'Proximate and ultimate causes' are terms that EPs use to help explain our different layers/strategies. The proximate cause for having sex might be physical pleasure. But the ultimate cause of having sex is reproduction. Mother Nature has wired us so that most things having to do with our survival and that of our offspring, as well as mating and reproduction, feel good. We generally have sex because it feels good, not because it makes “mini-mes.” But the proximate cause and the ultimate cause can be one and the same. Plenty of people engage in sex to fulfill its ultimate cause, to make babies. (And perhaps some religious people do so despite its proximate cause, ‘pleasure.’ Pleasureless sex, for reproduction's sake.) And, really, a religious or moral practice that makes sex a duty for its ‘ultimate cause’ is essentially trying to beat the animalistic program of sex’s proximate cause. It wants to insert conscious and willing control—reason over passion.
What are the ultimate and proximate causes of knowledge-seeking? They appear to be very bound up in each other. Clearly, making sense of the world, having schemas, and understanding causal relationships benefited our ancestors’ survival and reproduction. This is where we come from, and this is who we are. We might say, then, that the ultimate cause of knowledge-seeking is survival and reproduction. In fact, it appears that our proximate causes of knowledge-seeking may be related to our ultimate causes of knowledge-seeking: survival and reproduction. Being a knowledge-seeker (a philosopher, say) aids one in gaining status, power and resources (survival) which helps in gaining access to potential ‘high quality’ mates (reproduction). But also, when we engage in the pursuit of gaining any kind of knowledge (e.g., knowledge regarding whether one’s husband is having an affair, what teacher is the best in the school, which candidate is more likely to reduce taxes, what is the best, healthiest diet), it is often about one’s survival (and offspring’s) and reproduction in the here and now.
But in another sense, the proximate cause for knowledge-seeking is pleasure. It feels good to try to figure out causal relationships even if there is no immediate benefit in the here and now because it is driven by an ancient program. It is because this program’s ultimate cause is related to survival and reproduction that when we engage in any epistemic pursuit, it lights up our reward centers. Does it do me any good to speculate on why certain things are the way they are? Is there a benefit to me personally to ask whether sexual orientation is genetically determined, environmentally determined or both? No. Not really. But it feels good to pursue these questions because it feels good to pursue all epistemological/causation questions. There’s a joke in here about masturbation, I think.