Why does David Geary say human babies are born premature?

David Geary says a human baby born with a brain as mature as a newborn chimpanzee's would need close to two years of gestation. Instead infants arrive early and dependent, then spend a long childhood learning to hunt, forage and make tools, with some skills not mastered until around 30. Geary and Mark Flynn argued 25 years ago that paternal care and protection trace back to gorilla-like australopithecine families.

• Chris Williamson raised the idea that births on Mars might rely on C-sections, removing the limit on infant head size.

Source: our own transcription of the episode. The full conversation is on Modern Wisdom (2026-11-05). Read the whole episode summary →

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