I remember the day our food bill effectively doubled. We were visiting our friend Martha, who announced that her family had switched to organic meat, eggs and milk. When my wife asked her why, she looked as though she’d been asked why she bothers to brush her teeth in the morning.
“Don’t you know?” she said. “Growth hormone in animal products — it gives girls their periods by age eight.”
My wife then investigated — by polling fellow mothers in our Toronto schoolyard. In this way, she learned what “everyone” knows about growth hormones in food: They accelerate the onset of puberty, particularly in the case of girls. She started patronizing our local health food store, which in the three years since she started shopping there, has grown to the size of a used car dealership.
I, dubious, turned to my favourite research tool: Google. I learned that the average onset of adolescence has dropped over the past century: The average North American girl started menstruating at age 14 in 1900, an age that has gradually declined to about 12 today. This pretty much absolves bovine growth hormone, which wasn’t marketed until 1994 when a company named Monsanto began selling it as Posilac. So if growth hormone really were the culprit, the age of adolescence onset would have started slipping about 15 years ago, instead of more than 100 years ago. Plus, Posilac is not used worldwide — it has been banned outright in all EU countries, and Health Canada refused to clear the substance on the grounds that it was harmful to animals. And yet, Europe and Canada have seen this hastening of adolescence onset as well.
What, then, accounts for the gradual drop in average maturation age in girls? Most researchers speculate that it has something to do with changes in overall diet and lifestyle that occurred when the world began to industrialize. We all started eating more meat and more fat, and we all started getting a lot less exercise. Marcia Herman-Giddens, a leading American researcher in premature adolescence, puts it this way: “In the animal industry, to hasten puberty, they keep the animals confined, they feed them really rich diets, and the animals grow really fast. This is exactly what we are doing to our children.”
A diet that is high in fat and protein can trigger the release of enzymes that leads to the overproduction of estrogen. This might explain why early puberty is more pronounced in girls; boys depend on the hormone testosterone for their initial growth spurt. It could also explain why black girls tend to reach maturation earlier — African-Americans are still among the poor in North America, and poor people eat poorly.
Were it only that simple. Japanese girls, who arguably have the healthiest diet on earth, have had an even more precipitous drop-off in menses onset — from about 16 years at the turn of the century to about 12½ by 1970. Even more confusing is the “Latina conundrum,” which goes as follows: If the African-American girl’s susceptibility to early puberty were caused by poor diet, then Hispanic girls — who are pretty much on par economically in North America — would be equally susceptible. In fact, the opposite is true: No group of girls, at least in the US, has a lower rate of early puberty onset.
Researchers point out that Latina girls are most often breastfed, most often share a bed with parents as babies, and most often come from an intact, multi-generational family. So is that it? The early onset of adolescence is prevented by a warm, loving bond between family and children? Some studies have shown links between precocious puberty (the exhibition of pubertal characteristics before age nine) and children of divorce, adopted children, abused children and those who have been in any way transplanted.
So is it obesity? Bad diet? Estrogen exposure? Fractured nuclear families? It’s hard to say. There exists a whole body of research claiming that the culprit is an industrial chemical called phthalate, which acts like estrogen when in the body; if this is the case, preadolescent girls should be warned against licking shower curtains.
Which brings me to my own opinion: As a parent of two daughters, I am nauseatingly aware of the degree with which our culture is transfixed by sexualized young girls. They appear, pouty and Britney-fied, on after-school TV shows, on ads for lip gloss, on the covers of CDs targeting tweens. Parents are alarmed by this (justifiably, in my estimation) and react when they detect signs of adolescence in, say, their 11-year-old. One assumption leads to another, and pretty soon the local IGA is carrying organic milk and wieners. It could be, however, that the early onset of puberty is a symptom of evolution, much in the way that every generation is getting slightly taller. If this is true, parents would do well to consider the following possibility: Just because we interpret something as bad doesn’t necessarily mean it is.
Stay in touch
Subscribe to Today's Parent's daily newsletter for our best parenting news, tips, essays and recipes.