I went to a middle school in rural North Carolina. "Rural North Carolina" should really tell you a lot about my early years; though I wouldn't call it "backwoods" (many - if not most - of my classmates were army brats, if I may use the term), I'll tell you one thing about my school: in 1997, our Social Studies textbooks still referred to the Soviet Union and Czechoslovakia. Also, those people came by and passed out those little green plastic New Testaments, and I got in trouble for asking if that was a violation of church and state.
So I randomly remembered this girl I sat next to in seventh grade Social Studies. She was a cheerleader who had written in white-out on her backpack "Hold my poms while I STUNT with your boyfriend."
Just like that. In not-quite-backwoods North Carolina, that message of female competetition for mates in middle school. And it stuck with me, only in the back of my mind, I guess, for nearly ten years. I guess I just thought the sexualization of young girls was relatively recent, because I could never remember it when I myself was a young girl, but thinking about it now, I can see that it was starting even then, with a little implication that a.) having a boyfriend is one of the most important things about your young female life, and b.)since she was prettier than me, she was inherently superior - at least enough that she could steal my boyfriend. The fact that I was (am) an ugly thing and had no boyfriend only drove the message home even further.