Why Cook?

Why cook? Well, there are the usual candidates (health, social, bonding, family), but what if cooking might define us as human?

James Boswell had this to say in 1773:

My definition of Man is – ‘A Cooking Animal’. The beasts have memory, judgement, and all the faculties and passions of our mind, in a certain degree; but no beast is a cook” (Journal of a Tour to the Hebrides with Samuel Johnson)

‘No beast is a cook’ – and with good reason it seems. Consider a simple British breakfast of scrambled eggs on toast with sausages, bacon and coffee. Simple? No other animal would be so crazy as to attempt this feat just to eat:

Eggs (collecting, shelling, blending, heating, stirring); bacon (husbandry, butchery, curing, smoking, slicing, frying); sausage (mincing, seasoning, stuffing, frying); toast (agriculture, milling, kneading, fermenting, baking, slicing, toasting); coffee (harvesting, roasting, grinding, infusing, straining). Not to mention milking cows and refining sugar for the coffee, harvesting and grinding salt and pepper for the eggs, producing butter for the toast and for frying, and making utensils and creating sources of heat for cooking.

Phew – all that just for breakfast?

But this is routine for many. And because cooking is commonplace, it’s not easily recognized for its uniqueness (and humanity).

But what if cooking not only defines us as human, what if cooking drove the evolutionary process that took us from homo erectus to homo sapiens – from upright man to wise man?

Chewing and digestion take up a huge amount of a non-human primate’s waking hours. Six hours a day in the case of our closest non-cooking relative, the chimpanzee. And all this chewing and digesting can only keep up with the energy needs of a small brain.

The problem arises because brains are massive consumers of energy in proportion to their size. Even at rest, the human brain must maintain the electrical activity of ~86 billion neurons, and this is where most of the energy goes – into maintaining the electrical charge of brain cells.

The human brain represents only 2% of body weight, but it receives 15% of our cardiac output, 20% of available oxygen, and 25% of total body glucose. Energy-utilisation is controlled by the brain, so it looks after itself first – put it under stress and it will consume up to 90% of available glucose (which is why we feel nauseous when stressed – the body is hypo-glycemic). Weight-for-weight, and under normal circumstances, the brain needs twenty-times more energy than skeletal muscle.

So, what has all this got to do with cooking?

Cooking helps our brain, and might have been necessary for its expansion. It can be thought of as a kind of pre-digestion process that enabled us to efficiently extract the huge energy that the brain needs from a relatively small amount of food. This meant that we could make do with a remarkably small gastro-intestinal system, which in turn increased our agility and helped us to hunt for food.

In parallel with cooking, the brain helped too by learning to identify inedible bits in food (stones, twigs) and removing them, and by learning that washing removed dirt and surface contaminants, thus lessening the load on the digestive process.

The result is that our brains are massive when compared to our digestive system, and while cooking itself can be time consuming, it’s time well spent. Cooking enabled a large brain to go from being an energy liability to being a working asset.

So that’s why cooking matters. Homo erectus learned to cook and doubled its brain size. The primates that carried on with their raw food diet, did not. As well, cooking bonded the tribe and contributed to social activity – in short, cooking made us social and intelligent. Homo erectus became Homo sapiens. It’s no coincidence that humans, the cleverest of species, are also the only animals that cook.

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