In fact it is never mentioned in the books how old Dumbledore really was. JKR mentioned his age (150) and McGonagall's age (70) in a chat.

Nevertheless numbers and dates are not her best subject. A great example is her scetch of the Black's Tapestry: Pollux Black, Sirius' grandfather, fathered his daughter, Sirius' mother, at age 12

And no one on the tapestry, and only few of her "wizards of the month" have reached an age of 100 or above. Mungo Bonham was 98 or 99, Yardley Platt 111, Idris Oakby 113, and Grogan Stump 114 years old.

So nobody of a really astonishing old age. While during the Middle Ages most wizards seemed to live longer than the usual Muggle of that age, no wizard mentioned reached the age of Dumbledore or Marchbanks - at least not without a Philosopher's Stone (Flamel).

So despite that Dumbledore and Marchbanks ages might be considered canon, and even though wizards and witches can become that old, it seems to be quite unusual.

 

But you got to remember that the magical world had been through 2 wars within a century (I Think).

 

Not the British magical world- Grindelwald's campaign was mainly in Central and Eastern Europe, according to Wikipedia. I'd have checked the Lexicon, but it isn't loading for me for some reason.

 

Well, WWII affected Britain pretty much, so wizards and witches might have suffered then, too. It could be a reason, but it still is astonishing that over several centuries only few wizards reached an age of more than 100 years.

Concerning fanfiction it is easier to ignore the age given by JKR and just label Dumbledore and Marchbanks as 'very old'.

 

Really, I always thought that Ginny should be played by a ginger.

 

http://fc01.devianta******/fs17/f/2007/222/1/d/Dumbletard_by_Omnywrench.jpg

 

Maybe age in Wizards is related to their magical power?

As for Epilogue casting... I can easily imagine David Tennant as a middle-aged Harry Potter. If he does it, I hope he plays it with the eccentricity of the Doctor. Might explain why he ended up with Ginny.

In all seriousness, they'll probably just cut the Epilogue from the film. It might be a bit hard to explain on film why "this person ended up with this person" and why Harry named his son Albus Severus. I don't care how big a fan of Rowling the filmmakers are, that moment probably had them going "wtf?".