Early puberty

There's something funny about the reasoning here. It's an article on a study of data from the NICHHD study on early child development. They found that 15-month-old girls "who avoided their mother following the separation or could not be comforted by her return" started puberty earlier than "(b)abies who smiled, vocalized, reached, or otherwise demonstrated appreciation that their mother was back."

From this and the observed fact that girls seem to be starting puberty earlier than they used to, the authors conclude (or should I say hypothesize?) that lack of attachment caused the early puberty in the NICHHD girls. They further hypothesize that the species wide early puberty is caused by stress in the environment, which apparently causes animals to breed earlier.

"An evolutionary biology perspective says, 'look, the thing that nature most cares about -- with respect to all living things, humans included -- is dispersing genes in future generations,'" says Belsky. "Thus, under those conditions in which the future appears precarious, where I might not even survive long enough to breed tomorrow, then I should mature earlier so I can mate earlier before that precarious future might get me." This is the evolutionary logic, according to Belsky, which led to the prediction -- and now evidence -- that early insecurity should be related to earlier pubertal development.

This sure seems fuzzy to me. Maybe it's the metaphorical language ("I should mature earlier") when I'm sure the actual researchers are probably thinking about epigenetic factors, some hormone released in the brains of insecure babies causes some genes to turn on early.

But the actual reasoning chain seems fuzzy to me, too. Something about being insecure at 15 months causes girls to start puberty earlier than other girls. Therefore this recent drop in age of puberty is caused by a species-wide insecurity in baby girls. The reason one group of girls starts puberty earlier than another group is the same reason average girls now go through puberty earlier than average girls used to. It just doesn't follow. It's interesting, and I'm glad they did it, and we can probably learn something useful from it, but I don't see how the big step follows.

Puberty in second grade

I haven't written about the recent study about girls of 7 or 8 growing breasts and pubic hair, because several ideas were swirling in my head. I still haven't sorted them out, so I guess I'll just blurt them out.

There is a syndrome whereby toddlers grow breasts. I've always assumed something like that was some gene getting turned on by accident of DNA or of environment. This doesn't seem to be that.

Reported age of menarche has been dropping for a hundred and fifty years. Much of this seems to have to do with nutrition. Your body needs a certain amount of body fat before it figures it's ready to breed, and girls are getting that body fat younger than they used to.

Or it could be that a certain percentage of young girls have always done this, but medical books, written by men we  hope are not especially interested in 7- and 8-year-old girls, hadn't noticed. Because cadavers for dissection  used to come pretty much exclusively from poor people, there is at least one case where the size of an organ shrunk by a disease of poverty was taken as a standard. Maybe richer girls get enough fat earlier than the poor girls who formed the baseline for 19th century medical texts. (I love speculation about research; it's so much easier than actual, you know, research about it.)

Or it could be that all these organophosphates and other chemicals we're putting into food containers and the food itself are changing the average sexuality of girl humans. And boys.

Or it could be a combination of nutrition and some long-term genetic change. I'd like to know if it's happening in Botswana and Bolivia, too. Or cosmic rays from the hole in the ozone layer. Or the flying spaghetti monster willed it. I need to go get some more coffee.