Assessing Craniofacial Secular Change in American Blacks and Whites Using Geometric Morphometry

Abstract

American crania have changed significantly in the past 150 years. In the sagittal plane, most of the change is associated with a downward movement of the cranial base, especially at basion. Secular change in American crania is proximately related to a decrease in cranial base breadth and an increase in cranial capacity, and ultimately a reflection of improved infant growth due to better health and nutrition. The environment of 20th century Americans has no parallel in history. Activity levels are at an all-time low, and diet has improved to the point where overnutrition has surpassed undernutrition as our most serious malnutrition problem (Flegal et al., 1998). In addition, epidemic infectious diseases are now mostly controlled, and mortality is at an all-time low (Armstrong et al., 1999). It is not surprising that there is a biological response to this unparalleled environmental change.