There are few better ways to get yourself into trouble in scientific circles than to carelessly claim that a species evolved a characteristic for a purpose. Say, for example, that a certain moth turned gray so it could blend more perfectly into Industrial Age England. Or even worse, that ants learned to farm aphids so they could have a more reliable food source.
These inexcusably careless choices of words will result in critics crying foul: No! Evolution is neither a directed process nor an intelligent one. Moths have no more control over their coloring than a rock; ants can no more learn a complex novel behavior than can a wrist-watch. For shame.
But in fact, is this criticism really justified? A simple semantic clarification easily removes the ambiguity and can probably satisfy the most nit-picking, anti-anthropomorphizing critic. (Granted, scientists can be pretty spectacularly nit-picking...) Saying that a mutation is "for the purpose of X" is short-hand for "among many other random mutations, this particular one improves the odds of reproductive success by causing the effect X". That is, some moths were more likely to survive the 1800's because some mutated gene they happened to possess turned them gray, which in turn helped them blend in better with soot-covered bark and rock. Saying that a species "learns to do X" is short-hand for "a certain set of random, individually advantageous mutations within a population of the species has resulted, for better or for worse, in a descendant that displays some behavior X". That is, through some unspecified set of random mutations, an ant colony whose collective behavior results in the care for and protection of a "herd" of aphids whose secreted sugars the ants then feed upon, descended from primitive ancestors which could not.
Phew! Much easier to say the little buggers learned to farm!
Then again, perhaps as we speak there are moths leafing through a catalog, saying, "Gee, Martha, gray seems to be all the rage this year". And maybe ant colonies send their little ones off the local Ag U to major in aphid nutrition...