Final Report Summary - ADAPT (Life in a cold climate: the adaptation of cereals to new environments and the establishment of agriculture in Europe)
This project explored the concept of agricultural spread as analogous to enforced climate change and asked how cereals adapted to the new environments to which they were exposed when agriculture was introduced into Europe during the period 7000–4000 BC. The study material was a large collection of barley and wheat landraces (historic varieties) collected from different parts of Europe. We used DNA sequencing methods to obtain information on the genetic relationships between different groups of landraces, and we examined the extent to which groups of landraces evolved in order to become more greatly adapted to the environments in which they were being grown. We also used published and unpublished archaeological reports to compile a database recording the presence or absence of barley, wheat and other early crops at different farming sites throughout Europe. This database enabled us to follow the spread of agriculture through Europe, and revealed times and locations where pauses in this spread occurred. Originally we thought that these pauses might have been caused by the need for barley and wheat to adapt to the European environment. This hypothesis was not strongly supported by our results, which suggested that environmental adaptation was not an important factor influencing the spread of agriculture. Instead, our results indicate that most of the genes that enabled barley and wheat to adapt to European environmental conditions were already present in the early crops before the movement of agriculture out of the Fertile Crescent. The genes that were important in environmental adaptation increased in frequency at some locations in Europe, but this is more likely to have occurred after agriculture reached those regions, and hence would have influenced the sustainability of agriculture, rather than its initial establishment. This is an exciting discovery because our database of early crops shows that there are places in Europe where agriculture contracted after its initial establishment, notably in the Lower Danube region and in the Northwest European Plains, where some crops that were initially cultivated were subsequently lost. Our findings suggest that Neolithic crops were so genetically diverse that it was initially possible to cultivate them in most European environments, but sustainable cultivation and increased productivity was only possible after the crops had evolved to become more adapted to their local environments. Where such adaptation occurred, crop productivity increased and hence agriculture could be sustained. Where adaptation did not occur, or occurred at a relatively slow pace, a contraction such as those in the Lower Danube and Northwest European Plains would have occurred. These conclusions also align with proposals from archaeological studies that human population growth in early farming societies was characterized in some regions by ‘boom and bust’. According to our findings, in those cases where the increase in a human population outpaced the rate at which their crops adapted to the local environmental conditions, a population ‘bust’ occurred.