In the 19th century, anthropologists argued that skull capacity equated directly with intelligence. Caucasians, so the theory went, had larger brains—and thus were smarter—than American Indians and people of African descent. It was a convenient, if false, viewpoint in a white-dominated society. As the 20th century dawned, early skull examiners pointed to another characteristic, cranial index, or head form, as a means of discerning races and ethnic groups. At that time, some anthropologists went so far as to predict traits such as criminality and lunacy based on the shape of the human skull.

James Collins

Morphometricians like Corey Sparks can chart how thehuman cranium differs between populations, and how it changes in a given population over time.

In 1912, Franz Boas stunned the world of anthropology by reporting striking differences in cranial form between American-born children of immigrants and their European-born parents. After collecting and analyzing measurements from over 13,000 subjects, Boas proclaimed that environment, not heredity, determined skull shape. The skull was plastic: You couldn't use it to reliably distinguish ethnicity or race, let alone intellect.

David Hurst Thomas, curator of anthropology at the American Museum of Natural History, summarizes Boas's revelation in his book Skull Wars, published in 2000: “Boas found that nobody knew what a ‘race' really was.” Instead, human form and behavior stemmed from environment: the foods a person ate, the kind of home he or she grew up in, the society to which the individual belonged. Over time, Boas's outlook became widespread—became in its own way as dogmatic, some anthropologists now say, as the earlier racist outlook.

Recently, two physical anthropologists reanalyzed Boas's head-form data. They report that Boas—now considered the founding father of modern American anthropology—was wrong. Their findings may lead to a new understanding of human races and the origin of certain ancient skeletons, including the recently discovered Kennewick Man, whose cranial characteristics have stirred controversy among anthropologists.

Corey Sparks, a doctoral candidate at Penn State, and Richard Jantz, a professor at the University of Tennessee, published their findings in the October 7, 2002, issue of Proceedings of the National Academy of Sciences (PNAS).

Sparks is tall, blond, and bespectacled, with a cover-your-mouth laugh. At Penn State, he is conducting paleodemographic research: examining medieval skeletons from a Danish collection to determine how mortality may relate to changing agricultural practices. Sparks began his scrutiny of Boas's work as a master's student at Tennessee, where Jantz was his thesis adviser. “Jantz had a copy of Boas's Materials for the Study of Inheritance in Man, which includes the head-form data,” Sparks says. “One day he called me in to his office, showed me the book, and said, ‘Corey, know what you need to do?'” Sparks opens the book, in which page after page of columns record LH (length of head), WH (width of head), and WF (width of face) from seven ethnic groups: Bohemians, Central Italians, Poles, Hungarians, Scots, Sicilians, and a set of people of Jewish ancestry from five European countries. Measurements taken from multiple generations of families make it possible to determine whether skull characteristics are heritable. Boas and his assistants had collected the data in 1909 and 1910 in schools and other institutions and in immigrants' homes in New York City. Sparks's task: Enter the numbers into a computer and figure out how best to analyze them. He settled on a battery of standard statistical assays developed in the first half of the 20th century, along with more modern genetic analyses.

“In evaluating skull shape,” Sparks notes, “Boas looked at three variables. These days a physical anthropologist”—whether doing forensic work or studying bones from an archaeological dig—“will typically make around 80 measurements. Boas focused on cranial index: the ratio of head width to head length. In many cases, he compared pre-adult children with their parents. That approach downplays the fact that the cranium changes as an individual grows and matures. Boas concluded that, in only one generation, dramatic changes in head form had taken place.”

Boas himself did not theorize why such change had occurred; in a paper published in 1912 in American Anthropologist, he wrote: “I have no solution to offer,” and “I have only stated the results of my observations.” Other anthropologists have suggested new foods and different child-rearing practices.

Says Sparks, “Working from Boas's data, we found that some change had indeed taken place, but not much. After you factor out age, the amount of change is not statistically significant.” The reanalysis actually suggests an overall stability of the cranial index, even in a changing environment where people may abandon old cultural traditions, enjoy better nutrition, contract new diseases, or experience a lower infant mortality rate. As Sparks and Jantz state in their PNAS article, skull differences between same-age related individuals born in Europe and America are “negligible in comparison to the differentiation between ethnic groups.” Says Sparks, “We found that the dominant force for all traits was genetic.”

Notes Jantz, “Boas's head-form studies have been cited by many people critical of what morphometricians are doing.” Morphometricians are physical anthropologists who analyze bones, focusing mainly on skull shape. By thoroughly measuring a skull, some morphometricians believe they can correctly identify its owner's continent of ancestral origin with up to 90 percent accuracy: They can state that a skull comes from a person whose forebears originated in Africa, Europe, or Asia.

At the University of Tennessee, in Knoxville, Jantz frequently does forensic work for law enforcement agencies. While a graduate student there, Sparks helped dig up skeletal remains, then affirmed their origin as human. He emplaced bodies (corpses donated to science, and unclaimed bodies released by medical examiners' offices) at the William M. Bass Forensic Anthropological Research Center, known less formally as the “Body Farm.” There, scientists investigate such subjects as comparative decomposition rates (bodies rot faster in cars than on the ground), interactions between insects and corpses, and the malodorous gases given off during putrefaction. The studies help law-enforcement personnel determine the time of death in murder cases.

