn’t finish it; the topic rapidly became too large and started to look like a book rather than a post. Then last month I posted this on Twitter:

In the same way that Darwin provided a new perspective on life, astrobiology provides a novel perspective that allows us to see life anew.

Recently I’ve also been referring to astrobiology with increasing frequency in my blog posts, and I referenced astrobiology in my 2012 presentation at the 100YSS symposium in Houston and just last month in my presentation at the Icarus Interstellar Starship Congress in Dallas.

It will be apparent to the reader, then, then the idea of astrobiology has been slowly growing on me for the past few years, and the more I think about it, the more I come to realize the fundamentally new perspective that astrobiology offers on life and its evolution. Moreover, astrobiology also is suggestive for the future of life, and what we will discover about life the more we explore the cosmos.

Astrobiology: the Fourth Revolution in the Life Sciences

The more I think about astrobiology, the more I realize that, like earlier revolutions in the life sciences, the astrobiological point of view gives a novel perspective on familiar facts, and in so doing it potentially orients science in a new direction. For this reason I now see astrobiology as the fourth of four revolutions that instantiated the life sciences in their present form and continue to shape the way that we think about biology and the living world.

Here is my list of the four major revolutions in biological thought that have shaped the life sciences:

● Natural selection Independently discovered by Charles Darwin and Alfred Russel Wallace, natural selection gave sharpness of focus to many vague evolutionary ideas that were being circulated in the nineteenth century. With natural selection, biology had a theory by which to work, that could unify biological thought in a way that had not previously been possible. Of the Darwinian revolution Harald Brüssow wrote, “How can biologists cope conceptually and technically with this enormous species number? A deep sigh of relief came for biologists already in 1859 with the publication of Charles Darwin’s book ‘On the Origin of Species’. Suddenly, biologists had a unifying theory for their branch of science. One could even argue that the holy grail of a great unifying theory was achieved by Darwin and Wallace at a time when Maxwell was unifying physics, the older sister of biology, at the level of the electromagnetic field theory.” (“The not so universal tree of life or the place of viruses in the living world” Phil. Trans. R. Soc. B, 2009, 364, 2263–2274)

● Genetics After Darwin and Wallace came Gregor Mengel, who solved fundamental problems in the theory of inheritance and so greatly strengthened the Darwinian theory of descent with modification. As Darwin had provided the mechanism for the overall structure of life, Mendel provided the mechanism that made natural selection possible. Mendel’s work, contemporaneous with Darwin, was forgotten and not rediscovered until the early twentieth century. It was not until the middle of the twentieth century that Crick and Watson were able to delineate the structure of DNA, which made it possible to describe Mendelian genetics on a molecular level, thus making possible molecular biology.

● Evo-devo Evo-devo, which is a contraction of evolutionary developmental biology, once again went back to the roots of biology (as Darwin had done by formulating a fundamental theory, and as Mendel had done by his careful study of inheritance in pea plants), and returned the study of embryology to the center of attention of evolutionary biology. Studying the embryology of organisms with the tools of molecular biology gave (and continues to give) new insights into the fine structure of life’s evolution. Before evo-devo, few if any suspected that the homology that Darwin and others notes on a macro-biological scale (the structural similarity of the hand of a man, the wing of a bat, and the flipper of a dolphin) would be reducible to homology on a genetic level, but evo-devo has demonstrated this in remarkable ways, and in so doing has further underlined the unity of all terrestrial life.

● Astrobiology Astrobiology now lifts life out of its exclusively terrestrial context and studies life in its cosmological context. We have known for some time that climate is a major driver of evolution, and that climatology is in turn largely driven by the vicissitudes of the Earth as the Earth orbits the sun, exchanges material with other bodies in our solar system, and the solar system entire bobs up and down in the plane of the Milky Way galaxy. Of understanding of life gains immensely by being placed in the cosmological context, which forces us both to think big, in terms of the place of life in the universe, as well as to think small, in terms of the details of origins of life on Earth and its potential relation to life elsewhere in the universe.

This is obviously a list of revolutions in biological thought compiled by an outsider, i.e., by someone who is not a biologist. Others might well compile different lists. For example, I can easily imagine someone putting the Woesean revolution on a short list of revolutions in biological thought. Woese was largely responsible for replacing the tripartite division of animals, plants, and fungi with the tripartite division of the biological domains of Bacteria, Archaea and Eukarya. (There remains the question of where viruses fit in to this scheme, as discussed in the Brüssow paper cited above.)

tree-of-life 2

Since I have included molecular phylogeny among the developments of evo-devo (in the graphic at the bottom of this post), I have implicitly place Woese’s work within the evo-devo revolution, since it was the method of molecular phylogeny that made it possible to demonstrate that plants, animals and fungi are all closely related biologically, while the truly fundamental division in terrestrial life is between the eukarya (which includes plants, animals, and fungi, which are all multicellular organisms), bacteria, and archaea. If any biologists happen to read this, I hope you will be a bit indulgent toward my efforts, though I certainly encourage you to leave a comment if I have made any particularly egregious errors.

