Harry doesn't know Re: Lifespans?

[potioncat]

No: HPFGUIDX 131598

"Chys Lattes" wrote:
> Ok so DD is like 150 right? (But Harry doesn't know this yet.) 

Potioncat:
This never gets discussed! Harry doesn't know how old DD or McG are. 
Not that most kids care, but he'd be surprised, wouldn't he? Even if he 
took the time to do the math, he could come up with 80 or so for DD. 
(Lot's of people did.) Would he possibly guess that McG is 70+?  

Most "normal" fans don't know how old DD is. There are hints that 
wizards live a very long life, but we're not actually told in the 
books "how" long they live. Ok, I know everyone of us knows, but we 
aren't normal. Why did JKR make a point of saying that Harry doesn't 
know this yet? I wonder how it's going to fit into the plot? It might 
be something that wouldn't catch us too off guard, but would surprise 
less knowing fans. Any ideas?

And another thought just crossed my mind; I wonder how many of the old 
Headmasters DD actually knew.