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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Grand Strategy Annex

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project astrolabe logo smaller

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The Conceptual Problem of Earth-Originating

LocalSupercluster we are here

Biota, Intelligence, Civilization, and Institutions

There is a subtle conceptual problem involved in identifying earth-originating biota, intelligence, civilization, and institutions and their long-term, large-scale development. If industrial-technological civilization continues in its trajectory of development, we can expect our species and our civilization will spread throughout our solar system and eventually to other star systems. By now, this is an idea familiar to everyone. When earth-originating biota, intelligence, civilization, and institutions are found on other planets of our solar system, in built environments orbiting planets or the sun, or throughout other planetary systems of other stars, what will we call ourselves and our civilization?

You are here galaxies

That is just the beginning of the potential complexities. As earth-originating species and institutions spread across the galaxy, this cosmological expansion will constitute an adaptive radiation of an order of magnitude beyond any adaptive radiation that took place on Earth, when all earth-originating biota were confined to Earth. An adaptive radiation of such magnitude will likely mean changes of a proportional magnitude. This proportional magnitude will involve not only expansion in space but also expansion in time. Adaptive radiation may take advantage of the time-dilation properties of a relativistic universe, distributing organisms or institutions across both time and space. This latter form of adaptive radiation, when the institution concerned is civilization, I have called a temporally distributed civilization (cf. Spacetime Constraints and Possibilities). In the same spirit we might speak of temporally distributed species, intelligence, and institutions.

Earth-originating life and its corollaries (for intelligence, civilization, and institutions are corollaries of life), once established off the surface of the earth, i.e., once established extraterrestrially, becomes extraterrestrial life even though it is earth-originating. Moreover, given the spatiotemporal scale of the universe, earth-originating life that expands extraterrestrially will rapidly adapt itself to local conditions, undergoing adaptive radiation. As a consequence, this extraterrestrial earth-originating life (and its corollaries) will come to differ from the earth-originating biota that has remained on the earth, even as this life that has remained on the earth has itself continued to evolve and therefore differs both from extraterrestrial earth-originating life as well as the earth-originating life that was the common ancestor of both.

Milky Way poster

It is even possible that earth-originating life might expand in cosmological-scale adaptive radiation, some great catastrophe could subsequently befall life throughout our galaxy (such as a massive gamma ray burst from the supernova), sterilizing most of the living worlds, after which life would again expand into the galaxy from its remaining protected niches, perhaps even returning to a sterilized earth. Is this, then, terrestrial life, or extraterrestrial life? It is easy to see how we might dramatically multiply our terminology at this point. There will be Earth-originating biota (EOB), Earth-originating civilization (EOC), extraterrestrially-originating biota (ExOB), extraterrestrially-originating civilization (ExOC), and so forth. Is this helpful? Does it matter? Well, the particular label we use to describe life and its vicissitudes doesn’t matter, but what does matter is the natural history of life, and when life attains the capability of projecting itself over cosmological distances, the natural history of life will involve just such cosmological considerations as I have recounted here. Natural history will become cosmological history, and astrophysics will be as relevant to life and civilization as is geography to geocentric life and civilization.

Milky Way Orion Spur you are here

I have worked on a variety of terms to try to accurately express the large scale structure of life in the cosmos, and most of my formulations to date have been unsatisfying. I have expressed the idea of the origin of life and civilization as eobiology (following Joshua Lederberg, the prefix “eo” means early, so “early biology” or the origins of life — cf. Eo-, Eso-, Exo-, Astro-) and eocivilization (by analogy with eobiology — also cf. The Terrestrial Eocivilization Thesis). I have expressed the idea of non-terrestrial civilizations as exocivilization (cf. The Law of Trichotomy for Exocivilizations). One way to express the idea of earth-originating biota, intelligence, civilization, and institutions would be with the term terragenic. While “terragenic” is not a particularly attractive word, it does communicate the meaning I would like to convey in an intuitively accessible fashion. Also, it immediately suggests its complementary term, which is a much more satisfying word: xenogenic.

Earth is the locus of all that we know of life, civilization, and technology in the cosmos. In other words, all known life is terragenic; all known civilization is terragenic; all known technology is terragenic. We could narrow the focus a bit more and note that all known civilization is anthropogenic and most known technology is anthropogenic (as I observed in The Genealogy of the Technium, there are instances of terragenic non-human technology in the form of non-human animal tool use), with the human beings responsible for these anthropogenic creations themselves being terragenic. All of this is true at this early point in the history of humanity and its civilization, but this will not always be the case. The adaptive radiation of life into the cosmos will mean that the terrestrial origins of life, intelligence, civilization, and institutions may become clouded in a distant and complex past in which life and its corollaries emerge, expand, adaptively radiate, are extirpated, and re-emerge and re-adapt from sources of life no longer terrestrial.

We are now in a position to make the necessarily distinctions between terragenic exocivilizations and xenogenic exocivilizations, or even terragenic astrocivilization and xenogenic astrocivilization. For example, a xenogenic terrestrial civilization would be the result of alien invasion and extirpation of human beings in order to build their own civilization on Earth. All of these terms might be useful and accurate, but until we have dramatic examples before our minds to fill in this schematically formulated concepts they will seem a bit empty and artificial. This is not real objection except for our intuition.

