Ancient DNA research goes nuclear

It is one of the most fascinating questions we face: how did Homo sapiens —modern humans—evolve? When did they start using tools, how did they develop language and why did Homo erectus and then Homo sapiens thrived while other human species, such as the Neanderthals, became extinct? The availability of advanced genetic technologies, most notably the polymerase chain reaction (PCR), originally held great promise to answer these questions; in theory, sequencing the DNA from fossils could paint a picture of the molecular evolution not only of humans but of other species as well. In practice most of these expectations have not been realized, as the analysis of ancient DNA is anything but easy. The very small amount of DNA in fossil samples, the decay of the molecules over time and contamination with DNA from other organisms have proven to be considerable hurdles. As a result, most knowledge about molecular evolution comes from the analysis of mitochondrial and plastid DNA, simply because it is more abundant and easier to analyse.But the analysis of ancient DNA is about to enter a new era. Two recently developed techniques—multiplex PCR and a new genomic sequencing technology—allow the recovery of meaningful sequence data from nuclear rather than just mitochondrial or chloroplast DNA. Many of the field's leading researchers are already excited about the prospects. “I think we will see a number of studies dealing with functional genetics, where you take and amplify sequences, and see phenotypic features that say something about how the animal behaved or looked like,” said Eske Willerslev, from the Department of Evolutionary Biology at the University of Copenhagen, Denmark. “We will definitely see much more in the next two years because there's a huge potential out there.”> …in theory, sequencing the DNA from fossils could paint a picture of the …