Before the religions of the Middle East forbade eating the pig, it had already slipped off the menu. Around 7000 - 4000 years ago pigs are commonly found in archaeological sites as part of the domestic rubbish, but 3000 years ago there is a sharp decline in the eating of pork. Chickens were domesticated somewhere in Asia, possibly India or Thailand, and then spread across the world to become a dominant food source. One idea proposed is that the chicken took the pigs role as a protein source and proved more useful in hot dry environments. As chickens need less water than pigs and have the added benefit of producing eggs. Whether this change in dietary behaviour is coincident with late Holocene climate shifts, which made the Middle East more arid, only further research will tell.