In fiction, beings that can change shape can do so extremely rapidly and are immediately able to function in their new shape. While there is some precedent for the latter in nature (butterflies can fly more or less on emergence from their cocoon, and most ungulates can run within hours of birth), these critters are "hard-wired" for such feats.

On the other end, humans take months to years to learn to walk in childhood, or when recovering from major injury or very long periods of inactivity. (The scene from Kill Bill where manages to go from virtual immobility after months of being in a coma to driving a truck in the span of perhaps an hour is, at least in my experience, considered extremely unrealistic.)

Let's say we have a creature which has the ability to alter its form significantly. Body proportions and distribution of mass are considerably altered, perhaps even mass is significantly altered, such that the creature's balance and coordination is significantly different. How long, realistically, would it take the creature to learn to move again?


  • Although a lot has changed, the creature's nervous system remains its own (unlike in this question); senses are mostly unaffected and nerves still control the same muscles. The creature is clumsy but not totally incapable of movement; it still has good control of what muscles move, they just tend to move too much or too little, and/or it needs to move in a way it isn't used to moving.
  • The transformation takes about a month, but the creature is mostly sessile during this time. It has some very limited opportunity to move its limbs, but little or no opportunity to move around. (At least it doesn't need to re-learn how to breathe... that would end badly!) The transformation isn't necessarily permanent, but it's going to be keeping the new form for a while (months, at least; given it essentially "loses a month" every time it changes, it's not going to be doing this all the time!).
  • The creature can't simply rewire itself to know how to move immediately. It doesn't have that ability, and didn't have that ability as an infant; it had to learn to walk the first time much like a human does. However, after the transformation, it does have the neurological malleability of a very young child.
  • The creature was bipedal and wants to be bipedal again. The new form is reasonably suitable (about as much as, say, a two-year-old human) for bipedal locomotion.
  • For the most part, the creature is moving around about as much as an average human toddler (it is a toddler after all, at least in the literal sense!) that will naturally help it improve, but isn't specifically focused on doing so. However, it is also engaging in 1-2 hours of daily targeted exercises designed to improve balance and coordination.

Now, it probably goes without saying that this will be a long process and "success" is fuzzy. So for the sake of being able to give a reasonable answer, let's say that I am specifically interested in how long until the creature can walk (bipedally!) with only occasional falls. Let's also say I'm specifically interested in the first time it tries to master a(ny) new form; as Willk rightly observes, the situation might improve dramatically with practice.

(Note: I've tried looking for information on humans learning to walk, but while it's trivial to find information on when we start walking, it's much harder to find information on milestones once they start. The only source I managed to find was a youtube video that gives six months from first steps to running. Is this reasonably accurate? Is this even a reasonable model for the situation of my creature? Would it be plausible for my creature to get to the "usually doesn't fall over" stage quicker; say, in a month? Running can take longer; I just want walking without falling over.)

  • $\begingroup$ It is a difficult question to answer without knowing the ending shape and the development phase of the end shape. A child learns incredibly quickly but with a lot of faults, as it is highly malleable and makes a lot of connections to other neurons, discarting them just as quickly if unused. Older creatures tend to have less malleable nervous systems. This will also help with estimating the flexibility of the neurons for reconnecting and understanding the new body (proprioception, motor control, etc.) $\endgroup$
    – Trioxidane
    Commented Sep 19, 2020 at 15:09
  • $\begingroup$ Also: why isn't the nervous system altering during the change? If you're doing an overhaul, why not this too? Limbic system and temporal lobe can be left alone while much of the cerebellum, occipital/temporal/parietal lobe, motor/sensory cortex are overhauled. You might not get instant results, but like a horse standing quickly albeit unsteadily is a good bet $\endgroup$
    – Trioxidane
    Commented Sep 19, 2020 at 15:16
  • $\begingroup$ @Trioxidane, will edit to clarify some of your points. Note that I didn't say the nervous system didn't change (but mind the edit), I said the creature still has its own nervous system; it isn't starting totally from scratch trying to learn to control its body as would be the case in the referenced question. It's just dealing with its balance being off and needing to move differently due to changed proportions. $\endgroup$
    – Matthew
    Commented Sep 19, 2020 at 17:56
  • $\begingroup$ Is shapeshifting permanent or temporary? $\endgroup$
    – Otkin
    Commented Sep 19, 2020 at 18:06
  • $\begingroup$ @Otkin, edited to clarify. Not necessarily permanent, but the creature isn't going to be changing again any time soon. $\endgroup$
    – Matthew
    Commented Sep 19, 2020 at 18:40

5 Answers 5


Three to four years for full recovery

The nervous system is complex with a lot of unknowns. Humans, despite the relative long timebin the womb, come out more "unfinished" than most animals. Walking, growing, sexual maturity and more are all taking a very long time. It is difficult to say we're learning them, as they are still growing in the brain and for walking for example the body simply isn't ready to support itself for quite some time.

