The average human brain is about three pounds. This makes it a much bigger proportion of our bodies than what is seen in other animals. Especially notable is our large cerebral cortex, which is responsible for memory, communication, and thinking.
So how did we get these big brains?
A team of researchers in the UK have proposed one possible answer: Over the past 2 million years, we worked our brains extra-hard in evaluating complex social situations and deciding who to cooperate with, they write in their paper, published August 12 in the journal Scientific Reports.
Robin Dunbar, an evolutionary psychologist at Oxford who was a coauthor of the study, previously proposed something called the “social brain hypothesis,” which is the idea that “the disproportionately large brain size in humans exists as a consequence of humans evolving in large and complex social groups.”
This is just an idea, of course, and it’s difficult to prove. By using computer models, however, the researchers hoped to show how this might have played out in the distant past.
The new study, Dunbar said in a press release, “reinforces this hypothesis and offers an insight into the way cooperation and reward may have been instrumental in driving brain evolution … [This suggests] that the challenge of assessing others could have contributed to the large brain size in humans.“
Evolution works in favour of those who try to help people just as successful, or more successful, than themselves, the authors note. The catch here is that one is forced to do a lot of mental judging when trying to figure out exactly how successful another person really is. And that’s a colossal, and pretty much never-ending, cognitive task.
The scientists bolstered support for the hypothesis by running computer models that simulated how people make decisions when coming into contact with others. They were able to see how these model humans judged their counterparts, and this was used to determine which behaviours become stronger over time, as this process is carried out.
These judging behaviours have been very strong in humans, as they are used (and were even more so in the past) to ensure survival. Over time, the brains of the human population have expanded, and the models suggest that this phenomenon could be part of the reason why.
And this new information could be used to help us in the future, too. The researchers think what they learned could be applied to engineering intelligent, autonomous machines to act out appropriately when coming into contact with one another. For example, driverless cars of the future will need to manage themselves, but also know how to cooperate with other driverless cars.
So, while this information provides some interesting theories about human evolution in the past, it could be even more influential as we figure out how technology will evolve in the future.
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