Simulating The Social Brain Hypothesis

An Oxford University team of two led by Tamás Dávid-Barrett published an open access paper in the Proceedings of the Royal Society B testing the social brain hypothesis. In a nutshell, the social brain hypothesis was created by the other author of this paper, Robin Dunbar, who theorized in 1993 with anthropologist Leslie Aiello, that intelligence among humans is a function of surviving and reproducing in large and complex social groups and not solving ecological problems.

Social Brain

In order to investigate their hypothesis, they looked at Encephalization Quotient is a measure of brain size relative to body size. The cat’s EQ of about 1, which is expected for its body size. But most primates have brains that are larger than expected for their body size. Chimps have an EQ of 2.5. Humans have almost three times as much, at around 7.5. Dolphins have an EQ of more than 5, and rats and rabbits are way down on the scale — below 0.4. Aiello and Dunbar published their findings, along with a run down in the fossil record, in the widely cited 1993 paper in Current Anthropology. They correlated that the larger a species’ group size, then the larger its brain—particularly the neocortex, the outer layers where most of the serious thinking goes on.

The current paper, “Processing power limits social group size: Computational evidence for the cognitive costs of sociality,” describes how the authors used agent-based modelling to serve up coordination problems to agents. Solving these problems required synchrony of behaviors, meaning each agent had to do the right thing and the right time in just the right way for the group to progress. In effect they simulated in computer models.

They found out that the viability of group size increased as calculation, or figuratively speaking cognitive, capacity increased. Furthermore, their simulations demonstrated the need for complex language through the situations where group size increased and the agents had to switch to deeper information processing strategies that allowed them to differentiate among their problems.

I like research like this, however I do not appreciate how it is digested and regurgitated in the press. The press is running headlines like “Big brains developed big brains to deal with society,” implying that evolution has some goal or some design. This is not true. It is true however, sociality is a selective pressure. And to be social required large frontal lobes, but is not the sole region for human intelligence.

3 thoughts on “Simulating The Social Brain Hypothesis

  1. So the 27 trillion ants on earth should have the largest brain size? Ants seem to be reproducing at a faster rate than humans without the social-cultural complexities you are alluding to.

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