Fig 1
Blogger "Agnostic" posits a link between falling crime rates and shorn female pubic hair (HT: Ulysses). A sampling:
[T]he timing [of cropped, then shaven pubic hair] should make us think of how the prominence of body hair responds to whether the violence level in society is rising or falling. In this case, women began minimizing their hair as the world got safer. In contrast, during the rising-crime times of the '60s through the '80s, hair only got more prominent. As far as I can tell, it's not the state of pubic hair specifically that responds to the violence level, since there don't appear to be cycles up and down in shaving it or leaving it alone. In earlier waves of violence, the evidence isn't crystal clear but is suggestive.
...we've seen before that people become more sexual when violence levels rise, and more prudish when they fall. Then it shouldn't be surprising if people chose to sexualize their appearance more during rising-crime times, and to asexualize it in falling-crime times. Hair is one of the most strongly sexual parts of the body -- that's why married women cover it up around the world, and why in other parts even unmarried girls must cover it up to maintain their honor and reputation for chastity. So it is only fitting that they would try to minimize their hair in safer times. A flowing mane of hair and a full bush might give men the idea that she's more of a wild animal than her otherwise hairless skin had let on. That's the last thought you want to give men in safer-prudish times, although you might well choose to play it up in dangerous-wilder times.
Figure 2
Although Agnostic's analysis is intriguing, I think he's looking the wrong way for a correlative link. Rather than violence being the catalyst that encourages lawn-mowing, we should instead consider a well/aggressively groomed pubic region as an indicator of the overall sexualization level of society. If one mentally superimposes another timeline over the top of Agnostic's chart, one sees that the steadily shrinking bush correlates, with perhaps a bit of latency, with feminism's rise to power and it's focus on loosed female sexuality as a barometer of a fully flowered femininity. Thus while I agree with Agnostic that head hair is a strong sexual signal, suggesting youth, vitality, and (in modern culture) femininity, it's not sexy per se. If pure eros is what one is after, then the degree to which raw sexual signals are displayed is a better barometer. What better way to do this, than by boosting breast perkiness and overall size (suggesting youth and fertility), and aggressively trimmed pubic hair (suggesting sexual availability and a certain joie de vivre when it comes to recreational bedroom activities).
Figure 3. Source: Wired [pdf]
American women and girls are aping the sexualized images embodied by Playboy models whether they realize it or not. Breast augmentation surgeries tripled in the 11 years from 1997 to 2008, from 101,000 to over 300k. (An additional, 80,000 underwent breast reconstruction surgery subsequent to mastectomy in 2011, these instances are not rolled into the 300,000+ figure). Full Brazilian waxes seem to be de rigeur for the under-30 set and are on the rise for older women, according to this article in the Atlantic. Labiaplasty [warning: wikipedia link NSFW, unless you are employed at a gyno office]--a surgical procedure that trims back exposed labia folds--is on the rise as well and is a $6.8B industry in the US. The entire point of all this trimming, ripping, snipping, cutting, and stuffing is to accentuate the sexual cues a woman/girl projects into the environment: the terraformed woman is ready and raring to copulate, and wants every male in sight to know it whether her clothes are on (varying degrees of exposed cleavage) or off (denuded and surgically enhanced vulvas).
Figure 4. Source: Wired
Another distinct socio-cultural factor that boosts possibility, in addition to American women being far more overtly sexualized in attitude, dress, and comportment than they were formerly, is that breast enhancement and pubic hair trimming is an attempt to regain femininity lost through weight gain. Continuing to use Playboy centerfolds as a data source, when Playboy debuted in 1953, the women depicted inside its pages were of a shape and size that resembled a slightly more svelte version of the average woman of the time. However, as American women and men have gotten fatter (Figure 2), the BMI of Playboy models held steady at a nudge over 18 (Figure 3). The female ideal highlighted in Playboy--which has diverged steadily from the real, overweight American woman*--is one that tracks what men find attractive in women. That's not to say that it does so perfectly; for instance, Playboy model bust sizes have declined over time while their cup size has held steady (Figure 4). The result that their breasts are much more prominent relative to the rest of body, lending in some cases to an extreme anime-girl type look. But for real-life women, breast augmentation may help serve to provide balance to a form where sexual attractiveness is dampened or muted by abdominal fat that obscures the human female's natural hourglass shape, particularly her waist-to-hip ratio.
Quick note about teh menz before I close. They, too have been getting waxed and implants too (mostly buttock implants), reflecting an increased focus on physical attractiveness driven at least in part by the outsized cultural influence of homosexual men. But my sense is that the number of dudes getting their junk shaven will not approach the scale of women, partially because the mechanism of attraction for men is different than it is for women. Physical attractiveness for women is key, and all this woman-scaping in an age of commodified female sexuality makes sense. It's "girl game" on steroids. Ditto for homosexual men. For straight men, however, the story is different. Man-scaping at best has only a tangential impact on his ability to attract women, whose road to arousal is more emotional and situational than visual.
* who gained 24 pounds from 1960 to 2002 but whose height has only increased 0.8 inches