I remember reading an article years ago about a village that put out an absurd amount of Olympic long distance runners. The article noted that the village was on a high plateau and far from other places. The extreme difference in height led to better lung capacity and the normalcy of having to travel by foot long distances just raised a bunch of people who conditioned their bodies from birth to be adept at long distance running. None of it resulted in any major changes in population physiology as it’s just training your body to deal with environmental conditions after birth and doesn’t cause the mutations in the genome that would mark evolutionary changes.
I mean, obviously there are some physical differences between races. They look different, some have more prevalence of certain diseases or conditions, but races are entirely a social construct. Scaled out, the differences in races aren’t more severe than the differences in variability in smaller groups within a race, or even a family. It’s like, yeah, uncle Steve’s side of the family all have kinda pointy ears because he passed that on to his kids but his brother didn’t pass that gene on but they’re still family. Zoom out and view all humans not as different races but one giant group and uncle Steve’s branch all just have darker skin or straighter hair, but they’re still clearly part of the human family.
While it is suggesting it was common at the time, it doesn’t outright state they’re talking about that time. At earlier points in history it certainly was acceptable, but we probably don’t have pictures of it to go in textbooks. This reeks of them having a general point to make and having a picture that almost fits that point. I’ve made more tenuous connections for college papers before.
Also, while it’s not as drastic, I was doing some looking into family history recently and I found some ancestors who got married around that time. The marriage certificate listed the wife as 17 and the husband as 21… but the math didn’t add up when I found their birth certificates and on the marriage certificate she was aged up from 15 and he was aged down from 22. It was in a small farming community and at that point in time and place schooling was largely abandoned during harvest and as soon as kids were old enough to help out on the farm full time they would just stop with school. And for women, helping out on the farm meant taking care of the house and raising kids generally. Time at school was a waste for them so they just got right to the adult stuff immediately.