Neanderthals and modern humans — chimps and bonobos: similarities and differences in development and evolution

Abstract

Being our closest living relatives, chimps and bonobos provide the best available comparative evidence to study the evolutionary split between our sister taxon — the Neanderthals — and ourselves. Here, we analyze craniofacial development in these taxa from birth to adulthood using geometric morphometric methods. In both Homo and Pan, ontogenetic trajectories of sister taxa differ by their length, position and/or direction in shape space, as well as in the relationship between cranial size and shape. Modern human and bonobo ontogenies represent “abridged” versions of Neanderthal and chimp spatiotemporal developmental patterns, respectively, where “shortening” of trajectories is likely to represent evolutionary novelty. When examined in detail, however, the Neanderthal-human and chimp-bonobo splits do not represent equivalent forms of evolutionary developmental diversification. Rather, it appears that each bifurcation is the result of a different unique evolutionary event, during which the ancestral mode of growth and development was modified in a taxon-specific manner.