Of Hair and Men

What is it with men and long hair (on a woman)? Every time, literally every time, I mention going to the hairdresser to the BF he immediately gets that scared bunny look. He's ridiculously afraid I'll get a short cut. Thing is, I'm quite sure that if I ever did, he'd have a heart attack.

Now, someone, please, please, explain to me why men have such fascination with long hair. Is it genetically ingrained? Is it a tradition passed on from one generation to the next? What?

I don't get it. I just don't.