Early humans make their marks as hunters.

The earliest undisputed remains of Homo sapiens, dating to around 100,000 years ago, come from caves at the mouth of South Africa's Klasies River. For the past 15 years, a heated debate has centered on whether those ancient coastal humans occasionally hunted in simple ways, such as driving their prey over cliffs, or obtained meat solely from carcasses left by lions and other predators.

A new analysis of animal bones previously unearthed at the Klasies River site suggests that H. sapiens exhibited much more hunting prowess than either side of the debate has given them credit for.

"Early modern humans at Klasies River mouth were active hunters," contends anthropologist Richard G. Milo of Chicago State University. "Their behavior appears to have been as near-modern as their anatomy."

Milo conducted a microscopic study of the frequency and distribution of butchery marks on more than 5,400 animal bones found among H. sapiens remains in a Klasies River mouth cave. He presented his analysis at the annual meeting of the Paleoanthropology Society in St. Louis last week.

Nearly one in five of the animal bones bears incisions typical of butchery, Milo says. That proportion far exceeds a prior estimate for the same material reported by Lewis R. Binford of the University of New Mexico in Albuquerque.

Butchery marks appear on bones from animals of all sizes and congregate at major skeletal joints, where a fresh kill would have been most easily cut into pieces. The prime body parts, such as upper legs, found in the cave indicate ready access to carcasses by hunters, Milo notes. The remains display few signs of carnivore chewing or gnawing.

In addition, the broken tip of a spear point is embedded in a neck bone from an extinct giant buffalo, one of the largest Stone Age game animals in southern Africa. Deep gouges in five vertebrae from other ancient creatures may represent stab wounds inflicted by human weapons, according to Milo.

Early H. sapiens at Klasies River probably formed coordinated hunting groups that exploited the behavior and habits of their prey, Milo proposes. In his view, hunting parties drove animals into pits studded with pointed stakes and may have run smaller game off nearby cliffs.

"This is a very important study," remarks Alison S. Brooks, an archaeologist at George Washington University in Washington, D.C. "Milo has exploded the argument that Middle Stone Age people were not competent hunters and did not produce projectile points."

Brooks theorizes that the folk at the Klasies River mouth ambushed animals from carefully chosen hiding spots and then thrust spears into them.

Other evidence suggests that human ancestors living in Africa between 400,000 and 90,000 years ago made sophisticated stone tools and other items linked to modern cultural behavior (SN: 12/2/95, p. 378). In Europe, wooden hunting spears have recently been dated to 400,000 years ago (SN: 3/1/97, p. 134).