Work in Progress: Ecology of the Intelligence Niche
Friday 14 October 2022
In last week’s newsletter I mentioned the intelligence niche, also called the cognitive niche, and in the past week I have been digging around more in an attempt to find the source of the idea and its history of discussion. I haven’t (yet) found the smoking gun, or what I imagine to be the smoking gun. I have a vague — very vague — recollection of this idea being discussed in the 70s and 80s, and this is what leads me to believe that there is a smoking gun. However, I find very few sources, and none from the 70s, so it is entirely possible that my recollection is wrong, but at some point the idea was sufficiently widely discussed that I heard about it before I took an explicit interest in such things. One could argue that the idea of an intelligence niche is present before this terminology was adopted. For example, the penultimate paragraph of David Attenborough’s Life on Earth mentions the possibility that another species might “take our place” if we vacate our niche:
“This last chapter has been devoted to only one species, ourselves. This may have given the impression that somehow man is the ultimate triumph of evolution, that all these millions of years of development have had no purpose other than to put him on earth. There is no scientific evidence whatever to support such a view and no reason to suppose that our stay here will be any more permanent than that of the dinosaur. The processes of evolution are still going on among plants and birds, insects and mammals. So it is more than likely that if men were to disappear from the face of the earth, for whatever reason, there is a modest, unobtrusive creature somewhere that would develop into a new form and take our place.”
But what is “our place”? I think this is the question that can throw light on the problem of an intelligence niche, because “our place” on Earth is not at all clear. As a species, we appeared first in Africa, having descended from trees and adopted an upright posture, freeing our hands to gather or to carry what we gather, we were freed from the jungles and woodlands of our ancestors and could walk out onto the African savannahs. E. O. Wilson thinks that we so perfectly adapted to the African savannah that this is the landscape that human beings are naturally drawn to and to which we respond (and this is an aspect of our biophilia).
That may or may not be true. Certainly in its favor is the fact that many hominid species came and went over millions of years, so clearly we did adapt to the environment; if we had not have adapted to this environment, we would have gone extinct. So, given the adaptation of Homo sapiens to the African savannah, one could argue that this is “our place” on the planet, the biome of our origin and thus our “natural” habitat. At one time this was true, but it is true no longer, so that to argue that the African savannah is “our place” is to argue that this is our rightful place, which introduces a normative element that can’t have any scientific basis unless we allow science to violate the is/ought dichotomy.
One could, at this point, invoke a concept of natural necessity — in fact, I believe that we need to recognize this modal category as is resolves a lot of philosophical problems, but it’s not really on the table at present — and argue that expressing a natural necessity with quasi-normative language is simply a confusing way to express natural necessity, and that we can do without the confusing language. However, if human beings are adapted to the African savannah as a matter of natural necessity, and there is no moral “ought” involved in saying that we ought to be living on the African savannah, we would have to acknowledge that this is a pretty weak necessity, as it did not necessitate our living on the African savannah for the entire history of our species, which our subsequent history demonstrated.
At the same time that our ancestors were adapting themselves so well to the African savannah, our brains were growing disproportionately large. A lot of explanations have been offered for this unlikely evolutionary turn of events — unlikely because the brain consumes a lot of our energy, and that kind of energy drain needs to be justified in the context of natural selection. If it didn’t buy our ancestors differential survival and reproduction, a large brain probably would have been the target of biological parsimony and wound up on the ash heap of natural history. There are arguments that this was driven by eating meat, first as scavengers and later as hunters, and there is probably something to this, but is that enough to produce our freakish human encephalization? Myself, I think the human brain was mostly driven by sexual selection, and that it is a Fisherian runaway like the horns of the extinct Irish elk or the tail feathers of the still very viable peacock, which are also credited to sexual selection. (In this sense, we are all sapiosexuals.)
Whatever the explanation for our big brains, we have them, and our ability to exapt this survival engine for language and technology and planning for the future meant that, unlike all other species on the planet, we were not fated to speciate, to live, and then to go extinct all within the same biome in which we appeared. The use of canoes to travel along the shoreline and the use of bone needles to sew form-fitting clothing meant that, even during the last glacial maximum, human beings were able to travel the entire planet and settle in every biome.
