Comparisons of Age-at-Death Distributions among Extinct Hominins and Extant Nonhuman Primates Indicate Normal Mortality

Abstract

Most modern mammalian populations exhibit higher mortality at both ends of the age-at-death distribution. Yet our hominin ancestors reportedly do not exhibit this same distribution, with explanations ranging from predation to taphonomic causes. This paper compares mortality distributions of extant non-human primates to fossil hominins by applying the D0-14/D ageat-death estimation method. Using subadult and adult counts for four extinct hominin taxa, we fitted the hominin data to a modern human mortality curve, resulting in hypothetical mortality distributions. With the expectation that fossil hominin taxa likely fall somewhere on the continuum of non-human primate to human life histories, we compared the distributions to those of five extant catarrhine primate populations. Subadult mortality amongst the extinct hominin groups was typically within the range of that of extant non-human primate groups, and the previously reported high mortality amongst young and middle aged adults in hominin assemblages may be explained by normal, multi-cause deaths.