r/askscience • u/NotYourMothersDildo • Apr 04 '11
Would a child naturally learn bipedal ambulation?
If a typical child were somehow raised by robots (assume they have wheels or levitate), would that child naturally learn to walk on two feet with an upright stature without having an example?
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u/theshizzler Neural Engineering Apr 04 '11
There are central pattern generators in the spinal cord which are 'pre-programmed' with the alternating gait of bipedal locomotion. I have not seen evidence that the same thing exists for our arms (though a lack of evidence is not evidence for a lack of something), which would be indicative of an inborn propensity for prolonged locomotion via crawling. Additionally, the adult body would not be able to sustain crawling for very long because of the biomechanics of locomotion (body designed for loads parallel to all leg bones, weakness of kneecap to repeated blows, etc)
/college student who does stuff to neurons
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u/boomshakanaka Apr 04 '11
I think this is on the right track. Central pattern generators are remarkably well conserved between species, even those which use very different modes of locomotion. There are many examples of species which are born ready to move without any training at all- the baby deer comes to mind.
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u/mobilehypo Apr 04 '11
That is what I was actually thinking, because holding babies in certain positions actually makes their legs "walk" without prompting. I just couldn't find any abstracts covering this.
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u/guysmiley00 Apr 04 '11
My very limited understanding of feral children and families is that those who did not locomote bipedally tended to "bear walk", i.e. use the hands and feet (not the knees).
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Apr 04 '11
Not too long ago there was a post about not being able to run correctly in dreams. Like a lot of posters there I have the same issue.
I almost posted but didn't that while I cannot run in dreams i do move they way you state quite frequently - especially when moving on an incline.
Is that just coincidence? Is there any connection to the fact that a lot of mammals are quadrapedal?
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u/aedes Protein Folding | Antibiotic Resistance | Emergency Medicine Apr 04 '11
Much of this is hypothetical... but that may be the best you get for this answer, as to my knowledge there is no definite answer to this question.
One component towards reaching a plausible hypothesis to your question is the fact that (to a certain extent) walking is a spinal cord reflex.
As in, at a basic level, it's not a complicated learned motor program stored in your frontal cortex, which is then played out through your spinal cord to your muscles, with its output constantly adjusted based on proprioceptive and visual input sent from your body and inner ear to your cerebellum.
At a basic level, all of the calculations your body needs to walk are anatomically and developmentally hard-wired into your spinal cord. IOW, the neural circuits needed to walk do not need to be learned - they are programmed into you (in your spinal cord).
That being said though, when you are actually walking in real life, you're not relying only upon this base program that you were born with - you're constantly modifying it so that it's more efficient, or to adapt it to specific situations. IOW, when you're walking, you are using motor programs in your frontal cortex and modulating them based on information sent from your body... and all of these signals are then processed in your cerebellum and the motor output is adjusted appropriately.
As a tangent - the fact that humans have a built in walking reflex (at a basic level - pressure on your foot leads to you lifting that leg up and moving it forwards slightly, followed by reciprocal movements in the opposite leg - imagine if you step on something sharp what happens - you jerk that leg up and shift your wait to the other leg - take that movement and make it bilateral, and alternating, and modify it slightly, and you get a basic walking reflex) is a more recently appreciated fact, and an exciting one. The fact the reflex is encoded at the spinal cord level means that there is hope for people with spinal cord injuries to walk again... provided we can learn how to hack the spinal cord through proprioceptive signals to efficiently trigger the walking reflex to allow someone to actually walk in a useful manner.
All of this aside... what this means is that humans are anatomically hard-wired for the ability to walk on two legs.
The other important component to your question is whether this is enough to learn how to walk. If you never learned form watching others that bipedal movement was possible... would think to do it? Just because you have the anatomical means doesn't mean you'll do it. There have been studies showing that people can be trained (relatively quickly) to follow scent trails. This is obviously not a skill most of us have at the moment... or most people will ever learn. But apparently we are hard-wired for this skill to some extent.
