Denisova

Entrance to Denisova Cave, looking out into the Anuy River valley.

In 2010, geneticists working with the Max Planck Institute for Evolutionary Anthropology discovered something surprising in a tiny fragment of bone -- the genome of an ancient population that had been completely unknown to paleoanthropology.

That's not the sort of thing that happens every day.

My lab is in a unique position to work on this information and uncover biological details of these ancient people. The initial results of genetic sequencing have provided some starting points for our work. Mitochondrial DNA has been recovered from two individuals, a distal fifth carpal phalanx (that is, a pinky bone) and a third molar. The pinky bone has produced a whole genome at roughly 1.8x coverage. The similarities with Neandertals show this individual to have come from a population roughly as divergent from living people as the Neandertals were, but almost as divergent from Neandertals as from us [1] (I explain this further in the Denisova genome FAQ). They appear to have originated from a common population with us and Neandertals around 250,000-400,000 years ago. The mtDNA sequence of these individuals presents a possible mystery -- roughly twice as different from most living people as we are from Neandertals, it may represent traces of an even more ancient population [2] (again, I describe the full scenario in the FAQ, and the initial mtDNA result in my post on the work by Krause and colleagues). It remains unclear whether these genetic results may allow us to connect the Denisovans to any known fossil population. They're too close to us to represent the Homo erectus population that first inhabited Asia more than 1.8 million years ago, but we cannot yet rule out the hypothesis that the Denisovan genome has some ancestry within this ancient Asian population. We do know that the genes from these ancient people live on today, in Melanesia, New Guinea and Australia. But on the whole, the relationships of the Denisovan genome are a mystery. We just don't know if the genome comes from any known fossil population.

Our lab is working to understand the biology and relationships of this ancient population. We are comparing the genome to those of living people to examine which elements have been inherited from the ancient Denisovans into living populations. Most of all, we are interested in what the functional genetics of this genome may tell us about the phenotype of ancient Denisovans. A whole genome can give us insight about aspects of biology that we could never uncover from skeletons, everything from digestion and muscle metabolism to the immune system. We're working to put together a picture of this ancient population, using the knowledge that we are getting every day from studies of human genetics worldwide.

Excavations underway in the East Gallery of Denisova Cave, July 2011.

I was at Denisova Cave in the summer of 2011, where excavations are still underway. The site has tremendous promise, and we may hope that more discoveries will be coming out in the next few years.

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References