The earliest evidence so far for adhesive production by anatomically modern humans dates to around 70,000 years ago, according to the researchers. It is likely that members of Homo sapiens in Africa figured out how to create tar on their own — a case of independent invention — but scientists have not ruled out that they learned the birch bark tar production techniques from Neanderthals.
Tar has many possible functions. Kozowyk, though, said, “During the Paleolithic, it’s unlikely that tar was used for much more than hafting tools.”
“In historic times," he added, "tar was used to waterproof boats and ships, containers and to protect wooden buildings, so its use is not limited to hafting tools. But these require production on an industrial scale that is not seen until more recently.”
Placing materials in ceramic containers can help with tar production. There is no evidence that Neanderthals ever produced pottery, however.
“There was probably no need for pottery until quite recently — speaking on a scale including hundreds of thousands of years of human evolution — and even in most modern human hunter-gatherer societies, pottery is an exception,” Kozowyk explained.
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Neanderthals and early anatomically modern humans might have instead crafted containers out of wood and plant fibers. But if they did, preservation of such items is so poor that there is no firm evidence of them dating to the times of the oldest tar production.
Neanderthals and anatomically modern humans diverged long before then. An emerging theory is that the divergence occurred at least 500,000 years ago, with each group evolving on its own path until interbreeding occurred. The latter mixing, as well as similarities among the groups, however, have many anthropologists believing that Neanderthals and other hominids, such as Denisovans, should be considered as Homo sapiens.
“I used to argue that ‘anatomically modern humans’ — including fossils that essentially look like us today — are the only group that should be called Homo sapiens,” Chris Stringer of the Natural History Museum in London said. “Now, I think that anatomically modern humans are only a sub-group within the species Homo sapiens, and that we should recognize the diversity of forms within early Homo sapiens, some of which probably went extinct.”