The Contradiction of Desires

Hello. I am not a professional biologist at all, so my ideas may be odd, but here is the question that interests me: why is following one’s own desires so often harmful? Harmful food that is perceived as tasty, that is, food which by purely animal logic ought to be eaten almost as much as possible; a sedentary way of life dictated by laziness, which would seem to be a completely natural desire and yet leads to one disease or another; and so forth. For some reason it seems to me that desires ought to direct us toward what the organism needs, otherwise what is their biological meaning? Usually, according to my self-observations, this does work, but such incomprehensible examples spoil the picture. I have some thoughts, and I would be interested to know what professionals say about them. In the case of harmful food, let us take for simplicity an extreme case, some abstract hamburger permeated with flavorings, taste enhancers, and other substances the organism does not need for vital activity or that may even be harmful. Without knowing the biochemical foundations of taste, I may suppose that long ago, under wild conditions, tastes were tuned to specific fruits and the like, that is, to established combinations of substances, and were tuned in such a way that they react to certain signaling substances rather than to the vitamins and other useful things themselves with which those signaling substances happen to coexist in fruit. In this way our culinary, and then chemical, knowledge has led to the deception of previously functioning programs, to the creation of new combinations of substances in which the signaling substances coexist with completely different ones. In the case of a sedentary lifestyle, perhaps things are simpler: in the past there was little time for rest, since one had constantly to hunt or do something of that kind, so any rest was an absolute good, and no protection against the extreme situation of unlimited rest existed, because such a situation was impossible. But now such a situation is possible, and again conditions have changed and the old programs no longer fit. In the second example I even saw a certain global law of nature, something like protection against the complete victory of one species over all the others, though of course it looks rather weak as a restraining factor on the dominance of a species, so that life should always remain diverse and continue developing, nature’s striving for constant movement. That is just a thought, without any claim to founding a new school of philosophy. :) By the way, do you know whether anything in my thoughts already has some name and supporters? :) I saw something similar in a science-fiction story in which Disease was described almost as one of the main natural forces, impossible to defeat completely, and this was shown in a society where medicine had found cures for all diseases, roughly speaking, but Disease found a loophole in the form of mental and quasi-mental disorders. So, another conclusion from the idea that the development of civilization seems to make our programs obsolete is this question: are we moving toward a crisis, or is this a constant process in evolution?