Ancient DNA as a Means to Investigate the European Neolithic

Abstract: The transition from a hunter-gatherer lifestyle to a farming lifestyle, i.e. the Neolithisation, is arguably the most important event in human prehistory. While the geography and dating of the Neolithisation is well known, the process is still under debate, especially if it occurred through diffusion of ideas or with migrating farmers. The process accelerated when alternative use of domesticated animals increased. Especially the use of dairy products, and the consumption of unprocessed milk, appears to be of importance. As milk consumption (lactose digestion) is dependent upon genetic components, it is debated whether the genetic disposition allowed for dairy production to evolve, or if the usages of dairy products added selection pressure that eventually lead to present day allele frequencies. Molecular genetics have the potential to solve this and similar questions, but only if the contamination problem, where authentic DNA can be distinguished from modern contaminating DNA, can be resolved.Here I investigate the nature and extent of contamination with modern human DNA in museum specimens and explore several approaches to minimise this contamination and to authenticate DNA results from ancient humans. I use real-time quantification, pyrosequencing and FLX-generated clonal sequencing assays to generate data on ancient humans and ancient dogs. I further use the techniques to study the development of lactase persistence and the nature of animal domestication.The results presented show that sample-based contamination is extensive, but can be minimised if treated with bleach. I retrieved authentic HVSI sequences from 30 Neolithic hunter-gatherers and farmers from Sweden, of which eighteen also yielded nuclear data indicating that the farmers had a higher frequency of the allele linked to lactase persistence compared to the hunter-gatherers. I conclude that genetic data from ancient humans as well as from ancient animals can be retrieved and used, but only under high stringency.