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Photo of Alan Mann

It Ain't Necessarily So
Popular Theories About Human Origins Should Be Taken with a Pinch of Salt


What does it mean to be human? What special features make us unique, different from every other species on the planet? And when in our evolutionary history did humanness first appear? We call ourselves Homo sapiens sapiens, which lays claim to a large measure of wisdom for our kind. But we have great trouble defining ourselves or discovering when we emerged onto the world scene. We don't even know what to think of a similar species like the Neanderthals, who shared that world with us for a while before disappearing. Were they our ancestors? Or more like cousins? Did we fight or compete them into extinction? Did something else happen to them?

These questions increasingly occupy anthropologist Alan Mann.

He would like to find solid answers, but it's a frustratingly difficult task. The problem isn't a lack of sapience among researchers; it's a lack of evidence out in the field. Mann wants to understand "why we look and behave the way we do today," but he admits that our ancestral line left a pretty skimpy fossil record, compared to creatures like dinosaurs. On the other hand, we did better than insects. In spite of the popularization of the notion by Jurassic Park, not many of them got caught in amber for future scientists to examine. But early primates didn't leave all the splendid complete skeletons that tyrannosaurus rex and other dinosaurs did. Anthropologists get very excited when they find the rare primate skeleton, like that of Lucy. This little australopithecine from eastern Africa was an adult (roughly 3 million years old), small-brained but fully bipedal. She weighed about 60 pounds and stood a little more than three feet tall.

Often, Mann says, we can't even tell the adult size of one of our ancestral species. Bones rarely survived intact or as parts of complete specimens; soft tissue left no trace at all. "We were extremely lucky some years ago," he points out, "when Mary Leakey found a hominid footprint trail in East Africa. She's often said how delighted she'd have been if one of these creatures had been a total klutz, tripped over its own feet, fallen flat in the volcanic ash, stood up, brushed itself off, and left a soft tissue impression for us to find."

It didn't. And that's one reason Mann likes teeth. More of our early ancestors' teeth have survived than anything else of theirs. Teeth are also informative in ways that bones can't be. The shell of enamel covering the crown of a tooth is the hardest part of an animal and one of the few substances that preserves a record of its owner's development. "Bone is a dynamic material. It's constantly being remodeled. Certain cells break bone down; then new bone is deposited. It's always being changed. But enamel is formed by cells that secrete an organic matrix around which a mineral crystal is deposited. Once the enamel is formed, it never changes. So enamel preserves a record of the animal's growth and development, its youth, and any metabolic disturbances it experienced. If it was sick or had a high fever, these things will be preserved and carried right through the animal's lifetime."


Mann spends his summers in southwestern France, studying the teeth - and other surviving bits and pieces - of the creatures who immediately preceded us. The Neanderthals also seem to have overlapped modern humans in time, which makes them all the more fascinating. The way Neanderthals have been depicted in the popular press, however, disturbs Mann. In the absence of clear evidence, humans speculate and project their own feelings onto other folk. The Neanderthals were unfortunate enough to "conform to our expectation of what the brutish should look like: they had low foreheads, big brow ridges, big projecting faces. If you go back and read Conan Doyle, for example, when Sherlock Holmes talks about the typical and habitual criminal, that criminal has the same features. It's common in our culture to depict the brutish in those terms." Such stereotypes arose, at least in part, from forms of racism that have now been widely discredited. "Some years ago, Europeans could treat other living humans as less evolved than themselves. That's almost impossible to do these days, but dead Neanderthals may serve as handy substitute 'whipping persons.'" It's easy to feel superior to a hulking "cave man" who carries a club over his shoulder and speaks only in grunts.

This cartoon version of Neanderthal becomes more sophisticated, even sympathetic in novels like those of Jean Auel or William Golding. Still, the ancient creatures are presented as limited, incapable of language, and on their way out. Superior modern humans will inherit the world from them. Yet, says Mann, we have no real evidence for Neanderthals' supposed inferiority. "They were very successful in living through difficult climatic and environmental conditions in Europe. They had brains at least the size of ours. They were capable of making stone tools. They buried their dead. But many of us refuse to share humanity with them. Now there is a move afoot in my field to deny them the appellation of Homo sapiens. Some scholars posit a separate, long, dead-end evolution for them. I honestly do not know how they are related to us, and I can tell you that nobody else does. The question should be left open. We can't answer it yet from the existing fossil record."

It's important to Mann to try to make his field as scientific as possible. "That means looking for data, collecting evidence, interpreting it as far as we can - but we must stop short of making up fairy tales that go beyond what we know, into the realm of what we think we know or would like to know." While he enjoys the novelists' imaginings about prehistory, he sometimes wonders if his colleagues don't project more of themselves onto the past than they realize. For instance, going out to dinner with other anthropologists at conferences, Mann started to notice that "virtually all of them will attack their meat first. Some will eat their veggies, but a lot will leave them aside. Then we go back to the conference and talk about the evolution of hunting. It's a central theme. What would happen if a group of vegetarians from another culture were to reconstruct our past? Would they put all that emphasis on hunting?"

