In the light of theoretical foundations based in evolutionary life-history theory the talk offers an account of the processes at work in the origins of agriculture in south-west Asia and its spread westwards into Europe. It argues that the large-scale adoption of sedentism and farming created a Malthusian population pull as a result of the increased reproductive success associated with the increased energy availability and improved recruitment to the next generation that ensued, coupled with the higher densities that could be sustained in favourable regions by the new subsistence system. This enabled its possessors to take advantage of the existence of large areas of Europe that were very well-suited to the new subsistence system but only very thinly occupied by hunter-gatherers.
Farmers passed on farming knowledge, practices and the plant and animal resources themselves to their children, through the generations, in a conservative process of vertical transmission. Thus, all aspects of culture and practice, as well as the adaptive environment, were transmitted together, tightly connected by common descent to the genes. Some of these practices and resources were those which gave these people their selective advantage, especially the domesticated plants and animals and the knowledge to ensure their continuing reproduction. Others would simply have been ‘hitch-hiking’, carried along with the expanding population, for example the language they spoke.
However, the population booms set off when farmers arrived in new areas favourable to their subsistence system in many cases did not last, but were followed by busts or slower population declines. The reasons for these remain unclear. In some cases, it may be a result of the onset of cooler and wetter climate conditions, but the pattern raises the question of whether the arrival of farming sets off an intrinsically cyclical phenomenon, in which population increases rapidly, and then exceeds local carrying capacities.
The argument developed depends fundamentally on the rapidly growing body of evidence available for population patterns, especially from the increasing number of analyses of DNA from ancient human genomes, but also from population history reconstructions based on summed radiocarbon probability distributions.
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Department of Linguistic and Cultural Evolution