Neandertals and humans each get a grip

At Middle Eastern sites ranging from 140,000 to 50,000 years old, Neandertals and ancient humans left behind a puzzling legacy. Although, for many researchers, Neandertals’ brawny bodies, sloping faces, and other skeletal traits mark them as a separate species from modern Homo sapiens, the two groups in this region made virtually identical sharpened stone tools. That’s hardly a sign of a parting of the ways between species.

The key to unraveling this evolutionary paradox lies not in the nature of ancient implements but in the design of the hands that used them, according to a report in an upcoming Proceedings of the National Academy of Sciences.

An analysis of fossil hand remains, conducted by anthropologist Wesley A. Niewoehner of the University of New Mexico in Albuquerque, indicates that Neandertals from the Middle East and Europe had hands with a structure well-suited to gripping relatively broad objects, such as pieces of stone that they used to hammer flakes off smaller stones.

In contrast, according to Niewoehner, early H. sapiens in the Middle East resembled more-recent human populations by having hands better suited for gripping tools with handles and making precise finger movements. The existence of this so-called “precision grip” exclusively among ancient humans in the Middle East indicates that they used tools with handles much more frequently than their Neandertal neighbors did, Niewoehner theorizes.

Niewoehner used a computer program to generate and compare three-dimensional images of the joint surfaces of fossil finger and hand bones. His analysis focused on the 100,000-year-old remains of five H. sapiens individuals found in Israel. Other hand fossils came from six European and seven Middle Eastern Neandertals, as well as more than 30 humans dating from 30,000 years ago to the 20th century.

Niewoehner’s findings fit well with preliminary evidence that, compared with Neandertals, the ancient H. sapiens in the Middle East more frequently made handles for their stone implements and resharpened worn tool edges, says anthropologist Steven E. Churchill of Duke University in Durham, N.C., in a commentary slated to appear with the new report.

Other anatomical evidence indicates that Neandertals did more manipulation of objects with their mouths and more heavy lifting than humans did, adds anthropologist Erik Trinkaus of Washington University in St. Louis. The new data on hands add to suspicions that Neandertals and H. sapiens behaved differently 100,000 years ago, although neither population was dominant over the other, Trinkaus holds.

Archaeologist Ofer Bar-Yosef of Harvard University says that the behavioral implications of grip differences between Neandertals and ancient humans remain unclear. “Technical knowledge and teaching were critical to toolmaking, not just hand anatomy,” Bar-Yosef contends. He notes that around 30,000 years ago, European Neandertals made tools of equal quality to those of nearby humans.