craniometry

craniometry is the study of the shape and form of the human head or skull, sometimes known also as craniology (the difference lies largely in that the former implies precise measurement, the latter less so). As it is such an obvious observation that people vary considerably in the size and shape of their heads and faces, it is hardly surprising that attempts to put this to scientific and other uses stretch well back in time. The modern and quantitative study of craniology derives essentially from the nineteenth century, when it became widely accepted that evolutionary ideas could be explored through detailed comparisons of skulls. In effect it is a specialized branch of anthropometry, the quantitative study of the human body.

The practice of craniometry consists of taking precise measurements using ‘landmarks’ on the skull. The skull is not a single bone, but is made up of several interlocked plates, such as the two parietal bones at the sides and the central frontal bone. Where these bones meet can be easily identified, and these places form many of the major landmarks of the skull — for example, the ‘bregma’, where the two parietals and the frontal meet, which is in effect the highest part of the skull. The distances between the various points can be measured, and thus form the basis of craniometry. In this way, a structural model of the skull, consisting of the angles and lengths between the landmarks, can be formed, and thus it is possible to compare one skull with another, and to make statistical comparisons between populations. Measurements are made most easily on skulls, but some can also be taken from the heads of living people as part of more general anthropometric studies.

The development of craniometry owes much to many pioneers of the nineteenth and twentieth centuries, of whom perhaps the most important was Rudolf Martin, professor of anthropology at the University of Zurich (1864–1925). He provided the systematic basis for craniology, much of which is used today. Another important contributor is W. W. Howells, emeritus professor of anthropology at Harvard University, who developed a more practicable set of measurements, and greatly enhanced the statistical treatment of such data. Although often confused with phrenology, the study of variation in the size and shape of the human skull within the biological sciences owes more to classic medical and comparative anatomy than to this discredited and largely subjective approach.

The study of the human skull has been one of the most fertile, important, controversial and abused branches of anthropology. Comparisons of human skulls with those of fossil hominids that have been unearthed have been the main source of information and inference about the pattern of human evolution, and the relationships between humans and other primates. Differences in shape reflect evolutionary history and relationships. Furthermore, data on cranial variation was used extensively in discussions in the earlier part of this century, following the rediscovery of Mendel's work, in debates concerning the continuous or otherwise nature of evolutionary change.

Comparisons can also be made between human populations. Externally we can see that people from different parts of the world look different, and this is reflected in their cranial anatomy. The patterns of measurements can be used to explore relationships between populations, and the history of human diversification. For example, modern European skulls are characterized by large faces and noses, and relatively long skulls; modern East Asians are lightly built, with very short, flat faces. Craniometry allows these similarities and differences to be treated not as racial types, but as patterns of biological variation, and to be understood in terms of history and adaptation.

However, although modern craniometry eschews the use of head shape to classify people into races, this has not been the case in the past, and craniology has a blacker history. Cranial shape was assumed by many to be a direct measure of racial affinity, such races being seen as fixed biological units. In Nazi Germany such measures as the cephalic index (how broad a skull is) and nose shape were used to categorize people, and to define the Jewish population and degrees of Jewish admixture. Similar but less extreme programmes occurred in other countries, either as part of attempts to introduce eugenics programmes or through attempts to define criminal types.

The scars left after World War II by these atrocious programmes of research meant that the study of human skull shape and size fell into disrepute. Human variation, the core subject of anthropology, was increasingly explored through genetics and other biological markers, and became functional and adaptive in orientation rather than a search for racial affinities. In recent years, however, the introduction of new computer-based techniques of measurement, and the greatly enhanced power of statistical analysis, has meant that there has been a resurgence of interest in this subject, and, stripped of its non-Darwinian and racist past, the study of the human head remains a topic of major importance.

Robert Foley

Bibliography

Lahr, M. M. (1996). The evolution of modern human diversity: a study of cranial variation. Cambridge University Press.
Spencer, F. (ed.) (1982). A history of American physical anthropology. Academic Press, New York.

See also anthropology; anthropometry; evolution, human; heredity; skull.