Heat does some of digestion before a meal begins
Cooking changes food’s structure. Heat softens tough plant tissues, making them easier to chew, and can make starches easier for digestive enzymes to break down. It also unfolds some proteins, changing how readily the body can process them. Cooking does not make every food more nutritious, but for many foods it can make calories and nutrients more accessible.
That matters because digestion takes work. Chewing, moving food through the gut, and breaking it into absorbable molecules all consume time and energy. When heat has already softened a meal, the body can spend less effort processing it and may get more usable energy from the same food.
A changed meal can change the pressures of life
For human ancestors, reliable access to cooked food could have altered the daily balance between eating and doing other things. Softer, more energy-rich meals may have reduced the need for prolonged chewing and made it easier to meet energy demands. Over many generations, diets built around prepared food could also influence which traits were advantageous.
This is the core idea behind the cooked-food hypothesis: cooking was not merely a convenient way to serve food, but a technology that changed the food humans had to live on. It does not mean fire alone explains human evolution, or that every cooked meal is superior. It means a fire could take on part of the work that teeth and digestion would otherwise have to do.
