When I showed
axa the Crack Van overview of Doctor Who history, she said, "Wow, the Doctor is so much younger now!" Which was exactly what I was thinking myself. But then I started wondering - how much younger is he really? So I went to imdb, checked the actors' birth years (though not dates, so I might be off with some months), and came to the conclusion that Eccleston is not unusually young for the Doctor, though Tennant is (only Davison was younger when he landed the part).
The breakdown, for those of you who are interested:
Doctor #1 (William Hartnell): 55-58 years old.
Doctor #2 (Patrick Troughton): 46-49 years old.
Doctor #3 (John Pertwee): 51-55 years old.
Doctor #4 (Tom Baker): 40-47 years old.
Doctor #5 (Peter Davison): 30-33 years old.
Doctor #6 (Colin Baker): 41-43 years old.
Doctor #7 (Sylvester McCoy): 44-46 years old.
Doctor #8 (Paul McGann): 37 years old.
Doctor #9 (Christopher Eccleston): 41 years old.
Doctor #10 (David Tennant): 34-35 years old.
The only doctors who were ever older than 50 were Hartnell and Pertwee. Tom Baker was younger than Chris Eccleston when he got the part (though admittedly he stayed on for a while).
So the Doctor didn't get much younger. He just got prettier and better dressed. :-)