Think Tank
January, 1976
Lady DaysIn 1840, Norwegian girls used to have their first menstrual period around the age of 17. Today, the average age is 13. For the past 130 years, the age of menarche has been dropping at the rate of four months per decade in the U.S. and in Europe.J. G. Vandenbergh at North Carolina's Department of Mental Health experimented with animals to see what was causing this. Beginning with variations in diet and environment, he found that 47.3 percent of the variation in age resulted from the pres...
