I was just eating a rather rare steak when I started wondering whether eating foods cooked was something I would instinctively want to do if the practice hadn't been taught to me.
So, is cooking food an evolved behavior, inspired by nutritional value or health benefits, or is it a practice learned, and passed down through culture alone?
Its almost certainly instinctual, humans along with other great apes (any many other animals) show a preference for cooked foods over raw in testing, the number that prefer it increases drastically if they are have sampled cooked foods before. So it is likely as built in as your desire for sweets and salt.
Just becasue something is instinctual does not mean you don't have to learn HOW to do it. Language is instinctual in humans, but what language you learn is up to your upbringing (the same is true in some birds), and denied another human to interact with until puberty you will not develop language. that does not make language itself cultural, just the particular language you learn.
No one would argue lions do not have an instinct to hunt, but they still have to learn how to be successful at it.
Cooked food is a learnt trait rather than an evolutionary one. On a certain psychological level its a society norm so you would be hard pressed to find an individual who wouldn't mind eating completely raw meat/steak.
But, say if you chuck a few humans into the wilderness at an early age and not teach them how to cook meat they may not actually cook their food. As early prehistoric humans discovered fire they eventually noticed/learnt to cook food and passed on the knowledge . You would have to research the history of that since I don't actually know the details.
Cooking food makes more sense on a psychological level as we cook food based on our cultural upbringing, and our memories and knowledge. A human would prefer cooked meat based on his upbringing or understanding that eating processed meat is safer as it means food contains less pathogens. The way we cook food depends on where we are from (eg.An Indian would cook meat differently from, lets say an Italian because their environment provides them with different ingredients and/or devices, pans/pots)
I hope that wasn't too confusing.
A study found that great apes prefer cooked food, which contradicts the notion that the preference results from human evolution.
Cooking food properly is generally beneficial for nutrient availability and taste, so the cooking itself is not what causes the animal preference: pulverising with a blender would have some similar effects on preference. Animal preference is based on sensation of sugar, fat, salt, aromatics, which generally are higher when the cells of the food matter have disamalgamated and volatilized.
As @John has pointed out above and in their other answer there exist solid biological evidence that humans (and other mammals) are better at digesting cooked food than uncooked one, and likely to prefer cooked food given a choice.
It is however harder to prove a causal relation that humans adapted to eating cooked food. Indeed, this would require that humans are exposed to cooked food during a reasonably long period of time (on an evolutionary time scale), and that those who are less adapted to digesting cooked food become less fit and gradually elimited from the population. It is more plausible to assume that cooking was discovered as a way of getting more benefits from food, and thus being more fit in respect to the human groups that were not cooking or were being uncapable of digesting cooked food. In other words, it is more likely learned than adapted behavior. But plausibility is not a hardcore scientific argument.
What further complciates this question is that our gut microbiota has certainly adapted to the cooked food. The gut microbiome is not encoded in human genome, but it is partially inherited during birth, and its further changes are mainly determined by the living conditions. So, it is safe to claim that this microbiome has adapted to humans eating cooked food, and it has certainly undergone genetic selection in this direction.
