I am curious as to whether or not the Doctor is generally supposed to age. Obviously the actors that play the character do, but is the actual character's appearance supposed to be frozen in time until the next regeneration? It seems clear that the Doctor (and Time Lords in general) age at some rate prior to their first regeneration. Thus the first doctor went from being a child born on Gallifrey to a relatively old man bouncing around the universe in the TARDIS. One wonders though if pre-regenration Time Lords experience a fairly normal (if somewhat extended) humanoid lifespan? The question then becomes do regenerated bodies age or are they meant to be relatively frozen. This becomes more noticeable with Eleven since his story seems to cover a relatively long period time without any noticeable ageing ( i.e. he goes from around 900 to 1200 with no change in appearance). One of the things I suggest to a friend was that you could justify the fact that the reason each of the regenerated Doctors seemed to get younger is that as a Time Lord approaches their 13th (and presumeably final) regeneration, the process extends life by giving more youth in the hopes of running out the clock. One might event suggest that the 13th regeneration would completely reset the Doctor's proverbial clock and he comes back as a baby in the hopes of having a long but relatively normal final lifespan. Thus a Time Lords life cycle would come full circle.
I don't think there is anything definitive, but, as you mentioned the actors do age. Troughton was noticably older in The Two Doctors, but, was that Troughton the actor or The Character The Doctor
The Seventh Doctor looked somewhat older in the '96 movie than he had at the end of the original series. I think that, barring accidents, a single Time Lord incarnation would age slowly but progressively over the course of maybe 400-500 years (since the Doctor was reputedly around 450 when he had his first regeneration), so a total TL life expectancy would typically be around 5200-6500 years, each incarnation growing to old age and then resetting to somewhere between young adulthood and middle age. The Doctor, however, is an exception to the rule because he leads such a dangerous life; thus his individual incarnations have comparatively short lifespans compared to a typical Time Lord ensconced in the hallowed, safe halls of Gallifrey. His first incarnation was the only one that "died" of old age; his other regenerations were all the result of violence or other factors (enforced punishment, radiation poisoning, a fall from a height, spectrox poisoning, a TARDIS crash, surgical error, unspecified war injuries (?), vortex energy overdose, and radiation poisoning again). So his incarnations don't show their age because they don't last long enough to do so. Although this notion is somewhat undermined by the fact that Eleven had a 200-year age jump in-story and didn't change in appearance at all.
Or I wonder if it's a conscious thing that a TL would do? Like 11 didn't age visibly because he didn't want to look older, perhaps that's why River was always so worried about him using regeneration energy, he was using it to keep himself younger looking. I mean 10 once used some of his energy to help restart the TARDIS in the parallel universe when they first met those new Cybermen. "I just took ten years off my life" What would be interesting through - is if the 13th regen was exactly that, he comes back as an infant and has to grow up all over again. And lives one final very very long life - providing he doesn't need to regenerate. Although then again that's really only 2 more Doctors so either they simply ignore the 13 regen's rule or they simply say that the 14th regen is a total reboot to the Doctor, maybe TL's lose a lot of their old memories. Perhaps his memories only go back to his time as the 2nd Doctor. His entire first 'life' is forgotten. 15th, only goes back to the 3rd, 16th only to the 4th and so on
The fourth Doctor was aged in 'The Leisure Hive', and the tenth in 'Last Of The Time Lords'. Admittedly, both occasions were the result of technology rather than natural ageing, but they do show the process occurs. I'd speculate that Time Lords have a certain degree of control over the ageing process. Free from distractions and harmful influences a Time Lord could slow, or perhaps even hold in check, natural ageing. But a busy, eventful life might allow it to proceed as it does for other species.
And the Fifth Doctor was aged by some kind of timey-wimey technobabble in "Time Crash." And of course Hartnell, Troughton, and Pertwee were all visibly older when they returned in "The Three...," "...Five...," and "...Two Doctors," but we were supposed to overlook that since they weren't supposed to be older in-story.
Well, the first Doctor presumably aged till he was the 70(by human standards)-ish man we first saw. Tom Baker visibly ages over the course of his time, partly because his seven year run was the only one long enough for it to be really noticeable, but also because he was ill for much of his final season and that showed. And as Christopher pointed out, the seventh Doctor was noticeably older in the TV movie than he was when we last saw him before that. (And if you accept the season 6b explanation, the 2nd Doctor aged visibly after The War Games). So yep, he ages. But incarnations don't usually last long enough for this to be noticeable, much as this complicates the already awkward issue of the Doctor's quoted ages!
