The use of cooking food dates 2 million years. There were good reasons for it, and there are still plenty.
Without the use of the fire, men had access only to limited assembly of proteins. But from the time of the beginning of cooking, men was able to exploit a much larger fan of nutrients.
Larger diversification of food. Foods that are toxic when raw (like for example phasine from green beans that coagulates red blood cells and can be deadly) became finally accessible; hard vegetables and roots and some types of meat became more tender and consumable; many components of the diet became better absorbed. Cooking processes also got rid of the problem of preserving food for longer: bacteria were definitely defeated with temperature.
A bigger brain. With access to a wider source of nutrients and a better absorption of them, men obtained such a considerable advantage on survival that cooking is considered to be a very important step in man’s evolution. The human brain could increase its size thanks to the availability of better food and to the easier absorption of it; energy expenditure that was used by the intestine in the long process of metabolizing raw food, was finally available for the work and growth of the brain.
Better assimilation. Through cooking, not only some toxins become inactive but also proteins and complex sugars are more easily assimilated. Moreover, certain vitamins, which we often associate with raw vegetables and fruits, are only assimilated after cooking. For example, beta-carotene is better absorbed when cooked. Another molecule fundamental as antioxidant, lycopene from tomatoes, is ONLY absorbable when cooked.
A different physionomy. With the use of fire in the Palaeolithic kitchen, a series of evolutionary modifications took place: shorter and wider jaws that changed shape and dimension along with the growing brain slowly replaced big jaws hosting powerful molars used to crunch hard meat. As a memory of this transition there are still people fighting with the growth of the last useless molars (the wisdom teeth) in a not so big mouth anymore
Alive vs dead food? Raw food eaters often state that eating raw food makes the rich enzymes contained it available while eating cooked food would destroy them. They forget to consider however, that such enzymes are completely killed by hydrochloric acid in the stomach. We can never absorb enzymes from food, neither cook or raw.
However, there would be other cases in favour of raw eating, like for example the better availability of vitamins. Vitamins as vitamin A, C and vitamins B can indeed be destroyed by heat but not ALL types of cooking: in fact, steam cooking preserves most vitamin C in vegetables. However even keeping your veggies in the refrigerators is a cause of loss of vitamins even without cooking. Other vitamins can stand heat pretty well, like vitamins D, E and K.
What type of cooking? The problem is the type of cooking, and not cooking itself. Boiling vegetables would deprive them of some vitamins, as we said, and also of the very important minerals. However, it suffices to save the cooking water and drink it, or to stir-fry them to keep all the good ions. Other molecules can be lost in some types of cooking, especially boiling. One example is sulforaphane obtained from broccoli and other cruciferous vegetables, which is an inhibitor of cancerous cells. Such molecule is not accessible in boiled broccoli but it is present in microwaved ones.
Thus there is cooking and cooking and avoiding grilling and charring is also a very good idea. Cooking meat or fish at high temperature produces nasty molecules called heterocyclic amines, while grilling, barbequing or smoking meat or fish releases polycyclic aromatic hydrocarbons. Both these substances are dangerous as cancer developers (colon, skin, prostate, lungs, liver, pancreas). Another carcinogenic substance deriving from cooking is acrylamide, which is formed when baking or frying food rich in sugar and poor in proteins (like cereals and potatoes).
Men seemed to know or sense this in the early stages of evolution, and cooking was in fact not on open fire but wrapped in leaves and cooked underground without direct contact with fire or coals.
So in conclusion, is the advantage to raw or cooked food? It does not seem that there is a winner, at least not for everybody. Keep in mind however that a sole raw eating is not a good idea. A study showed that people maintaining a 70-100% diet of raw food lose a lot of weight, sometimes too much, and women can suffer of menstrual irregularities. Further, eating raw food on the long term leads to a loss of bone mass and often a low level of necessary good HDL cholesterol.
So summarizing, what is good for our body and mind:
- eating some raw and some cooked food to widen the spectrum of nutrients
- tomatoes and carrots are better cooked, broccoli raw or microwaved
- when cooking vegetables, favouring steaming or stir-frying,
- no cooking at high temperatures and only cook for a short time. Veggies need to be still crunchy
- no grilling, barbequing or smoking meat and fish
Chip Rowe 2015. Top 10 Design Flaws in the Human Body From our knees to our eyeballs, our bodies are full of hack solutions. Nautilus
Sivault C., Venesson J. 2015, La cuisson est-elle notre poison ? Alternative Bien Etre, 110