The complicated origins of our species

Creation myth: In the ritual rooms of the Pueblo cultures in North America, a hole in the ground symbolically represents the passage of the tribes into this world. (Photo: Wikipedia.) The ritual rooms of the Pueblo culture in North America, known as kiva, typically contain a hole in the ground, the sípapu. It symbolically represents the origin of the tribe, the passage through which its people first came into this world. Creation myths in other cultures, like the biblical one of the Garden of Eden, also like to pin down the origin of mankind to one place and one event, even if the place may be out of our reach. The scientific study of the origins of our species has over the last few decades very successfully focused on the ‘Out of Africa’ model, which posits that Homo sapiens arose between 200,000 and 150,000 years ago in sub-Saharan Africa. Migrating out of Africa to Eurasia between 60,000 and 80,000 years ago, it spread around the world and successfully replaced archaic populations such as Homo erectus and the Neanderthals, who had migrated out of Africa at earlier times. The quest to establish specific details of this population history has often been framed in terms derived from the genesis. Thus, Homo sapiens’ native habitat became the Garden of Eden, and efforts to establish genetic characteristics of a founder population were often described as a search for the genes of Adam and Eve. To a certain extent, these apparently unscientific descriptions remained close to the actual results, as mitochondrial DNA, for instance, pointed to a common ancestor, a ‘mitochondrial Eve’ who lived around 200,000 years ago, and the spread of genetic diversity could be traced to specific parts of Africa. With the spectacular developments in recent years delivering the genome sequences of the Neanderthal and a new Homo population, the Denisovans, the story is becoming more and more complicated, however. New archaeological finds in unexpected places are adding to the complexity, and the popular story of a geographically well-defined ‘cradle of mankind’ and a small founder population may turn out to be a simplification, if not another creation myth.