Purpose and reason are both human concepts, like I say, wired into the logic cuiruits of the brain. If purpose and reason existed in everything that happens, then many evolutionary chains would not have happened. The whole reason life is on earth is because of pure chance, there was a cause, and an offect, but no reason for it. If it haddent have happened, it wouldent be a big problem to anyone or anything.

The cause where the conditions, and the offect was the basis for life, but no reason, the earth wasnt created and specially placed for an exact reason and purpose, it just happened by chance.

And even then, there was no reason for the universe to be created (if it was even ever created, as they say it was) it was pure chance, cause, and chain reactions of the offect, that caused its creation.

And I agree, animals do things for a reason or a purpose, but the root in the purpose trails back to the source of it all, chance, cause, and offect.