A totally unscientific comment on girls and puberty: My daughter, now 12, showed signs of early development of sweat glands at about age 7 or 8. I began to buy only meats not treated with hormones, and the evidence of sweat glands disappeared. Then hormone additives were approved in dairy cows. Within a few months, the sweat gland evidence was back. I switched to more expensive, less convenient milk produced without the additive--condition went away. It was a nuisance, so I decided to give SAfeway milk one more try. Within 2 weeks the evidence came back. Now we're back on hormone free milk, and have been for a long time. My daughter has some breast development and early signs of pubic hair, but is still not menstruating. I'm keeping my family off of the milk with hormone additives, and continue to use mostly natural meats! (Incidentally, she is a big consumer of soy products and shows no signs of hormone effects from any of those products).

The LA Times has a good summary of the questions concerning girls hitting puberty. http://www.latimes.com/news/health/lat_hormone991101.htm

Here's my summary of their article. The article is well worth a read, but I didn't want to blatantly violate copyright rules by copying the whole thing into this posting.

Are girls hitting puberty earlier than before? Yes. According to Pediatrics, the journal of the American Academy of Pediatrics, 15% of white girls and 48% of African American girls showed signs of breast development or pubic hair by age 8.

In 1890, the average age of menarche in the United States was 14.8 years. Today it's 12.5, according to the study in Pediatrics, which tracked 17,000 girls to find out when they hit different markers of puberty. Other developmental changes begin much sooner, often at age 8.

What seems to be causing it? Better nutrition and changing sociological factors.

Why does it divide across races? The reason for the racial disparity is unclear.

How does it relate to beef and hormones? But few experts blame this earlier maturation on the sex and growth hormones farmers give cattle. "That's just another urban myth," said Ruth Kava, director of nutrition for the American Council on Science and Education. "Lack of exercise and increased body fat are much likelier suspects." Dietary hormones aren't taken too seriously because many other factors are known to affect puberty's onset. Nutrition, body fat, ethnicity and maternal genes have all proved to play a role. Some suspect social influences: our culture's sexualization of young people, society's pressure on young girls to look grown-up, and even the presence or absence of a girl's biological father. But estrogen artificially implanted in steer? Not likely.

What might delay it? Body fat also triggers the pituitary gland, a small gland in the brain that is the traffic signal for puberty. Thus, heavier girls mature faster than lean girls. The increase of childhood obesity has almost definitely brought down the age of puberty. Conversely, dancers and female athletes who train hard may have very delayed or absent periods.

Finally, father-daughter relationships may play a role. In a study published in September in the Journal of Personality and Social Psychology, researchers at Vanderbilt University in Nashville concluded that girls who have close relationships with their biological fathers during their first five years of life experience relatively late puberty, compared with girls raised without their fathers present or by stepfathers. Researchers speculate that exposure to the scent of unrelated adult men accelerates puberty, while exposure to the scent of a biological father inhibits it--a phenomenon that occurs in other mammals

It doesn't speak to the issue of soy drinks, but I am sure you get their take on the issue.