Reassessment of Cranial Plasticity in Man: A Modern Critique of Changes in Bodily Form of Descendants of Immigrants

The reconstruction of biological relationships in humans using the cranium relies on the assumption that the multivariate distances derived from cranial data have a genetic component. This notion has been criticized by some authors based mainly upon one study of Franz Boas. This study focused on the idea that within one generation the cranial form of a population can be significantly altered by a sudden change in the environment. Boas.s original study has been cited for the past ninety years as evidence of cranial plasticity.

A modern critique of Boas.s original study has been long overdue and is pursued herein using modern genetic and statistical methods. Heritabilities of cranial traits derived from Boas.s data reveal a high genetic component to the traits. Multivariate distances between parents and their American-born offspring are small, and when Boas.s original comparisons are conducted using modern statistical methods, the significant changes witnessed by Boas are often due to random chance. While small differences do exist between parents and offspring, these differences are negligible when compared to inter-ethnic differences.

Findings indicate that the genetic component of the human cranium is substantial, and cranial data can be used as a proxy for genetic data. Critiques of studies based upon population comparisons based on craniometric data need to be reconsidered in biological anthropology based on the small environmental component contained in cranial variation.