The first direct evidence of thrown spears dates back to about 19,000 years ago. That's the age of the first known atlatl, or spear thrower- a device that allows a long, flexible dart to be thrown accurately at a range of 35 metres or more (New Scientist, 15 May 1999, p 40). Stone points that look like they were designed to be used with thrown spears date back to about 35,000 years ago.
But other evidence seemed to support the idea that spear throwing evolved much earlier. Analysis of the arm bones of Neanderthals, who lived between 230,000 and 30,000 years ago, and early humans living at the same time show that both were much stronger in one arm than the other; the difference is as great as that seen in professional tennis players today. That suggests they threw spears, rather than using both arms to thrust them.
But Steven Churchill at Duke University in Chapel Hill, North Carolina, thinks this reasoning is flawed. A two-handed spear thrust will put far more stress on the dominant arm holding the back end of the spear than the front arm, he says. This would explain the differences in strength found in fossil bones.
To test this idea, Churchill and his colleagues Daniel Schmitt and William
Hylander initially measured the dimensions of a number of Neanderthal
humerus bones. This showed they are thicker front to back than side to side,
which is what would be expected if the bones had adapted to cope with an
Contact: Claire Bowles