This is a very good and important question. We do know the answers:

Cooking roughly doubles the nutritional value of food. The heat breaks down complex, undigestable molecules to simpler ones. It also eliminates bacteria and parasites.

Most species would benefit a lot from cooking food, if they could figure out how.

Somewhat controversial book on how fire shaped our species: https://smile.amazon.com/Catching-Fire-Cooking-Made-Human/dp...

That nutritional availability may apply to plant matter (and not in all cases), but certainly not to meat, which likely was the major part of the diet.

On the contrary, cooking destroys enzymes and evaporates water-soluble vitamins.

Bacteria are also very useful for digestion and all meat is aged even today (obviously).

My take is that it was simply a chance discovery of enhanced taste.

> meat, which likely was the major part of the diet

Countless evidence proves that meat always constituted a small fraction of human diet from the paleolithic.

Starch has always been the main staple food.

Starch was the staple after agriculture but the real staple was fruit and possibly small animals. Just look at chimps. Practically all cultures when they have the chance, prefer fruit. But even to this day a lot of people cannot afford them as a big component of their diet

But fruit as we know it isn't anything like most fruit available for our ancestors, most of them anyway. Much lower calorie and harder to access those calories.

But our past as successful hunters definitely has evidence, my favorite is our domestication of wolves.

What is that evidence?

I just doesn't make sense to me, humans always were the most effective hunters and meat is much more nutritious than starch.

> but certainly not to meat

Here is a study showing that cooked meat provides significantly more energy than raw meat.

https://www.pnas.org/content/108/48/19199

Mice study... But I'll give it a more thorough read anyway. Thanks.

I still am not convinced from my own experience, replying to another user I mentioned that when eating raw meat there is noticeably less residue, which would indicate more is assimilated.

What is the effect of heat on protein? Does it aid in making it easier to digest or does it have a negative impact on protein content and availability?

Well, I certainly don't see how burning the protein would make it more suitable for assimilation, I think it's a myth that's just been repeated without any evidence, if there is any I'm interested in hearing it, intuitively it doesn't make sense.

Fermentation & aging by bacteria on the other hand does breakdown meat and eases digestion, and it's a tradition all cultures have kept in some form, as evidenced by numerous dishes still consumed today.

"Burning" may not be the right word. Denaturing (i.e., the proteins losing their quaternary structure) may be what increases bio-availability

IIRC it's easier (smaller energy cost) to absorb nutrients from cooked food than raw food.

So there's an immediate evolutionary advantage to eating cooked food - you get more energy out of the same total food calorie input.

That, and cooking allows you to eat things which would have otherwise been inedible (e.g. by denaturing their poisonous proteins). Saves you a million years of cat-and-mouse co-evolution to be able to consume it.

I think you meant poisonous plant compounds, but fermentation is a more effective process for this and is lower-tech.

That doesn't apply to meat though (at the very least).

Water-soluble nutrients are destroyed by heat.

Also, heat denatures protein, that would make it harder to use, not easier.

Do you have a source for this claim you keep posting? Quick search immediately appears to be the opposite, that cooked meat is easier to digest than raw

https://www.forbes.com/sites/quora/2017/03/20/why-cooked-mea...

They don’t have sources, because the available scientific evidence strongly suggests that they’re wrong.

The classic study on this used pythons to measure the energy cost of digestion. Cooked meat was significantly cheaper to digest than uncooked meat: https://www.sciencedirect.com/science/article/pii/S109564330...

Another study on mice measured metabolic changes following a diet of cooked vs uncooked food. Again, mice did better with cooked meat than with uncooked (they lost weight on both as a pure meat diet is not a perfect food or mice, or humans for that matter): https://www.pnas.org/content/108/48/19199

The source you're linking doesn't reference its sources either, it's just the same thing we can find everywhere (raw meat is "dangerous" etc., when raw meat dishes are so common across cultures), again unsourced.

B vitamins are water soluble and heat will evaporate water...

Likewise for vitamin C.

The other is personal experience. Try eating tartare and then some cooked meat and compare digestion & satiety. With raw meat I reach satiety much quicker. Perhaps an experience closer to most is raw fish as sushi etc.

