Eusocial insect colonies achieve an impressive degree of social differentiation and specialization without the kind of intelligence found among mammals. Some scientists call this collective behavior social intelligence.

Eusocial insect colonies achieve an impressive degree of social differentiation and specialization without the kind of intelligence found among mammals. Some scientists call this collective behavior ‘social intelligence.’

In a couple of blog posts, Is encephalization the great filter? and Of Filters, Great and Small, I argued that encephalization is the great filter — clearly implying that this is a single filter that is more significant than another filters, and that encephalization is the great filter. The “great filter” is an idea due to Robin Hanson, according to whom, “The Great Silence implies that one or more of these steps [to visible colonization] 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.”

In the second of the two blog posts noted above, Of Filters, Great and Small, I considered the different possible structures that filters might take, and this is a more nuanced view of the great filter that departs from the idea that a single element of the great filter is uniquely responsible for the great silence and the Fermi paradox. The journey to higher forms of emergent complexity seems to be robust, and therefore likely to have been repeated elsewhere, but it is also a long journey of later emergent complexities multiply supervening upon earlier emergent complexities. This structure of emergent complexities over time is itself a structure more complex than any one of the emergent complexities taken in isolation. In so far as we understand the great filter in this content, we understand a more nuanced view than the idea of one step among many steps along this journey being the unique hurdle to the aggressive expansion of life in the universe, and therefore its visible traces discoverable through cosmology.

Even given this more nuanced view of the great filter, later forms of emergent complexity will be less common than earlier forms, and within the structure of the great filter we can identify particular emergent complexities where the iterated structure falters. If we place this stalling point at exponential encephalization, we might find a universe filled with complex life, but with few or no other intelligent species capable of building a civilization. This is the sense in which I wish my claim that encephalization is the great filter to be understood.

Recently I have had reason to revisit the idea that encephalization is the great filter, and this is primarily due to having read The Social Conquest of Earth by E. O. Wilson, which emphasizes the role of eusociality in the construction of complex societies. I think that Wilson is right about this. Wilson notes that eusociality has emerged on Earth only a handful of times, making it a rare form of emergent complexity: “Eusociality arose in ants once, three times independently in wasps, and at least four times — probably more, but it is hard to tell — in bees.” (p. 136) We can compare this rarity of eusociality as an adaptation to the rarity of intelligence as an adaptation.

The insects that have achieved robust eusociality — perhaps I should say arthropods — are very different from mammals. We must go back more than 500 million years to the split between protostomes and dueterostomes to find the last common ancestor of the two. With the arthropods we share being bilaterally symmetrical, but the split between us — hence the split between our brains and central nervous systems (CNS) — is about as old as the split between mammals and molluscs: chordata, mollusca, and arthropoda are distinct phyla. On the one hand, we know from a recent fossil find something about the CNS of the earliest chordates, which we thus have in common with most other terrestrial animalia (cf. How early a mind?); on the other hand, we also know that neural structures have evolved independently on Earth (cf. The ctenophore genome and the evolutionary origins of neural systems), so that we might speak of neurodiversity among terrestrial animalia. Different brains, when sufficiently complex, are substrates for different forms of emergent consciousness, i.e., different forms of mind.

It is not only dramatically different kinds of minds that might give rise to dramatically different forms of encephalization, and thus intelligence and civilization. Part of the differentness of eusocial insects is their reproductive specialization, which goes along with a genetic structure of a colony in which the superorganism of the colony benefits overall from a majority of individuals not reproducing. This is also dramatically different from human societies. It has been objected to Wilson’s thesis of the eusociality of human beings that human beings are not eusocial, but rather prosocial, and that human cooperative societies cannot be compared to insect cooperative societies because there is no parallel to reproductive specialization among human beings. This, I think, is an unnecessarily narrow conception of eusociality. All we have to do is to recognize that eusociality can take multiple forms (as minds and intelligence can take multiple forms, supervening upon multiple distinct neural structures), some of which involve reproductive specialization and some of which do not, in order for us to recognize human cooperative societies as eusocial.

