The idea of cannibalism has long occupied a small and frightening niche in human imagination -- and is generally considered both aberrant and more talked about than practiced. Some current work in archeology, however, suggests that the practice is both more common and more widespread than people; (including archeologists) like to think. PNS associate editor Walter Truett Anderson, author of "Evolution Isn't What It Used To Be" (W.H. Freeman), is a political scientist who writes widely on technology and global governance.

We tend to place the eating of human flesh somewhere beyond the margins of ordinary human behavior, but there are signs that it has not been so uncommon as we like to think.

Cannibalism is identified with demented murderers real or imagined (Jeffrey Dahmer and Hannibal Lecter), terrible ordeals (the Donner Party), or the supposed practices of primitive tribes. The word itself comes to us from the Spanish Carib, because the people of the West Indies were thought to eat human flesh.

Many scientists now believe that many people at many times and places resorted to cannibalism. This view is still controversial -- and somewhat disturbing even to those who hold it -- but it's increasingly prevalent.

One strong believer is Professor Christy Turner of Arizona State University. Turner is a bioarchaeologist, a specialist in reconstructing the ancient past from the fossilized remains of long-dead animals and human beings. For over 30 years he has been brooding over the evidence found at sites once occupied by the Anasazi -- the long-vanished "ancient ones" of the American Southwest, believed to be the ancestors of today's Hopi Indians.

These excavations unearthed heaps of human bones that had clearly been hacked and burned, resembling the bones of animals from which the flesh had been stripped and roasted.

Turner's first article about American cannibalism, published in an academic journal in 1967, met with not only doubt but downright hostility. It challenged many people's beliefs about human beings in general and Native Americans in particular. But Christy and his colleagues persisted in their research, studying some 15,000 skeletons, and in an about-to-be-published book, he will claim that cannibalism "was practiced intensively for almost four centuries" in the Southwest.

Other archaeologists are coming to similar conclusions about other people at widely different times and places. This shift of opinion reflects not only a growing interest in the subject, but technological progress -- the use of devices such as electron scanning microscopes to study bone fragments, combined with increasingly sophisticated computer data bases.

These findings remain controversial. Arguments and counter-arguments have flamed through scientific conferences, science magazines and webzines. Skeptics maintain that all evidence of everyday cannibalism is circumstantial, that the unexplained marks and burns remain just that -- unexplained. The cut marks may be the scars of warfare or ritual sacrifice, or the result of ways that bodies were prepared for burial.

Turner is unimpressed by these arguments. In a recent Science magazine article, he said: "There is no known mortuary practice in the Southwest where the body is dismembered, the head is roasted and dumped into a pit unceremoniously, and other pieces get left all over the floor."

Other anthropologists point out that the human bones are often found among the bones of animals such as deer -- and all are broken and charred. This indicates, they argue, that human and animal bones were treated in the same way -- broken open for marrow, for example. It also shows that, since animals were available at the same time, the cannibalism was not the last resort of people facing starvation.

Even those who accept this interpretation of the evidence remain uncertain about what it means -- what it really tells us about the daily lives and customs of the people. They are especially puzzled about the motivation: If the eating of human flesh was not caused by extraordinary circumstances, then what did cause it?

Several answers have been proposed. Maybe cannibalism was a religious ritual, maybe it was used to control and terrorize subject populations, maybe it was a means of limiting population growth. None of these paints an attractive picture of life in the good old days, but perhaps the most unsettling possibility of all is that there were no extraordinary reasons -- that, at least in some times and places, cannibalism was simply a routine way of obtaining food.

"It is something that humans do," said geologist Yolanda Fernandez-Jalvo in a recent online debate about the subject. "We are omnivores and eat meat."