Does Intelligence Stabilize the Biosphere?

I was lucky enough to be involved in building The Madingley Model, an integrated of the whole biosphere which can simulate, in a computer, the complete life cycle of most animals on Earth, from aphids to wolves, to sharks, to centipedes, to mice. Individuals are born, search for food, grow, shrink, die, predate on each other, and reproduce.

One of the important ideas that emerged from working on the model was that the intelligence of the world's animals and plants might help make the whole biosphere more stable. By intelligence, I mean any combination of deliberate, non-random behavior, learning, decision making and so on. This definition differs from the most common conception of intelligence, which is very human centric, and also differs from most conception of intelligence used in discussions of artificial intelligence (AI), which seems to very much focussed on robots with human-like abilities that move around and do things like household chores (!). My definition of intelligence is a more general concept that includes all of the above, but also refers to any kind of process that integrates information in order to make a 'smart' decision of any kind.

So far as I can tell, all living things exhibit this kind of intelligence to some degree, not because it is a necessary condition of being alive, but simply because intelligence is such a huge advantage. The kinds of intelligence that large birds, mammals, and even squids and octopuses exhibit can be truly amazing, as a quick tour of youtube can show you. But even bacteria follow chemical gradients, and have complex signalling behaviours that enable them to coordinate their actions in large groups. Amoebae go into dormant, very tough ‘cyst’ states when times are hard, and only come out when times get better. The simplest multicellular animals show all kinds of intelligent behaviours. Plants are also intelligent, too, integrating all kinds of signals in order to make smart decisions, and they even show some ability to remember, learn, and signal to other plants.

The relevance to the Madingley Model and ecosystem stability? Well, initially we kept everything in The Madingley Model as Einstein would (apocryphally) have wanted it — as simple as it could be, but no simpler. Therefore, we made the simple assumption that all animals and plants are really stupid. The trouble was that this version of the model would always blow up on us. We’d get utterly ridiculous boom and bust dynamics, with lots of animals one minute, then them all dying off the next, then things going extinct, then something coming back and starting a boom again. And meanwhile the plants were being alternately left completely alone, or suddenly being eaten down to the bare ground. All was chaos. It was not what we had in mind. Yes, in the real world, there is lots of random, perhaps chaotic variation in some parts of some ecosystems, but no ecologist I know thinks the whole ecosystems are that chaotic.

Then we made just one simple concession to animal intelligence, by letting predators learn about their prey, in a very simple way. If a particular type of prey became more common, we made the predators get better at hunting it, as if they were learning to recognize that type of prey, or learning to catch it more efficiently – just as predators do in reality. And hey presto, that one simple change, in one aspect of the behaviour of just one kind of animal, suddenly created a very stable, well-behaved global biosphere.

This result made me think differently about the whole biosphere. I had always had a passing curiosity in plant and animal intelligence, but now I see it as absolutely crucial in creating a biosphere that is much more stable and that is, therefore, much better able to sustain yet more biodiversity, yet more intelligence, and yet more life — including us. Thinking about this issue has led me to a hypothesis for how intelligence increase stability, which I call 'triple whammy stability'. In summary, intelligence means that when species fall on bad times and become rare, they go under the radar of both their enemies (whammy one) and their prey (whammy two), which in turn acts to rescue the unlucky species, making for more diverse communities that can better tolerate change in the future (whammy three). I hope to expand on triple whammy stability in a future post, because it seems to be applicable quite broadly, even outside ecology.

Of course, intelligence will not be stabilizing absolutely all of the time. Now and again a really unusually intelligent species might gain such a huge temporary advantage over everything else, that it might push ecosystems into much more chaotic states, causing those ecosystems to lose both diversity, and intelligence. But I would predict that if such a species continued in this way, one of two things would happen. Either the species would push the ecosystem into a state that was so chaotic it could no longer be suitable for supporting that species at all. Or the species would become so common that it would become an irresistible target for enemy species, such as disease-causing pathogens. In either case, our super-intelligent species would either go extinct, or become much rarer than it had been, allowing nature's virtuous circle of diversity and intelligence to begin to build things back up again. Oh wait...

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