Raw food kept us small-brained, but cooking made us human

Jean-François Millet (1814–1875) ,Wikipedia/The Yorck Project: 10.000 Meisterwerke der Malerei.

 Metabolic constraint imposes trade-off between body size and number of brain neurons in human evolution.

Abstract. Despite a general trend for larger mammals to have larger brains, humans are the primates with the largest brain and number of neurons, but not the largest body mass. Why are great apes, the largest primates, not also those endowed with the largest brains? Recently, we showed that the energetic cost of the brain is a linear function of its numbers of neurons. Here we show that metabolic limitations that result from the number of hours available for feeding and the low caloric yield of raw foods impose a trade-off between body size and number of brain neurons, which explains the small brain size of great apes compared with their large body size. This limitation was probably overcome in Homo erectus with the shift to a cooked diet. Absent the requirement to spend most available hours of the day feeding, the combination of newly freed time and a large number of brain neurons affordable on a cooked diet may thus have been a major positive driving force to the rapid increased in brain size in human evolution.

Proc Natl Acad Sci U S A. 2012 Oct 22. [Epub ahead of print]
Fonseca-Azevedo K, Herculano-Houzel S.
Source Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, 21941-590, Rio de Janeiro, Brazil.

@ Metabolic constraint imposes tradeo... [Proc Natl Acad Sci U S A. 2012] - PubMed - NCBI:

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