>>76524499
>Girls are getting their periods and displaying signs of puberty earlier.
https://pubmed.ncbi.nlm.nih.gov/9093289/
>1997
>The mean ages of onset of breast development for African-American and white girls were 8.87 years (SD, 1.93) and 9.96 years (SD, 1.82), respectively; and for pubic hair development, 8.78 years (SD, 2.00) and 10.51 years (SD, 1.67), respectively. Menses occurred at 12.16 years (SD, 1.21) in African-American girls and 12.88 years (SD, 1.20) of age in white girls.

https://research.reading.ac.uk/research-blog/2020/07/13/children-arent-starting-puberty-younger-medieval-skeletons-reveal/
>In England, just before the industrial revolution, historical sources suggest menarche occurred between 12-14 years. By the 1840s, girls had their first period between 14-17 years. While we have a rich record for ages of menarche, there are no written sources to tell us when children in the past first entered puberty.

>bones of 994 medieval adolescents from medieval England
>The average age at which children entered puberty was the same as for most boys and girls today: between ten to 12 years. But medieval teenagers took longer to reach the later milestones, including menarche.
>The adolescent growth spurt that signals the most obvious external physical changes occurred between 11-16 years, and menarche at 12-16 years, with the average age at 15 years. In medieval London, some girls were as old as 17 before they had a period
>For these teenagers, growing up in a rapidly expanding and overcrowded London, 26% had not completed puberty before they died at 25 years of age

>While data is more limited, evidence from Roman Britain and medieval Spain show the same age for the onset of puberty at ten to 12 years.

Seems like cleaner enviorment and more food decrease the chance of delayed puberty development milestones. Now micro plastics and other shit in the year of our lord 2025 might make it 1 year earlier however.