We discuss the relevance of ancient DNA studies for novel approaches to a variety of fields of scientific inquiry, including population and evolutionary genetics, prehistoric archaeology, paleopathology and history of human diseases. To exemplify the potential of ancient DNA research, we provide accounts of studies currently conducted at our laboratories in four different areas: 1) origins of the dog and phylogeny of prehistoric Italian canids; 2) paleogenetics of ancient Roma; 3) antiquity for variant alleles implicated in disease predisposition; 4) molecular investigation of pathologic lesions in Italian mummies of Renaissance age. The implications of the results obtained are briefly outlined.