The most developed brain of the molluscs is that of the octopus, a solitary hunter. Octopi have been hunting in the depths of the sea for hundreds of millions of years, and, apparently, they have never experienced competition on the basis of intelligence, and, perhaps because of this, have never experienced an encephalization event. (Recently in How early a mind? I quoted E. O. Wilson to the effect that, “A Homo sapiens level of intelligence can arise only on land, whether here on Earth or on any other conceivable planet.” ) So octopi have a respectable level of intelligence, but are far from being eusocial. The eusocial insects have a much less powerful brain than octopi or mammals, but they did make the breakthrough to eusociality. Only human beings made the breakthrough to both eusociality and high individual intelligence.

Since reading Wilson on the eusociality of human societies, I can come to think that human civilization is what happens when eusociality coincides with intelligence. Termite mounds and bee hives are what happens when eusociality coincides with insect-level intelligence. And this observation of the interaction of eusociality and intelligence immediately suggests two possible counterfactuals to human civilzation, which I will sketch below. Understand that, in this context, when I use the term “human civilization” I am using this is in its most generic signification, covering all the many different human civilizations that have existed, i.e., the class of all human civilizations (which is the class of all known civilizations constructed by a biological being both eusocial and intelligent).

I noted above that we can employ a conception of eusociality less narrow than that restricted to eusocial insects with reproductive specialization. Similarly, the other element in civilization — intelligence — ought also to be construed broadly. Many different kinds of intelligence interacting with many different kinds of eusociality suggest many different possibilities for civilization distinct from the class of human civilizations. At the present time I am not going to consider kinds of eusociality and intelligence as much as degrees of eusociality and intelligence, and I will assume that the insect transition to reproductive specialization represents eusociality taken to a higher degree than eusociality has progressed in human beings. Similarly, I will assume that human intelligence represents a higher degree of intelligence than now-extinct branches of the genus homo, i.e., our ancestors with lower degrees of encephalization and lower intelligence.

From these assumptions about degrees of eusociality and intelligence, two counterfactual classes of civilization are suggested:

High Eusociality/Low Intelligence

A species might be less intelligent than human beings (i.e., possess a lower degree of encephalization) but more eusocial than human beings, and be able to build a civilization.

Low Eusociality/High Intelligence

A species might be more intelligent than human beings (i.e., possessing a higher degree of encephalization, or a thicker neocortex) but less eusocial than human beings, and be able to build a civilization.

This formulation has the virtue of existing human civilization embodying the principle of mediocrity: our eusociality and intelligence are balanced; we are not as eusocial or as individualistic as we might have been, and we are not as intelligence or as unintelligent as we might have been. We are in the “Goldilocks zone” of coinciding eusociality and intelligence, and this human “sweet spot” for civilization may account for the fact that civilization emerged independently in widely separated geographical regions, not as a result of idea diffusion, but rather as a consequence of independent invention.

In the High Eusociality/Low Intelligence class of civilizations, we would see somewhat individually intelligent beings capable of a high degree of cooperation through eusociality forming socieites (superorganisms) quite early in their history. We can see the degree to which bees and ants and termites can develop societies based on eusociality and an almost negligible individual intelligence; with a degree of eusociality approaching this, but in a species endowed with more cognitive capacity, cities might be built that look like something between a human city and a termite mound, and this might happen spontaneously. If this had happened with an earlier human ancestor — a counterfactual ancestor with greater eusociality than any actual human ancestor — it could have preempted the emergence of human civilization by occurring millions of years earlier.

In the Low Eusociality/High Intelligence class of civilizations, civilization may have come about at the level of scattered bands of hunter-gatherers, or, at least, human beings in small groups may have been able to develop science and technology without large social institutions such as governments, universities, and corporations, which discipline unruly human beings and make it possible for them to work cooperatively together. One can imagine that a more intelligent (counterfactual) species of the genus homo might have been sufficiently intelligent to pursue science at a much earlier period of its history, and one can imagine members of such a species coming together for scientific purposes much as our ancestors came together at Göbekli Tepe (which I first wrote about in The Birth of Agriculture from the Spirit of Religion) possibly for religious rituals, even before they gathered in settlements for agriculture.

