Study Suggests Neanderthals Enjoyed Long Childhoods

Nasty, brutish and short.

Until about the last decade or so, that is how many of us were accustomed to thinking about Neanderthal life.

But a lot has changed since then, not least of which is the emergence of smoking gun DNA evidence that Neanderthals are, in fact, family.

Now a new study runs counter to earlier thinking by suggesting that Neanderthals reached maturity at about the same rate as modern humans.

"Neandertals have long been seen as the James Deans of human evolution — they grew up fast, died young, and became legends," Ann Gibbons writes in Science. "But now, a rare skeleton of a Neandertal child suggests that our closest cousins didn't all lead such fast lives — and that our own long childhoods aren't unique. The find may reveal how Neandertals, like humans, had enough energy to grow bigger brains."

A leading theory says that big brains take longer to develop, so in humans, childhood lasts longer to allow our brains time to grow. Chimpanzees, with much smaller brains than modern humans, mature much faster.

Back in 2010, NPR's Christopher Joyce reported on this "live fast, die young" hypothesis, which was bolstered by studies of Neanderthal skulls. As Chris wrote at the time: "Like the 'slow food' movement, 'slow growth' gave complex brains more time to 'cook,' so to speak, and then learn all those things a fancy brain could learn."

That hypothesis was based largely on the study of Neanderthal's teeth. Hominid teeth have telltale lines, similar to tree rings, that show their development from birth until the end of childhood.

But that single benchmark may not have been enough. Thanks to the discovery of a 49,000-year-old partial Neanderthal child's skeleton at El Sidrón Cave in northern Spain, the latest research has benefited from looking at more than just teeth.

While the teeth did help put the age at death for the ancient Neanderthal child at 7.7 years, the team of scientists led by Antonio Rosas also measured the maturation of the skull, spine, elbow, hand, wrist and knee of what is believed to have been a boy. In six key places that calcify during development, the Neanderthal boy appeared to have matured at the same rate as a child his age today.

Gibbons writes: "The team noted that the child's brain had reached only about 87% of an average adult Neanderthal's brain size, whereas modern human brains reach 90% of their adult size by age 5."

In other words, Neanderthals may have matured even a little more slowly than modern humans.

Even so, it's just one skeleton, which might not be representative of an average Neanderthal child, scientists caution.

"Neandertal first molars typically grow at a faster rate than modern human molars ... which makes this individual unusual," paleoanthropologist Tanya Smith of Griffith University in Nathan, Australia, who studies Neanderthal tooth development, is quoted by Gibbons as saying.

"Also, the brains and bodies of adult Neandertals vary in size, and this individual might have grown up to be a relatively small-brained Neandertal," [anthropologist Marcia] Ponce de León and [neurobiologist Christoph] Zollikofer [from the University of Zurich in Switzerland], write in an email quoted by Gibbons.

Copyright 2021 NPR. To see more, visit https://www.npr.org.