(Though this is about cooking, it’s GQ with a finite answer, so I’m guessing think it probably belongs here rather than Café Society. Correct me if I’m wrong, mods)
Whence comes the method of cooking ingredients for a very short time over intense heat?
My WAG is that historically people cooked over open fires using thin-skinned vessels; thus there was no regulated heat, and it was necessary to cook hot and fast. Does anyone have a more definitive explanation?
I’m not sure, but I think that it requires less fuel/energy to stir-fry food than most other cooking techniques. Efficiency has traditionally been an important factor in chinese cooking (due to limited sources of both food and fuel), and stir-frying is a quick and efficient way of sterilizing food. Plus, it keeps the vegetables crispy and tasty 
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Yes, I read that it was due to the scarcity of cooking fuel. By chopping the food into small, quickly-cooked pieces it’s possible to cook them over a very small area of heat. You stir the food around to make sure it all gets over the hot spot long enough to cook. Very efficient use of a little fire.
This is the suggestion anthropologist Marvin Harris uses in his book Good to Eat/The Sacred Cow and the Abominable Pig. If you look it up, there might be some references substantiating this. My copy’s at home.
Mind you, food also looks better if you stir fry it. Otherwise it’d be a brown goo 