One way to express the earth-originating character of all known life and its corollaries and to project this on cosmological scales would be to adopt the word “local” as it is employed in cosmology. In astronomy and cosmology there is a use of the word “local” that is both revealing and instructive. “Local” is what includes us — like the local group of galaxies or the local cluster of galaxies — while that which is non-local does not include us. When astronomers mention the “local group,” the “local cluster,” or the “local supercluster,” they are talking about, respectively, the group of galaxies that include our Milky Way, the cluster of galaxies that includes our Milky Way galaxy, and the supercluster that includes our own Milky Way galaxy. By analogy and extension, we can easily understand “local life,” “local intelligence,” “local civilization,” and “local institutions.”

It is often said today that, “Galaxies are the building blocks of the Universe.” I’m certain that this has been repeated by many cosmologists; I don’t know who originated the line, but it can be found, for example, as the first sentence of Carlton Baugh’s review of The Road to Galaxy Formation by William C. Keel (Nature 421, 791-792, 20 February 2003). Our local galaxy may prove to be be source and origin of life, mind, intelligence, technology, civilization, and institutions for the cosmos at large, in which case the petty distinctions we will make as earth-originating life makes itself at home in our local galaxy will come to mean but little in the long term. In this case, the only sense of “local” that will really matter is that of our “local galaxy.” Thus the Milky Way become not merely a building block but the foundation stone of a universe of life and its corollaries.

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Grand Strategy Annex

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Theses on Easter

4 April 2010


Theses on the Occasion of Easter Sunday

A Theoretical Account of Ritualized Celebration

1. Distinctions must be made among myth, ritual, and celebration.

1.1 Myth, ritual, and celebration, though distinct, are logically related.

1.11 A celebration is an occasion for a ritual,
A ritual is an opportunity to participate in a myth,
Therefore a celebration is an occasion in which to participate in a myth.
Q. E. D.

1.2 Rituals of burial are older than agricultural rituals of life-death-rebirth, even extending to other species (Neanderthals, now extinct), and may well be the origin of life-death-rebirth rituals.

2. Among the most ancient of continually observed celebrations is that of the life-death-resurrection of the Year-God, eniautos daimon.

2.1 The celebration of the life and re-birth of the Year-God, eniautos daimon, is at least as old as settled, agrarian society.

2.11 Agriculture and the written word together produced settled, historical civilization.

2.12 Settled historical civilization has defined the norm of human history from the Neolithic Agricultural Revolution to the Industrial Revolution.

2.2 Settled agrarian society coincides with the origins of civilization.

2.21 The celebration of the life and re-birth of the Year-God, eniautos daimon, coincides with the origins of civilization.

3. Once the breakthrough to history has been made by way of the written word, it is the nature of historical civilization to commemorate nodal points of the year, whether with solemnities, festivities, or both.

3.1 Historical civilization is predicated upon the presumed value of the history that brings that civilization into being.

3.2 Nodal points of the year celebrated in historical civilizations are observed as validation of their historicity through the performance of rituals.

3.21 In a temperate climate, summer and winter solstices and spring and fall equinoxes are nodal points of the year.

4. The mythology of a settled, agricultural civilization emerges from the same regularities of nature observed of necessity by agricultural peoples.

4.1 The calendrics of celebration emerges from the regularities of nature observed of necessity by agricultural peoples.

4.11 The mythology and calendar of celebrations of settled, agricultural civilizations come from the same source.

4.2 Celebrations are the points of contact between the two parallel orders of mythological events and the actual historical calendar.

4.21 A civilization validates its mythology by establishing a correspondence between mythological events and historical events.

4.3 Enacting a myth in historical time, by way of a ritual, makes that myth literal truth by giving to it a concrete embodiment.

5. Easter is one species of the genus of life-death-rebirth celebrations.

5.1 The particular features of the Easter celebration are the result of the adaptive radiation of the dialectic of sacrifice and resurrection.

6. Easter is that species of life-death-rebirth celebration specific to Christendom.

6.1 Christendom was primarily a construction of the Middle Ages.

6.11 Christendom was the legacy of Medieval Europe that disappeared with the passing of medieval civilization but which, like the Roman Empire before it, is with us still and remains a touchstone of the Western tradition.

6.12 Christendom was an empire of the spirit and of the cross as Rome was an empire of the will and of the sword.

6.13 To have once been Roman, and then to have been Christian, and finally to have become modern, is the condition of Western man.

6.2 Easter is a celebration specific to civilization, the civilized celebration par excellence.

7. The naturalistic civilization that is emerging from the consequences of the Industrial Revolution represents the first significant change in the social structure of human society since the Neolithic Agricultural Revolution.

7.1 With the advent of the Industrial Revolution, we have ceased to be an agrarian society.

7.2 For the first time in history, life-death-rebirth celebrations face interpretation by a non-agrarian society.

7.21 Not only should we not hesitate to find new meanings in ancient celebrations, of which Easter represents the latest adaptive radiation, but rather we should actively and consciously seek meanings relevant to the present in such celebrations.

8. As the painters of the renaissance drew upon the traditions of pagan antiquity already at that time a thousand years out of date, so too the post-Christian Western civilization will draw upon the traditions of Christendom for hundreds if not thousands of years to come.

8.1 The period of time that we have come to call the modern era — roughly the past five hundred years — has not been the modern era proper but rather has been the period of the formation of modernity.

8.2 Modernity simpliciter has but begun.

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Grand Strategy Annex

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