Toward a Radical Biology

Darwin mentioned the origins of life only briefly and in passing. There is the famous reference to, “some warm little pond with all sorts of ammonia and phosphoric salts, — light, heat, electricity &c. present” in his letter to Joseph Hooker, and there is the famous passage at the end of his Origin of Species which I discussed in Darwin’s Cosmology:

“Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”

Darwin, of course, had nothing to go on at this point. Trying to understand or explain the origins of life without molecular biology would be like trying to explain the nature of water without the atomic and molecular theory of matter: the conceptual infrastructure to circumscribe the most basic elements of life did not yet exist. (The example of trying to define water without the atomic theory of matter is employed by Robert M. Hazen in his lectures on the Origins of Life.)

Just as Darwin pressed biology beyond the collecting and comparison of beetles in the backyard, and opened up deep time to biology (and, vice versa, biology to deep time), so astrobiology presses forward with the project of evolutionary biology, pursuing the natural origins of life to its chemical antecedents. Astrobiology is a radical biology in the same way that Darwin was radical biology in his time: both go to the root to the matter to the extent possible given the theoretical, scientific, and technological parameters of thought. It is in the radical sense that astrobiology is integral with origins of life research; it is in this sense in which the two are one.

The humble origins of radical ideas

The radical biology of Darwin did not start out as such. In his early life, Darwin considered becoming a country parson, and when Darwin left on his voyage on the Beagle as Captain Fitzroy’s gentleman companion, he held mostly conventional views. It is easy to imagine an alternative history in which Darwin retained his conventional views, went on to become a country parson, and gave Sunday sermons that were mostly moral homilies punctuated by the occasional quote from scripture the illustrate the moral lesson with a story from the tradition he nominally represented. Such a Darwin from an alternative history would have continued to collect beetles during the week and would have maintained his interest in natural history.

Just as Darwin came out of the context of English natural history (which, before Darwin, gave us those classic works of teleology, Paley’s Natural Theology and Chambers’ Vestiges of the Natural History of Creation — a work that the young Darwin greatly admired), so too astrobiology comes out of the context of a later development of natural history — the scientific search for the origins of life and for extraterrestrial life. While the search for extraterrestrial life is “big science” of an order of magnitude only possible by an institution like NASA, in this respect it stands in the humble tradition of natural history, since we must send robots of Mars and the other planets until we can go there ourselves with a shovel and rock hammer. From such humble beginnings sometimes emerge radical consequences.

I think we are already beginning to see the potentially radical character of astrobiology, and that this development in biology promises a paradigm shift almost of the scope and magnitude of natural selection. Indeed, both natural selection and astrobiology can be understood as further (and radical) contextualizations of the theme of man’s place in nature. When Darwin wrote, he contextualized human history in the most comprehensive conception of nature then possible; today astrobiology must contextualize not only human history but also the totality of life on Earth in a much more comprehensive cosmological context.

As our knowledge of the world (which was once very small, and very parochial) steadily expands, we are eventually forced to extend and refine our concepts in order to adequately account for the world that we now know. Natural selection and astrobiology are steps in the extension and refinement of our conception of life, and of the place of life in the world. Life simpliciter is, after all, a “folk” concept. Indeed, “life” is folk biology and “world” is folk cosmology. Astrobiology brings together these folk concepts and attempts to bring scientific rigor to them.

The biology of the future

Astrobiology is laying the foundations for the biology of the future. Here and now on earth, without having surveyed life on other worlds, astrobiologists are attempting for formulate concepts adequate to understanding life at the largest and the smallest scales. Once we take these conceptions along with us when we eventually explore alien worlds — including alien worlds close to home, such as Mars and the ocean beneath the ice of Europa — it is to be expected that further revolutions in the life sciences will come about as a result of attempting to understand what we eventually find in the light of the concepts we have preemptively developed in order to understand biology beyond the surface of the Earth.

Future revolutions in biology will likely have the same radical character as natural selection, genetics, evo-devo, and astrobiology. Future naturalists will do what naturalists do best: they will spend their time in the field finding new specimens and describing them for science, and in the process of the slow and incremental accumulation of scientific knowledge new ideas will suggest themselves. Perhaps someone laid low by some alien fever, like Wallace tossing and turning as he suffered from a fever in the Indonesian archipelago, will, in a moment of insight, rise from their sick bed long enough to dash off a revolutionary paper, sending it off to another naturalist, now settled and meditating over his own experiences of new and unfamiliar forms of life.

The naturalists of alien forms of life will not necessarily have the same point of view as that of astrobiologists — and that is all to the good. Science thrives when it is enriched by new perspectives. At present, the revolutionary new perspective is astrobiology, but that will not likely remain true indefinitely.

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four revolutions

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Grand Strategy Annex

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