Why do humans "need" to cook animal meat?

It seems there's an aspect of safety to it: are other animals (eg, house cats, dogs) not vulnerable to the same diseases we get from modern food processing of meats?

But it also seems there's something else to it: is raw animal flesh is harder to digest for us, no matter how fresh or processed?

I've read so many conflicting things about it, like how cooking is really a way to avoid disease, but that the human body is capable of processing protein from raw meat just the same. An example is how other countries eat raw meats that Americans would not. But then I've also read things about how cooking meat is what allowed humans an energy advantage early in our development as a species (I'm not clear how more calories are "unlocked" by cooking) or how denatured protein plays some role in usability. I also know that my person experience with raw meats doesn't help me understand it, because sushi seems to be fine but raw eggs will upset my stomach.

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    $\begingroup$ Possible duplicate of Why cooked food considered nutritious if proteins decompose at much lower temperatures? $\endgroup$ Commented Aug 7, 2017 at 19:06
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    $\begingroup$ "I've also read things about how cooking meat is what allowed humans an energy advantage early in our development " -- Cooked food requires less energy to digest, not that it contains more calories. Currently I'm not able to find the source, but if my memory serves me, it's ~10-15% less energy demand. $\endgroup$
    – user22020
    Commented Aug 7, 2017 at 19:13
  • $\begingroup$ Because in general (sushi &c excepted), it tastes a lot better? $\endgroup$
    – jamesqf
    Commented Aug 7, 2017 at 19:42

1 Answer 1


Humans do not "need" to cook food, but in general cooking food facilitate digestion and absorption of nutrients.

Heat cause denaturation of proteins. Once denatured, proteins are more susceptible to the enzymatic digestion. Thus, more nutrients are absorbed. There are also macroscopic phenomena in play, for example, a cooked piece of meat is more tender than the raw one, making mastication easier and less energy consuming.

The fact that you may feel your stomach upset because of raw food is probably due to the fact that you were never used to it. Your intestinal flora has been selected during the year to deal with the food you usually eat, any "new" food may cause the same symptoms. Humans that eat regularly raw food will not feel the same way.

Generally speaking, cooking food help killing bacteria, so your body does not need to deal with lots of infections that would occur otherwise. This, on the other side, makes your body weaker compared to the one of a wild animal, for example, that is used to deal with such bacteria. Of course, many animals also die because of food poisoning or food-related infection, only the "stronger" survive so there is a strong selective pressure in wild animals to have "a strong digestive system" (and a strong immune system as well). This selective pressure is less pronounced in modern human society but it is still present in less modernized areas.

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    $\begingroup$ Taste is relative. Some likes raw food more than cooked one. $\endgroup$
    – alec_djinn
    Commented Aug 8, 2017 at 5:12

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