SCIENCE / MEDICINE : Australian Tools May Date to 50,000 Years

Stone artifacts found in northern Australia indicate that people roamed the island continent at least 50,000 years ago--about 10,000 years earlier than previously thought, scientists reported last week in the journal Nature. A team of Australian archeologists found more than 1,500 man-made artifacts, including a grindstone, primitive tools and strangely shaped pieces of quartz, about eight feet below the ground at the base of the Arnhem Land plateau in the Northern Territory.

Richard Roberts of Wollongong University and his colleagues then examined some of the artifacts using thermoluminescence dating--a method that determines the age of artifacts containing crystal structures, such as sand grains, by looking at how long ago they were last exposed to heat energy, in this case, radiation from the sun.

Results of the dating “suggest the arrival of people between 50,000 and 60,000 years ago in northern Australia,” the researchers said. The new dates “are not only the oldest yet proposed for aboriginal occupation, but also may mark the time of initial human arrival on the Australian continent,” the researchers said, noting that no man-made tools or artifacts were found in sediments dating back farther than 60,000 years.

Roberts and his colleagues speculated that early humans arrived in Australia by sea from the Malaysian region.