Recent advances in genetics have shown that hybridisation occurred during human evolution, yet its morphological impact remains underexplored. Ancient DNA is a powerful tool but given the conditions required for its preservation, it is best combined with fossil morphology. Studies of non-human primates have suggested a signature hybrid morphology including extreme size, high levels of variation, and markers of developmental instability, but how phylogenetic distance and admixture proportion affect these characteristics is unknown. Non-mammalian studies suggest extreme morphotypes are more likely in early generation hybrids and with greater divergence between parents. To understand the hominin fossil record, we must study admixture in taxa that approximate hominin hybridisation as closely as possible. Here, we use macaque proxies (Chinese and Indian Macaca mulatta) with comparable divergence time (in generations) to Homo sapiens / Neanderthals. Our sample is large, multigenerational and of known hybridity. We focus here on the pelvis, which has potential fitness implications for hybrids if successful parturition is compromised. We find no individuals showing extreme morphology. Instead, we see a significant, but weak, hybrid signal that is proportional to the relatively small morphological difference between the parent taxa. The similarity in shape between the full-bred macaques is in contrast to that between Neanderthals and H. sapiens, despite comparable phylogenetic divergence between both hybridising pairs. The greater disparity between the hominins may owe something to adaptation their respective environments, but may also reflect the extent of cultural buffering in hominins, which allows for greater neutral evolution. This work highlights one of the fundamental ways in which hominins may differ from our primate relations and provides a way forward for unpicking the effects of hybridisation on hominin morphology.
Speaker: Dr Laura Buck.
Affiliation: Liverpool John Moores University.
Zoom registration information: contact Lucy Timbrell email@example.com