There are, of course, weedy species that spread to other biomes beyond that in which they appeared, but no other animal has managed to flourish and out-compete endemic species in every other biome, facilitated by the technology that we built with our own hands. So that’s where we are now, living in every terrestrial biome, and this begs the question as to where our place on Earth is, when nowhere in particular seems to be our place, but we are nevertheless able to make any place home by our niche construction efforts. And this is another important aspect of the intelligence niche problem: niche construction. Some time ago I wrote a blog post about civilization as intelligent niche construction, The Ecological Conception of Civilization, in which I defined civilization as niche construction by an intelligence species. In that post I quoted this on niche construction:
“…organisms… interact with environments, take energy and resources from environments, make micro- and macrohabitat choices with respect to environments, construct artifacts, emit detritus and die in environments, and by doing all these things, modify at least some of the natural selection pressures present in their own, and in each other’s, local environments… All living creatures, through their metabolism, their activities, and their choices, partly create and partly destroy their own niches, on scales ranging from the extremely local to the global” (Niche Construction: The Neglected Process in Evolution, F. John Odling-Smee, Kevin N. Laland, and Marcus W. Feldman, Monographs in Population Biology 37, Princeton University Press, 2003)
We have all heard that beavers are “ecosystem engineers,” and human beings are ecosystem engineers on a much larger scale; beavers are local ecosystem engineers, while we are planetary ecosystem engineers, or, if you will, biosphere engineers. I noted last week that our agriculture dominates the biosphere, which would return to wildness and wilderness if we were to disappear. So long as we manage our food supply for eight billion human beings, the biosphere will be dominated by biospheric engineering.
Working along these lines I found the paper “Social intelligence, human intelligence and niche construction” by Kim Sterelny (a well known philosopher of biology), which addresses both the evolution of human intelligence and niche construction. In the conclusion Streleny writes:
“Hominin evolution is hominin response to selective environments that earlier hominin have made. In contrast to social intelligence models, I have argued that hominins have both created and responded to a unique foraging mode, a mode that is both social in itself and which has further effects on hominin social environments… Individuals did not face the ecological filters on their environment alone, but with others, and with the technology, information and misinformation that their social world provides. Ecological and social complexity became fused, as the ecological problem of extracting resources as individuals from a world we did not make became the economic problem of extracting resources collectively from and in a human world.”
In this paper Sterelny does not mention “intelligence niche” or “cognitive niche,” but, clearly, the social niche that Sterelny postulates was niche construction facilitated by intelligence, and which in turn facilitated the further development of intelligence, and with the further development of intelligence in Sterelny’s social intelligence–ecological complexity model we get something like an intelligence niche.
Most uses of “intelligence niche” start appearing after 2003 and most of these reference Simon Conway Morris’ Life’s Solution: Inevitable Humans in a Lonely Universe, which was published in 2003. However, neither “intelligence niche” nor “cognitive niche” appear in Morris’ book. Here is a use of “intelligence niche” from The View from the Center of the Universe: Discovering Our Extraordinary Place in the Cosmos by Joel R. Primack that cites Morris:
“Simon Conway Morris responds to the arguments of the Impossible camp in a recent book. Regarding woodpeckers, Conway Morris says that although there are no woodpeckers on the island of Madagascar, another group of birds have become true substitutes; elsewhere, three groups of mammals have converged on a woodpecker-like habit. He thus argues that other animals did evolve independently to occupy that ecological niche. But the question we’re really interested in here is whether something would have evolved again to fill our niche — the intelligence niche. And would it have evolved with the original distinguishing characteristics of humans — not only intelligence but manual dexterity and toolmaking?”
After this the article by Charles Lineweaver appeared in 2008, and then most of the references to a possible intelligence niche then cite Lineweaver, as in Paul Davies’ The Eerie Silence:
“Because evolutionary convergence is so widespread and powerful, the niche metaphor has some force. But it must be used with great care. What we want to know for SETI is whether there is an ‘intelligence niche’, which on Earth humans obligingly filled, starting a few million years ago in Africa when our ancestors first walked upright and began using tools — a train of development that led all the way to radio telescopes. And if that reasoning is sound, might we also expect ET to similarly put the ‘I’ in SETI for us? There is no consensus on the answer. Charley Lineweaver, an astrobiologist at the Australian National University, is highly sceptical of the intelligence niche argument’.”
