Social Intelligence

HYPOTHESIS

The social intelligence hypothesis states that social intelligence, that is, complex socialization such as politics, romance, family relationships, quarrels, collaboration, reciprocity, and altruism, (1) was the driving force in developing the size of human brains and (2) today provides our ability to use those large brains in complex social circumstances. That is, it was the demands of living together that drove our need for intelligence generally. Archeologist Steve Mithen believes that there are two key periods of human brain growth that contextualize the social intelligence hypothesis. The first was around two million years ago, when the brain more than doubled, from around 450cc to 1,000cc by 1.8 million years ago. Brain tissue is very expensive metabolically, so it must have served an important purpose. Mithen believes that this growth was because people were living in larger, more complex groups, and had to keep track of more people and relationships, which required a greater mental capacity and so a larger brain.

The second growth in human brain size occurred between 600,000 and 200,000 years ago, when the brain reached its modern size. This growth is still not fully explained. Mithen’s believes that it is related to the evolution of language. Language is probably the most complex cognitive task we undertake. It is directly related to social intelligence because we mainly use language to mediate our social relationships.

So social intelligence was a critical factor in brain growth, social and cognitive complexity co-evolve.

http://en.wikipedia.org/wiki/Social_intelligence