Archaeologist Dean Snow of Pennsylvania State University analyzed hand stencils found in eight cave sites in France and Spain. By comparing the relative lengths of certain fingers, Snow determined that three-quarters of the handprints were female.

"There has been a male bias in the literature for a long time," said Snow, whose research was supported by the National Geographic Society's Committee for Research and Exploration. "People have made a lot of unwarranted assumptions about who made these things, and why."

Archaeologists have found hundreds of hand stencils on cave walls across the world. Because many of these early paintings also showcase game animals—bison, reindeer, horses, woolly mammoths—many researchers have proposed that they were made by male hunters, perhaps to chronicle their kills or as some kind of "hunting magic" to improve success of an upcoming hunt. The new study suggests otherwise.