Research press release





今回、Mauricio Gonzalez-ForeroとAndy Gardnerが報告した新しい予測モデルによれば、ヒトの脳の大きさは、いくつかの異なる要因に応答して進化したものであり、それらの要因のうちの60%が生態学的課題に、30%が協力行動に、10%が集団間の競争に関連しており、個人間の競争は比較的重要でないとされている。この新知見は、社会的複雑性がヒトの大型の脳が進化した原因ではなく結果である可能性が高く、人間性の本質が社会的駆け引きではなく、生態学的課題の解決と文化の蓄積である可能性が高いとする点で興味深い。

Ecology was the major factor driving the evolution of our big human brains, a Nature paper suggests. The study helps to inform a major debate in the story of human evolution.

Researchers have spent decades arguing over why the human brain has evolved to be so unusually large. A number of theories exist; among them the ‘social brain hypothesis’, which suggests that bigger brains evolved to help manage our increasingly complex social lives, and the ‘expensive tissue hypothesis’, which posits that meat-eating allowed brains to evolve at the expense of the gut. A fundamental problem with these theories, however, is that they rely on correlative data and so are unable to disentangle cause and effect.

According to a new predictive model by Mauricio Gonzalez-Forero and Andy Gardner, human brain size evolved in response to a number of different factors that were 60 per cent ecological, 30 per cent cooperation-related and 10 per cent related to competition between groups. Competition between individuals was relatively unimportant. The findings are intriguing because they suggest that social complexity is more likely to be a consequence rather than a cause of our large brain size, and that human nature is more likely to stem from ecological problem-solving and cumulative culture than it is from social manoeuvring.

doi: 10.1038/s41586-018-0127-x

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