I just wrote for Broadsheet about a new study that found specific genes associated with determining when puberty begins for girls (and in one case, boys), which throws at least a small monkey wrench into the theory that the Evils of Modern Society (hormones in our food, pesticides, childhood obesity) are messing up little girls, so soon we’re gonna have hordes of menstruating toddlers on our hands. That post is pretty much me ranting about how our culture’s attitude toward female sexuality is a MUCH bigger problem than a relatively modest decline in the age of menarche over the last 30 years. But over here, I want to discuss the part I didn’t have space for.
The Nature Genetics study also provides a clue for why girls who are shorter and fatter tend to get their periods months earlier than classmates.
The genes sit right next to DNA controlling height and weight.
I’m sorry, did they just acknowledge the existence of “DNA controlling height and weight“? Somebody pinch me. Moving right along…
Researcher Dr Anna Murray said: “This study provides the first evidence that common genetic variants influence the time at which women reach sexual maturation.
“Our findings also indicate a genetic basis for the associations between early menstruation and both height and BMI.”
Now, of course they’ve also got the expected caveat in there, way before the quote from Dr. Murray.
However, [the researchers] also accept that the onset of puberty is influenced by factors such as nutrition and exercise, and the effect of a single gene is likely to be relatively small.
In the Broadsheet piece, I also talk about a recent post by Tara Parker-Pope over at Well, in which she points out that there was a much more dramatic drop in the average age of menarche between the mid-19th and 20th centuries, which is widely attributed to improved nutrition and medical care. So yeah, genes are not the only factor at play here. But of course, somewhere around the ’70s, “Improved nutrition, yay!” gave way to “We’re all eating too goddamned much and too many of the wrong foods,” and then that led to panic about fat little girls sprouting pubic hair before they’re out of diapers. And everybody sorta forgot about genes, since their existence might mean that living A HEALTHY LIFESTYLE does not give one absolute control over one’s body. Perish the thought!
Now, after all these years of hearing that early menarche is associated with both shortness and fatness — ergo, we must put chubby little girls on diets! And, you know, will them to get taller! — someone comes along and shows a genetic link among all three characteristics. You don’t say.
From the anecdata files, as I’ve mentioned before, I was a skinny kid who hit puberty early (noticeable boobs by age 9, first period at age 10), and only then began to put on weight. I didn’t have “excess” body fat prior to menarche, but I sure as hell had fat genes and short genes. (At the time, I was pretty tall for my age, but then everyone else kept growing.) So for the very little that my personal experience is worth, this makes a lot more sense to me than the thought that shortness and fatness cause early puberty.
Also, the aforementioned Well post is primarily about a recent Danish study that showed the average age of beginning breast development dropped by a full year over the course of fifteen years — though the average age of menarche didn’t drop nearly as quickly. My first thought, naturally, was, “Fuck, it’s all gonna be about how Europe is catching up to the U.S. in terms of fatness.” But wait, what’s this?
Alterations in reproductive hormones and BMI did not explain these marked changes, which suggests that other factors yet to be identified may be involved.
They controlled for BMI and got the same result! Fatness did not cause early breast development! Yippee!
I’m not optimistic that we’ll stop hearing about how THE OBESITY CRISIS BOOGA BOOGA BOOGA is pushing younger and younger girls headlong into adulthood any time soon. But at least we’ve got some evidence that other factors are at play. And since in the U.S., children (not to mention adults) are apparently no longer getting fatter, I will be really curious to see what happens in the next few years. If that plateau holds, and the average age of menarche keeps declining at the same rate (which is not nearly as fast as the hand-wringers would have us believe, mind you), they’ll have to find another culprit. I mean, they’ve already got hormones and pesticides lined up for that — and for all I know, there might even be a noteworthy connection there — but CHILDHOOD! OBESITY! has long been the favorite scapegoat. It would be delightful to see the attention shift to something else. (Of course, that would involve anyone outside the fatosphere actually noticing that childhood obesity is no longer on the rise.)
Anyway, read the Broadsheet post for the rest of what I think about the panic over precocious puberty. Which is not much, generally speaking. Then tell us what you think about all this.