B vitamins have a different boiling point than water. Certainly won’t go flying somewhere. The reason you feel satiety sooner is because it’s harder to digest. Do you eat to feel satiety or to get nutrition? As someone who loves a good tartare or sashimi, it’s good to eat every once in a while but I tell you you’re going to run into issues with a raw diet. It might take years but if you’re not careful they might be hard to fix

Here's another: there is noticeably less residue compared to cooked meat, with equal quantities.

What kind of issues do you think would arise?

What do you mean by 'residue'?

Less fecal matter.

Can you please stop posting your anecdotal experience and framing it as fact? For someone asking for proof from everyone who disagrees, you don’t seem to be living up to your own standards.

> What I never understood is why cooking was needed by early humans.

It's unlikely that it was needed per-se, but the discovery of cooking would have significantly improved the sanitary conditions of food as well as the available caloric budget, which would allow for later advances. It put calories in the bank, so to speak, or allowed accessing calories otherwise unavailable letting early humans occupy niches or enter ecosystems they couldn't otherwise have.

> The only thing I could think of is that the caloric advantage of digesting meat offered an immediate advantage.

Digesting meat is easier when cooked, it's also much more sanitary leading to lower incidences of disease and lower parasitic loads, translating to higher survival rates & lower ongoing energy use.

Many plant foods are also largely to entirely indigestible to us without cooking, they may have been in use before cooking as e.g. mere fibrous matter, but cooking also made these available as energy sources, or significantly less dangerous.

For instance sweet potatoes are inedible raw but not toxic (unlike cassava) and the sprouts are edible (unlike potatoes), so they might have been consumed from wild forage for the sprouts and as filler (for the tuber) until people stumbled on the ability to cook them and unlock the tuber's stores.

IIRC the thinking is that you need less intestine if your food is cooked. So less internal upkeep costs, less internal risk of stuff getting stuck, infected, etc.

You're also less likely to catch a parasite if you cook stuff, that would be a caloric catastrophe.

Also cooking stuff allows you to share costs with other people. One big fire for everyone, nobody needs their own extra capacity.

From what I read, the #1 thing is that if you eat "paleo" food, then cooking it nearly doubles the net caloric intake. That's huge!

For "modern" foods that have undergone thousands of years of selection to improve palatability, the difference is not so big, but still, a common dieting technique is to eat more uncooked food, because it reduces the effective calorie intake.

As others have said, it increases available calories and nutrition. It also makes sense, thermodynamically. You're using outside, normally unavailable energy (the fuel) to process your food so that you're not using the precious little energy you've managed to store in your body. It increases the total available energy to your body by indirectly supplementing with sources you normally couldn't.

It generally tastes better cooked, or at least was different. For those who started doing it, they got the unknown benefit of more energy absorption leading to a long-term societal evolution to do so to most food (as they had a better survival chance).

Wouldn't it only have tasted better as a result of evolution selecting for gene lines that preferred cooked food(more efficient calorie intake)?

Not necessarily! Due to chemical reactions, certain foods are sweeter, less bitter, and so forth when cooked. (e.g. onions caramelize, glucosinolates [0] in kale leach out when blanching)

Evolution already predisposed us to like sugary foods (e.g. fruit) and dislike bitter ones [1].

[0] https://en.wikipedia.org/wiki/Glucosinolate

[1] https://en.wikipedia.org/wiki/Bitter_taste_evolution#Toxins_...

Cooking introduces you to the idea of smoking. Being able to preserve meat for months and months without leaving your reserves outside for scavengers, or without being forced to spend valuable calories to unfreeze it in the worst day of winter, is a game changer

And cooking turns parasites into food also.

The less energy and body mass spent in the digestive system, the more you got for brains ... and walking.

IIRC Animal can absolutely digests cooked food better. The problem is that most animals are incapable of figuring out how to cook food.

Perhaps they knew warm food was relatable to a fresh kill?

