What's the life span of Wookies?
I mean Chewie is sort of old, but the new images of him, he looks the same age, younger if anything. Because in the prequel trilogy he was there fighting the trade alliance army when order 66 was issued* so therefore an adult, and also some sort of higher ranked officer, so not some raw recruit. And this new film is . . . 50 years later. is it?
* Sidenote: all of this is another of the major flaws in the prequel trilogy. So years later ( New Hope ) when ObiWan and Han are arguing the presence/power of the force and Chewie is right there in the room . . . why doesn't he mention his history fighting alongside a Jedi master. Maybe the war left him with PTSD and he isn't able to talk about it.