Teenagers Were Invented Around The Time Of World War II
Depending on who you ask, your teenage years are either the best of your life (says your uncle who still wears his high school class ring, despite his finger looking like a tied-off sausage) or a cringefest that makes us wish the memory eraser from Men In Black were a real thing (says everyone else). If you could ask your great-great-grandpa, though, he'd likely ask you what the hell a "teenager" was, before telling you to get back to tilling that goddamned corn field.
"Never too old for an ass-whoopin'!"
That's because up until the 1940s, teenagers weren't really a thing. We don't mean that people used to time-warp from age 12 to 20. We mean that the cultural concept -- this ethereal, not-quite-child-yet-not-quite-adult period in human development -- simply wasn't considered to exist prior to the Great Depression. Up until then, you were either a child or you were an adult.
That all changed with a single spread in the December 1944 issue of Life.
Note the two girls standing in the back who are contributing nothing but friction.
In a historic attempt to quantify this "new" American youth phenomenon, Life excitedly told of the "teen-age" girl -- specifically the white, middle-class teen-age girl. They did so maybe a bit too excitedly, as evidenced by their up-close examination of Dorothy's too-tight sweater:
Perhaps the thing Dorothy should've "known better" about was allowing a Life photographer within 90 yards of her.