1.4 – Human skulls: Boas head shape studies revalidated

While individuals differ, biological differences between races are small. There is no reason to believe that one race is by nature so much more intelligent, endowed with great will power, or emotionally more stable than another, that the difference would materially influence its culture.
–Franz Boas, “Race and Progress” (1931:6)

The issue of race is a core part of the history of anthropology. Anthropologists studied human nature and human difference, born as a scientific study of savages (see Human Nature and Anthropology). However, from over a century ago, a prominent founder of anthropology championed an anti-racist line. Anthropology should have won the battle on race long ago, with Franz Boas.

Eugenia Shanklin’s article “The Profession of the Color Blind: Sociocultural Anthropology and Racism in the 21st Century” urged anthropologists to get much more worked up about race, since the Boas victory only meant “American anthropology won the battle and lost the war” (1998:670). Shanklin had taken her own message to heart, publishing an undergraduate textbook titled Anthropology and Race: The Explanation of Differences (1993).

Boas worked to sever a deterministic connection between biology and behavior. Far ahead of his time, Boas revealed how motor movements–ways of walking, dancing, posing, smiling–are part of our learned behavior, learned so well that they feel natural. Since these things are learned, people of different physical appearance can learn them.

In addition to severing the connection between race and culture, Boas measured heads of immigrants and their children in New York City. This work challenged the physical basis of human racial categorization. Measuring heads of people from central and southern Europe, Boas determined that within one generation of arrival there were already measurable changes in head and body form. Environmental factors like nutrition and hygiene played a larger role than anyone had realized. Contrary to popular belief, this was not always a good change–Sicilians were stunted in their new environment.

Many people found the study outrageous, dismissing it from the beginning. In the early 2000s, some anthropologists returned to the data and claimed Boas got it wrong. Another group of anthropologists re-examined the data and said Boas got it mostly right:

As Boas hypothesized, our results show that children born in the U.S. environment are markedly less similar to their parents in terms of head form than foreign-born children are to theirs. . . . This finding thus corroborates Boas’s overarching conclusion that the cephalic index is sensitive to environmental influences and, therefore, does not serve as a valid marker of racial phylogeny. (Gravlee et al. 2003:135).

Others say there is some room for variation based on nutrition and climate, but cranial form can still be used for exploring genetic questions (Relethford 2004).

Apart from the back-and-forth within the number-crunching community, the larger picture is clear:

Human head shape is considerably plastic.

Environment and cultural practices play an enormous role in shaping our heads. Certainly genes regulate the unfolding process of skull development and growth. And those skilled in the use of calipers can use particular skull features as a proxy for understanding ancestry and inherited genes. However, genes do not determine skull shape. That shape is the dynamic result of developmental systems.

Consider three cases:

First, many ancient societies practiced rather severe forms of cranial manipulation, mostly absent from contemporary societies. So much for ancient societies as a natural baseline! Interestingly, neurosurgeons report “there does not seem to be any obvious evidence of negative [cognitive] effect on the societies that have practiced even very severe forms of intentional cranial deformation” (Lekovic et al. 2007:1137).

Second, in contemporary societies with cribs and a back-to-sleep campaign, there are infants going through “helmet treatment” to keep their heads round. Excessive use of cribs, bouncy chairs, and carseats can result in flat-headed folk. We now have to educate parents to teach their infants how to turn their heads. In other words, infants allowed to follow their natural path can end up with quite unnatural head shape.

Third, researchers have determined that deliberate infant head molding, although not practiced in its extreme form, is still widespread:

Our data lead us to question the validity of using skull shape for racial or ethnic classifications or both. Historically and currently, the ubiquitousness of infant head molding that resulted in various head shapes, even those that might not necessarily be identified as deformed, suggests that labeling crania as typical or atypical for certain groups is incorrect. Further, we suspect that, in many instances, the genetic traits so often described by physical anthropologists . . . may well be the unrecognized result of manual manipulation of the infants’ cranial bones. (FitzSimmons et al. 1998:90)

A final surprise is that one of the original re-examiners of the Boas data, initially critical of Boas, has again reappraised the findings:

Change in Hebrew cranial indices resulted from abandoning the practice of cradling infants in America. U.S.-born Sicilian children experienced an environment worse than the one in Europe, and consequently experienced impaired growth. We conclude that the changes Boas observed resulted from specific behavioral and economic conditions unique to each group. (Jantz and Logan 2010:702)

It comes back to the central idea of human nature:

There is no such thing as a natural–or genetically determined–head shape.

Of course, to echo Tim Ingold’s words about human nature–see Human Nature and Anthropology–human head shape is not anything we please. But we cannot describe our heads outside of the particular historical and environmental circumstances in which we grow.

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Sources

Boas, Franz, 1931. Race and Progress. Science 74(1905):1-8.

Benedict, Ruth, 1934. Patterns of Culture.

——, 1946. The Chrysanthemum and the Sword: Patterns of Japanese Culture.

Burkholder, Zoë, 2006. Franz Boas and Anti-Racist Education. Anthropology News 47(7):24-25.

Cunningham, Michael L, and Carrie L Heike, 2007. Evaluation of the infant with an abnormal skull shape. Current Opinion in Pediatrics 19(6):645-651.

FitzSimmons, Ellen, Jack H. Prost, and Sharon Peniston, 1998. Infant head molding: a cultural practice. Archives of Family Medicine 7:88-90.

Graham, John M., 2006. Tummy Time is Important. Clinical Pediatrics 45(2):119-121.

Gravlee, Clarence C., H. Russell Bernard, and William R. Leonard, 2003. Heredity, Environment, and Cranial Form: A Reanalysis of Boas’s Immigrant Data. American Anthropologist 105(1):125-138.

Hubbe, Mark, and Walter A. Neves, 2007. On the misclassification of human crania, with reply from Williams and Armelagos. Current Anthropology 48(2):285-288.

Jantz, Richard L., and Michael H. Logan, 2010. Why does head form change in children of immigrants? A reappraisal. American Journal of Human Biology 22(5):702-707.

Lekovic, Gregory P., et al., 2007. New World Cranial Deformation Practices: Historical Implications for Pathophysiology of Cognitive Impairment in Deformational Plagiocephaly. Neurosurgery 60(6):1137-1147.

Mossop, Brian, 2010. Tummy Time: Why babies need more of it than they’re getting. Slate, December 2.

Pomatto, Jeanne K., et al., 2006. A Study of Family Head Shape: Environment Alters Cranial Shape. Clinical Pediatrics 45(1):55-63.

Relethford, John H., 2004. Boas and beyond: Migration and craniometric variation. American Journal of Human Biology 16(4):379-386.

Shanklin, Eugenia, 1993. Anthropology and Race: The Explanation of Differences.

——, 1998. The Profession of the Color Blind: Sociocultural Anthropology and Racism in the 21st Century. American Anthropologist 100(3):669-679.

Timreck, T.W. dir. 1980. Franz Boas