Hand ax refinement through time. (Proceedings of National…)
Archaeologists have discovered dozens of primitive tools fashioned by direct human ancestors in Kenya and Ethiopia 1.75 million years ago.
The Acheulean age of toolmaking, noted for its thinner, more symmetric weapons, appears to have developed with Homo erectus, earlier and over a wider area than previously thought, according to a study published Monday in the National Academy of Sciences journal.
Analyzing tools, rock sediment and the geological history of the Turkana Basin in northern Kenya and the Konso region in southern Ethiopia, researchers concluded Acheulean tools including hand axes, cleavers and picks and core-axes began taking on greater refinement just as Homo erectus came into the picture.
The tools discovered in Konso had thick-pointed tips and long, durable cutting edges, similar to the tools found hundreds of miles south in Kenya, the scientists reported. The tools show more craftsmanship – more edged sides and scars of chipping and shaving – than do those of the previous tool era, the Oldowan.
Researchers studied nearly 50 sharpened rocks, including 18 classified as picks, hand axes or cleavers , some nearly 8 inches long. Tools found in Ethiopia and Kenya dated at 1.2 million years old show the same characteristics of these earlier Acheulean tools, but with better craftsmanship, according to the study.
Over a period of about 500,000 years during the Acheulean, Homo erectus left the design of its large, unwieldy weapons like the pick and core-ax mostly untouched. Smaller weapons, like the hand ax and cleaver that it may have used for woodwork, digging or preparing a carcass, became thinner and more precise in shape and size, researchers found.
Homo erectus in Ethiopia used mostly basalt rocks for their weapons, though on rare occasions it appears the species shaped animal bones too. Another recent study suggests that Homo erectus also cooked their food, further boosting the growth of our ancestors’ brains.
The study is available here.
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