The Long Way Back to Ourselves

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Fire, Cooking, and the Invention of a Long Childhood

This episode traces how fire and cooking reshaped the human body, noting a chimpanzee spends about six hours a day chewing raw food while you spend under an hour. It presents Richard Wrangham's cooking hypothesis, then complicates it: a 2011 analysis found habitual fire use only becomes archaeologically dense around 400,000 years ago, long after Homo erectus had evolved smaller teeth. The chapter also corrects the obstetrical-dilemma explanation for helpless infants, citing research showing pelvis width does not affect walking efficiency, pointing instead to the mother's metabolic limits during pregnancy. Childhood, often assumed a natural, protected state, is instead evolution's most expensive investment, paid in calories and mothers' lives.