What are the major theories proposed in support of the origin of food production ? How the change in subsistence economy brought revolution during this period ? (Answer in 250 words)

- What are the major theories proposed in support of the origin of food production ? How the change in subsistence economy brought revolution during this period ? (Answer in 250 words)
Introduction
Explanations of the shift to food production divide into those that make it a response to external pressure and those that make it a social choice. Each must then account for what followed.

Body
1. Environmental and demographic theories: Childe's oasis or propinquity theory of 1936 made post-Pleistocene desiccation force people, animals and plants together at shrinking water sources. Braidwood answered with the nuclear zone hypothesis — domestication began in the hilly flanks of the Fertile Crescent where the wild ancestors actually grew, once culture was ready for it, as at Jarmo. Binford and Flannery relocated the cause to marginal zones, where population spilling out of rich areas broke the density equilibrium, and Boserup and Cohen generalised this into population pressure as prime mover. Younger Dryas cooling is the current climatic version, tested on the Natufian.
2. Social and co-evolutionary theories: Hayden derives cultivation from competitive feasting by aggrandisers and Bender from the demands of alliance and exchange. Rindos treats domestication as unintended co-evolutionary symbiosis rather than invention, and Cauvin reverses the order altogether, a revolution of symbols preceding the economic one, with Gobekli Tepe as the exhibit.
3. What the change produced: sedentism, storage, pottery and ground stone, and the village — at Mehrgarh, wheat, barley and humped cattle by the seventh millennium BCE. Shorter birth spacing raised fertility and population; surplus permitted craft specialisation, property and ranked society. Skeletons record the cost in falling stature, caries, anaemia and new zoonoses.
4. How far revolution: the process took millennia and occurred independently in several centres, so it was not an event.

Conclusion
Childe's word holds for consequences, not for tempo. Agriculture was a slow, repeated and largely unintended transition whose demographic and political effects were nonetheless revolutionary.