Per Möller, Professor of Quaternary Geology at Lund University, together with researcher colleagues, has investigated soil samples from old sedimentary strata in inland Alaska. These untouched sediments provide a view of conditions thousands of years ago around and after the end of the latest ice age. In their soil samples, the reseachers have found mitochondrial DNA which is present in the somatic cells of all animals, among them woolly mammoth and horse. These fossil DNA residues come from the urine, faeces, skin and hair of the animals that lived at this site long ago. According to previous data, both these species became extinct in North-West America between 15,000 and 13,000 years ago. But these new finds indicate that both the woolly mammoth and the horse survived until about 10,500 years ago. The appearance of humans on the scene had so far been regarded as the cause of the rapid extinction of the large mammals in the area. According to these new finds, humans and both the woolly mammoth and the wild horse co-existed over several thousand years. Research into extinct animals had so far mainly been based on macrofossils, i.e. fossils of mainly skeletal bones and teeth. Several thousands of individuals of a certain species may be needed for a single macrofossil find. Per Möller and colleagues say that fossil mitochondrial DNA can provide a more refined opportunity to find traces of single individuals.