Hi Anna, I'm not sure where you're getting your information from, but this is incorrect, you may find the following study of interest:

https://www.southampton.ac.uk/news/2005/11/evolution-explains-age-of-puberty.page#:~:text=They%20found%20that%20Paleolithic%20girls,age%20of%20puberty%20in%20girls.

The text:

"They found that Paleolithic girls arrived at menarche - the first occurrence of menstruation - between seven and 13 years. This is a similar age to modern girls, which suggests that this is the evolutionarily determined age of puberty in girls."

The mistake normally comes from the fact that poverty and malnutrition, which was especially amplified due to the Industrial Revolution, led to stunted growth and delayed menstruation.

Basically, both men and women suffered from stunted growth as a result of malnutrition, which delayed puberty, though not by as much as you say. The 15 to 17 is linked to the first menstruation cycle in women. Menstruation became very late during periods of malnutrition, even later than puberty mainly because the girls couldn't build up enough fat to actually start menstruating.

So, it wasn't puberty per se, it was menstruation that was especially delayed.

But it's complex. The most famous example of stunted growth from malnutrition is Audrey Hepburn. Her small childlike body was the result of malnutrition in childhood, which stunted her growth, and led her to not start menstruating until 17.

Winston Churchill famously in the 1910s highlighted that the British Empire was a great risk due to how stunted the men and women were as a result of extreme poverty.

The interesting thing is, this extreme poverty was very much the result of the Industrial Revolution, not agriculture. Across the agricultural revolution, malnutrition has varied based on crop success. Prior to it, so in our preagricultural days, it's believed we had good malnutrition.

The interesting thing is, when it comes to maturity, as said in the article provided, our complex society is rather fascinatingly, leading us into a situation where we can't educate our children to become mature enough to be adult at the time they reach sexual maturity, which is the real mismatch the modern world is creating, our intellectual development, is behind our physical development, simply because our society is now so complex we don't have time to learn enough fast enough to keep them in sync, which is causing endless problems.

Anyhow, hope that all makes sense, thanks for the comment, Anna.