The Early Farming Dispersal Hypothesis states that the spread of agriculture—that is, the dependence on domesticated plants and animals for food—was accomplished, for the most part, by the spread of human population out of their agricultural homelands. Such spreads, argues archaeologist Peter Bellwood, occur most positively and coherently when the people are already dependent on agriculture for most of their subsistence needs, and they possess the knowledge to establish those techniques in new environments.
Alternatively, the spread of ideas, called diffusion, argues that existing populations of hunter-gatherers learned about farming strategies and adopted them. Under Bellwood's hypothesis, farming was not likely to have been spread by hunter-gatherers adopting new, unfamiliar farming strategies, unless and until they were in direct and continuous contact with farmers.
If the Early Farming Dispersal Hypothesis is correct, one should be able to trace the origins of a particular agricultural group by the spread of their language and cultural material.
Sources
Bellwood, Peter 2009 The Dispersals of Established Food-Producing Populations. Current Anthropology 50(5):621-626.
Bellwood, Peter 2005. First Farmers. Oxford: Blackwell.
Bellwood, Peter. 1996. Phylogeny vs. reticulation in prehistory. Antiquity 70:881–890.
