I don’t think it’s super straightforward. Another thing laymen know: Most younger people in southern Europe don’t look old.

I actually live in southern Europe and most of my friends who are >35 and have been out and about for most of their lives do indeed look much older than they are.

I think that’s because locals have some level of adaptation to their region. In Australia, you can really see how the high levels of sunshine affect the Northern Europe descendants who live there today. Some 30 yo women look easily 40.