Neanderthals had brain ability, tool skills, and cultural advancement comparable to Homo sapiens, so why did they go extinct while humans survived? Fernando Ramirez Rozzi of the Laboratory of Human Evolution at the French National Center for Scientific Research in Paris is now trying dental forensics to solve the evolutionary enigma.
Like trees, teeth preserve a layered record of their growth. Dental enamel contains considerable information because tooth growth is closely tied with the rest of the body’s development. Ramirez Rozzi compared enamel layers from Neanderthals and Paleolithic modern humans as well as from Homo antecessor and Homo heidelbergensis, thought to be common ancestors of both. The Paleolithic human teeth show they reached peak maturity at 18 to 20 years—roughly what people do today. The enamel on Neanderthal teeth, however, was deposited much faster, suggesting they reached maturity at 15 years. H. antecessor and H. heidelbergensis fell in between, suggesting that development sped up in the Neanderthal lineage while it slowed down among our direct ancestors.
Rapid development is a common evolutionary adaptation for species faced with high mortality. “It’s possible that this faster development was a boon when Neanderthals first developed and spread through Europe,” Ramirez Rozzi says. But this same adaptation could have sparked the decline of the Neanderthals 100,000 years later. “They had even bigger brains than we did. A shorter maturation means they would have had to come up with more food to fuel the brain, especially during the early years,” he says. “That kind of demand would have made them much more susceptible to food shortages caused by fluctuating climatic or other conditions.”