He concedes with a smile that our ancestors ate some meat because of the broken bones at their sites. But how much did they eat? Did they delight in it? Was it only an occasional pleasure, hard to come by and less important than other foods in the total diet? "How many insects did they eat? For our culture the notion that our ancestors consumed lots of insects is difficult to take. Yet this is an available resource with wonderful nutrition." In the Biblical book of Leviticus, grasshoppers and locusts are specifically mentioned as being kosher foods. Combined with grains, says Mann, they yield a complete protein. Of course, no insect would be preserved in an early site. Vegetation, fruits, tubers, all disappear almost completely. Their absence was part of what led Robert Ardrey to argue, in a book called African Genesis, that our australopithecine ancestors evolved on the open savannah lacking any vegetable food sources. That's why they became "killer apes," always on the hunt.

Another famous book built its own just-so story on top of this "mighty hunter" theme. "Desmond Morris, in The Naked Ape, tried to justify the then current situation in which males were dominant and females subordinate in most human societies. So he reconstructed early hominid males as going out hunting for food while the females sat around the fire and collected a medicinal herb or two. They also developed their sexuality to lure the guys back from the bush with the food; otherwise females would have starved to death." And that is why human females are still subordinate to the males who bring home the bacon, or whatever is considered tasty. "Morris wanted to understand a modern scenario, went back into the past (with his own preconceptions), reconstructed the past from the present point of view, and then turned around and justified the present on the basis of this reconstructed past."

Our ancestors are extinct, Mann notes, and so are their ways of life. "Using models from any living animal is fraudulent. The living are not like the extinct. When we look at the earliest bipeds, Lucy and others from three million years ago, what do we know about them? They were social. They walked like us, but we don't know why they became upright-postured creatures. We don't find stone tools associated with them until almost the end of their evolutionary time. They had brains the size of chimpanzees' or a little larger in a skull with ape-like proportions. Even the earliest did not have the large tusk-like canine teeth of apes. They also had something truly bizarre - huge back grinding teeth. About one and one-half times the size of a modern human's.

We don't know what those teeth were adapted to. We don't even know what kind of environments early hominids lived in. The fossil record documents that our ancestors were there, but more than that we cannot say."

Will we ever be able to say more?

"For the early phase of evolution, it will be a very long time before we gain any more insight. It will take a huge amount of data collection, plus the introduction of very sophisticated techniques. For example, developments in bone chemistry may give us insights into the kind of diet these early creatures were eating. We may come to more fully understand the underlying genetic mechanisms of patterns of growth and development. This was what my research was on 30 years ago. A book I wrote on the australopithecines attempted to understand how they grew. Did they have a prolonged childhood like humans or a more abbreviated pattern like apes? I used the dentition as a way of calibrating their growth and development. This was accepted, and then in the mid '80s it began to be challenged. There is now an enormous debate focusing on the question."

Mann suspects that answers will be so long in coming that he has chosen to concentrate these days on the nature of modern human origins. Particularly, on our relationship to the Neanderthals. It tantalizes him that human fossils from the last 200,000 years of our evolution have been sought - and discovered - in so limited a geographical range. "From northern Iraq to the China Sea, there's not a single human fossil. I have a research appointment at the University of Bordeaux for several months of the year, and I'm developing a project to go to south Asia with some French colleagues. A joint expedition to look for the fossils of humans who were contemporary with the Neanderthals in Europe. At the moment, there's a theory that modern humans originated in Africa and, for unexplained reasons, swept out of Africa, to destroy or at least replace species like the Neanderthals. Is this true? I would like to look for fossils in south Asia where there hasn't been much examination."

He knows that we will continue to do a lot of speculating and tell a lot of fairy tales about our ancestors, but he would like for everyone "to know exactly what we have" in the way of real evidence. "These creatures had a combination of features that you cannot find in any living form. That is a fantastic thing. It's wonderful that our discoveries have documented as much of our past as they have."

Alan E. Mann received his Ph.D. from the University of California, Berkeley, and came to Penn as an assistant profesor in 1969. He is currently professor of anthropology and curator of the physical anthropology section of the University Museum. He has written numerous articles on human evolution and his textbook with M.L. Weiss, Human Biology and Behavior, has been issued in several editions. In addition to his regular field work and writing, Dr. Mann is a dedicated teacher and has won the Lindback, Ira Abrams, and College Alumni Society awards for outstanding teaching.


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