Heidi Julavits said this quote
“ Crushes thrive in small spaces. Humans must be programmed to respond positively when faced with a small sampling of other humans in, say, caves. You're stuck in a cave with three other people - all mankind, presumably, was hidden away in such tiny groups during the winters until the thaw - and so, in order for the species to thrive, you must be biologically compelled to fuck at least one person in your cave, despite the fact that, when surrounded by a plenitude of Neanderthals at the Neanderthal summer barbecue, none of them struck your fancy. Without the element of choice, and in conjunction with captivity, you find love, or at least you find lust. ”