Yeah, I understand that this graphic is simplistic. Still, if you labeled this "Evolution of Dances It Is Appropriate To Dance at Weddings & Other Non-Red Light Events", it would be even more accurate and just as telling.
It surely says something that dancers can now simulate sex in from of hundreds with no shame. Ah for the days when one could simulate the courteous interaction between the sexes in front of hundreds with no shame.
Still, the seeds of the 2011 image were already planted in 1970. Dance was something that was overly romantic, age segregated, and strictly between one male and one female. You could label the picture above "Getting Married" if you wanted to. It would be accurate given a community setting. But of course, only the first couple of steps would be done in public. These days we don't do romance in a community setting. Honestly, we don't do romance at all. All our movies teach us romantic techniques like buying flowers and learning to dance so that we can do what romance leads to...sex. I hate to break it to you, boys, but that's not romance.
Romance leads to love, which is not sex, or even "a relationship". Love is focused and dedicated service of another. When this service is romantic, you get married to the object of your love, and serve her for the rest of your life.
The cute couple in 1970 thought that the dance was all about them and their teenage hormones, and 2011 is what came of it. It's only natural.
Dancing was quite romantic before it was one-on-one, folks. Entire lines of women facing entire lines of men. Pairing off, swinging to new couples, back into lines facing each other. Smart advances, coy retreats. Done in front of family, done in front of town. Charged with hormones and responsibility, romance and family. People stopped dancing as communities because they stopped mating in a community setting. Your baby-boomer parents and grandparents set you up for this crassness.
Next time you see her, go ahead and thank grandma for all those booty-shake videos on YouTube. Or maybe suggest to her that she take up contra dancing.
Total aside: even the name "contra dancing" is sexy. It's "contra" because it sets you up against your partner, face-to-face. It involves conflict and conquest. I'd rather take a woman that way than just have her squat and bob her head at my hip level, as is the current custom.