Our gastrointestinal tract is designed for fruit, like most apes. Not plant or meat. Out of adaptation to new locales without abundant fruit, we've had to learn how to properly preprocess things were not very good at processing ourselves.

Except chimps hunt, and get important nutrients from meat, early humans hunted and scavenged meat, and nothing about our digestive system allows us to get as much out of plant matter (including fruit) as an herbivore can; for one thing, we can't digest cellulose.

https://www.americanscientist.org/article/meat-eating-among-...

See reply to other comment. The reason to eat fruit is to get easy access to sugar, which we need especially due to our brains. Like how some birds require nectar to be able to power their flight.

All animals supplement diets, but despite cows licking saltstone we still observe them getting the majority of intake from other sources.

So looking it up, all I can find is that the brain imposes relatively high caloric needs with respect to other organs, but not that those calories need to come from carbohydrates. Do you have any sources on the latter claim? The last time I got exposed to this claim was when a doctor (not a nutrition expert) told me that we must eat fruit for breakfast because our brains need the sugar. To me, both anthropology and personal experience seem to contradict this idea. Maybe I can change my mind.

We need sugar to power our brains, but we need protein and fat to build our brains. That requires more than incidental amounts of protein.

For that to be a good counter-argument, you would need to demonstrate that vegetable protein was “merely incidental” in the case you are arguing against.

Vegetable protein was and still is less abundant than vegetable sugars, if I'm not mistaken? Agriculture eventually made that less of an issue but this was not the case until not that long ago (tens of thousands rather than hundreds of thousands of years). It's easier to eat a bug or any small prey than spend a morning gathering spinach and watercress. Humans also ate leftovers from predator kills, like the partially digested contents of herbivore stomachs that had been killed by let's say wolves.

Vegetable protein was part of our diet but not by any means the main source of protein. Humans did not eat pulses until quite recently (10-15 thousand years ago?)

> Vegetable protein was and still is less abundant than vegetable sugars, if I'm not mistaken?

I'm no expert here, but humans do tend to need far more carbs than protein to be healthy - or at least can operate on something like 10% protein per joule of food consumed. And that's with a decent safety buffer. I think the predictions (based on natural experiments - i.e. famines) were that you could push as low as 4% before a human body can't handle it. Though I'd guess that if you get anywhere close to that your body is going to start making some significant trade-offs.

Also: Don't forget about nuts and seeds.

> Vegetable protein was part of our diet but not by any means the main source of protein.

I think a citation (or three) is needed here.

People can be perfectly healthy on a wide range of carbohydrate intake. Native peoples in the Arctic lived almost entirely on animals, for example, whereas there were tropical island societies that lived almost entirely on plant sources.

> People can be perfectly healthy on a wide range of carbohydrate intake

Again, citation needed there. The recommendation of all major national and international dietetics associations (based on currently available peer-reviewed studies) is that a healthy diet should consist mostly of carbohydrates.

There certainly are "extreme" diets, but these seem to require at least a bit of genetic adaptation:

> "a new study[0] on Inuit in Greenland suggests that Arctic peoples evolved certain genetic adaptations that allow them to consume much higher amounts of fat than most other people around the world"

https://www.npr.org/sections/thesalt/2015/09/17/441169188/th...

[0] https://science.sciencemag.org/content/349/6254/1343

No, merely that we can't get enough fat and protein to build brains from fruit.

You can definitely do that today.

I have no idea if our pre-human ancestors could or couldn’t do that in the rift valley while they were inventing cooking without fire — I don’t even know if it is possible to find out now if they could have done it then — but you can do it today.

Nah. Our digestion is not based on fermentation, but on using acid to break things down. It’s closer to a dog’s than a gorilla’s.

Chimps are known to hunt and eat meat. Bonobos too.

Its important to distinguish the majority of diet with the occasional snack, which often happens to supplement a particular nutrient or mineral.

My cats eat vegetables daily too, but it only makes up a percent of their diet.

Forget the gastrointestinal tract and look at our teeth. We have a wide variety of different teeth suitable for an omnivorous hunter-gatherer diet.

On the contrary, our stomach acidity is higher than even carnivores, indicating we are adapted to scavenging.