I never said we run primarily on logic or reason. The self aware human, the thinking/being human is simply capable of these things. What you're saying is, for example, a horny human sitting around without these things, would just as likely hump anything in sight as opposed to someone they'd be attracted to. Perhaps that is the case (in his natural form), however, that doesn't mean these attractions do not exist. Without order, society, and learned and expected behavior, everyone would be doing as they please, though perhaps without the capacity to understand why they do what they do.