Princeton University - Council of Science & Technology

POPE PRIZE

Essay 1
Losing the Race Against Time: Rebuilding the San Francisco-Oakland Bay Bridge
Christi C. Niehans

Essay 2
Chemical Weapons Burn in Arkansas
Brian D. Muegge

Essay 3
Mann's History
Melissa M. Galvez

Essays 4
Postpartum Cases: Tadoka and Mental Health
Amy B. Saltzman

Honorable Mention
Julia B. Saltz

Mann's History

On the coffee table in Dr. Alan Mann’s office, wedged between piles of papers and a bowl brimming with tootsie roll pops, sits a human skull. It is white and smooth and clean; it is probably fake but remarkably realistic nonetheless. On top of the file cabinet is an 200 year old head of a New Zealand man, which, because it was mummified, comes complete with a mop of black wiry hair and small white teeth. It is joined by two more large skulls with thick brow rides and protruding jaws, the marks of some poor Neanderthal long departed from this earth. On the other side of the room, basking in the sunlight from the window, is a Mickey Mouse phone. It is quite simple to say that Dr. Mann, an anthropology professor at Princeton University, studies human evolution. Yet within that one term are contained worlds of knowledge—the molecular structure of tooth enamel, weight distribution and bone density, syntax, neurology, nutrition. Any other sort of scientist would know about one of these things in great detail; but Dr. Mann studies what makes us human, and so he is required to know a fair amount about it all. He shrugs it off, however, saying: “It’s just part of being a professional”. But Dr. Mann knows quite a bit about a host of other things as well: cycling, forensics, and how to cook a mean mergaz sausage. In the past 34 years he has not only taught anthropology at the University of Pennsylvania and Princeton, but has helped prove the innocence of a 15 year old boy, lead countless numbers of college students on archaeological digs, and spread the word on the importance of flossing. He is not the crusader type—not on a mission to fix the world wielding human skulls—but he infuses everything he does with the notion that we can learn infinite amounts about who are by knowing where we come from, at the most distant and exotic level. Like a canyon is scarred with the surges and flows of a mighty prehistoric river, our bodies are marked by evolutionary forces, revealing aspects of ourselves from the mundane to the philosophical. Oftentimes for anthropologists, the journey towards this knowledge starts with a trip to the prehistoric caves of southern France. For Dr. Mann, the journey indeed returns to the small village of Marillac summer after summer. Yet in the beginning and at the end, and at all points in between, it is essentially about a tooth. Part I: Practical in Princeton Dr. Mann is not very specific about how he became interested in human evolution and physical anthropology. A small man with a close-clipped beard and an instantly friendly demeanor, (“Would you like coffee? Tea? A tootsie roll pop?”), one expects him to tell some wild story about being three years old and playing with bones in his basement, or having an epiphany in front of the gorilla cage at the zoo. But no; a class he took in his senior year of college merely sparked his interest, and he went on to receive his Ph. D at the University of California at Berkeley in 1968. He began working as an assistant professor of anthropology at the University of Pennsylvania in 1969, as a professor at Princeton in 1986, and as a Research Associate in the Laboratoire d'Anthropologie of the Université de Bordeaux in 1990. Despite not being able to pin down the moment he became enamored of the subject, Dr. Mann knows about the sheer, inexplicable appeal of very very old humans: “I meet kids all the time who are fascinated by fossils”, he says. “My colleague has a son with a Neanderthal costume, that he runs around the house in. It’s just a furry suit—he looks like a small ape.” In Dr. Mann’s class at Princeton, Human Adaptation, he focuses on three major evolutionary adaptations that brought us from primates to homo sapiens: bipedalism, dentition changes, and increase in brain size. Scholars don’t know, he says, why man first got off his four feet and stood up on two legs some 6- 8 million years ago. Some theories suggest it was to free up the hands to make tools, or to carry infants or food; or perhaps just to see farther along the grasslands. After that, there were changes in the type of teeth and the size of the jaw, probably to accommodate a more varied diet of vegetables and meat, followed by an increase in brain size and capacity some 2 million years ago. Like the other steps of the process, anthropologists don’t yet know why the brain grew; possibly it was helped by the increase in nutrition that the new teeth allowed. Regardless, what Dr. Mann teaches is how this adaptation effects humans today, from causing varicose veins, to impacted molars, to making childbirth (before the introduction of the Cesarean section) a potentially fatal procedure. For example, the arteries and veins of our circulatory system pump blood to all parts of the body; but as we age, the veins in our legs become