Though Davies cites Lineweaver, he mentions convergent evolution in this paragraph, and it is evolutionary convergence that is the real theme of Morris’ book, which does not explicitly mention an intelligence niche, but much of which is concerned with the discussion of convergent evolution:
“…convergences involving sensory systems are of considerable importance in assessing the likelihood of recurrent emergence of such biological properties as intelligence. Linked to this is the generally rather neglected evidence for convergence in behavior…” (p. 141)
And, after several pages of the discussion of the habits of burrowing animals:
“A recurrent theme of this book is not only the implications of convergence for evolution, but also the problems it can pose for its resolution. Not, I hasten to add, in terms of the reality of evolution. This is emphatically not in question; rather the reverse: the details of convergence actually reveal many of the twists and turns of evolutionary change as different starting points are transformed towards common solutions via a variety of well-trodden paths. Rather, convergence, if not identified, may lead to blatantly erroneous phylogenetic reconstructions.” (p. 144)
What is the relationship between convergent evolution and an intelligence niche? Back in newsletter 165 I mentioned listening to Improbable Destinies: Fate, Chance, and the Future of Evolution by Jonathan B. Losos, which was all about convergent evolution, which is now a major area of research in evolutionary biology. Morris adds intelligence to the mix of convergent properties. I assume the reasoning goes something like this: environments impose certain selection pressures on organisms, so that a clade that remains within a given environment may converge upon the optimal form for that environment.
The most obvious example of this is selection for hydrodynamic body architecture in an aquatic environment. Fish evolved in this environment and their bodies are the paradigm of hydrodynamic optimality. Evolutionary lineages that have returned to the oceans, whether dinosaurs or mammals, have approximated a hydrodynamic shape as they adapt to the aquatic environment, with the most dramatically changed mammals being the cetaceans. Cetaceans have experienced convergent evolution of an especially vivid kind. They look like fish, except that they flap their tails up and down instead of side to side. Now, given that human beings evolved in response to selection pressure, including the evolution of our large brains, there must be a niche for a large-brained intelligent species, and some other species could converge on large-brained intelligence and thus be a candidate for the niche we have filled on Earth.
However, I think we will need to tighten up our biological conceptual framework when it comes to convergence, because there is a tendency to let out the boundaries of what counts as convergence when one shifts from a micro-evolutionary context to a macro-evolutionary context. In micro-evolution, convergence can take place on a genetic level, so that two distinct species are selected for retaining the same genetic mutations that result in genetic similarity that is not a function of descent from a common ancestor. This is remarkable, but quite well documented (cf. the book by Losos mentioned above). However, the kind of evolutionary convergence discussed above, like the convergence on a hydrodynamic body architecture for aquatic species does not involve convergence on a genetic level. There are different genetic mechanisms governing the body plan of the fish and of the dolphin.
Now, at the level of biology studied in evo-devo (i.e., evolutionary developmental biology), it can be shown that in some cases the same genes are responsible for the same structures, even in phylogenetically distant species. Thus, if memory serves, there is a gene that governs eye development in many different species, and these eyes can take radically different forms, as in compound eyes of insects and the camera eyes separately (and convergently) evolved in cephalopods and mammals. So there are macro-evolutionary trends that trace to the genetic level, but that does not mean that all macro-evolutionary convergence is an expression of evo-devo principles.
There is a parallel conceptual looseness in the discussion of extremophiles: what counts as an extremophile changes as we ascend from the simplest organisms — e.g., methanogens, which are common extremophiles at the very base of the tree of life — and more complex forms of life, including eukaryotic and multicellular life forms. Thus there is a book about extremophile fishes (I was reading this in the past week), and these fish certainly do live under conditions under which other fish could not survive, but they aren’t extremophiles in the same sense that methanogens are extremophiles, and, by the same token, genetic convergent evolution is not convergence in the same sense that fish and dolphin body plans represent convergence. In any discussion of convergence upon intelligence through selection pressure to fit an intelligence niche would have to take account of these different senses of convergence.
But we still don’t have an answer to the question of what our place is in ecology and in the biosphere. It would perhaps flatter us not a little to call ourselves apex predators and situate ourselves at the top of the food chain. One often hears this, but one of the important legacies of human evolutionary psychology is that, in our long history, we have been both prey and predator. In terms of evolutionary time, we were probably prey for much longer than we were predators, although we have been predators during our most recent evolutionary spurts, including that evolutionary spurt that gave us our large brains: encephalization was parallel with predatorization. However, our predatorization has not been complete; human beings are still occasionally killed and eaten by true predators — by mountain lions, grizzly bears, and the like — that are not the prey of any animals except an armed human being. A human being without technology has no defense against a true predator.
While our place in the ecology of the terrestrial biosphere overlaps with that of the apex predator, the two do not perfectly coincide; a human being cannot predate a mountain lion with his bare hands, and a mountain lion can’t build a canoe and decamp to a different biome. So if human beings occupy an intelligence niche that is distinct from the apex predator niche, what exactly is that niche? It seems to be a biospheric-scale niche that can only be occupied by intelligently produced and employed technology, non-specific to any particular feeding behavior, which defines the rest of the trophic pyramid.
