Computer simulation reveals how we worked together to evolve bigger brains

Illustration for article titled Computer simulation reveals how we worked together to evolve bigger brains

Why do humans have such enormous brains for our size? One popular explanation is that we needed the added cognitive capacity to deal with large, complex social groups. And now, a fascinating new computer simulation suggests that cooperation really did make us smarter.


A team of researchers at Trinity College Dublin simulated fifty very simple brains, each with only three to six neurons. The brains then faced each other in a pair of classic psychology games, the Prisoner's Dilemma and the Snowdrift Game. In both instances, doing the helpful thing can backfire if the other person betrays them — whether it's refusing to implicate the other person in a crime or volunteering to dig them out of a snowbank — but both sides can achieve acceptable results if they cooperate. Choosing to cooperate is only a really good strategy if you have played enough times to know whether your partner is trustworthy or not.

The researchers used these games as a very simple proxy for the cooperative behaviors we see among humans and our primate cousins, but the results were still intriguing. ScienceNOW reports:

After playing one of the games, the brains reproduced asexually. Individuals that did better were programmed to be more likely to have offspring. Then all of the brains in the new generation had a chance to undergo a random mutation. The mutations could change the brain's structure, number of neurons, or the strengths of the connections between those neurons. Each simulation ran for 50,000 generations, with 10 runs of the simulation for each of the two games.

As time went on, the researchers measured how much the brains cooperated with each other and how many neurons the brains had-an indicator of how intelligent they were...Bigger brains did better as cooperation increased. That meant they got to reproduce more, which meant more brains had the capacity to cooperate with others.


The researchers aren't suggesting that this model has actually proven that social cooperation is what made bigger brains evolve. However, they do argue that the presence of such cooperative behaviors should be enough for intelligence to evolve, even if the story of primate evolution is almost certainly more complex than that. The social intelligence hypothesis probably doesn't explain everything about our evolutionary past, but it's likely a key piece of the puzzle.

Proceedings of the Royal Society B via ScienceNOW. Top image via Shutterstock.

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Corpore Metal

Personally, I think the brains of mammals grew large both cooperative and competitive reasons. It was the complex and surprising interplay between the two forces that drove for larger, smarter brains. We see mostly solitary mammals, we see pack, herds and bands of mammals and we see mammals that oscillate between those modes all the time—like primates.

That said, I think it's a mistake to generalize from what we discovered here from these neurode simulations all the way up to something as complicated as a mammal brain. Biologists and mammal ethologists already have huge amounts of evidence to support the hypothesis that cooperation favors larger brains in later generations (Or competition favors larger brain size in later generations, etc. etc. etc. It works both ways.) and so these simulations seem unnecessary to me to underscore any points here.

Having said that, I still think this research is very useful but in an entirely different area. What these simulations might be very useful in showing us is how neurons might be behave in the histological development of fetal mammal brains. There could be very similar processes that happen early in the development, growth and differentiation of tissues in fetal brains. There could be the equivalents of the Prisoner's Dilemma or the Snowdrift Game happening in those early days and months of a growing fetal brain.

What I'm really referring to here is the Neural Darwinism ideas of Gerald Edelman:


And other related hypotheses by other neurologists.

I think we can also see examples of this sort of thing going even in adult brains as neural networks change, grow and prune themselves over time as new memories and experiences are formed.

I'm not a neurologist or biologist, it's that these are some of the ideas that came to me in thinking about this stuff.