Childhood gets longer
Brains too big to finish growing before birth force a long, helpless, teachable infancy.
- When
- —
- Duration
- 826 thousand years
- Known to
- ± 300 thousand years
- Era
- Early Pleistocene, Quaternary
A large-brained infant cannot pass through a pelvis narrowed for efficient bipedal walking, so human brains do most of their growing after birth. The result is an infant far more helpless than any ape's and a childhood far longer, which requires help from others and creates an extended window for learning. Tooth development in Turkana Boy shows this stretching had begun but was not complete: he grew faster than a modern child would. The long human childhood is assembled gradually across this epoch.