By Bruce Bower
DNA extracted from a 40,000-year-old pinky bone and a 100-year-old lock of hair has provided glimpses of two Stone Age human migrations to Asia, including an early foray marked by interbreeding between ancient people and some mysterious, well-traveled members of the human evolutionary family.
Denisovans, an ancient humanlike population previously identified via nuclear DNA taken from a finger bone excavated in Siberia’s Denisova Cave, contributed a small portion of genes to living New Guineans, Australian aborigines, two aboriginal groups in the Philippines and populations on several nearby islands, say geneticist David Reich of Harvard Medical School in Boston and his colleagues.
Earlier analyses of modern human mitochondrial DNA, which is maternally inherited, had suggested that a single wave of humans took a southern coastal route from Africa to Asia around 65,000 years ago. Patterns of nuclear DNA alterations in an ancient Denisovan and in living groups instead point to at least two Stone Age human migrations into Asia, Reich’s team reports in a paper published online September 22 in the American Journal of Human Genetics.
A one-two punch of human migrations into Asia, including early interbreeding with the mysterious Denisovans, also emerges from an inspection of an Australian aboriginal man’s DNA, led by geneticist Morten Rasmussen of the Natural History Museum of Denmark in Copenhagen. Those results appear in a paper published online September 22 in Science.