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Stiffer Competition, Bigger Brain?

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Social competition may help explain the tripling in size of the human brain over the past 2 million years.

That's the conclusion of a new study by a University of Missouri professor after examining 153 hominid skulls.

Professor David Geary found that ancient population growth led to increased social competition, a connection he linked to evolutionary increases in brain size.

He also looked at possible links between brain growth, climate change and ecological demands. But the links between competition and brain size were most consistent.