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What's going on? Is it something in the water? That's a possibility. Scientists think it may be linked to obesity, though they've also proposed a witches' brew of other explanations, from chemicals in the environment to hormones in cow's milk and beef. But the truth is that all anyone knows for certain is that the signs of sexual development in girls are appearing at ever younger ages. Among Caucasian girls today, 1 in every 7 starts to develop breasts or pubic hair by age 8. Among African Americans, for reasons nobody quite understands, the figure is nearly 1 out of every 2.
Even more troubling than the physical changes is the potential psychological effect of premature sexual development on children who should be reading fairy tales, not fending off wolves. The fear, among parents and professionals alike, is that young girls who look like teenagers will be under intense pressure to act like teenagers. Childhood is short enough as it is, with kids bombarded from every direction by sexually explicit movies, rock lyrics, MTV videos and racy fashions. If young girls' bodies push them into adulthood before their hearts and minds are ready, what will be forever lost?
The danger, as authors Whitney Roban and Michael Conn pointed out in a report for the Girls Scouts of America called Girls Speak Out, is that the stages of childhood development--cognitive, physical and emotional--have got out of synch. Roban and Conn call this "developmental compression" and pepper their study with poignant quotes from girls struggling to cope with pressures they are ill equipped to handle. "Boys," complains a fourth-grader in their report, "are gaga over girls with breasts."
In retrospect, pediatricians and psychologists say, there have been hints for the past decade or so that something strange was going on. But it wasn't until 1997 that anyone put her finger on it. That's when Marcia Herman-Giddens, now an adjunct professor at the University of North Carolina School of Public Health, published her famous paper in the journal Pediatrics. Herman-Giddens noticed in her clinical work that more and more young girls were coming in with breasts and pubic hair. Intrigued, she launched a major study of 17,000 girls to get a statistical handle on the problem.
What she and her colleagues found was that the changes of puberty were coming in two stages, each with its own timetable. The average age of menarche, or first menstruation, had already fallen dramatically (from 17 to about 13) between the middle of the 19th century to the middle of the 20th--mostly owing to improvements in nutrition. (Menstruation is considered the technical start of puberty; the outward signs of sexual maturity usually come earlier.) But since the 1960s, average age of first menstruation has basically remained steady at 12.8 years. For African Americans, it's currently about six months earlier, possibly reflecting genetic or nutritional differences.
What was striking about Herman-Giddens' report was the onset of secondary sexual characteristics: breast buds and pubic hair. Significant numbers of white girls--some 15%--were showing outward signs of incipient sexual maturity by age 8, and about 5% as early as 7. For African Americans, the statistics were even more startling. Fifteen percent were developing breasts or pubic hair by age 7, and almost half by age 8.