AI Models and the Evolution of Human Cognition

Across a wide variety of animals, mammals in particular, there’s certain characteristic changes in the number of neurons and the size of different brain regions as things scale up. There’s a lot of structural similarity there and you can explain a lot of what is different about us with a brute force story which is that you expend resources on having a bigger brain, keeping it in good order, and giving it time to learn. We have an unusually long childhood. We spend more compute by having a larger brain than other animals, more than three times as large as chimpanzees, and then we have a longer childhood than chimpanzees and much more than many, many other creatures. So we’re spending more compute in a way that’s analogous to having a bigger model and having more training time with it. And given that we see with our AI models, these large consistent benefits from increasing compute spent in those ways and with qualitatively new capabilities showing up over and over again particularly in areas that AI skeptics call out. In my experience over the last 15 years the things that people call out are like —”Ah, but the AI can’t do that and it’s because of a fundamental limitation.” We’ve gone through a lot of them. There were Winograd schemas, catastrophic forgetting, quite a number and they have repeatedly gone away through scaling. So there’s a picture that we’re seeing supported from biology and from our experience with AI where you can explain — Yeah, in general, there are trade-offs where the extra fitness you get from a brain is not worth it and so creatures wind up mostly with small brains because they can save that biological energy and that time to reproduce, for digestion and so on. Humans seem to have wound up in a self-reinforcing niche where we greatly increase the returns to having large brains. Language and technology are the obvious candidates. You have humans around you who know a lot of things and they can teach you. And compared to almost any other species we have vastly more instruction from parents and the society. You’re getting way more from your brain than you get per minute because you can learn a lot more useful skills and then you can provide the energy you need to feed that brain by hunting and gathering, by having fire that makes digestion easier. 

Basically how this process goes on is that it’s increasing the marginal increase in reproductive fitness you get from allocating more resources along a bunch of dimensions towards cognitive ability. That’s bigger brains, longer childhood, having our attention be more on learning. Humans play a lot and we keep playing as adults which is a very weird thing compared to other animals. We’re more motivated to copy other humans around us than the other primates. These are motivational changes that keep us using more of our attention and effort on learning which pays off more when you have a bigger brain and a longer lifespan in which to learn in. 

Many creatures are subject to lots of predation or disease. If you’re mayfly or a mouse and if you try and invest in a giant brain and a very long childhood you’re quite likely to be killed by some predator or some disease before you’re actually able to use it. That means you actually have exponentially increasing costs in a given niche. If I have a 50% chance of dying every few months, as a little mammal or a little lizard, that means the cost of going from three months to 30 months of learning and childhood development is not 10 times the loss, it’s 2^-10. A factor of 1024 reduction in the benefit I get from what I ultimately learn because 99.9 percent of the animals will have been killed before that point. We’re in a niche where we’re a large long-lived animal with language and technology so where we can learn a lot from our groups. And that means it pays off to just expand our investment on these multiple fronts in intelligence.

Carl Shulman on the Dwarkesh Podcast

August 21, 2023