I would say that is actually our ability to adapt our world to our needs... Humans really do not have much going for them.. lots of animals are better equipped with natural weapons, most are faster, see better, smell better, hear better. But is our mind and ability to manipulate the world around us that sets us apart. We are the *the only species* that changes it's environment to suit it's needs. All other animals must simply adapt to changes in the environment or die.
Our ability to get a grip on things (prehensile grip) was clearly very important to that end. We don't just monkey around with the utensils. Our brains give us the ability to whip up more interesting dishes than just pureed bananas.
It certainly plays a part, yes. Cooking food gives you many advantages, for example, it helps breaks down molecular bonds before digestion starts, this makes it easier to absorb. Cooking food also destroys bacteria and other nasties that can kill you.