In series 6, during The Impossible Astronaut, the age difference between the two Doctors we see (the Tesselecta and the Envelope #1 Doctor) is said to be 200 years old. In the Time of The Doctor, when the TARDIS returns, the Doctor says that it has been 300 years. My question is, during The Impossible Astronaut, he hasn't aged a day in 200 years between 2 versions of himself. And yet, here, in 300 years, he is suddenly all old and wrinkled. So how come he ages so quickly in Time of The Doctor and not in The Impossible Astronaut?

Is this a discrepancy, or is there some aspect of Time Lord ageing process that I'm unaware of?

  • 1
    Rule one: The Doctor lies
    – AncientSwordRage
    Commented Jan 18, 2014 at 10:36
  • Not relying on the Doctor's statements here.... More so on the actual timeline...
    – Stark07
    Commented Jan 18, 2014 at 16:16

7 Answers 7


We don't know, but we can make educated guesses.

We've seen one other Time Lord hit the end of his regeneration cycle: The Master, in Old Who. When he reached the end of his last body, the Master fell apart. Almost literally:

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So when the Doctor reaches the tail end of his last lifespan and appears to suddenly age rapidly, there is precedent for it being just because he's finally actually reaching the end of his life: after aging 200 years in Impossible Astronaut, he then added another 300+ years on top of that.

  • 7
    Other, less founded theories might involve the idea that being near the TARDIS let him age more gracefully; or that some property of Trenzalore made him age more visibly; or that his visible aging is the result of some subtle long-term attack by the Daleks. The possibilities are endless and speculation won't turn up any solid answers.
    – BESW
    Commented Dec 30, 2013 at 5:22
  • 2
    Yes, I too felt that the TARDIS might be a part of this. He was stranded without his TARDIS for 300 years. The end of life cycle also makes sense. Maybe it's because it was his last body.
    – Stark07
    Commented Dec 30, 2013 at 5:26
  • Has it been explicitly established that the Doctor's regenerations are more traumatic when he's not inside his TARDIS? This would support the "no TARDIS = faster aging" theory. Commented Jan 17, 2014 at 15:23
  • @blazemonger that's a solid question right there.
    – AncientSwordRage
    Commented Jan 18, 2014 at 10:37

Time Lords age more slowly than humans. The Doctor is not aging faster as soon as he gets to Trenzalore. He is just aging. As you said, 200 years doesn't show a wrinkle on him. But age is cumulative. He doesn't just start form zero every time that he counts his age. By "The Time of the Doctor", the eleventh incarnation is approximately 300 years old. The time that he initially spent at Christmas added another 300 years onto his age. So by that point, the eleventh incarnation would be 600 years old and finally showing age. And the time on Trenzalore after that only added more years in a very strenuous situation.

  • Yeah, that is true. Just wondering about the typical lifespan of a regeneration.
    – Stark07
    Commented Dec 30, 2013 at 5:58

Note that we have seen one other aged Doctor, of course: the First. We only seem him old, in fact. Since that is definitely his first incarnation, we can assume that he aged normally (for a Time Lord) up to that point. Going by the other times the Doctor refers to his age, we can assume that he was about 230 years old when he first started travelling with the Tardis. This is quite a bit less than the (roughly) 600 years that Eleven was before he started showing age, though. We can perhaps speculate that, if left to age normally, each incarnation would last longer before needing to regenerate.


His regeneration energy could keep his current incarnation young but being at the end of his cycle he doesn't have the energy to sustain youth without killing himself. In the episode in which Tennant regenerated he used his excess regeneration energy to do many things i.e. grow back a hand (which also by R.E. grew into a meta-crisis), the master aged him rapidly but with the help of every human's thought he partially regenerated to regain youth; matt smith after getting a new cycle became young again even though he fully regenerates into peter later in the special. Also in Angels take Manhattan he "wasted" R.E. to heal River song's wrist which could have kept his youth. It is my guess but in the whoinverse there are many examples that support my hypothesis


He didn't age faster than normal, it's just that the Doctor most likely spent over a thousand years in his 11th (13th) incarnation and unsurprisingly became elderly, decrepit and weak.

  • @LJRob, what makes you say he spent over 1000 years in that incarnation, I might have missed something?
    – Mac Cooper
    Commented Apr 16, 2014 at 9:13
  • Well, think about it. The Doctor spent a few centuries travelling on his own after losing Amy and Rory, then add that to how long he spent on Trenzalore (900 years altogether), then he spent easily over a millennia (thousand years) in his 11th/13th form
    – L.J Rob
    Commented Dec 16, 2014 at 19:09
  • oh was 900 years mentioned in the episode? Haha, I thought you were just randomly guessing, my bad :D
    – Mac Cooper
    Commented Dec 16, 2014 at 19:58
  • Yep, it's confirmed he spent 900 years on Trenzalore, because there's a novel called Tales of Trenzalore. It's very much considered part of the storyline. Soz for my late reply, I got suspended :(
    – L.J Rob
    Commented Jan 30, 2015 at 16:23
  • For onscreen evidence, in "The Day of the Doctor" the eleventh Doctor said his age was "twelve hundred and something, I think", while in "Deep Breath", the first episode with the just-regenerated twelfth Doctor, he said "I've lived for over two thousand years".
    – Hypnosifl
    Commented Aug 2, 2021 at 17:38

I always figured it was because Time Lords don't age in the same pattern humans do. So suppose a hypothetical Time Lord regenerates into an infant. He then grows and goes through puberty, then he reaches maturity and the aging process slows down, so he appears 30 at the age of 120 (since the regeneration,) then about 35 at the true age of 500.

Then, when the Time Lord reaches a certain point, it speeds up because he's reached the end of his life.


This isn't hard to reconcile.

Between the age of 20 and 35 you won't seem to change much; but then just wait until you progress between 45 and 60. Oh, boy, just wait!

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