There is, in lab rats, a process by which young females mature sooner if they are exposed to the pheromones of mature male rats. There seems to be a similar process in humans, though not reliant on pheromones, which accounts for the fact that children are entering puberty several years sooner than they were as recently as the 1950's. Not only are little girls' breasts more commonly beginning to develop at ten--even eight in some cases--rather than twelve years of age, but interviews with pedophiles indicate that, forty years ago, it was difficult to get a child interested in sexual activity while, currently, their interest is peaking at a much earlier age. It is probable that being raised in a society that is obsessed with sex has had that outcome in a cause and effect universe.
Such influences make it all but impossible to ignore the attraction of the sexes. Not only are pubertal youth, at whatever age, driven by a lifelong cuddling habit, a desire for oral gratification, frothing curiosity, a liking for genital stimulation and intense pubertal stress but they are also surrounded by an endless array of magazines, books, TV shows, movies, videos and clothing fashions purposely designed to stimulate them sexually so they will buy the product. And many of those products, intentionally aimed at twelve year olds or even ten year olds, are jam-packed with sexually explicit material. One magazine published for what used to be considered children went into great detail about what girls need to do to turn on the guy of their choice. It may be that endless stimulation which accounts, at least in part, for early maturation.
The female shape originally falls under the category of "Curiosity," of course, because, for the male, it's something different that he is likely to investigate just like everything else that gets in his way. However, the male's curiosity is greatly intensified by the gross exaggeration of the female shape by certain factions of society, including females, who want to profit from those curves in one way or another.
There have been situations that have demonstrated the effects of intentionally making the female body more enticing than it naturally is. Years ago, in Africa, bare breasted women noticed how much more attention men were paying to European women who were wearing tight sweaters so some native women began wearing sweaters to cash in on some of that attention. The effect which that had on men motivated them to chase those women down and cut their sweaters off with knives.
For a long time, the fashion industry has been aware of the tendency women have to buy chothes that enhance their attractiveness. To maximize that effect and to profit from it, fashion designers intentionally change the appearance of women's fashions every now and then. They accentuate one part of the female anatomy for awhile and, when the effect of that wears off, they draw attention to different female body parts so that males will not stop rubber-necking and women will continue to buy...buy...buy to keep up with the latest fasion.
Historically, women have been so intent on being in style that they have actually damaged their health in the pursuit of that objective. When tiny feet were in style in a part of Asia, women bound their feet so tight that they were barely able to walk. Not to be outdone, modern Western females wear high heels which enhance the appearance of their legs, buttocks and the general angularity of their profile but, in so doing, they often damage their feet. Beyond that, many women have paid lots of money to have their breasts enlarged in spite of lawsuits that have been filed by women who claim that breast implants have seriously harmed their health.
Large numbers of the females who go to such great lengths to be as attractive as they can be are imitating the models they see in women's magazines. Those models are hard to keep up with because, in addition to being some of the best looking women on earth, they often starve themselves to look even moreso--but even that is not good enough for, after the pictures are taken, they are computer enhanced to create an alluring image that promotes an aire of mystery around the human female who, in nature, is as common as men.
Yet that mystery persists because fashion designers, movie producers and attention-hungry women, themselves, never stop trying to appear far more desirable than they really are. Stated as simply as possible, while profit and sex conscious society has made volumnuous enticements out of female breasts, for example, those mammary organs are nothing more than modified sweat glands which specialize in producing milk out of the components of blood and sweat. It is merely the hype about them and other anatomical differences between the genders which renders it all so enticing.
For those and other reasons, younger and younger children are increasingly aware of the above-mentioned sexual enticements. When, to that, is added the often explicitly sexual behavior of adults around them, it seems as if there is a huge party going on to which they, as usual, have not been invited.