Tasmania's earliest settlers.

Tasmania's earliest settlers

Evidence from two rock shelters in Tasmania indicates humans colonized the island more than 30,000 years ago, at least 8,000 years earlier than previously thought.

It is possible humans reached Tasmania 36,000 years ago when a drop in sea level created a land bridge to Australia, 200 miles to the northwest, says archaeologist Richrd Cosgrove of La Trobe University in Melbourne, Australia. Evidence indicates humans occupied Australia 40,000 years ago.

Cosgrove excavated the sites from December 1987 through February 1988. Sediment from a limestone cave nestled above a river valley contains stone flakes and anumal bones and is radiocarbon-dated at 30,420 years of age, he reports in the March 31 SCIENCE. A sandstone shelter perched above another river valley yielded similar remains and an age of 30,840 years.

The location of the sites in flat, exposed highlands near where the largest Tasmanian ice sheet extended 18,000 years ago suggests early settlers weathered severe cold to hunt a variety of animals, including kangaroos, birds and wallabies, Cosgrove asserts. Fragments of emu eggs are also present at both rock shelters, he adds. Previously archaeologists argued that the earliest Tasmanian settlers made their living along the coast of near lakes.

There are no remains of now-extinct large mammals at the sites, Cosgrove says. These creatures were probably extinct before humans settled Tasmania, he contends, although separate kill and consumption sites some distance from the rock shelters cannot be ruled out. Other researchers have uncovered evidence that humans and the extinct mammals coexisted in Tasmania 20,000 years ago, with the latter group disappearing 11,000 years ago.