IF YOU think kids grow up quickly these days, think again. The uniquely human
habit of taking 18 years or so to mature is a recent development in our
evolutionary history. Growth patterns of fossil teeth have shown that a
prolonged growing-up period evolved long after our ancestors started walking
upright and making tools.
Our great ape relatives, the chimpanzees and gorillas, take about 11 years to
reach adulthood. Scientists speculate that delaying this process allows children
to absorb our complex languages, culture and family relationships. What’s more,
we need extra time for our large brains to grow—they are half…
