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Why do humans swing their arms while walking?

by Yashbhatt
Tags: arms, humans, swing, walking
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Simon Bridge
#19
May16-14, 11:48 PM
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But there needs to be some stimulus to cause it. If there were no external factors affecting it, then all the random kind of mutations would have survived instead of a few.
Sure there is a feedback mechanism - but there does not need to be a single outside stimulus.
Anyway - a wide variety of different gaits, for two-legged motion, is exactly what you do see in Nature.
Even within humans, different people walk differently - just sit by a busy street and watch.

People's arms swing for a variety of reasons - they all boil down to getting simians to have an upright stance, so the question changes into "what are the evolutionary pressures favoring an upright stance?" Always remembering that an upright stance is unusual - so we don't expect it to be an optimal solution.
Yashbhatt
#20
May17-14, 12:05 AM
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I think an upright stance was needed for hunting. We needed to hold weapons in our hand.

Or was it the other way round? We started walking upright and then we invented weapons because we had our hands free.
Chronos
#21
May17-14, 01:05 AM
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With arms swinging in cadence with legs you are bettered prepared to avoid a head injury when you fall.
Simon Bridge
#22
May17-14, 01:07 AM
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I think an upright stance was needed for hunting. We needed to hold weapons in our hand.
You mean it was needed for tool use, weapons being among the tools to be used. There are many animals which hunt but which do not have an upright stance... they seem to manage.

But we do not advance personal theories here - do you have references to back up this opinion? ;)

Maybe humans started out as scavengers and gatherers so reaching is useful - then you need to be able to run away with your booty ... see what I mean. You get a choice of possibilities - probably all of them have a part.

Please see:
http://humanorigins.si.edu/human-cha...istics/walking
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819487/
http://www.thenakedscientists.com/fo...p?topic=4623.0
Simon Bridge
#23
May17-14, 01:10 AM
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Quote Quote by Chronos View Post
With arms swinging in cadence with legs you are bettered prepared to avoid a head injury when you fall.
Interesting - do you have a reference for that?

But that would put a feedback mechanism in place with the big head wouldn't it?
Chronos
#24
May17-14, 01:35 AM
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Here is one http://phys.org/news168027773.html. It does not entirely affirm my point, but, provides a reasonable explanation. Brain protection is a side benefit.
OCR
#25
May17-14, 02:26 AM
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If you continue to the page bottom, to "See also" you can read a bit more information about "walking with two legs"...

http://en.wikipedia.org/wiki/Bipedalism

However, this Cheetah uses four... "structures?"

https://www.youtube.com/watch?v=YqpO58x7vuE
Yashbhatt
#26
May17-14, 03:32 AM
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@Simon No, just casual thinking. I forgot that is against the site rules.
Simon Bridge
#27
May17-14, 04:20 AM
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Quote Quote by Yashbhatt View Post
@Simon No, just casual thinking. I forgot that is against the site rules.
Not a problem - we all have opinions. The trick is to support them.
Notice I asked Chronos about a reference and got some form of substantiation back?
So we can at least be assured about where he's coming from there.

I'm not going to always absolutely insist on peer-reviewed references - that would get onerous very fast. Though there are situations where this would be appropriate.
Pythagorean
#28
May17-14, 05:29 AM
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Quote Quote by Simon Bridge View Post
You mean it was needed for tool use, weapons being among the tools to be used. There are many animals which hunt but which do not have an upright stance... they seem to manage.
Weren't the immediate ancestors of man mostly vegetarian (+ insects)?
Yashbhatt
#29
May17-14, 06:06 AM
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I think the ancestors only ate meat and roots of plants and maybe some fruits.
Pythagorean
#30
May17-14, 06:19 AM
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Quote Quote by Yashbhatt View Post
I think the ancestors only ate meat and roots of plants and maybe some fruits.
Early humans ate meat, but I'm pretty sure their ancestors did not:

http://www.nature.com/scitable/knowl...mans-103874273

I think the transition to a meat diet is often considered part an important step in human evolution.
Yashbhatt
#31
Jun11-14, 11:04 PM
P: 145
I think the reason that swinging arms helps in gaining forward momentum seems to be the right one. I myself tried it. I took some weights in both hands and tried walking back and forth. One can really feel the forward momentum. I also tried with weight in only one hand.


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