This was an interesting read; I was shocked to find so many seemed to enter straight into PhD programmes after completing school. Most were done by the time they were 25. Wow!
I don't think that was unusual at the time? Mean age of finishing a PhD has gone up over the decades, though I can't give a figure from memory, and there may be a U.S./Europe difference too.
Getting a PhD young is mostly the luck of a birthdate and a benevolent advisor (and probably a non-experimental topic). Isn’t the uk system 3-year which makes it more likely. The trick is the pertinence of the work that’s done and who you impress.
