Humans are born premature relative to other primates

Kimerer LaMothe, The dancing species: how moving together in time helps make us human, Aeon.

Further support for this thesis comes from anthropologists and developmental psychologists who have documented the importance of bodily movement to infant survival. As the American anthropologist Sarah Blaffer Hrdy affirms in her book Mothers and Others (2009), human infants are born premature, relative to their primate cousins: a human foetus intent on emerging from the womb with the neuromuscular maturity of an infant chimpanzee would need to stay there for 21 months. Instead, hopelessly dependent human infants must have a capacity to secure the loyalty of caregivers at a time when their sole means for doing so is by noticing, recreating and remembering those patterns of movement that succeed in connecting them to sources of nurture. In a view shared by Hrdy and others, this capacity for the responsive recreation of bodily movement forms the roots of human intersubjectivity. In other words, infants build their brains outside the womb in relation to mobile others by exercising a capacity to dance.