Why Do We Cook Food?
By the BrainSnail editorial team. How these articles are written and checked, and how to tell us when one is wrong.
Cooking makes food safer, easier to digest and better tasting, and there is a serious argument that it changed the course of human evolution. No other animal cooks, and the timing of when we started may explain some unusual features of our bodies.
Safety first
The most immediate reason is safety. Heat kills most bacteria, parasites and viruses that cause food borne illness, which is why cooking temperatures for meat and eggs are specified so precisely in food safety guidance.
The second is digestion. Heat breaks down tough plant cell walls and denatures proteins, unfolding them so digestive enzymes can reach them more easily. Cooked food yields more usable energy for less digestive effort, which has been measured directly in feeding studies.
What heat does to food
Cooking triggers a set of physical and chemical changes:
- •Proteins denature and coagulate, firming meat and setting eggs
- •Starches gelatinise, absorbing water and becoming digestible
- •Collagen in tough cuts converts to gelatin during long slow cooking
- •The Maillard reaction and caramelisation create hundreds of flavour compounds
- •Cell walls in vegetables soften, releasing nutrients
The cooking hypothesis
The primatologist Richard Wrangham argued that cooking was central to human evolution. Compared with other primates our teeth and jaws are small, our guts are short, and our brains are enormously expensive to run.
His argument is that cooked food, being softer and more energy dense, allowed the digestive system to shrink while freeing energy for a larger brain. Chewing time supports the point: chimpanzees spend around half their waking hours chewing, while humans spend a small fraction of that. The dating of controlled fire use is debated, which is the main open question in the theory.
Where cooking costs something
Cooking is not purely beneficial. Vitamin C and several B vitamins are heat sensitive and degrade, and water soluble nutrients leach into cooking water if it is discarded.
Very high temperature cooking also creates some undesirable compounds, including acrylamide in browned starchy foods and certain compounds in heavily charred meat. Food safety agencies suggest cooking to golden rather than dark brown and avoiding burnt portions, which is a modest adjustment rather than a reason to change how you eat.
When cooking increases nutrition
The assumption that raw is always healthier does not hold up. Cooking tomatoes increases the availability of lycopene substantially. Cooking carrots improves access to beta carotene. Cooking spinach reduces oxalates that block calcium and iron absorption.
Some foods are effectively inedible raw. Kidney beans contain a toxin that requires proper boiling, and many staple root vegetables need cooking to be safe or digestible. The sensible position is that some foods are better raw, some better cooked, and variety handles it.
How cooking changed society
Beyond biology, cooking has social consequences that anthropologists have written about extensively. Cooking requires a fire, and a fire is a fixed location that people gather around and return to.
It also introduces delay between acquiring food and eating it, which creates opportunities for sharing, division of labour and food being kept for others. Most primates eat as they forage, individually and immediately. The hearth turns eating into a scheduled communal event, and a large amount of human social structure has been built around that pattern ever since.
The takeaway
We cook food to make it safer, more digestible and better tasting, the extra available energy may have supported the evolution of our large brains and small guts, and cooking increases the nutritional value of some foods while reducing it in others.