"At the same time as the age of puberty has dropped, the “age of consent” – at which people are allowed to have sex – has gone up. In the nineteenth century, children could often get married or have sex at anything between twelve and fourteen years of age. Nowadays, the average is sixteen. Many countries set the barrier even higher." James McCONNACHIE - Sex - The world's favorite pastime - Fully revealed, p. 339
Mary ROACH (2008) Bonk - The curious coupling of sex and science
James McCONNACHIE (2010) Sex - The world's favorite pastime - Fully revealed