Both counterfactual scenarios I have described above could have resulted in civilization on Earth emerging tens of thousands or hundreds of thousands of years earlier than it did in fact emerge. I suppose it would be equally possible to formulate counterfactuals in which different classes of civilization emerged much later.

Each of the three classes of civilizations considered here — moderate eusociality/moderate intelligence, high eusociality/low intelligence, and low eusociality/high intelligence — have distinct advantages and disadvantages, in terms of the viability of the civilization that results. However, cognitive capability begins to play a much greater role in civilization after industrialization when civilization becomes technological and scientific. If a given civilization can survive to make the breakthrough to science-driven technology, all other things being equal, the species with the greatest intelligence will have the greatest advantage in deploying science to further the ends of that species. I suspect that a high eusociality/low intelligence civilization would be stagnant, and possibly so stagnant that the breakthrough to industrialization never occurs. I also suspect that human beings were just smart enough to make that breakthrough, as indicated by the single point of origin of the industrial revolution. Short of that threshold, any civilization remains cosmologically invisible, exclusively bound to its homeworld, and incapable of long-term existential risk mitigation. This scenario is consistent with the great silence, and may constitute another approach to the Fermi paradox.

The research questions that follow from these considerations include: Are there intrinsic limits to eusociality among beings whose biology is not consistent with reproductive specialization? Are there intrinsic limits to intelligence for biological beings of known biochemistry? How do eusociality and intelligence interact biologically and ecologically? Does either constitute a check upon the other?

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Cooperation among human beings has its limits -- as illustrated by the story of the Tower of Babel -- and one limit to cooperation is our level of eusociality.  With a higher or lower level of eusociality, civilization would have had a different structure.

Cooperation among human beings has its limits — as illustrated by the story of the Tower of Babel — and one limit to cooperation is our level of eusociality. With a higher or lower level of eusociality, civilization would have had a different structure.

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Grand Strategy Annex

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Closest neighboring stars to our sun.

Seth Shostak, one of the most eminent SETI researchers, has suggested (in his lectures for The Teaching Company) that the Principle of Mediocrity can be extended beyond the idea that there are no privileged perspectives and therefore nothing unusual or exceptional about our solar system, our planet, or even life on earth, to embrace the idea that there is nothing unusual or exceptional about intelligent life, civilization, and the emergence of the industrial technology that makes SETI possible. I should also note in this context that this extension of the Principle of Mediocrity is thoroughly consonant with the argument that I made in The Continuity of Civilization and Natural History.

In several recent posts I have written about Paul Davies’ book The Eerie Silence: Renewing Our Search for Alien Intelligence (e.g., Silent Worlds, Empty Worlds). Paul Davies’ perspective represents what Davies calls “new SETI” in contradistinction to “old SETI,” which is represented by Shostak. We can recast the distinction between old and new SETI a bit by characterizing the traditional SETI undertaking of listening for alien radio broadcasts or sending our own radio signals out into space as a narrowly conceived search for peer civilizations to our own.

Under this interpretation, the traditional SETI undertaking can be seen as a process of elimination, and this process of elimination extends back into history before radio technology. Before our technology gave us the level of knowledge that we have of Mars today, it was widely speculated that there might be a technological civilization on Mars. There have been several proposals for what has generally been called extraterrestrial signaling before radio technology. Karl Friedrich Gauss, the great mathematician, suggested laying out a diagram of the Pythagorean Theorem in the wilderness of Siberia, with appropriately contrasting colors of vegetation. Joseph Johann Littrow suggested flaming trenches carved into the Sahara desert as a way to signal the inhabitants of Mars. Neither scheme was pursued.

