Kids may wish for shorter zit-filled childhoods and adolescence. But taking longer to mature may have given humans an evolutionary edge over Neanderthals by giving their brains and social skills more time to develop. Now dental records of early human fossils show how that developmental delay crept in over time.
The average Neanderthal may have reached adulthood a few years before most modern humans, according to Tanya Smith, an evolutionary biologist at Harvard University. She and her colleagues used synchrotron X-rays imaging to create a 3-D image of the teeth from 11 Neanderthals and early human fossils. (A synchrotron is a beam of X-rays as thin as a human hair and very intense such that it can reveal teensy details.)
“Teeth show biological rhythms – intrinsic or internal clocks that capture each day of their growth, as well as stress during development,” Smith said. “Being born is stressful enough that this leaves a characteristic stress line we can identify – a birth certificate.”
But she cautioned that the closely related human and Neanderthal populations make it difficult to pin down a precise difference in the actual ages of maturity. Other research has shown that modern humans still have Neanderthal genes from back when the two populations mated.