Contrary to their hunting reputation, Stone Age Siberians killed mammoths only every few years when they needed tusks for toolmaking, a new study finds.

People living between roughly 33,500 and 31,500 years ago hunted the animals mainly for ivory, say paleontologist Pavel Nikolskiy and archaeologist Vladimir Pitulko of the Russian Academy of Sciences. Hunting could not have driven mammoths to extinction, the researchers report June 5 in the Journal of Archaeological Science.

On frigid tundra with few trees, mammoth tusks substituted for wood as a raw material for tools, they propose. Siberian people ate mammoth meat after hunts, but food was not their primary goal....