Harnessing ancient genomes to study the history of human adaptation

Ancient genomes can inform our understanding of the history of human adaptation through the direct tracking of changes in genetic variant frequency across different geographical locations and time periods. The authors review recent ancient DNA analyses of human, archaic hominin, pathogen, and domesticated animal and plant genomes, as well as the insights gained regarding past human evolution and behaviour. The past several years have witnessed an explosion of successful ancient human genome-sequencing projects, with genomic-scale ancient DNA data sets now available for more than 1,100 ancient human and archaic hominin (for example, Neandertal) individuals. Recent 'evolution in action' analyses have started using these data sets to identify and track the spatiotemporal trajectories of genetic variants associated with human adaptations to novel and changing environments, agricultural lifestyles, and introduced or co-evolving pathogens. Together with evidence of adaptive introgression of genetic variants from archaic hominins to humans and emerging ancient genome data sets for domesticated animals and plants, these studies provide novel insights into human evolution and the evolutionary consequences of human behaviour that go well beyond those that can be obtained from modern genomic data or the fossil and archaeological records alone.