Upon reading this arresting article by Elizabeth Weil about some girls entering puberty today before the age of 10, I thought it valuable to place the issue in an historical perspective. Weil reviews a 1970s study finding that the average age of menarche takes place between 12.5 and 12.8. Later, she cites a 1960 study of institutionalized British children concluding: “Puberty began, on average, for [these institutionalized] girls at age 11.” But Weil does not place this material in as broad a historical context as she might.
In his 1992 book titled Today’s Children, David A. Hamburg, M.D., then president of the Carnegie Institute, wrote: “The onset of menstruation, on average, occurs at twelve and a half years in the United States, whereas 150 years ago the average age of menarche was sixteen.” In short, within the arc of U.S. history, when it comes to sexual development, girls have been maturing earlier for more than a century and a half. This precocious maturation has probably been so gradual that it has caught us unaware.
Weil offers three reasons for earlier pubertal development. First, puberty occurs when girls gain body weight, or more precisely, fat. A higher fat index sets off an endocrinal chain action that culminates in earlier puberty. Since obesity has become rampant among American children, we see precocious puberty becoming more common. Next, she cites data suggesting that artificial forms of estrogen are filling our environment. Perhaps the use of packaged products containing artificial estrogens that contaminate our water supply and clutter our homes induces early pubertal development. Third, family stress, specifically divorce, commonly plagues American families. Such stress seems to precipitate puberty, perhaps through spiking stress hormone levels in girls, elevating their estrogen levels. All three of these reasons, which are recent developments, may be causing the early onset of puberty.
Let’s push these ideas further by juxtaposing these data alongside a growing body of research about human brains not achieving total cognitive maturation until about age 25. Young adults are still developing their capacities for complex thinking processes, such as weighing the pros and cons of their actions, placing their own decisions in broader societal contexts, etc., into their mid-twenties. So their sexual development may have accelerated, but not their brain maturation.
Let’s further contextualize matters. The world in which humans now develop has become more complex and demanding. A successful passage through adolescence is taking us longer, due to a need for more extensive education and training processes. In short, adolescence is lengthening at both ends, especially for girls, owing to an earlier entrance into puberty and a prolonged educational period needed to launch successfully into adult life.
Finally, there is the matter of the media, which fills our homes and our children’s lives with novel and confusing messages. As the number of media gadgets in our homes has proliferated, the media has gradually elbowed parents aside in claiming the role of value creator and role-model generator. Children in maturing bodies and immature brains are being entertained—indeed, parented—by media creations that offer them attractive renditions of risk-taking, ruthlessness, and reliance on sex, violence, impulsivity, and deception to solve their problems. All this has become their daily fare, right under their parents’ unsuspecting noses.
We face the impingement of many historical factors on our children’s lives, and this should catch our attention. Yet most parents still tend to see their parenting job as complete when their children enter their teens. Most see the media as relatively harmless, and very few are aware that earlier onset of puberty has become the norm. In short, we live in a brave new world, for which parents and children alike are poorly prepared.
Read more about When the Media is the Parent at Dr. Drinka's website.
 David Hamburg, Today’s Children: Creating a Future for a Generation in Crisis (New York: Times Books, 1992), 182.