The carnal need to mate felt between two highly intellectual people, who try and justify it to themselves, and re-enforce it to each other by describing their relationship as a spectacular intellectual bond, when actually they just need to fuck each others brains out.
PhD rocket scientist: "She's got a Nobel Prize - we are clearly made for each other. We'll be together forever, we've talked it all through already. It makes total sense."
Friend of rocket scientist: "Nah, that's just intelligent lust. Get over it."