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Evolution/walking on all fours

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Question
I like studying science I diffrence ways like wildlife and anatomy of humans and animals...so for a month or so now I've been studying and testing if a human has a capability to walk on all fours, I think our anatomy structure prevents us from doing it. I've tested it but I have my back leveled instead of in the air and my legs a little bent. While doing the research I got use to it(still walk on 2 legs)and is able to run and keep my head held. Is it the human structure that prevents us from doing it? Will it put less strain on our body for example our spine? A know every human is diffrent and if their able to hold their weight.

Answer
Interestingly, you will find an article in a Nat Geo Magazine of a few years back (ask your librarian to find it for you) of a rural Turkish family who had several children who walked on all fours.  All were of very low IQ, and of course, none got any physical therapy in rural Turkey, so grew up walking on all fours.  Be sure to get the article and read it.  Hugely interesting.

Since we evolved from some common primate that is now extinct, for sure that primate walked on at least the two back legs, and supported itself on occasions with a front arm.  But, there are problems with this, in that an animal using a fore limb for significant locomotion or balance, cannot carry much.  Since mutations happen in all directions, in all plants and animals, in every generation, one had to have mutated to be able to walk upright, and the advantages are tremendous-----that animal can carry more, and see farther than an animal of the same height, forced to  stoop while walking.  In 40 generations, that would be the one that got to pass on those genes, and those like it, would out-compete ones still dragging an arm.  Being able to carry more makes one valuable to the tribe.  One being able to see father can warn of danger.... huge assets to any tribe.

Evolution cannot "back up"... that is, there would be no reason to  go back down on all fours....

At this point in modern humans,  the position of the neck enters the skull from below, not from the back as it does in our nearest living relative, the chimp.To walk stooped would put tremendous strain on the neck, that is, if you wished to see where you are going !!!  To see where one is going when walking on all fours, the chin must be thrust forward.   So yes, the way the neck inserts into the skull is one anatomical difference that prevents us from going back on all fours.  As well, there is no animal that has a rump HIGHER than its shoulders.  Worse, our knee must bend deeply to prevent a higher rump, and that then would put lots of stress on the hip. So, to return to all fours has a tremendous cost in stress, and then in pain, and has no advantage at this point in our evolution... one cannot hunt this way---where can he hold a spear? , and certainly cannot run as fast as he can in an upright position. Humans have walked upright since Lucy, Ardi and several other hominids... i.e., for millions of years.  For anyone to take up four "paws" at this point isn't a viable option for very long.

Being upright for sure has its disadvantages... the most notable is the lumbar spine.  When children are born, the back from the tail bone to the base of the skull is flat.  When those children begin to learn to walk, the lumbar spine curves in.  And anyone who lives long enough will have lumbar spinal problems.  In comparison, that is a fair price to pay to be able to see farther, carry more, and hunt more efficiently, and thus live longer.

Everything, even in evolution, is a trade off, anatomy included.

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And feel free to write if I did not cover all you had in mind.  

Evolution

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Elisabeth DeWald

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I've been a public school teacher for 26 years. My major was history, but along the way, picked up minors in math, biology, zoology, and other life sciences. My whole life has been on one side of the desk or the other. Husband and Dad were both MDs so science and medicine was a natural for me. My dad once told me that I knew more medicine than most doctors. I can easily answer almost any life science question, most history questions, and lots of medical questions.

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Taught math,history, science, geology, chemistry, biology in a public school setting

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None at the present time

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none

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Majored in history in college, minored in all those subject mentioned. Masters degree in education. Grad courses, but no degree in religious studies, U of Chicago, Divinity School.

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Award at my one of my colleges of Best Student, in History as a year end award.

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I tutored for two years in math. Math however, if not used daily fades. My area of competency is in honors first year algebra, at this point.

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