Study Debunks Human-Neanderthal Hybrid Claim

Dec. 4, 2007 -- Did modern humans interbreed with Neanderthals and, if so, did the mating result in a half-human, half-Neanderthal hybrid ? The answer is possibly yes to the interbreeding but no to the hybrid, according to the authors of a new study that is already making waves among leading anthropologists.

At the center of the study, published in the Journal of Human Evolution, and the current debate, is a 29,000-year-old Romanian skull that is one of the oldest fossils in Europe with modern human features. But those features aren't quite a perfect match with us, which has led some experts to suspect it was a cross between a Neanderthal and a modern human.

That's not so, according to Katerina Harvati, and her colleagues Philipp Gunz and Dan Grigorescu.

"It differs from living people only in subtle ways, and always well within the range of modern human variation," Harvati, who led the recent study, told Discovery News.

"It has, for instance, slightly heavier eyebrows than the average person, and is generally somewhat more robust than average," she added, explaining that modern humans have gradually evolved to become more slight and slender than Upper Paleolithic people were.

Harvati is a senior researcher in the Department of Human Evolution at the Max Planck Institute for Evolutionary Anthropology and is an adjunct associate professor of anthropology at City University of New York Graduate School.

She and her team took detailed 3-D measurements of the Romanian skull, called Cioclovina calvaria, and compared these with a similar head shape analysis of Neanderthals, modern humans and fossils of other hominids found in Europe, Africa and countries bordering the eastern Mediterranean Sea.

The researchers also studied animal hybrids and developed an unprecedented list of proposed criteria for evaluating whether or not a fossil specimen is a hybrid.

The criteria include the following: greater or much smaller size than the parental species, on average; evidence for developmental instability; possible occurrence of rare attributes, such as having extra teeth or bone joints; and possessing an intermediate shape.

"Cioclovina did not meet any of these criteria -- a strong refutation of the hypothesis that it represents a hybrid," Harvati said.

The scientists support the Single Origin model of human evolution. This holds that modern humans evolved between 200,000 and 100,000 years ago in a single location -- mostly likely Africa -- with subsequent migration displacing archaic hominid populations, including Neanderthals, around the world.