The best way might be looking at people who've been there. Astronauts. They feel wobbly at first, but are able to do quite a few things in a one week, possibly two depending on the training and person. Full recovery can take up to four years. This is because balance and walking have been rewired for use in space.

Your shape shifters seem to have mostly just different proportions. This is advantageous, as they'll need to mostly relearn proprioception and the power that goes with it. I would think a month for seemingly normal behaviour is likely. If the dissociation is bigger

If the proportions get more complex, like the feet orientate more like wolf paws, it'll take more training than astronauts. The area's of the brain need to completely rewire, as the most used/complex nerves are different from the old. This goes further than just relearning to walk from an astronaut, but still I would say it's in the same ball park. Quite a lot of nerves change tasks during a lifetime and in three to four years of training it's quite likely it happens.

  • $\begingroup$ Wow! I totally hadn't thought about astronauts, but that's a great analogy; the circumstances are probably the most similar to mine as we're likely to see in real life. Slightly backward because it's the environment that changed rather than their bodies, but it's totally plausible that the converse (same environment, different body) would have similar results. In both cases, you're used to moving differently and have to relearn. BTW, "If the dissociation is bigger"...? I think you forgot to finish that sentence? (Been there, done that 😉.) $\endgroup$
    – Matthew
    Commented Sep 19, 2020 at 19:43
  • $\begingroup$ This also reminds me of astronauts telling stories about how their reflexes are different, e.g. releasing an object in midair expecting it to float. Now that you make me think about it, I bet my critter would have similar difficulties. (I wonder if I can think of a way to incorporate that...) $\endgroup$
    – Matthew
    Commented Sep 19, 2020 at 19:46

3 weeks.

I had the misfortune of recently having a condition known as "Bells Palsy". Its when nerves on half of your face seize up and you loose control of many of your facial muscles. I looked like a stroke victim.

I had a week with a totally paralysed half face (couldn't even shut my left eye to sleep), about 3 days of mad twitching as the nerves started to recover. And then about 3 weeks where the muscles worked individually and would respond if I focused on them, but I couldn't use them right anymore.

3 weeks of slurred speech, biting my lips when eating, spilling liquid while drinking, winking at inappropriate times, lopsided smiling, kissing partner feeling wrong, cutting myself while shaving cause I couldn't keep the skin taught, and crying from one eye cause I'd stared at a computer for hours and forgotten to blink that one.

After 3 weeks of being not in control of my functional face, I got it back. It was gradual and I didn't really notice I was improving at the time, I could only see the improvement in hindsight (oh yeah I haven't droolled toothpaste for a few days now. Nice!)

Your shapeshifter will go through a similar process. They have the nerve connections, they can make any individual muscle work by focusing on it, and they know the process and sequence they need to do to accomplish a task. I estimate itll take them about 3 weeks of messing up before they can pass for normal again.

  • 3
    $\begingroup$ That sounds terrifying. Hope it'll be ok. That being said, the cause is unknown. It might be that everything is still in tact, but a viral infection is just shutting things down temporarily. Regaining control isn't the same as (re)learning control of a whole body. $\endgroup$
    – Trioxidane
    Commented Sep 19, 2020 at 18:15
  • $\begingroup$ I knew a guy who had Bell's Palsy once. Recovery took a little longer in his case, but then again he (a) had a brain injury, and (b) wasn't compliant with the whole "no sugar" thing. $\endgroup$ Commented Sep 19, 2020 at 21:22

Without knowing the creature's biology it is not possible to give the exact time period needed to start walking. As the OP noted, different species learn movement skills at different paces, with some of them having them at least partially encoded in their genomes. So, in order to make accurate predictions, we need to know much more about the creature in question. However, we can try to establish the timeline in relative terms.

