Why do apples taste good?

Ehh . well, sorta . ehh . no.Populations evolve because of selective pressures. These pressures force populations to evolve to meet the terms of the environment, or the population, as often happens, goes extinct.Human metabolism evolved to crave fats and sugars since our ancestors (living in a sparse environment) had no way of knowing whether they were going to eat again for quite some time and fats and sugars pack a big calorie punch that can be stored for the lean times to come.Now we do away with the lean times and humans still crave fats and sugars. We can’t help it. It’s part of us.Our environment has changed. We gobble up fats and sugars by the truck-load; develop obesity, heart disease, hypoglycemia, diabetes, Democrats, all that bad stuff. Some members of the population can handle this new environment better than others. They thrive on junk food and democrat politics and they have more and healthier offspring than the others.Soon (over many generations) these “junk-food democrats” become more prevalent in the population as the others, who cannot thrive in a junk-food world, die off.The selective pressure is the change in environment from limited junk-food to copious availability of junk-food. Those who can cope (because their metabolism is such that this steady diet of junk doesn’t kill them) have a selective advantage, thrive and survive and reproduce like rabbits. Those that can not cope have a selective disadvantage and die off leaving but a few couch-potato offspring. Over the generations, the base level of human metabolism, as represented by the new majority of the population, has become a “junk-food democrat” metabolism.Looking back on this scene a thousand years from now, we would say that human metabolism evolved due to selective pressures (Natural Selection).