Men and Women Can't Be "Just Friends"? The age-old question is addressed in a sloppy study in Scientific American.
Humans aren't Bonobos, but in human connections there is always some sex in the air. The popularity of "friends with benefits" relationships among the youth, and now middle-aged singles - makes that clear. Lots of other things are in the air too, like competitiveness, childish emotional wishes, familial-type feelings, feelings of tribal affiliation. loneliness, delight or amusement in another's company, shared intellectual or recreational fun, exploitative aspirations, etc., etc.
My profound and earth-shaking point here is simply that human interactions and connections partake of all aspects of being ... human.
There's one thing I know for sure: Put a guy and a gal who are pals in a comfy place away from home, add alcohol, stir, and anything can happen. Alcohol numbs the prefrontal cortex.