Tan&Nerdy wrote: I agree that how long the characters have been around isn't neccesarily how old they are depicted as. In the current animated series, the Chipmunks and Chipettes are between the ages of 7-12 chronologically speaking (we're not sure exactly where they fall in the range [In Family Spirit, it is mentioned that Dave met the Chipmunks seven years previously, although we don't know how old they were when that meeting happened] [In Monster Madness, Alvin mentions that even though he is chronologically under the age of 13, he has the physical maturity of someone older or equivlent than that]).
To answer your question about how old The Chipmunks were 7 years before Family Spirit when they met Dave, storyboards for the episode Slippin’ Through My Fingers show that in Dave’s dream sequence, they were supposed to be babies (presumably this idea was scrapped during animation to save on the time and money it would take to design and render new CGI models for them). However, it’s unclear if it was implying that Dave met them when they were that young or if it was just Dave’s imagination.
I would also like to point out that the characters are a fictional species of chipmunk. So they don’t have to have short lifespans like real ones do.