Neandertals show staying power in Europe.

As recently as 28,000 years ago, Neandertals lived in central Europe, according to a new study. This indicates that they survived several millennia longer than most scientists have assumed.

The pushed-forward age estimate challenges the view that these heavily built relatives of modern humans took refuge in southwestern Europe shortly before dying out around 30,000 years ago. However, ongoing debate over whether Neandertals contributed significantly to the evolution of modern humans appears unlikely to abate.

"I was floored by these new Neandertal dates," says anthropologist Fred H. Smith of Northern Illinois University in DeKalb, a member of the team that derived the age estimates from Neandertal fossils found at Croatia's Vindija Cave. "This adds support to the idea that there was a good deal of genetic exchange between Neandertals and modern humans."

In earlier work, Smith asserted that Neandertal fossils at this site share several anatomical features with modern humans.

The new investigation, published in the Oct. 26 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES, rests on accelerator mass-spectrometry radiocarbon dating of two Neandertal skull pieces from the cave. This technique measures precise numbers of carbon isotopes in small samples of organic material.

One fossil dates to about 28,000 years ago, the other to 29,000 years ago, Smith and his colleagues report. This evidence for Neandertals' extended European survival indicates that they lived in the same region inhabited by modern humans for at least several thousand years, holds Erik Trinkaus of Washington University in St. Louis, a coauthor of the study. That's plenty of time for extensive interbreeding, Trinkaus argues.

As an example of prehistoric genetic mixing, he cites the recently discovered 24,500-year-old skeleton of a child that--at least in the view of some researchers--exhibits both modern human and Neandertal characteristics (SN: 5/8/99, p. 295).

Moreover, stone and bone tools at Vindija Cave contain some features considered typical of Neandertals and others characteristic of modern humans. Neandertals probably made all of these implements, Smith says, thus challenging the influential theory that modern humans adopted a uniquely advanced tool-making style beginning around 35,000 years ago.

It's also possible, Smith maintains, that Neandertals traded with modern human groups to obtain some of the tools that scientists discovered at Vindija.

Christopher B. Stringer of the Natural History Museum in London finds the Croatian evidence intriguing but still suspects that Neandertals interbred with modern humans just occasionally and only in isolated areas. Cold-adapted Neandertals probably died out due to rapid climate shifts in Europe with which modern humans coped "a bit better," Stringer says.

He also remains skeptical of Smith and Trinkaus' argument that Neandertals fashioned complex tools, such as those uncovered at Vindija, long attributed only to modern humans.