Hormones on Overdrive

A
couple of years ago, when I was teaching second grade, I found myself
at parent-teacher conferences reassuring two mothers whose girls were,
undeniably, showing signs of puberty. “I don’t understand it,” lamented
one. “She wants to know what that ‘onion’ smell under her arms is, and
why her breasts are growing when no one else’s are.”

It’s difficult and confusing for little girls in second grade, not to
mention first, to be hit with puberty. Eight-year-olds find these
changes scary, and even disgusting. They feel set apart from their
peers and that makes them angry. Research suggests that early puberty
may have negative consequences for girls’ mental health and quality of
life. Most of the credible research in this area focuses on early
menstruation, not puberty (which arrives much earlier), but at least
one study of thirty-three girls from ages six to eleven showed that
those who go through puberty before nine are more likely to be
depressed, aggressive, socially withdrawn, and to experience sleep
problems and obsessive behavior. In a larger study of 1,700 girls in
Oregon, those who claimed to have matured earlier than classmates were
more likely to drink and smoke, and twice as likely to have experienced
substance abuse and disruptive behavior disorders.

This can’t be good news. Although I didn’t fully grasp the extent of
the trend back when I was teaching second grade, today’s girls are,
across the board, growing up faster and reaching puberty earlier than
their mothers did. American Academy of Pediatrics guidelines now state
that girls who develop breasts and pubic hair at age six or seven are
no longer necessarily abnormal. But while the “normalization of early
puberty” may lessen the sharp feelings of separation among girls who
experience it, does this mean we should shrug off the shift? Or are we
obligated to ask ourselves whether first-graders entering puberty can
possibly be a good, normal thing?

The phenomenon of widespread earlier puberty was first highlighted in
the scientific community in 1997, when North Carolina physician and
researcher Marcia Herman-Giddens published a breakthrough journal
article on the subject, based on her study of 17,000 girls across the
country. Herman-Giddens’s research showed that by eight years old,
forty-eight percent of black girls and fifteen percent of white girls
show clear signs of puberty, such as breast buds and pubic hair. In
extreme cases, these developments are occurring in girls as young as
three.

Herman-Giddens considers early puberty a serious public health issue.
“Is it going to keep getting lower? Are kids going to get to be
[pubescent at] five and four and three? And is this supposed to be
happening? I don’t think so. I don’t think that’s what nature
intended,” she told the New York Times Magazine. Since her work was
first publicized, the entire scientific community, from
endocrinologists to primatologists, has been trying to figure out
what’s causing the shift.

There is at least one reason most experts agree on: childhood obesity.
Kids are getting too fat, and heavier girls may enter puberty earlier.
Percentage of body fat, which rises naturally around the time of
puberty, is believed to be one of the triggers for the onset of sexual
maturation and eventual ovulation. (This is why underweight girls
experience delayed menarche, and serious female athletes cease to
menstruate when their overall body fat dips too low.)

But the big picture is probably too complicated to be reduced to a
single cause-and-effect explanation. Other, more controversial research
suggests potential causal relationships between puberty and such
diverse influences as absentee fathers, the presence of stepfathers,
stress, milk, chemicals, and TV.

Hypotheses related to divorce and stepfathers can mostly be traced to
the work of two researchers, Jay Belsky and Bruce Ellis, who’ve
explored a generality called “the absent father theory,” hinged on the
notion that the biological processes of puberty can be triggered by
exposure to stress, and/or exposure to sex hormones known as
pheromones. What’s been shown so far is that girls with more distant
family relationships mature earlier, especially if the interactions
with their fathers early in life were of poor quality or absent. The
presence of an unrelated male in the household, such as a stepfather or
mother’s boyfriend (no matter how consistent) may speed development
even more. These findings are backed up in nature, where scientists
have observed that puberty is inhibited in prairie dogs whose
biological fathers are present, while puberty begins in prepubescent
mice exposed to the pheromones of unrelated males.