Hartnell, in fact, was only 55 when the series began. He hadn't aged well. (Although the long white wig made him look older.)
In the Alternate Universe created in "The Wedding of River Song," Amy asked the Doctor that if time was standing still, why was he still aging? He said that time was still passing normally for him. So I'd say yes, he ages.
Didn't River decide to make herself look progressively younger just to mess with people after she regenerated in LKH? Obviously a joke for the audience because she was meant to be much older in her earliest appearance, but perhaps Time Lords have a certain amount of wiggle room inside of a regeneration. Or perhaps it's just the Time Ladies that have extra control, ala Romana and her "trying out" several different looks.
I suspect he ages, but it would appear to be at a far slower rate when compared with humans. He also lies about his age, or he has simply forgot how old he is.
Yes, I know, but he played older - at least until his health meant too much of it wasn't playing. And back in the 70s things like the Doctor Who Monster Book always described him as a septuagenarian, so that stuck!
There's also the bit where the Master prematurely aged Ten. That's why he looked like a little Gollum thing. While physical aging is possible, it doesn't seem to actually kill them. They just keep shriveling up or something.
River chose to age backwards. He probably can too. Fastforward, fastreverse or pause probably hurts quite a bit. But forwards or backwards at normal speed should be fine.
Well certainly the three modern doctors have got younger as they regenerated, but this hasn’t always been the case, in fact I think it goes younger/older/younger/younger/older/older/younger/older/younger/younger and if the 12th Doctor is older than Smith this will break the modern cycle.
Beyond just whether the Doctor ages, the larger question is, do Time Lords (and Ladies) in general age? If you look at the stories set on Gallifrey, you see plenty of older Time Lords. So, unless they regenerate into old bodies, they must age. It seems unlikely that they'd regenerate into older bodies because that defeats regeneration's purpose of extending their lives, as well as for comfort reasons alone! Also, I seem to remember one older Time Lord talking to another older Time Lord in Deadly Assassin (I think), about a regenerating into a younger body due to aging. Mr Awe
Here are the age differences between the last screen appearance of one Doctor and the first appearance of the next (going by airdate, not production date, so some may be a bit high): "The Tenth Planet": Hartnell: 58 / Troughton: 46 "The War Games"/"Spearhead from Space": Troughton: 49 / Pertwee: 50 "Planet of the Spiders": Pertwee: 54 / T. Baker: 40 "Logopolis": T. Baker: 47 / Davison: 29 "The Caves of Androzani": Davison: 32 / C. Baker: 40 "The Ultimate Foe"/"Time and the Rani": C. Baker: 43 / McCoy: 44 Doctor Who (movie): McCoy: 52 / McGann: 36 Doctor Who/"Rose": McGann: 36 / Eccleston: 41 "The Parting of the Ways": Eccleston: 41 / Tennant: 34 "The End of Time": Tennant: 38 / Smith: 27 So you're technically right about the sequence, Starkers, but McCoy is actually 2 1/2 months younger than Colin Baker; it's just that there was a gap of 10 months between Baker's last appearance and McCoy's first. If Baker had returned for his regeneration sequence, they would've both been 44. And Pertwee was only 8 1/2 months older than Troughton. So I'd say there were two cases where successive Doctors were approximately the same age. Not to mention that McGann is 4 years older than Eccleston in real life; it's just that there's a huge gap between their respective appearances. All in all, I'd say the only substantial upward jump in age was from the Fifth Doctor to the Sixth; all the others regenerations either made the Doctor younger (more than a decade younger in five cases) or kept him approximately the same age.
Well re Baker/McCoy I was right, from the perspective I was looking at it from, which is the age of each actor when they take the role, hence Baker was 40 and McCoy was 43/44 when they took the role on. I think that's the only corssover where it actually makes much of a different. So from my point of view even if they replace Smith with a 30 year old, he'll be an older Doctor because he will be older than Smith was when he started, even though he'd be younger than Smith will be when he leaves. If that makes sense
What I like to think is that the doctor isn't actually 1200 at all, he's actually relatively younger than what we thought, he just think time goes faster than it really does. So Matt Smiths 200 year break may have actually only been a few months. it just felt like 200 years to him, also the TARDIS maybe makes time feel distorted. I like to think the Doctors not even 200 yet.