Is there any scientific explanation as to why humans like food that has been heated?

Answer 1

I would assume the benefits due to processing food by cooking favors the survival of those whoe prefer to eat it. It's interesting, because grilled/blackened/smoked meat is actually packed with carcinogens . . . but cooking meat will also prevent certain types of food poisoning. This means our ancestors that liked cooked food more often likely lived longer. The result is a bunch of people who like to eat smoked and cooked food today.

Answer 2

Food tastes and smells better. The volatile components of the food evaporate better when food is hot and the nose gets stimulated and the saliva also gets released. Cold food is difficult to eat (unless it is very hot in summer), harder and chills the stomach. Hot food stimulates secretion of gastric juices and enzymes and thus digestion is better.