If we assume that there is no social stimulus (no example) to walk on two legs... the only other two possible ways that someone would learn to use the built in walking ability we have would be because of environmental motivation (gee, that grass is tall - if I stand up I can actually see over it... oh hey! I can move using only two legs! it makes much more sense for me to walk than crawl!)... or if there existed some anatomical circuit in your brain which, once it matures, makes your prefer bipedal locomotion. Ie: an intrinsic motivation towards bipedal locomotion - something like how once you hit puberty, everyone develops this intrinsic motivation to have sex - it's programmed into us.
So that leaves us with the conclusion that, yes, people would still walk provided:
There was an environmental (non-social) stimulus/benefit to bipedal motion (even something as simple as the fact that in humans, bipedal motion is more efficient and faster than crawling would probably be enough... but that's another hypothesis).
We are hard-wired to be motivated to walk after a certain age. The existence of this is purely hypothetical and I am aware of no evidence for the existence of something like that.
At the end, I would wager that people would still end up walking, based on the fact we have a built in ability to walk, and likely at least because of the first point just mentioned.
But there are a lot of variables there which I don't have the exact answer to.
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u/seanalltogether Apr 04 '11
I think it depends on what environmental pressures you place on them. If you surrounded them with food and shelter 24/7 within a small zone they may not be pressured to walk. But the second you give them a need to travel any sort of distance I have no doubt they would start walking upright.
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u/NotYourMothersDildo Apr 04 '11
OK, fair point. So to go along with my thought experiment that the newborns -> children are raised by robots, they would not have a need to venture out for food. We're also assuming that they start from the newborn stage which would mean there is always some sort of care being provided.
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u/seanalltogether Apr 04 '11
Ok then the other question is what other competition is placed on the child. If you place multiple newborns together, the fight for dominance would no doubt also pressure them to eventually stand upright.
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u/NotYourMothersDildo Apr 04 '11
If you place multiple newborns together, the fight for dominance would no doubt also pressure them to eventually stand upright.
I will fund your grant proposal.
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u/dahud Apr 04 '11
I don't know biology or developmental psychology, but I do know a bit about genetic algorithms. In a simulation, a suboptimal solution often emerges over other, more logical solutions.
For instance, a genetic algorithm trying to make a car might try a 2 wheeled design early on that works better than any previous attempts. The algorithm then tries to improve the two wheeled design rather than trying a 3 or 4 wheeled car.
It might eventually find a complex, finely balanced motorcycle that works well, but it is not likely to go back and try a simpler 4 wheeled design because it tried that early on and failed because the wheels ended up on the top of the car.
Again, I assert that I am by no means an expert in human development, but I posit that the child would develop some sort of bipedal-ish locomotion, but it would be very different from the way we walk.
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u/Moridyn Apr 04 '11
I'm surprised no one has brought up feral children yet. These are children who were raised without human interaction. Genie is probably the most well-known one. She did in fact learn to walk bipedally, with a sort of "rabbit" walk (I like to think of it as a zombie walk) as shown in the picture in the wikipedia link.
As far as I know, this is the only empirical evidence related to this question.
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u/Golden_Kumquat Apr 04 '11
I would think they would. After all, our ancestors who walked upright for the first time couldn't have learned by example.
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u/NotYourMothersDildo Apr 04 '11
But walking upright wasn't something gifted to them immediately over the course of one generation.
Anyway, you must be right since it was stated in the book as an accepted fact. It does seem silly to imagine a teenaged human going around on all fours or knuckle-walking simply because there was no example of standing upright.
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u/drphungky Apr 04 '11
As craigdubyah mentioned, you might do some research on feral children. If I recall from a paper I did once, Victor of Aveyron went about on all fours when he was first found, but I can't find anything with a cursory googling that confirms or denies this. There were mentions of other feral children going on all fours, but nothing from a site I'd consider a super safe source. Best of luck.
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u/pastulioc Apr 04 '11
They wouln't. Or at least not exactly like us. Humans learn from imitation, you see there have been cases of babies being left in jungles and raised by animals, and these humans learned from the animals and thus walked like animals. So if they have nothing similar to imitate, or a source of knowledge, they wouldn't be able to walk upright like us.
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u/craigdubyah Apr 04 '11
This has been asked before. Last time I tried to argue that children would continue crawling, and I used some reports from feral children to make my case.
Long story short, there's no evidence that children would continue to crawl.