The findings might also suggest that the earlier age of puberty among
girls in divorced families is catalyzed by stress, which in turns
triggers puberty. Evolutionary psychologists argue that since the
survival of a species depends on the ability of its members to pass on
their genes, behaviors that facilitate reproduction and survival
persist and evolve because the people who employ them produce
prolifically. Meanwhile, less effective reproductive strategies
disappear because those who employ them produce few offspring. Thus,
early menarche may have evolved as a strategy to solve the specific
problem of life in a “hostile environment.”

According to the theory, females in dangerous environments (which a
modern-day stressful family situation could mimic) gained a
reproductive advantage because they were physically able to reproduce
earlier. Precocious development of curvaceous hips and breasts make a
girl attractive to potential mates at a younger age, increasing her
chances of early mating. And the earlier she mates, the better her
chances of reproducing before succumbing to the dangers of the
environment.

Whatever the reasons, life in divorced or remarried families promotes
early maturation. In nondivorced families, only eighteen percent of
girls go into menarche at age eleven or younger, while that figure for
girls in divorced and remarried families hikes up to twenty-five and
thirty-five percent respectively.

And one thing is absolutely clear: A link exists between early maturing
and sexual activities. However, that link is influenced by
characteristics of the adolescent and the family and by relationships
outside the family.

Researchers Belsky and Ellis worried at first about having their work
seized upon by “intolerant politicians” out to prove that divorce and
cohabitation are biologically destructive, and that the
African-American community is affecting the health of its own girls
through “socially deviant” behavior. But the backlash has not happened.
Rather, this particular body of research has been more or less ignored.
“Ours is not a popular theory,” Belsky says. “It is treated like
biological determinism, and that gives it a bad name among some people.
They think we’re saying biology is destiny here.”

More readily accepted and repeated in the public arena, at least, are
the theories about triggers related to diet and environment. Many
researchers are questioning whether milk consumption is somehow related
to early maturity, either through the milk itself or the variety of
hormones conventionally raised dairy cattle are now exposed to. Cow’s
milk has a high fat content; high levels of biologically available
hormones such as estrogen, progesterone, and testosterone; artificially
added hormones and growth factors; and other chemical contaminants from
the medications, environmental trash, and recursive feeds they are
given. The evidence is compelling enough that Herman-Giddens, for one,
has said that her milk-drinking days are over.

Other scientists have been examining the potential risks of chemicals
that have become prevalent elsewhere in our environment. There’s some
disturbing evidence to suggest that certain plastics may be wreaking
havoc in all sorts of ways, causing not just early sexual maturation
but other problems, from reproductive cancers to infertility. Dr. John
P. Myers, director of the W. Alton Jones Foundation and co-author of
Our Stolen Future, has said that experiments have linked early puberty
in mice to exposure to bisphenol A—used in polycarbonate plastic, such
as food and drink containers—and phthalate esters which are found in
cosmetic and beauty products, especially hair and nail products. But
the American Plastics Council insists that those claims are unfounded,
and that polycarbonate has been rigorously tested by both government
and industry researchers for forty years. “Any association between
[premature sexual maturation] and exposure from consumer products made
of polycarbonate is unfounded,” said the Council. Likewise, the
American Chemistry Council refused to take any blame, stating, “There
is a considerable body of scientific research that indicates that
phthalate esters are not the cause of early puberty.”

While those debates rage on, there’s one more lonely little theory—the
least publicized of all but possibly the most intriguing, if only
because it is at once so enormous and yet so much within our
theoretical control. Some researchers propose that society itself is
triggering precocious sexual maturity in our youth through the power of
suggestion. They believe it’s worth a long, careful look to see whether
the increase in images of sex on television fosters sexual maturity, in
much the same way that images of food stimulate salivation. In other
words, by surrounding our youth in a culture of soft porn—and make no
mistake, children as young as eight comprehend the sexual innuendo and
jokes on TV and in movies—we are coaxing them to develop sexually at
younger ages. Further, once we’ve shown kids enough repeated images of
unbridled sexuality to at least stimulate the desire to imitate adult
sexual behaviors (if not trigger the physical process of puberty
itself), then we begin to aggressively sell them fashion and
accessories that help them to do so.

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