The evolution of sex roles

Scientists study how gender differences developed

April 13, 2007|By Faye Flam | Faye Flam,MCCLATCHY-TRIBUNE

Could it be that Neanderthal females achieved an equality that is rare even by today's standards?

Some anthropologists make a case that our extinct female cousins hunted alongside the males during an epoch when our own ancestral women were gathering plants and doing other (essential) work. They argue that the appearance of gender roles was critical to humans' eventual domination of the globe - and that the importance of the women of the Pleistocene period has been vastly understated.

These assertions, controversial to be sure, play into growing scientific interest in prehistoric sex roles: How did our male and female ancestors divvy up the tasks of getting food, clothing and shelter, and how did those roles shape the evolving species?

Did primitive peoples form relationships, the males playing father to sons and daughters, or did they act more like our chimpanzee and gorilla cousins - promiscuous, violent, with males fighting over the females?

Groping toward a fuller understanding of how we became human, some researchers are looking at how and when we came to act as women and men.

Hominids diverged from the chimp branch of the family tree about 6 million years ago, producing a series of evolutionary dead-ends before the ultimately successful genus Homo emerged. H. neanderthalensis and H. sapiens grew out of the same line at different times.

The Neanderthals' ancestors diverged first, and they left Africa a couple of hundred thousand years ahead of ours. Homo sapiens arrived in Europe about 50,000 years ago. The two species overlapped for perhaps 20,000 years before the Neanderthals went extinct. Scientists still aren't sure why.

A lack of all but the most primitive weapons found at Neanderthal sites suggests they may have had to band together to kill large animals, says Steve Kuhn, an anthropologist at the University of Arizona. And numerous fractures found in skeletons of Neanderthal females, just like the males, indicate that both sexes may have participated in dangerous work.

Kuhn and his wife, anthropologist Mary Stiner, are the main proponents of a theory that says Neanderthals engaged in coed hunting - and did so, in part, because they lacked other options. Archaic humans, by contrast, came out of Africa with the ability to fashion early traps, nets and clothes, and to grind seeds into edible form.

In present-day hunter-gatherer societies, the women collect and process most of the plants, trap small game and sew most of the clothes, says James Adovasio, director of the Mercyhurst Archaeological Institute in Erie, Pa., and one of three authors of the new The Invisible Sex: Uncovering the True Roles of Women in Prehistory. (Men apparently make most of the shoes.)

Adovasio didn't set out to enter the battle of the sexes. He's best known for finding artifacts in Western Pennsylvania that push back estimated dates for the peopling of the Americas. Through chance events, he also came to specialize in relatively perishable artifacts - baskets, blankets, fishing nets, shoes and textiles.

What little is preserved is surprisingly well-made, he says. Some Stone Age impressions left in clay show fabrics woven as fine as Brooks Brothers shirts.

Most of these items, crucial for survival in harsh times, would have been created by women, he says. Yet virtually all texts and exhibits emphasize men hunting cave bears or mammoths or some other ridiculously oversize prey.

"If you pick up even some of the most recent prehistory books you'll rarely see any images of females doing anything," Adovasio says. (Also left out of the limelight were the men who made the shoes.)

A majority of researchers believe the roots of separate sex roles date far back in human evolution, probably to the time when the size ratio of male to female reached something close to our current differential.

In other animals, this ratio can reveal something about the relationship between the sexes. In species with a big difference, such as gorillas, the males often fight to control harems.

In species with males and females closer to the same size, the sexes are more likely to work in pairs, cooperate and share the burden of protecting their young.

Modern men and women are similar in body size compared with our closest relatives. So determining how long ago we reached our current ratio should point to when our ancestors stopped organizing themselves like apes and started acting more like people, says Stanford University anthropologist Richard Klein.

Some researchers see evidence placing this date at least 3.2 million years ago, the age of the diminutive australopithicine known as Lucy. Others favor a mere 1.7 million or 1.8 million years.

At any rate, by half a million years ago, our evolutionary limb had separated from the Neanderthals'. Their ancestors migrated from Africa to the Middle East and Europe by 250,000 years ago, while ours stayed put. When so-called modern Homo sapiens did reach Europe and Asia, others were already settled in.

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