In recent years, the increased availability of genomic data generated from ancient human remains has revolutionized the study of the past, and enabled researchers to tackle a range of questions that previously were targeted almost exclusively by disciplines in the Humanities such as History and Archaeology. Importantly, results obtained through characterizing the genetics of archaic hominins including evidence for adaptation, admixture, past demography, sex determination, or social structure, can be correlated with morphological and archaeological observations drawn from the fossil record. Admixture, defined as the exchange of genes between previously isolated species or populations, is now considered to be an important source of variation among ancient human lineages. The palaeogenomic studies are unravelling the complex evolutionary patterns of the human lineages, showing multiple admixture events in different moments and regions, as well as providing information on adaptations to environmental conditions, past migrations, demographic trends, and social structures.