Department of Anthropology, University of Michigan
Saturday All day, Plaza Level
Growth and development are the proximate mechanisms that result in adult form: as de Beer (1940: 98) put it, “phylogeny is but the result of modified ontogeny.” Understanding the evolution of human growth and development can provide insight into how unique aspects of human morphology and life history evolved. For example, a childhood of slow skeletal growth followed by an adolescent growth spurt arguably reflect humans’ cultural niche. But because fossil samples are small and fragmentary, it is difficult to tell when these traits evolved. Several studies have suggested that the relationship between skeletal and dental development – and therefore overall growth – in Pleistocene hominids was not like recent humans. These studies have been based on small fossil samples and rarely include a statistical test. Here I propose a resampling-based test of the hypothesis that the relationship between dental eruption and mandibular growth does not differ between cross-sectional samples of modern humans and Australopithecus robustus. Although A. robustus is not a direct human ancestor, its mandible has a relatively complete ontogenetic series, documenting variation within and across age groups from infant to adult. If the null hypothesis cannot be disproved for this sister taxon, there are implications for interpreting these variables in ancestral hominids. I discuss the relative merits of traditional statistics versus randomization-based methods for the study of growth in fossil samples, and suggest future avenues for understanding the evolution of human growth and development.
This research was supported by grants from the University of Michigan’s International Institute and African Studies Center.