Morphometricians like Jantz and Sparks also can chart how the cranium differs between populations, and how it changes in a given population over time: the latter type of analysis forms part of Sparks's current research into medieval Danish farmers.

At present, Jantz is one of eight anthropologists, including several morphometricians, who are suing the federal government for access to further study the bones of Kennewick Man, found in 1996 on the banks of the Columbia River near Kennewick, Washington, and currently locked away in a vault at the University of Seattle. No DNA could be recovered from Kennewick Man, but carbon dating of bone collagen set the skeleton's age at 9,000 years. Under the Native American Graves Protection and Repatriation Act, local Indian tribes have requested the skeleton for re-burial. What makes the situation significant—and politically charged—is that physical anthropologists say Kennewick Man's skull differs markedly from the skulls of modern and historic American Indians, which show a clear linkage to Central Asia. Kennewick Man's cranium, according to Jantz, looks more like the skulls of Polynesians and early natives of Japan.

Bosma Collection

Three examples of juvenile skulls from the Bosma Collection, housed in Penn State's anthropology department. They illustrate how the cranium changes as an individual grows and matures.

Some scientists, including David Thomas in Skull Wars, have cited Boas's head-form studies in contending that environmental factors could have caused skull shape to change significantly over 9,000 years. Such evolution implies that Native Americans could have descended directly from humans like Kennewick Man and the 15 to 20 other early North American skeletons, all of them 9,000 to 12,000 years old, that possess similar skulls. Jantz and his fellow plaintiffs believe Kennewick Man may provide evidence that other populations reached North America—perhaps traveling by kayak via a coastal route, rather than crossing from Central Asia on an ice-age land bridge, which is the current explanation of how our continent was first peopled. Preliminary examinations found that Kennewick Man's skull most closely resembles those of the Ainu, believed to be among the original inhabitants of Japan and now living in that country's northernmost islands.

A German of Jewish descent, Franz Boas emigrated to the United States in 1886. He became curator of anthropology at the American Museum of Natural History in New York City and a professor at Columbia University. He directed the Jesup North Pacific Expedition, which investigated cultural and linguistic ties between aboriginal peoples of Siberia and North America. Boas was an editor of Science magazine and a founder of the American Anthropological Association. He once wrote, referring to racist anthropology, that “far-reaching theories have been built on weak foundations.”

Boas led anthropology toward the study of human biology, language, and culture and away from what he called the “comparative method,” which ranked different cultural groups along a single axis of progress. His students included Margaret Mead, Ruth Benedict, Edward Sapir, and Ashley Montagu, all famous anthropologists in their own right, and all proponents of Boas's anti-racist viewpoint. Penn State historian of science Robert Proctor says, “Boasians turned away from bones altogether.” Or, as Skull Wars author Thomas states in an October 8, 2002, New York Times article reporting on the Sparks-Jantz paper: “Once we anthropologists said race doesn't exist, we have ignored it since then.”

Sparks and Jantz do not know why Boas concluded that the human skull was so fluid in response to environmental change. “Boas had a strong statistical background,” Sparks says. “For his era, he was one of the most numerically intensive anthropologists around. He pretty much did the type of analyses that people did back then. It was paper-and-pencil work—no computers. After new statistical methods were developed in the twenties and thirties, Boas did not go back and recheck his head-form data.

“Boas's correspondence with friends, rivals, and even enemies reveals his distaste for the scientific racism of his era. As a Jew, he no doubt understood firsthand the effects of racism on minority groups. We make no claims that his calculations were purposely skewed. But it does seem possible that he chose to ignore variation in skull shape between populations because he believed it might contribute to racist anthropology.”

Historian of science Proctor says of Sparks's and Jantz's study, “I'm afraid that some people may read this story wrong—it doesn't disprove Boas's main contribution, which was to distinguish race, language, and culture. Any race can develop any culture, or speak any language.”

Coincidentally, as of this writing, another paper, by anthropologists at the University of Michigan, the University of Florida, and Northwestern University, is scheduled for publication in American Anthropologist; it concludes that Boas correctly interpreted his head-form data. According to Jantz, these present-day anthropologists fail to acknowledge Boas's error in comparing children with adults. Nor, points out Sparks, do they consider cranial differences between ethnic groups.

Do the findings of Sparks and Jantz change how we should evaluate the stature of Boas or the impact of his work? Says Jantz, “Even if you say he's dead wrong in concluding that the skull is plastic, this represents just one component of a multifaceted career. Boas's immigrant study was the beginning of the demise of racial typology; I regard that as a good thing. Actually, I don't think anybody is doing racial typology today. However, that does not mean that cranial morphology is meaningless.

“Sometimes it's hard to see how Boas reached some of his conclusions. I don't know that Boas shaded his data. He put it all out there so people could study it. The amazing thing is that nobody has looked at it until now.”

Corey S. Sparks, M.A., is a doctoral candidate in anthropology in the College of the Liberal Arts, 312 Carpenter Bldg., University Park, PA 16802; 814-863-8255; css186@psu.edu. His master's thesis can be downloaded at www.personal.psu.edu/css186/interests. His adviser is James Wood, Ph.D., 517 Carpenter Bldg., University Park, PA 16802; 814-865-1936; jww3@psu.edu. Richard L. Jantz, Ph.D., directs the William M. Bass Forensic Anthropological Research Center at the University of Tennessee.