Image: Tooth comparison
Nature
The black lines indicate perikymata, characteristic ridges on teeth that are caused by periodic changes in enamel growth. The ridges are less densely packed in Neanderthal fossil teeth, indicating that the species had a shorter period of dental growth and therefore matured more quickly than modern humans, researchers say.
updated 4/30/2004 12:40:01 PM ET 2004-04-30T16:40:01

If you think your kids grow up fast, consider this: A new study suggests that Neanderthal children blazed through adolescence and on average reached adulthood at age 15.

The finding bolsters the view that Neanderthals were a unique species separate from modern humans, because the time for humans to mature to adulthood grew longer over the course of their evolution, said paleontologist Fernando V. Ramirez Rozzi, who led the study.

Rozzi, with the National Center for Scientific Research in Paris, based his study on analysis of Neanderthal teeth. It will be published in Thursday’s issue of the journal Nature.

If Neanderthals and prehistoric Europeans could be seen side by side 35,000 years ago, “the Neanderthals would be bigger,” Rozzi said. ”Probably human children of about 5 years old would play with Neanderthals that were 3 years old.”

“It’s a very exciting paper,” said anthropologist Katerina Harvati of New York University. “Our common stereotype of Neanderthals is that they’re brutish and stupid, even though it turns out they have larger brains on average than ourselves.

“Now, this work actually supports the idea that ... they were dealing with the world in fundamentally different ways.”

A breed apart?
For more than 100,000 years, Neanderthals roamed across a vast region from Spain to southern Russia and western Asia, overlapping with anatomically modern man for several thousand years. Scientists disagree about how much interbreeding occurred between the groups and whether Neanderthals passed on any of their traits before they vanished some 30,000 years ago.

Harvati said their quick maturation rate may have been an adaptation to a harsh environment that decreased their life span and made it important for youngsters to reach sexual maturity quickly.

For his study, Rozzi spent about 18 months examining growth patterns on the crowns of incisors and canines from 55 individual Neanderthals, comparing them with corresponding patterns from early modern humans and ancestors to both groups. Like rings on a tree, the time it takes for a tooth to grow can be measured by counting visible lines that form about every nine days on the enamel.

On average, Rozzi found Neanderthals developed teeth 15 percent faster than modern humans. Therefore, a Neanderthal’s physical development, which mirrors tooth growth, must have been faster as well, he said.

Skepticism voiced
Erik Trinkaus of Washington University in St. Louis said he’s skeptical of the research. Human growth varies widely within a population, he said. In fact, Rozzi’s study includes some Neanderthal teeth that took as long to develop as modern human teeth.

University of Illinois at Chicago anatomy professor Jay Kelley said he’s also concerned about making conclusions based on what are essentially assumptions about Neanderthal tooth growth.

“That’s a little dicey,” said Kelley, who wrote an accompanying article in Nature calling for more research on the subject.

A previous version of this report erroneously phrased part of a quote from anthropologist Katerina Harvati.

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