Subsequent technological advances have made it possible for us to eliminate the possibility of a peer technological civilization within our solar system. While we cannot yet rule out the possibility of life deep within the aquifers of Mars or in the ocean postulated to exist under the ice of Europa, any life that would exist under these conditions would not have given rise to industrial-technological development.

Traditional SETI searches for alien radio signals have, by this time, similarly extended the process of elimination of peer civilizations from nearby stars. That is to say, however disappointing it is for folks like me, we can say with a high degree of confidence that there are no peer industrial-technological civilizations associated with the nearest stars pictured in the diagram above. Had there been a radio-capable peer civilization on a planet orbiting Barnard’s Star, for instance, it would only take six years for a radio signal to reach us, and another six years for that civilization to receive our answer. While that rate of communication is slow compared to our familiar modes of communication, since we’ve been broadcasting our signals for more than a hundred years there has been plenty of time to send and receive several messages. Similar considerations hold for all the stars within a radius of the reach of our radio signals, which radius is now a little larger than a hundred light years.

Of course, we could receive a signal from Barnard’s Star tomorrow, of an only-just-recently radio-capable civilization, but we have other reasons now (lack of extra-solar planets, for instance, and being a red dwarf star) for eliminating other local stars as homes for peer civilizations. This does not eliminate the possibility of non-peer civilizations, which could include either non-radio capable civilizations (like the quasi-neolithic alien societies in the film Avatar) or civilizations so different from our own that we could not recognize them as peers to our particular species of technological civilization.

As our technology improves, it extends the traditional SETI task of the process of elimination farther and farther into the cosmos. It has been this gradually increasing range of technology and the implicit process of elimination that has gotten SETI researchers to thinking and coming up with the ideas that are part of what Davies calls new SETI. Similar considerations hold for the discovery of peer life, even if not intelligent or civilized life. By “peer life” I mean life more or less biologically similar to what we know on earth. The arrival of the Viking landers on Mars largely discounted the possibility of peer life on Mars, although, as I wrote above, there remains the possibility of luxuriant caves buried deep beneath the Martian surface, heated by the residual heat of the molten core. The imagination quickly jumps to visions like those of Journey to the Center of the Earth in contemplating such a scenario. But even this scenario will eventually be either confirmed or disconfirmed by science.

Exobiology and astrobiology are sciences uniquely dependent upon technology. Technological advances brought these sciences into being, and only further technological advances will be able to settle the questions posed by nascent exobiology and astrobiology. For example, when we become able to take spectra from the atmosphere of earth-like planets orbiting other stars — a technological possibility within the next few decades — we would be able to determine the presence of certain kinds of life on other planets, even if that life has not produced a technological civilization that could communicate after the fashion of traditional SETI assumptions.

As far as technological innovation, as well as scientific ingenuity, has pushed the SETI process of elimination outward, the bubble of the extent of our knowledge is still quite small in the galaxy. The map of our spiral arm within the Milky Way galaxy, showing cepheid variable stars as “light houses” in the cosmos, includes a scale that shows a thousand light years in the lower right hand corner. By this scale you can judge by eye a sphere of a hundred light years radius which is our “radio bubble” in the cosmos. As you can see, there remains plenty of space even in our nearest cosmic “neighborhood” for peer civilizations from which we have not heard, and which would not have had an opportunity to hear from us. And this is just the Milky Way. There are galaxies in the cosmos like stars in the Milky Way: almost too many to comprehend. Most of these will remain beyond our scientific knowledge except in the most abstract and schematic form of knowledge. Radical developments and departures in science would be necessary for human technological civilization, however far extended in space, to make an adequate survey of the universe and extend even the traditional SETI process of elimination to a statistically significant percentage of the universe.

However, although our scientific sample of the universe is very small in comparison to the whole, if the Principle of Mediocrity holds good, it is a valid sample. That is something to think about. If we could produce a rigorous and comprehensive statement of the principle of mediocrity, we would have a better idea of what exactly is eliminated by the SETI process of elimination.

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Grand Strategy Annex

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