Puberty starts a year earlier for girls now than in the 1970s

UPI:

Girls are entering puberty about a year earlier than they did back in the 1970s, according to global data on breast development.

The age of breast development — which represents the first clinical sign of female puberty — has declined an average three months per decade between 1977 and 2013, according to analysis of data combined from 30 different studies.