Researchers have found humans have a higher metabolism rate than closely related primates, which enabled humans to evolve larger brains.
The study found that, adjusted for body size, on a daily basis humans consume 400 more calories than chimpanzees and bonobos (closely related to chimps), 635 more calories than gorillas and 820 more calories than orangutans.
The study confirmed the researchers’ hypothesis that humans evolved a faster metabolism and larger energy budget to accommodate larger brains, which consume more calories. The higher metabolism also supports having more offspring and a longer lifespan. More. Paper. (paywall) – Herman Pontzer, Mary H. Brown, David A. Raichlen, Holly Dunsworth, Brian Hare, Kara Walker, Amy Luke, Lara R. Dugas, Ramon Durazo-Arvizu, Dale Schoeller, Jacob Plange-Rhule, Pascal Bovet, Terrence E. Forrester, Estelle V. Lambert, Melissa Emery Thompson, Robert W. Shumaker, Stephen R. Ross. Metabolic acceleration and the evolution of human brain size and life history. Nature, 2016; DOI: 10.1038/nature17654
Something about this explanation doesn’t quite work. Brains deteriorate quickly when deprived of essentials. The body can’t just “evolve” a higher metabolism to accommodate a more demanding brain. The whole thing would need to be a co-ordinated program.
And for what purpose? A primate can feed and protect itself and reproduce without being exceptionally intelligent.
Also, is it true that larger brains promote a faster metabolism in principle? What about whales?
Is it true that a fast metabolism supports having more offspring? Reptilians whose metabolism can drop to very low levels certainly produce more offspring than primates.
Is it true that a fast metabolism is associated with longevity? What about hamsters?
Reader insight into these questions is appreciated.
See also: The simple steps that made us human? The slide show ends with: “Because big questions need answering.” Yes, but one could be a bit more particular about the depth of the answers. These answers seem addressed to people who have no serious questions.
Human origins: The war of trivial explanations
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