Mixed up things especially about the body and the insides
Over the second half of the 20th century, the average age for girls to begin breast development has dropped by a year or more in the industrialized world. And the age of first menstruation, generally around 12, has advanced by a matter of months. Hispanic and black girls may be experiencing an age shift much more pronounced. […]
“If you basically say that the onset of puberty has a bell-shaped distribution, it seems to many of us the whole curve is shifting to the left,” says Paul Kaplowitz, chief of the division of endocrinology and diabetes at Children’s National Medical Center in Washington, D.C. More girls, he says, are starting puberty before age 8, putting them at “the lower end of the new normal range.”
Researchers are now turning their attention to what could be driving the trend. Many scientists suspect that younger puberty is a consequence of an epidemic of childhood obesity, citing studies that find development closely tied to the accumulation of body fat. But there are other possibilities, including the presence of environmental chemicals that can mimic the biological properties of estrogen, and psychological and social stressors that might alter the hormonal makeup of a young body.
