What is the origin of cooking?

The precise origins of cooking are unknown, but, at some point in the distant past, early humans conquered fire and started using it to prepare food. Researchers have found what appear to be the remains of campfires made 1.5 million years ago by  erectus, one of the early human species.

EARLIEST TYPES OF COOKING
The origins of cooking are obscure. Primitive humans may first have savoured roast meat by chance, when the flesh of a beast killed in a forest fire was found to be more palatable and easier to chew and digest than the customary raw meat. They probably did not deliberately cook food, though, until long after they had learned to use fire for light and warmth. It has been speculated that Peking man roasted meats, but no clear evidence supports the theory. From whenever it began, however, roasting spitted meats over fires remained virtually the sole culinary technique until the Palaeolithic Period, when the Aurignacian people of southern France began to steam their food over hot embers by wrapping it in wet leaves. Aside from such crude procedures as toasting wild grains on flat rocks and using shells, skulls, or hollowed stones to heat liquids, no further culinary advances were made until the introduction of pottery during the Neolithic Period.

The earliest compound dish was a crude paste (the prototype of the pulmentum of the Roman legions and the polenta of later Italians) made by mixing water with the cracked kernels of wild grasses. This paste, toasted to crustiness when dropped on a hot stone, made the first bread.