September 30, 2010
By Ker Than
National Geographic News
Around the world, the hooves of water buffaloes, goats, and other large animals may have propelled countless Stone Age artifacts back in time, at least as far as archaeologists are concerned.
In wet areas, wild or domestic animals' heavy footfalls can push stone artifacts deep into the ground, making them seem older than they really are—in some cases, thousands of years older—according to a new study.
Scientists often date artifacts of the Stone Age, which began about two and a half million years ago, based on the depths at which the items are found: The deeper the object, the older it is, generally speaking.
There are other methods to date artifacts, but many rely on elements not found in stone—such as carbon.
"We can only do carbon dating on organic material that is associated with the stones," said study author Metin Eren, an archaeologist at Southern Methodist University in Dallas, Texas.
So if a stone artifact is next to a twig, for example, Eren said, "we'll date the twig and just assume that the artifact is also that age."
But in the new study, published in the Journal of Archaeological Science, Eren and his team show at least one way this method can lead to false ages for artifacts.
Archaeologists have long known that animal trampling can reorient artifacts—sometimes long after humas have left a site—and several trampling experiments have been performed on dry ground.
The new study, though, is the first to investigate the effects of trampling on water-saturated ground, such as near a water source—where a disproportionate number of human settlements happen to be found.
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