Modern Humans Take a Spin Back in Time
Bower, B., Science News
Modern humans take a spin back in time
Scientists using a recently developed dating technique say anatomically modern humans apparently inhabited an Israeli cave known as Skhul about 100,000 years ago. Their conclusion, described in the April 27 NATURE, is consistent with reports that early modern humans were living at the nearby Qafzeh cave more than 90,000 years ago (SN: 2/27/88, p.138).
Nonetheless, the accumulating evidence for an early human presence in the Near East, more than twice as long ago as had been previously assumed, does not quell an ongoing dispute over the evolution of modern Homo sapiens. Some investigators say anatomically modern humans originated in Africa and spread throughout the world, replacing groups such as the Neanderthals, while others contend there was at least some interbreeding between early modern humans and Neanderthals.
Researchers had roughly dated Skhul at about 40,000 years old by comparing stone tools and the remains of animals and humans at the site with those from nearby caves.
The new age for Skhul was obtained by Christopher B. Stringer of the British Museum in London and his colleagues. They analyzed two teeth from an ancestral form of the cow or ox excavated more than 50 years ago and housed in a British Museum collection. The teeth came from sediment containing the remains of at least 10 early modern humans. Stringer's group calculated the age estimate through electron spin resonance (ESR) dating, a technique used with several archaeological samples over the last decade.
ESR measures the density of trapped electrons that gather in bone and other organic material as a result of environmental radiation after the material is buried. …