Several studies have now led to a scientific consensus that American girls are hitting puberty earlier. Now, a new study suggests that the same might also be true of boys. The New York Times has a very good article on this that gets into the nuances of the research and explains what this information might mean (and what it doesn't mean).
There are a couple of key things that I found to be particularly interesting:
• There's enough evidence now that scientists generally agree girls are growing breasts at a younger age than they used to. But it's a lot less clear whether or not their periods are starting earlier, too. In fact, the evidence accumulating on that is leading scientists to start wondering whether breast development and menstruation aren't as closely tied together as we previously thought.
• It's a bit difficult to know whether this study in boys actually represents a real change because earlier research on when boys hit puberty — essentially, the stuff this study is comparing modern boys against — is often flawed. One 40-year-old study mentioned in the story established guidelines for how all boys should be developing and when based solely on photographs of 228 white boys from a London juvie facility.
• Even if both boys and girls are hitting puberty earlier, scientists acknowledge that the social results are very, very different. Parents don't particularly care when their 9-year-old son's testicles get bigger. Parents are deeply concerned when their 9-year-old daughter grows breasts. And with good reason. Even if a woman otherwise looks very young, people start treating her differently once the boobs kick in — "differently" in ways that can be really problematic for a 9-year-old. I had a friend in grade school who had breasts by 4th or 5th grade. She'd get cat-called on the street by grown men.
• There is a legitimate medical tool that consists of a string of wooden beads used to estimate testicle volume. Doctors hold the beads up and compare the size of the beads to the size of the guy's nuts. You can't make this stuff up.
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.