Many of the Mladec remains were destroyed at the end of World War II in a fire in the Mikulov castle on the Czech-Austrian border.
Several attempts have been made to accurately date the remaining fossil assemblage accurately by dating the surrounding soil and animal remains, but the attempts have all failed.
The scientists behind the new study used a technique called accelerator mass spectrometry to show that the remains are about 31,000 radiocarbon years old.
"They are clearly morphologically modern and help establish that modern humans had entered Europe by 30,000 years ago," said Fred Smith, the chair of the Department of Anthropology at Loyola University in Chicago, Illinois. Smith was not involved with the study. (Morphology denotes the form and structure of an organism or its parts.)
"This is important because other finds that had been interpreted as demonstrating this are now known to be younger," Smith said.
The specimens all date to a time period belonging to the Aurignacians, an early modern human culture that existed about 30,000 to 40,000 years ago.
The Mladec collection also includes Aurignacian tools and art associated with early modern humans. At this time, bone and antler tools became common. Also, humans began to wear beads and pendants and to create bone flutes.
"The dating of the finds is important for the verification of the assumed Aurignacian origin of the fossils, and for the determination of their position within this cultural time period," said Maria Teschler-Nicola of the Natural History Museum of Vienna, Austria. She is a co-author of the study.
It is impossible to completely rule out the likelihood that the Neandertals may have made the artifacts that surround the Mladec remains. But the bones themselves are universally accepted by scientists as those of early modern humans, not Neandertals.
But there has been great debate over whether the remains show some Neandertal features or are the same as modern human remains, in terms of their structure and form.
"The Mladec individuals do not consistently exhibit the same Neandertal skeletal features, to whatever extent they possess them, nor do they yield any trace of Neandertal DNA," said Theodore Schurr, an anthropology professor at the University of Pennsylvania in Philadelphia.
"Therefore, based on these data, the Mladec remains show no strong evidence of interbreeding between Neandertals and anatomically modern humans, despite this population [of humans] having been around when Neandertals still lived in Europe."
A clear distinction between Neandertal and modern human features would support the "Out of Africa" theory, which holds that early modern humans dispersed from Africa and into Europe, where they replaced the Neandertals.
The new study does not specifically address the question of interaction between Neandertals and modern humans.
But some experts believe that humans and Neandertals interbred and that Neandertals, therefore, contributed to human ancestry.
"Many of us feel that there is evidence of some contribution of Neandertals to this early modern gene pool," said Smith, the Loyola anthropologist.
"This is reflected in certain details of the anatomy of some Mladec remains," he said. "For instance: the presence of remnant [rear skull] bones that are not present in the early modern Africans and Near Easterners. "
Smith acknowledges that other scientists believe these similarities between Mladec and Neandertal bones are just the result of random change and do not indicate any Neandertal contribution.
"However, now knowing that the Mladec sample is indeed a very early modern sample is important, regardless of which side of the debate one stands on," he said.
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