Evolutionary Shrinkage: Stone Age Homo Find Offers Small Surprise

Article excerpt

Big evolutionary insights sometimes come in little packages. Witness the startling discovery, in a cave on the eastern Indonesian island of Flores, of the partial skeleton of a half-size Homo species that lived there at the same time that ancient Homo sapiens inhabited nearby regions.

The new species, dubbed Homo floresiensis, reached the island at least 38,000 years ago and lived there until it died out near the end of the Stone Age, roughly 20,000 years later, conclude the authors of two papers in the Oct. 28 Nature. The researchers say that the Flores find represents an adult, probably a female, who stood about 3 feet, 3 inches tall (1 meter) and weighed approximately 35 pounds (16 kilograms).

This individual's brain was only about as large as those of australopithecines, which were apelike members of the human evolutionary family that preceded Homo.

One team, led by Peter Brown of the University of New England in Armidale, Australia, excavated and analyzed the new remains, which include a nearly complete skull, a partial pelvis, and two leg bones. Aside from its small stature and brain, the specimen closely resembles Homo erectus fossils, Brown's group concludes.

A second team, directed by the University of New England's Michael J. Morwood, evaluated thousands of stone tools and animal bones dug from the same cave. This team used radiocarbon measurements and three other methods to estimate the discoveries' age.

Brown's team proposes that H. erectus reached Flores by 800,000 years ago (SN: 3/14/98, p. 164) and evolved into the smaller species as a result of living on an island with limited food sources. "Future research on Flores will try to find the suspected large-bodied ancestor [of H. …