Hybridization in human evolution: insights from other organisms

During the late Pleistocene, genetically isolated lineages of hominins exchanged genes thus influencing genomic variation in humans in both the past and present. However, the dynamics of this genetic exchange and the associated phenotypic consequences through time remain poorly understood. Gene exchange across divergent lineages can result in myriad outcomes arising from the dynamics of the exchange, and the environmental conditions under which it occurs. Here we draw from research across various organisms illustrating some of the ways in which gene exchange can structure genomic/phenotypic diversity within/among species. We present a range of examples relevant to questions about the evolution of our hominin ancestors. These examples illustrate the diverse evolutionary consequences of hybridization and point to potential drivers of human evolution in the context of hybridization with other hominins including: influences on adaptive evolution, climate change, developmental systems, sex-differences in behavior, Haldane’s rule and the large X-effect, transgressive phenotypic variation.