Even older prehistoric tools unearthed

LOS ANGELES -- Ancient humans fashioned hand axes, cleavers and picks much earlier than believed, but didn't take the stone tools along when they left Africa, new research suggests.

A U.S.-French team made the findings at an archaeological site along the northwest shoreline of Kenya's Lake Turkana. Two-faced blades and other large cutting tools had been excavated there previously, along with primitive stone flakes.

Using a sophisticated technique to date the dirt, researchers calculated the age of the more advanced tools to be 1.76 million years old. Similar stone-age artifacts in Ethiopia and Tanzania were estimated to be between 1.4 and 1.6 million years old.

This suggests that prehistoric humans were involved in refined tool-making that required a higher level of thinking much earlier than thought. Unlike the simplest tools made from bashing rocks together, the early humans who shaped these more distinct objects planned the design and then created them.

This "required a good deal of forethought as well as dexterity to manufacture," said paleoanthropologist Eric Delson at Lehman College in New York, who was not involved in the research.

Results of the study, led by Christopher Lepre of Rutgers University and Columbia University's Lamont-Doherty Earth Observatory, appear in today's issue of the journal Nature.

Known collectively as Acheu-lian tools, they are believed the handiwork of the human ancestor Homo erectus. The teardrop-shaped axes were "like a stone-age Leatherman or Swiss Army knife," said New York University anthropologist Christian Tryon.

The axes were suited for butchering animals or chopping wood while the thicker picks were used for digging holes.

Most researchers think Homo erectus was the first pre-human to fan out widely from Africa. There's archaeological evidence that the first to leave carried only a simple toolkit. The earliest sites found in Asia and Europe contain pebble tools and flakes, but no sign of Acheulian technology like hand axes.

The tools were not too far from where the bones of Turkana Boy, the most complete skeleton of a prehistoric human, were unearthed in 1984.