Friday, March 26th, 2010

A New Human Relative, From a DNA Sample?

Could a finger bone found in a cave in these Siberian mountains change the human family tree? View from a rock above Denisova cave on to the excavation field camp. Credit: Johannes Krause.

Genetic analysis of DNA taken from a single prehistoric finger bone may point to a new branch of the human family tree. Writing in the journal Nature this week, a team of researchers describe their studies of mitochondrial DNA extracted from a child's finger bone that was unearthed in 2008. Unearthed in Denisova cave, in Siberia's Altai mountains, the finger bone was found to contain DNA significantly different from either Neanderthals or modern humans.

The find points to an 'out of Africa' migration about one million years ago, separate from two migrations associated with Homo erectus and the Neanderthals. However, the researchers were careful not to immediately call the find a new species, saying that further work, including a close analysis of the nuclear DNA, was necessary to make that sort of claim. We'll talk about the find, where it fits with our understanding of evolution and migration, and what it means to be a member of the human family.