flaccid, and are no longer able to effectively pump blood back up to a heart that is so high above the legs. The blood then pools in our leg veins and causes—unsightly, though not harmful—varicose veins. On the issue of childbirth, Dr. Mann cites a startling figure: 1 in 4 or 5 women have to have a Cesarean section to avoid a risky birth. This is because when humans became bipedal, the architecture of their pelvic bones evolved to support the weight in a new way, but in the process, it closed the cervical opening through which women give birth. This, in turn, made birth a difficult process when humans developed bigger brains—better for the development of language, tool-making, and all the other traits we associate with humanity, but bad news for women trying to have those babies. All of this, for Dr. Mann, is proof of how human biology is not perfect. From our beginnings as four-legged creatures with small brains and small skulls, we have evolved and adapted, but not without some deficiencies. As Dr. Mann says, “We function, but we break down.” For this reason, part of his class is educational in a uniquely non-Princeton way: in lab, he teaches his students how to floss properly, navigating teeth that have been crunched by an evolving jaw, as well as how to bend over and pick up heavy objects without hurting their backs. For Dr. Mann, the class is therefore not just about science; it’s about how we imagine ourselves: “Our biology still reflects our evolution; and if we understand that, we can understand the limitations of who we are, and how we’re not perfect”, he says. This can mean remembering your dentist appointments, (“You haven’t gone to the dentist in over a year! Shame on you!”, he told me), or it can mean using physical anthropology in a court of law, to show how faulty our eyes can be. In the last few years, Dr. Mann and University of Pennsylvania professor Janet Monge became involved with defending a 15 year old boy charged with rape. Just as they do with million year old skulls, the team analyzed the bone structure of the boy’s face and determined that it could not be the same as the boy seen on a surveillance tape connected with the crime. This evidence convinced the judge to reopen the case, and the boy was acquitted after DNA evidence came to light. Dr. Mann calls this “best thing I’ve done professionally” and says that he’s very proud of his work on forensics—he only works on cases where he’s convinced of the client’s innocence. Like teaching, it is an opportunity to pull himself out of the seemingly remote world of ancient teeth and bones, and into a modern application of anthropological self- knowledge. We are not perfect—because of evolution, things break down. We are not perfect—there are truths our eyes cannot distinguish. Beneath the dust of many centuries, under the layers of our skin, are these realizations. Part II: Philosophical in France Every summer since 1991, a tiny village deep in the south of France has welcomed Dr. Mann and a group of eager college students. The village is Marillac—a two hour train ride from Bordeaux, a 45 minute walk from the train station, with a population of about 300. The reason is an anthropology class, set up first at the University of Pennsylvania and now at Princeton. During the first three weeks the students take classes on physical anthropology and archaeology in Bordeaux, while for the second three, they all transfer to Marillac to work on a dig site. There the students live with Dr. Mann in a house next to a medieval chapel, and take their showers a mile down a road lined with sunflowers, in the locker rooms next to a soccer field. Usually, the group has dinner in Marillac’s only restaurant; often Dr. Mann makes a barbeque, cooking up spicy mergaz sausage and other treats of the Dordogne. This past summer two of the students kept kosher, so Dr. Mann went into Bordeaux frequently to get them kosher meat. There is clearly a family atmosphere about the place, a sort of roughing-it pastorally for the sake of science, as the students managed with their less than perfect or nonexistent French. Dr. Mann says that this contact with another culture is as important a component of the class as the archaeology and that he encouraged them to absorb French culture (while secretly worrying that the French wine would go to their heads.) The rest of the time, the group ponders what makes us human—culture, language, something physical?