Human ancestors threw stone-tipped spears at prey

Stone points unearthed in East Africa served as the business ends of the earliest known throwing spears, which human ancestors used to hunt prey around 279,000 years ago.

Hand-cast spears, consisting of sharpened obsidian tips attached to long, presumably wooden handles, allowed ancient members of the human evolutionary family to hunt animals from a distance and avoid dangerous confrontations with prey, say archaeologist Yonatan Sahle of the University of California, Berkeley and his colleagues. Although some researchers have regarded this type of sophisticated toolmaking as exclusive to Stone Age people, discoveries at Ethiopia’s Gademotta site put throwing spears in the hands of humankind’s immediate ancestors, the scientists conclude November 13 in PLOS ONE.

Until now, evidence of hand-cast spears dated to no earlier than about 80,000 years ago.

“It seems that cognitive capacity did not change much once Homo sapiens emerged around 200,000 years ago,” Sahle says. The pace of cultural innovations may have escalated much later as human populations got bigger, he says (SN Online: 11/13/13).

The Gademotta finds counter the long-standing idea that spear points attached to shafts, along with related advances in toolmaking and artistic expression, appeared after 100,000 years ago, remarks archaeologist John Shea of Stony Brook University in New York. “Gademotta toolmakers probably belonged to Homo heidelbergensis, out of which the human species evolved in eastern Africa,” Shea says. No hominid fossils have been recovered at Gademotta.

Stone points dating to roughly 500,000 years ago at a South African site are thought to have been tips of spears that were thrust into prey at close range, not thrown from a distance (SN: 12/15/12, p. 5).

Unlike the South African discoveries, 12 of 141 Gademotta stone points examined by Sahle’s team display microscopic edge damage suggestive of throwing. The markings resemble those produced in previous experiments on stone-tipped spears shot into a side of beef at speeds typical of heaving weapons from a short distance.

Microscopic lines near the bottoms of the Gademotta finds were created by strapping or otherwise attaching the spear points to shafts, Sahle suggests.

Seven of the stone points lay just below a volcanic ash layer dating to 279,000 years ago. The rest date to between 279,000 and 105,000 years ago.

Gademotta overlooked a set of now-dry lakes. Creatures such as hippos and antelope may have been targeted with the spears, Sahle speculates.

Whether a mental leap enabled Gademotta hominids to make javelinlike hunting weapons remains unknown, says archaeologist Lyn Wadley of the University of the Witwatersrand in Johannesburg.

Editor’s Note: This story was updated November 25, 2013, to clarify the date that researchers previously thought spear points attached to shafts appeared.