Samples and summary of faculty scholarly activities - St. John Fisher ...

Moffitt, Caspi, Belsky, & Silva, 1992); popular media speculates that the sexualization of young
girls may play a role (Irvine, 2006; Levin, 2005). Recently, an oft cited cause is a gradual
increase in children’s average Body Mass Index (BMI) and the related issue of childhood
obesity.
There is evidence suggesting that a fat-protein called leptin may be the underlying link
between the weight and puberty trend association. Kaplowitz (2006) explains that leptin levels
typically rise in girls, but not boys, at the time of puberty and states “we can speculate that
overweight girls with higher leptin levels are more likely to enter puberty and reach menarche at
an earlier age. Such a connection between leptin and normal reproductive functioning makes
evolutionary sense, in that it ensures that pregnancy will not occur unless there are adequate fat
stores to sustain the viability of the fetus” (p. 490). However, Wang, Needham, and Barr (2005)
caution that “the signaling pathway for leptin in the development of puberty is not known, and
further work is necessary to define this mechanism and the difference in leptin levels among
racial/ethnicity groups” (p. 1101). Wang, Needham, and Barr (2005) identify nutritional status;
genetic predisposition, including race/ethnicity; and environmental chemical exposure as
associated with age of puberty onset.
It should be noted that careful examination of puberty onset trends suggests that the “trend
toward earlier onset of puberty in U.S. girls over the past 50 years is not as strong as some
reports suggested” (Kaplowitz, 2006, p. 487). Indeed, within the United States, research suggests
that there is evidence supporting this trend, but only to a certain point. Specifically, the average
age of menarche decreased from approximately 14.8 years in 1877 to about 12.8 years in the mid
1960s (Kaplowitz, 2006). Most researchers have concluded that the general trend observed
during this broad historical time period is due to health and nutrition improvement within the