Most animals have brains in proportion to their body size – species with larger bodies often have larger brains. But the human brain is almost six times bigger than expected for our bodies. This is puzzling, as the brain is very costly – burning 20% of the body's energy while accounting for only 4% of its mass.
As evolution tends to remove waste, how come we evolved such large, energy-consuming brains? There are many different ideas out there, with the dominant hypothesis suggesting that challenging social interactions were the driving force. But our new study, published today in Nature, finds evidence against this idea and shows that human brain expansion was likely driven by ecology.
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