/jp/ - Otaku Culture

>>9296446
There are numerous studies out there showing it. Obviously, I doubt there is any reliable data for roman times because I don't think they were recording the average age of menarche back then. Here is a page that mentions it http://www.encyclopedia.com/topic/Menarche.aspx with a quote "Interestingly, this number has not been consistent throughout history. It appears that menstrual age has been decreasing from between fifteen and sixteen in the last half of the eighteenth century, to twelve to thirteen in the present day, at a rate of three months per decade (Tanner 1962)."

Also in Japan, as recently as the 1920's the average age was 15 http://www.ncbi.nlm.nih.gov/pubmed/7327541 with it now being as low as 12 something.

I'm sure there are more resources out there if you google average age of menarche or something.