Ontogeny of modern human longitudinal body and transverse shoulder proportions

Abstract

The ontogeny of transverse shoulder proportions is more complex than what is observed for bi-iliac breadth, suggesting that transverse shoulder to limb proportions are not solely influenced by ecogeographical conditions. Our analysis demonstrates that methodologies that incorporate critical dimensions of body form could shed new light on human adaptation in both paleontological and neontological contexts.

Ecogeographic patterns in fetal limb proportions

“…It must be noted that sample sizes, particularly for distal, lower limb elements, are much less than those of upper limb elements and femora. Despite this variation in sample size across elements and indices, these sample sizes are still robust compared with other skeletal studies of fetal remains (e.g., Bleuze et al, ; Frelat et al, ; Frelat & Mittereocker, ; Temple et al, ). Individuals of African ancestry display greater index values than those of European ancestry for brachial and crural indices, indicating a greater relative length of the distal elements compared with the proximal elements.…”

“…Researchers who have explored the origins of ecogeographic variation among adults by studying the postnatal period have detected population differences in body proportions (Bleuze et al, ; Cowgill et al, ; Frelat et al, ; Frelat & Mittereocker, ; Hadley & Hruschka, ; Temple et al, ). Much of this research notes that limb proportions fluctuate over development, with interpopulation variation in limb proportions being detected early on and achieving adult form with the onset of puberty (Bleuze et al, ; Cowgill et al, ; Frelat et al, ; Temple et al, , ). Cowgill et al () found population differences at less than 1 year of age that remained relatively consistent over the course of development.…”

“…Responses to environmental stress are both biological and cultural. Nutrition and socio economic factors play a critical role in overall development and may confound or moderate the general principles of ecogeographic patterning (e.g., Bleuze et al, ; Cowgill et al, ; Frelat et al, ; Frelat & Mittereocker, ; Pinhasi, Timpson, Thomas, & Slaus, ; Ruff, ; Temple et al, ). Simpson () and Mayr () postulated that the cultural factors that come into play may actually have promoted the development of ecogeographic clines in body form, by allowing habitation of marginal regions that focus and amplify selection—the so‐called Baldwin Effect.…”

“…The European ancestral group comprised 52.7% of the total sample ( n = 97; male = 63, female = 34); the African ancestral group is 47.2% ( n = 87; male = 53, female = 34). This sample is uniquely suited to assess the influence of sex on proportionality within and between groups which is unique compared to other analyses on immature skeletal samples where sex of the sample could not be accurately determined (Bleuze et al, ; Cowgill et al, ; Frelat, Coquerelle, & Trinkaus, ; Frelat & Mittereocker, ). Between‐sex differences in proportional indices among adults tend to be much smaller than the differences across broad geographically dispersed groups (Auerbach, ; Holliday, ; Trinkaus, ).…”