Our large brain continues to puzzle scientists. A paper published in Nature attempts to explain how it came to be so big, six times as large as those of mammals of comparable size.
According to the abstract, “establishing causes for brain-size evolution remains difficult. Here we introduce a metabolic approach that enables causal assessment of social hypotheses for brain-size evolution. Our approach yields quantitative predictions for brain and body size from formalized social hypotheses given empirical estimates of the metabolic costs of the brain. Our model predicts the evolution of adult Homo sapiens-sized brains and bodies when individuals face a combination of 60% ecological, 30% cooperative and 10% between-group competitive challenges, and suggests that between-individual competition has been unimportant for driving human brain-size evolution.” (internal references omitted).
The authors go on to conclude: “Our model indicates that brain expansion in Homo was driven by ecological rather than social challenges, and was perhaps strongly promoted by culture.”
The problem with all evolution-inspired brain research is that it assumes that our brain evolved from chimpanzee-like brains.
But if the human brain never evolved from an ape-like brain, then all Darwinian explanations turn out to be mere storytelling masquerading as science.
González-Forero, Mauricio and Andy Gardner. 2018. Inference of ecological and social drivers of human brain-size evolution. Nature 557, 554–557.