Claiming that reason is the product of evolution seems awfully old hat to me, a bare-basement assumption if we accept Darwin. More interesting would be to ask if “reason” existed before it evolved in humans. Logic didn’t, that’s pretty well established, but I can see a case for reason being a purely human activity that wouldn’t necessarily appear in all evolved sentient organisms.
Take an old-school sci-fi hive mind, for example; like in the fourth book of Donaldson’s Daedalus series; there’s no need to persuade anyone to do what the hive mind thinks is best for the hive. The hive mind would need fear to survive, though, and in the face of decision making beyond that, doubt… which would invite the creation of rationalization to manage that doubt, and therefore reasoning abilities.
Pope Benedict would have us think in humans that there is an additional layer of big-R reason above this, though, embracing, or consisting of, a soul. I agree there is another layer, but not with the soul stuff, and I see reason in action well before the church imprinted it with its peculiar ecclesiastical/mystical requirements.
As such, it’s possible to “reason” to 2+2=4, but 2+2=4 seems to be valid without reason’s help. If so, reason is not a hack that gets around our lack of direct experience of the universe, but a discovery, like the Curies finding radium.