An EU-funded project coordinated by Uppsala University in Sweden will study the origins and significance of lactose tolerance in Europe. The project, called LECHE ('Lactase persistence and the early cultural history of Europe'), is a training network with 13 participating universities in Europe. It will receive EUR 3.3 million over four years from the Seventh Framework Programme (FP7). Approximately 85% of adult northern Europeans are able to digest lactose, a sugar found in milk and other dairy products; however, in the rest of the world the ability to digest milk drops off sharply after infancy. In fact, as one moves south from Scandinavia, lactose tolerance in adulthood drops off. The persistence of lactase (the enzyme that breaks down lactose) in European adults is a genetic trait that appears to have emerged towards the end of the Stone Age. By around 7,000 B.C. European populations were farming, breeding domesticated animals such as cattle and, importantly, using pottery. Evidence of regular milk consumption has been found in pottery shards northeast of the Black Sea; it is assumed that the ability to tolerate lactose (a dominant genetic trait) migrated from there across the continent. Drinking milk dramatically increases the number of calories that can be obtained from an animal, compared to consuming its meat alone. This means that the ability to tolerate lactose would contribute significantly to a successful transition from hunting and gathering to an agrarian lifestyle. Dr Anders Götherström, coordinator of the LECHE project, considers lactase persistence to be fundamental to the development of agrarian culture in Europe. He explains that: 'mutations can be selected negatively or positively throughout evolution and history. But no other mutation seems to have had so positive a selection in the last 10,000 years as the one that creates lactose tolerance.' The mutation that makes lactose digestion possible in adults is assumed to have arisen separately in different parts of the world. However, other theories abound and there is much to be learned. The LECHE project brings together several research teams with expertise in genetics, organic chemistry and archaeology. It comprises 13 PhD candidates and 2 postdocs, with a total of 24 participants. They will use sophisticated chemical analyses of bones and pottery together with traditional archaeology to explore the history of milk consumption and husbandry practices in Europe. Researchers will use both modern and ancient DNA from cattle and humans to investigate when and where positive selection for the 'lactase persistence' gene started. Organic chemistry will also be used to analyse ancient pottery remains (by typing lipids, fatty acids and other organic compounds) to see when and where people started to store and use milk products. Researchers will look at stable calcium isotopes in ancient bone tissues, which will show whether a person consumed milk products; and nitrogen isotopes, which will indicate whether a person has been breastfed. The LECHE participants will share their findings in a large, central database. Mathematical models will be used to establish gene flow and selection in Neolithic populations, and this will be compared to the current distribution of lactose tolerance in adults as well as evidence of milk consumption found in ancient remains. The students will carry out individual research projects but will work overall as part of a team. They will participate in training workshops and summer schools that focus on both technical aspects relating to the science of the study (sequencing, data handling) and general issues such as presentation, writing and career planning. Study participants are based in universities in Sweden, the United Kingdom, Ireland, the Netherlands, Germany, France, and Denmark.