Stockholm — This year's Nobel Prize in physiology or medicine has been awarded to Swedish scientist Svante Pääbo for his discoveries on human evolution. Thomas Perlmann, secretary of the Nobel Committee, announced the winner Monday at the Karolinska Institute in Stockholm, Sweden. Paabo, 67, has spearheaded research comparing the genome of modern humans and our closest extinct relatives, the Neanderthals and Denisovans, showing that there was mixing between the species. "By revealing genetic differences that distinguish all living humans from extinct hominins, his discoveries provide the basis for exploring what makes us uniquely human", the Nobel committee said. "This ancient flow of genes to present-day humans has physiological relevance today, for example affecting how our immune system reacts to infections," the panel said. The medicine prize kicked off a week of Nobel Prize announcements. It continues Tuesday with the physics prize, with chemistry on Wednesday and literature on Th