During the conversation I noted the saying from Pascal, "there is a God shaped vacuum in the heart of every man which cannot be filled by any created thing, but only by God [...]". I then expanded, of all the desires that I have, even when they are satisfied, I still find myself unsatisfied. I abstract from normal human experience, there must be something that will satisfy this desire, and that it is immaterial, or supernatural.
To this one of the gentlemen responded, "I don't mean to be a buzz-kill, but I think that it is important to acknowledge where our desires come from - evolution. Biological needs have been "programmed" into us, since the individuals that continually sought to satisfy their desires prospered".
In the moment, I confess, I was quite speechless. Furthermore, when I asked for an example only more confusion was added. Upon reflection, I think we miss understood each other. At the time his explanation seemed empty to me. If there is any desire - evolution is it's cause. That is fallacious in the same way as the God-of-the-gaps theory; it explains everything and nothing all at once.
So, what did I mean? Certainly I would agree that I have physical desires (food, water, shelter, sex, etc.) and I acknowledge that those desires can be satisfied. Once satisfied, it is only a matter of time before the desire is found in me once again unsatisfied. I think this was the cycle my friend was referring to, however, my point was different. Even when all of these physical desires are satisfied, there is still a desire in me that is unsatisfied. This desire is therefore unique from the other physical desires.
Occasionally this supernatural desire can be mistaken for one of the physical desires, but it is easily found out which category it belongs to. The point that I wanted to make in the conversation was, sometime I mistake this supernatural desire for mere physical desires. I try to satisfy it with physical means, and though a physical desire may be satisfied in that instance, the supernatural desire goes unsatisfied, and leaves a sense of emptiness. However, I have found, when the supernatural desire is recognized as such, it can be satisfied in God.