—using their finds at the dig site, and visits to prehistoric caves as a jumping off point. The caves of Font de Gaume and Lascaux II and others in the southwest of France are especially interesting, because these contain paintings done some 12-25 thousand years ago. Bison, horses, and human hand prints are sketched along the bumps and dips of the rocky cave walls, just visible in the flickering light. These paintings, Dr. Mann says, can help us understand the origins of language—thought to be one of the characteristics that separates humans from other animals. They are not conclusive evidence of vocal speech, but they do prove that those early humans understood symbolism, which is a necessary precursor to language. In other words, when one early human painted a bison, he must have expected the other early humans to understand that the shapes he drew were meant to stand for the idea of a real bison. A two dimensional shape had become the carrier of the idea of “bison”. There is one important leap still to be made—that is, from using representational shapes to stand for ideas (such as a picture of a bison), to using non-representational shapes to stand for ideas ( such as letters and sounds, which are arbitrary communicators of ideas). Yet the cave paintings’ symbolism forms a necessary foundation for all of language, which Dr. Mann calls “absolutely unique as a communications medium.” Still, one of the biggest question in the field right now is, who made these paintings? Or more specifically, were the artists Neanderthals, or “modern humans”? Between the two there are differences of body and culture—a Neanderthal skull, like those on Dr. Mann’s file cabinet, has a prominent brow ridge, a long flat-ish skull, and a protruding jaw, as opposed to the roughly contemporaneous “modern human”, Homo sapiens, with a more spherical skull like ours. Neanderthals are also believed to have a more primitive culture, though basic questions like how they hunted or what they ate are still being investigated by anthropologists like Dr. Mann. Yet there is a gap in the archaeological evidence around the question of the paintings—the last known Neanderthal skeleton dates from 36 thousand years ago, whereas the paintings date from 32 thousand, and the oldest “modern human” skull is 28 thousand years old. This gap during which the paintings were made is the locus of much debate, since, according to what we have now, it looks like Neanderthals were living in Europe, and then, suddenly, “modern” humans appeared. Were the people who created the paintings a mixture of both species? Or did one conquer the other? The most common answer is a theory called “Out of Africa”. It claims that pre-modern humans evolved in Africa and spread out once to Europe, where they evolved into Neanderthals; meanwhile, modern humans evolved in Africa, spread out again, and took over Europe, exterminating the Neanderthals in the process. In that case, present day Europeans would be the direct descendents of Africans, with no Neanderthals involved. Yet Dr. Mann has another theory. His own research is focused on examining the microscopic structure of tooth enamel, a seemingly unimportant biological detail. However, enamel is created once and stays for the whole of a human’s life, unlike bone, which is broken down and recreated constantly. This means that it bears the imprints of each person’s genetic make-up, and is conserved largely intact at a person’s death. Using this knowledge, Dr. Mann has found that Neanderthal enamel is closely related to that of modern Europeans, and that modern European enamel is closer to that of Neanderthal than to that of modern African. All of this, says Dr. Mann, suggests that Neanderthals were in fact the ancestors, or partially the ancestors, of modern Europeans. It is an outside position, one with few supporters. But Dr. Mann sticks to it, quietly working to prove more conclusively that what he thinks is the truth. And this may be because, fundamentally, the question for Dr. Mann is about more than simple genealogy. If we accept that African Homo sapiens came to Europe, completely displaced the Neanderthals, and went on to become our most direct ancestors, what we would have is, as he calls it, a “holocaust”—we would be the descendents of a group of murderous conquerors. Perhaps there is no direct connection with our present behavior, but for Dr. Mann, it is the basis of knowing who we are. “Did we bop them all off?”, he asks of the Neanderthal extinction—or is it possible that Neanderthal and Homo sapiens intermixed, each contributing to the genetic make-up of the humans of today? If so, it would mean admitting the Neanderthal into the family tree, long considered still “primitive” at a the same time that homo sapiens in Africa were developing modern brain capacity. More importantly, it would help clarify who was capable of the intricate cave paintings, and if the artists had arrived in southern France by slaughtering all those who came before. There are, and will always be, large gaps in the kind of knowledge we can have about events that transpired millions of years ago. But for Dr. Mann, the teeth are the key—and perhaps may reveal a kinder ancestry than was thought before. On that same crowded coffee table in Dr. Mann’s office is a small gold statue of a monkey, à la The Thinker, pondering a human skull. Here is the paradigm turned upside down: the primitive watching us, the subject now the studier, the human now more than a piece of bone. It’s funny and cute and for Dr. Mann, apt: because the science of physical anthropology is first and foremost about ourselves, from the dusty bones on up. Dr. Mann is firmly rooted in the past, and in the present: in the classroom, the courtroom, the sunny fields of Marillac. He may never fully convince the scientific community of his Neanderthal theory. But for now that question is still in the future; he continues to add worlds, upon worlds, of knowledge.