Although the study was conducted in Denmark, experts believe that it applies to other parts of the First World, including Europe and the United States. This earlier age of maturation is even more striking when compared with the 19th century, when girls reached puberty at an average age of 15, and boys reached it at 17. Since then, the age of puberty has moved back steadily, until age 14 for boys and age 12 for girls were formally declared "normal" in the 1960s. These numbers were based on the average age of first period for girls and of voices breaking for boys.
It's not just scientific studies suggesting these figures are now obsolete; anecdotal reports of boys dropping out of choir schools when their voices break at age 12 or 13 are now widespread. According to Richard Stanhope, an expert in childhood hormonal disorders, specialists are now convinced that early puberty is a real phenomenon.
Early puberty can be hard on children who are mature physically but still young emotionally, experts warn.
"All the things we experience as teenagers are difficult enough to cope with, but when it happens at 10 or 11 it is much worse," Stanhope said. "These children are also at a much higher risk of being sexually abused, because it is hard for some adults to understand and behave appropriately towards them."
