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Have group-conflicts helped to increase size of our brain?

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Posted November 28, 2014
Picture: Brain. Image credit: J E Theriot via Flickr, CC BY 2.0.

Picture: Brain. Image credit: J E Theriot via Flickr, CC BY 2.0.

Our brains represent only one fiftieth of our body, but they burn one fifth of our energy. How our ancestors managed to afford such expansion of their cognitive abilities? Biologist Sergey Gavrilets at the University of Tennesse argues that it was driven by the need to fight with other groups and with the harsh environment.

“My results suggest that collaborative ability is more likely to evolve first by between-group conflicts and then later be utilized and improved in games against nature,” he says.

Two major types of explanation are offered when the evolutionary roots of human brain size are debated. Some scientists think that it was strongly affected by ecological factors, such as harshness of habitat or prevalence of parasites. However, these explanations have only weak empirical support.

“An alternative set of explanations coming under the rubric of the social brain hypothesis focuses on selective forces resulting from interactions with conspecifics,” the American researcher writes. These theories are more plausible from the empirical point of view.

For instance, strong positive statistical association between brain size and such parameters as population density or group size is observed. However, details of evolutionary story continue to be harshly debated. Gavrilets investigated, whether the need for collaboration in various collective action problems has facilitated development of cognitive abilities.

It is often argued that conflicts between different groups played an important role in shaping many human characteristics. In fact, this idea was already developed in Charles Darwin’s book The Descent of Man.

“Here, I have provided strong theoretical support to these arguments by showing that between-group conflict can select for increased intelligence and cognitive abilities used to coordinate group activities, potentially overcoming both the high costs of large brains and the collective action problem,” author of the study published in the Journal of Royal Society Interface claims.

According to his theoretical model mutual helping observed among the members of large groups was preceded and probably enabled by between group competitions. “As predicted by the theory above, cooperation increases dramatically in the presence of direct between-group competition to a level that cues of group competition have an automatic or unconscious effect on human behaviour that can induce increased within-group cooperation,” the biologist emphasizes.

Article: Gavrilets S., 2015, Collective action and the collaborative brain. Journal of Royal Society Interface, 12: 20141067. Source link.

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