Cephalization is the term you are looking for. It's been a long time since high school bio but I remember being fascinated by evolution.

I would also add there is an element of the expected pursuit of the woman after she has said no. Like, no means try harder. I think it's a good thing that a guy (or whoever) backs off once someone says they aren't interested. You shouldn't expect the guy you like to push past the first rejection then call the guy you don't like a creep for ignoring your no.

And the nurse's comment on finding a 13 yr old pregnant? "What have you been doing?" For fucks sake, I hate the world.