It's a familiar story to many of us: In prehistoric times, men were hunters and women were gatherers.
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Women were not physically capable of hunting because their anatomy was different from men. And because men were hunters, they drove human evolution.
But that story's not true, according to research by University of Delaware anthropology professor Sarah Lacy, which was recently published in Scientific American and in two papers in the journal American Anthropologist.
Lacy and her colleague Cara Ocobock from the University of Notre Dame examined the division of labor according to sex during the Paleolithic era, approximately 2.5 million to 12,000 years ago.
Through a review of current archaeological evidence and literature, they found little evidence to support the idea that roles were assigned specifically to each sex. The team also looked at female physiology and found that women were not only physically capable of being hunters, but that there is little evidence to support that they were not hunting.
Lacy is a biological anthropologist who studies the health of early humans, and Ocobock is a physiologist who makes analogies between modern day and the fossil record.
Friends in graduate school, they collaborated after "complaining about a number of papers that had come out that used this default null hypothesis that cavemen had strong gendered division of labor, the males hunt, females gather things. We were like, "Why is that the default? We have so much evidence that that's not the case,'" Lacy said.
The researchers found examples of equality for both sexes in ancient tools, diet, art, burials and anatomy.
"People found things in the past and they just automatically gendered them male and didn't acknowledge the fact that everyone we found in the past has these markers, whether in their bones or in stone tools that are being placed in their burials.
"We can't really tell who made what, right? We can't say, 'Oh, only males flintknap,' because there's no signature left on the stone tool that tells us who made it," Lacy said, referring to the method by which stone tools were made. "But from what evidence we do have, there appears to be almost no sex differences in roles."
The team also examined the question of whether anatomical and physiological differences between men and women prevented women from hunting.
They found that men have an advantage over women in activities requiring speed and power, such as sprinting and throwing, but that women have an advantage over men in activities requiring endurance, such as running. Both sets of activities were essential to hunting in ancient times.
The team highlighted the role of the hormone estrogen, which is more prominent in women than men, as a key component in conferring that advantage. Estrogen can increase fat metabolism, which gives muscles a longer lasting energy source and can regulate muscle breakdown, preventing muscles from wearing down.
Scientists have traced estrogen receptors, proteins that direct the hormone to the right place in the body, back to 600 million years ago.
"When we take a deeper look at the anatomy and the modern physiology and then actually look at the skeletal remains of ancient people, there's no difference in trauma patterns between males and females, because they're doing the same activities," Lacy said.
During the Paleolithic era, most people lived in small groups. To Lacy, the idea that only part of the group would hunt didn't make sense.
"You live in such a small society. You have to be really, really flexible," she said. "Everyone has to be able to pick up any role at any time. It just seems like the obvious thing, but people weren't taking it that way." ■