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Neanderthals get an evolutionary face-lift.

Neanderthals get an evolutionary face-lift

Recent genetic and archaeological studies have fueled the view that anatomically modern humans emerged in Africa around 250,000 years ago and spread through the world, replacing the species popularly known as Neanderthals (SN: 2/27/88, p.138). But proponents of an opposing theory arguing for at least some interbreeding between Neanderthals and modern humans -- as well as for classifying Neanderthals as a closely related subspecies of Homo sapiens -- are standing their ground.

At last week's annual meeting of the American Association of Physical Anthropologists held in San Diego, scientists presented evidence for an early stage of Neanderthal evolution in the Near East roughly between 145,000 and 100,000 years ago, during which Neanderthals displayed facial features similar to Homo erectus, a direct ancestor of modern humans.

It appears Neanderthals were native to the Near East, not migrants from Europe, says David Arter of the University of New Mexico in Albuquerque. The anatomical characteristics in early specimens point to "reasonably close genetic ties" to modern humans who also inhabited the region, he contends.

Arter and colleague Erik Trinkaus reconstructed a fragmented Neanderthal skull from the Shanidar cave in Iraq. The cave contains two layers of sediment with Neanderthal remains. Exact dating of the layers is uncertain, but radiocarbon tests suggest they are more than 45,000 years old. The reconstructed skull is from the older layer.

The Shanidar cranium has a relatively narrow nasal opening and flat face, Arter says. In contrast, later "classic" Neanderthals in the Near East and Europe have sloping foreheads, receding cheek-bones, large noses and protruding jaws.

A facial pattern similar to the early Shanidar skull is apparent on another Near Eastern Neanderthal fossil dating to between 97,000 and 145,000 years old, according to Tal Simmons, Anthony B. Falsetti and Fred H. Smith of the University of Tennessee in Knoxville. The skull, from the Israeli site of Zuttiyeh, is considered an ancestor of modern humans by some anthropologists, particularly because its face is flatter than the classic Neanderthal profile.

According to Simmons and her colleagues, the flat face of the Zuttiyeh skull projects from the brain case at an angle similar to that observed in H. erectus specimens, but not in modern humans.

Smith agrees, Saying, "The early Shanidar group and the Zuttiyeh skull are reasonable ancestors to later Near Eastern Neanderthals."

This interpretation is consistent with the view that Neanderthals and anatomically modern humans developed side-by-side in several regions of the world and interbred to some extent before Neanderthals became extinct.

Further evidence for this "regional continuity" in the evolution of modern humans comes from Mladec in Czechoslovakia, Smith adds. The 35,000-year-old site contains probably the oldest known sample of modern Europeans. However, Smith contends, the skeletal remains, particularly the crania, contain some Neanderthal-like features that suggest a genetic blending of populations.

The evolutionary place of the Neanderthals is still debatable, though. The only complete Neanderthal pelvis, recently found in an Israeli cave, differs markedly in shape from that of modern humans, says Yoel Rak of Tel Aviv (Israel) University. The find dates to about 60,000 years ago (SN: 4/9/88, p.232).

Other fossils discovered in Israel and placed at between 90,000 and 150,000 years old have more in common with modern humans than with Neanderthals, Rak asserts. He remains convinced the Neanderthals were a separate species that came to an evolutionary dead-end without interbreeding with modern humans.
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Author:Bower, B.
Publication:Science News
Date:Apr 15, 1989
Words:578
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