Tasmanian clues to human evolution
Skeletal studies of the aborigines who have inhabited Tasmania for more than 30,000 years (SN:4/8/89, p.223) present anthropologists with a problem. Some researchers cite anatomical links -- often based on measurements of the brain case and teeth -- between Tasmanian and Australian aborigines, suggesting the former group migrated from Australia across an ancient land bridge to their island home, about 200 miles to the south. Other investigators, focusing on different cranial features, find a weak connection between Tasmanian and Australian aborigines. Instead, they group Tasmanians with Melanesians living on islands northeast of Australia.
This South Pacific paradox stems from the different skeletal traits and statistical methods relied on by opposing scientific camps, asserts anthropologist Colin Pardoe of the Australian Institute of Aboriginal Studies in Canberra. However, Pardoe reports in the February CURRENT ANTHROPOLOGY, a comparative analysis of dozens of seemingly minor skull parts indicates that Tasmanian and Australian aborigines share far more anatomical similarities than expected, considering that the two populations have remained separate for 8,000 years.
This finding challenges the widespread assumption that many anatomical differences among human populations arose when great distances or geographic barriers prevented the passing of genes from one group to another through mating, thus allowing random genetic changes and local environmental influences to mold the anatomy of isolated peoples. On the contrary, Pardoe argues, mating across two populations may promote greater anatomical differences between the groups.
Tasmanians have endured the longest genetic isolation of any human group, Pardoe says. When rising seas swamped their land bridge to Australia 8,000 years ago, he maintains, islanders could not get to the mainland by canoe or raft.
Pardoe looked for the presence or absence of 35 minor anatomical features on the skulls of aborigines from Tasmania and regions throughout Australia. …