Variation in Human Body Size and Shape

TLDR

Human body size and shape have evolved under climatic selection, with modern populations exhibiting reduced average mass, established sexual dimorphism, and latitudinal gradients influenced by nutrition. The study aims to separate growth disturbances from long‑term genetic differences in body form caused by climatic selection across populations. The authors illustrate their approach with Inupiat children, applying a novel body‑shape index to evaluate relative body mass.

Abstract

▪ Abstract Evolutionary trends in human body form provide important context for interpreting variation among modern populations. Average body mass in living humans is smaller than it was during most of the Pleistocene, possibly owing to technological improvements during the past 50,000 years that no longer favored large body size. Sexual dimorphism in body size reached modern levels at least 150,000 years ago and probably earlier. Geographic variation in both body size and shape in earlier humans paralleled latitudinal clines observed today. Climatic adaptation is the most likely primary cause for these gradients, overlain in more recent populations by nutritional effects on growth. Thus, to distinguish growth disturbances, it is necessary to partition out the (presumably genetic) long-term differences in body form between populations that have resulted from climatic selection. An example is given from a study of Inupiat children, using a new index of body shape to assess relative body mass.