A theory called the cultural brain hypothesis could explain extraordinary increases in brain size in humans and other animals over the last few million years, according to a study published in PLOS Computational Biology by Michael Muthukrishna of the London School of Economics and Political Science and Harvard University, and colleagues at the University of British Columbia and Harvard University.
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Terrence Deacon wote a whole book arguing for this in his “The Symbolic Species” … and also Jacob Bronowski in his “Science and Human Values” and “Origins of Knowledge and Imagination.” and Ascent of Man and lots of his other stuff.