It takes about 3 to 6 months for humans to relearn how to walk if they recover from broken legs or other traumas that do not include brain injuries. Brain damage may make full recovery impossible. Full mastery of locomotive skills takes longer, up to 2 years if there was damage to bones and connective tissues.

Children need 9 to 18 months to learn how to walk. A lot of this time is spent on growing and training muscles necessary for upright walking.

If your creature shifts into a 'ready-to-walk' form with fully formed muscles and nervous system and it resembles humans in its biology it should take it about ⅓ of the time that was necessary to learn to walk the very first time. That is if the new form is not too different from the original one. The bigger the differences between the original and the new form the longer it will take to learn to walk, but it still should be faster than the very first time, because at least some of the pathways associated with muscle coordination should be preserved during the transformation.

If transformation always results in a perfectly healthy body with fully formed muscles and the creature is capable of retaining neural pathways related to locomotion the relearning time should decrease for all possible forms, not just the ones the creature already transformed into. If the creature suffers muscle atrophy during the transformation period the ⅓ of the original time to learn to walk might be the permanent lowest limit for the duration of relearning.


Very rapidly. Because of practice.

Your shapeshifters have a limited number of shapes that they use. They are shapes which they have practiced before. Like a martial art or riding a bike, they use learned muscle memory to quickly take on the movements of the new form. These shapeshifters dedicate 3 months every few years to taking on a shape and living in it. This is initially done in protected circumstances and under the tutelage of older shifters, then later in life during time set aside from the world to practice.

Often a shifter will have a favored shape that is comfortable (and often one favored by their master or school of thought) and then one or two special purpose shapes that they have not practiced as much. As with martial arts, shapeshifters who are familiar with their discipline can identify other shifters and their styles by their shapes and how they use them.

There are occasionally shapeshifters who are "flowers that grew in the dark". They have a self-taught style which is unpredictable to mainstream shifters. Some of these self-taught shifters have spent most of their lives in a nonhuman form, and then it is the human form which is cumbersome and unfamiliar. Some such shifters might not have been human in the first place.

  • $\begingroup$ Sorry, should have clarified; this is the first time the critter does it... but +1 because your answer is correct and you did mention practice time. $\endgroup$
    – Matthew
    Commented Sep 19, 2020 at 18:28

I'm going to post this as an answer rather than a post-mortem, as it's going to be on the lengthy side. Thank you everyone that answered! I consider all of the answers useful, and most were helpful. (Willk's is the exception because it operates on an incorrect assumption, which was totally my fault. As I already noted, however, it's still a correct and useful answer, just not applicable to my very specific situation.)

I've accepted this answer because it explores a real life scenario with I think is most closely parallel to my fictional situation, and thus clearly meets the "most helpful" criteria for acceptance. Again, it isn't my intent to take away from any of the existing answers, but only to give a more detailed summary of where I ended up in case it's useful to anyone.

I try to ask questions in a way that is more general, in order to attract answers that are more general, and thus more likely to be useful outside of the extremely specific situation that actually pertains to a particular story. (This is why I still value Willk's answer.) That said, for the very specific case that actually pertains to my story, and that apply to this answer, I can additionally state that:

  • This is the first time the creature has changed forms. This means it doesn't have the benefit of any prior practice.
  • The transformation involves alteration of total mass and of mass distribution, but not a radical change in style of locomotion. We're talking about something like the difference between an infant and an adult, or a chihuahua and a mastiff, not the difference between a horse and a human (or, even worse, a cat and a sparrow).
  • The transformation process is able to subvert muscular atrophy from disuse; it isn't having to build muscle mass on top of rewiring its reflexes.

As far as "learning to walk" and my target level of locomotion, we have on the one hand humans, which would need 2-3 years from birth, while ruminants on the other hand can, if we ignore bipedalism, manage in hours. Bipedal locomotion is harder, but also our creature has done it before, so we can probably consider that a wash. We can probably also cut down on the human time because the critter isn't also having to deal with a lack of muscular and skeletal strength. (For the same reason, while we shouldn't ignore Otkin's answer, we can probably similarly cut down on the 3-6 month time a bit; a human in the sort of situation Otkin cites is also dealing with atrophy.) Thus, Ash and Trioxidane are probably on the right track.

Accordingly, 3-5 weeks for "mostly competent" functionality seems plausible. However, it also seems reasonable that it will take years before the creature is completely competent in the new form to the extent that there are no remaining observable effects from the change.


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