How did we evolve from the ecological niche of our environment of evolutionary adaptedness to inhabiting a distinctive intelligence niche of a species that uses technology to survive and to cross any biome(s)? In Making Silent Stones Speak: Human Evolution and the Dawn of Technology by Kathy D. Schick and Nicholas Toth, we find the concept of niche expansion:
“Another striking feature of this period of our evolution is the geographic and environmental expansion our ancestors were able to accomplish. A tropical animal that could break out so rapidly from the environment in which it had been born and evolutionarily bred is a creature that had made behavioral adaptation and flexibility an important part of its way of life. Interestingly, the migration of Homo erectus out of Africa coincides with a similar biogeographic spread of carnivores such as lions, hyenas, and leopards. Anthropologist Alan Walker has suggested the Homo erectus may have become a member of the ‘carnivore guild,’ and that successful hunting skills may have facilitated such large-scale movements among these species.”
We can understand niche expansion as a mechanism that brings us from the African savannah — the ecological niche of our environment of evolutionary adaptedness — and the intelligence niche proper, which is not defined by any biome or by an regional ecosystem, but which is defined by the biosphere entire.
The idea of niche expansion can be useful, then, to describe the passage from our original niche to the intelligence niche, and it may be useful again if and when human beings establish a viable population off Earth and thus again expand our niche. There may be an unending sequence of niches that can be uniquely inhabited by intelligent species. The level, degree, and kind of intelligence may matter; human beings may be able to occupy an intelligence niche up to a given level, but not beyond. What is that level? That will be a question for another time. But the larger point here is that intelligence niches may be ranged both by scale and kind, that is to say, we may expand the intelligence niche to progressively greater spatial dimensions, or we may diversify into specialist intelligence niches that are different in kind rather than different in scale.
One more quote to probe the idea of both levels and kinds of niches, including levels and kinds of intelligence niches, this time from Michael Ruse, Evolution and Religion: A Dialogue (2008):
“…Richard Dawkins… seizes on the notion of biological arms races. Remember how this suggests that, in evolution, the prey gets faster to escape the predator, and the predator gets faster to catch the prey. Dawkins thinks that in military arms races in the twentieth century, we have seen a move from heavier armament and stronger guns and bombs to more sophisticated electronic equipment, and in the living world, he thinks that this means that there is bound eventually to be a move to brains. Big brains like humans. The Cambridge University paleontologist Simon Conway Morris has a different idea. He thinks that there are certain ecological niches, as it were, waiting to be occupied by organisms. Natural selection is always looking for these and pushing life into them. So, for instance, there was a niche for a tigerlike being with saber teeth, and at least twice this niche was occupied — once by marsupials and once by placental mammals. Conway Morris thinks that there is a kind of succession of niches, ending with one for intelligent beings, and so progress was pretty much bound to happen.”
Just after this Ruse wrote, “Conway Morris seems to assume that there is an ordering of niches, with the intelligence niche top. Even if he proves that we had to evolve, he doesn’t prove that we are thereby better.” Ruse (like Sterelny) is a well known philosopher of biology, and one would think that he would be a bit more careful in talking about one species being “better” than another, because this kind of evaluation has resulted in a lot of fallacies in the past, and it took us (collectively, as a species) a long time to get past this kind of thing. So it seems superfluous, but apparently it is not, to note that Morris does not say that human beings, or, for that matter, any species occupying the intelligence niche is better, only that it occupies a distinctive ecological niche that requires intelligence to inhabit. Also, we certainly know from ecology that “there is an ordering of niches,” and we call this ordering of niches the trophic pyramid. That much should be uncontroversial.
In any case, there are a lot of ideas in the above-quoted passage from Ruse, and a lot more could be said. I am particularly interested in the idea of a succession of niches, meaning that the unrolling of natural history sees some niches disappear and other appear over biological time. This seems to be the case from what we know of natural history. Ruse gives the example of the niche provided by the rainforest canopy, and this a niche that unfolded over biological time. Similarly, grasslands only exist after grasses evolve, and the ungulates that feed primarily on grass only evolve into this grass-eating form after grasslands exist, and this is relatively recent in the history of Earth. In other words, not only do species evolve, but the trophic pyramid itself may evolve over biological and geological scales of time.
I have also been coming at this problem from another angle recently, and so I am prepared to appreciate that the trophic pyramid has to evolve over the history of the biosphere. In the earliest period of the biosphere, immediately following upon the origins of life, the multi-tiered trophic pyramid of contemporary climax ecosystems did not yet exist. As life added to its complexity over the past four billion years, the trophic pyramid also added in complexity, and took a more sharply defined outline as organisms specialized as producers, consumers, predators, and decomposers (each experiencing the convergent evolution upon the forms favored by the role of ecological specialization).
