The advent of the Polymerase Chain Reaction technology has led to the emergence of a totally new field of research, known as molecular paleontology. PCR is indeed well suited to amplify the rare molecules that have been scarcely preserved in fossils through time. Although the claim of the retrieval of several million-year-old DNA had brought skepticism into the field of ancient DNA research, this new science has now rigorously determined its own limits. Paleogenetics provides an attractive approach to resolve questions as diverse as the phylogenetic position of recently extinct species, the genetic differentiation of past populations, the origin of human genetic pool, the occurrence of human colonization waves throughout the world, or the spreading of great historic diseases.