Well yes, in the evolutionary sense, certain genetic characteristics have a “purpose”, but the term is loosely applied. Strictly speaking to say a gene has a purpose would be to imply it has a design, an intention, a thought, which it doesn’t, unless you believe in some kind of teleological doctrine like intelligent design.
Even without a designer I think the goal of preserving life must be held in order to exist. You can’t even be ambivalent in this goal because of scarce resources that must be acquired.
Of course. A person can’t exist if he has no goal of preserving his life. And the goal of preserving his life involves a choice: that of life over death. And such a choice involves thought and is therefore purposeful. I agree with you.
But genes, gene pools, populations, societies, nations have no personality of their own, they don’t think. Only individual people do. Only individuals act. Only individuals engage in purposeful behavior.
If we’re talking about the (human) logic of action (which is what praxeology is all about) then it make sense to talk about purposeful behavior with reference only to human beings. If we define purposeful behavior a little more loosely, then of course animals can engage in purposeful behavior on an instinctual level (i.e. without the benefit of human reason). If we define puproseful behavior very loosely, then I suppose we could apply it to bactaria and such. It’s all a question of what you mean by the words “purposeful behavior”. I choose to apply it in the strict sense. You can choose to apply it any way you want.
Just to clarify a bit, praxeology is only concerned with demonstrated preference, preferences that are revealed in action. One can speak of preferences in a psychological sense, and they can be purposeful or not, but if they aren’t acted on, praxeology has nothing to do with them; if they are acted on and revealed, they are necessarily purposeful, human action being “purposeful behavior” by defintion.