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Offline GBSB

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EVOLUTION OF THE HUMAN BODY POSTURE
« on: 21/06/2006 22:28:55 »
EVOLUTION OF THE HUMAN BODY POSTURE

As long as we can trace the history of human beings, we can see that there were two main activities which were necessary to perform in order for humans to be able to survive.  
One of these activities was moving from one place to another (walking, running or jumping).
Another activity was to carry goods (mainly in the hands or on the shoulders.)
Like no other species, humans were carrying goods mainly on the shoulders and in the hands.
 
Till recently, human’s rarely traveled, even for small distances, without carrying some goods in the hands or on the shoulders.

The two main things that human beings had to take care of when moving (walking, running and occasionally jumping) from one place to another was, where he is stepping and how he is transferring body weight from one leg to another, with the intention not to hurt the surface of the bottom of the feet and not to lose balance (if he losses balance, he will fall on the ground). Because of that, he was transferring his body weight form one leg to another carefully and independently from the speed of the movement.
 
These two activities (traveling and at the same time carrying goods on the shoulders and/or in the hands) have big influences in forming the body posture. Because of that, the way of the body posture, from the bottom of the feet to the top of the shoulder, has evolved to be able to carry goods in the hands and on the shoulders, and at the same time be able to maintain balance.
 
Carrying the goods was one important activity which guided the evolution of the human body posture.
 
By doing this activity, the environment demanded from the human to see where he was going and where he was stepping.
The holding of the head and the neck has developed in such a way that he can with a minimum movement of the head, to see where he is stepping and where he is going. Because of that, his neck and head was slightly leaning forward.
For example, when walking through a forest, we need to be able to see where we are going and where we are stepping. The time span between looking in the direction where we are going and looking on the ground where we are stepping must be short. Because if we watch for too long where we are stepping, we will in a short time hit the tree and if we watch too long where we are going, we will in a short time trip on the birch or some other objects which is lying on the ground. As we change our focus in a short time, from where we are going and where we are stepping, the head and the neck from itself starts to lean slightly forward to enable us to see where we are going and where we are stepping, by mainly just moving our eyes with a minimum movement of the head.

If we walk through a forest without carrying some weight in the hands and on the shoulders, we can still do that with the many different types of body postures, concerning the body from the bottom of the feet to the top of the shoulders.
 
But if we carry some weight on the shoulders, or in the hands, in the long term we can do this activity only if our body from the bottom of the feet to the top of the shoulder is in an upright position and the neck with the head is in a relaxed slightly forward leaning position.
 
Carrying some goods on the shoulder and in the hands was an important contributing factor in gaining and maintaining physical strength and physical balance of the human body, and it was also a contributing factor in the evolution of the human race.  





« Last Edit: 10/12/2006 20:08:06 by GBSB »


 

Offline tony6789

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #1 on: 23/06/2006 21:46:35 »
actually there r hunchbacks



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Offline GordonP

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #2 on: 26/06/2006 16:57:46 »
I wonder what caused a particular species of ape to evolve an upright posture in the first place and what was the driving evolutionary force that totally changed the hip bone of this particular species.

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #3 on: 26/06/2006 17:00:27 »
PS
All the other apes survived without walking upright so it was not a survival response.

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Offline neilep

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #4 on: 26/06/2006 17:36:02 »
This is an interesting topic.

I would have thought that it was a necessity for us to stand upright was at least two fold.

1. Being upright is an invaluable ability for protection from being hunted

2. In contrast , being upright is a distinct advantage when it comes to hunting as the taller you are the further you can see unsuspecting dinner !!

..additionally, being upright helps to serve to reach higher fruits from trees etc.

Walking upright was probably one of the main landmarks that set us apart from the other apes. This must have contributed enormously to the manner in which our evolution was affected.



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another_someone

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #5 on: 26/06/2006 17:44:56 »
quote:
Originally posted by GordonP
I wonder what caused a particular species of ape to evolve an upright posture in the first place and what was the driving evolutionary force that totally changed the hip bone of this particular species.



Caused or allowed?

The normal assumption about evolution is that it is caused by random mutations, and some of these random mutations then prove to be useful in certain niches and this allows the mutated individuals to survive and thrive, and thus create a new species based upon those mutations.

First question – what are the disadvantages of a bipedal stance, and why have the other apes not taken it up?

One obvious disadvantage is the need for relatively flat feat that are convenient when one walks on flat ground, but would be problematic when climbing trees.  Humans have not only flat feet, but relatively flat hands, which again makes the hands more flexible in many ways, but although the hands can be used to grip branches, they probably need more effort to do so because their relaxed state is to be almost flat palmed.

A long, upright, body also exposes much of the front of the body to attack in a way that a body walking on four limbs does not.  On the other hand, a long upright body allows one to see further over open ground, as well as being more streamlined in the water.



George
 

Offline GordonP

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #6 on: 26/06/2006 19:39:35 »
quote:
Originally posted by neilep

This is an interesting topic.

I would have thought that it was a necessity for us to stand upright was at least two fold.

1. Being upright is an invaluable ability for protection from being hunted

2. In contrast , being upright is a distinct advantage when it comes to hunting as the taller you are the further you can see unsuspecting dinner !!

..additionally, being upright helps to serve to reach higher fruits from trees etc.

Walking upright was probably one of the main landmarks that set us apart from the other apes. This must have contributed enormously to the manner in which our evolution was affected.



Men are the same as women, just inside out !



G W Pipes
 

Offline GordonP

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #7 on: 26/06/2006 19:40:28 »
1 Why?

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Offline GordonP

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #8 on: 26/06/2006 19:42:58 »
2 seeing dinner is one thing, eating it another. Addtionaly climbing trees allows you to feed near the top of the tree.

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Offline GordonP

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #9 on: 26/06/2006 19:47:07 »
Hi George
Humans evolved flat feet, presumably while they were evolving a pelvic bone that allowed them to stand upright. Why?

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #10 on: 26/06/2006 19:52:43 »
Hi Gordon,

Standing upright doesn't preclude you from climbing trees still !

To answer your query and these are just my own conclusions, but standing upright enables you to see predators from farther away and also to peer down into high grass to see squatting predators about to pounce !...in my opinion of course....so you get an early warning..

...and seeing dinner from further away , I would have thought would expand your chances of seeking dinner, due to the wider field of view....but as I said..these are just my thoughts.....

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Offline GordonP

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #11 on: 26/06/2006 20:30:13 »
Hi Neilep
Standing upright offers no advantages over an ape sitting high in a tree.

The question is. Why did one particular species of ape abandon the safety of the trees for a life on the ground? Remember although evolution, given the right circumstances, can happen comparitively quickly, this species of ape must have survived on the ground for thousands of years before the transformation of the pelivic bone was complete. How did this species survive for long enough for the process to reach completion?

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #12 on: 26/06/2006 20:44:50 »
quote:
Originally posted by GordonP

Hi Neilep
Standing upright offers no advantages over an ape sitting high in a tree.

The question is. Why did one particular species of ape abandon the safety of the trees for a life on the ground? Remember although evolution, given the right circumstances, can happen comparitively quickly, this species of ape must have survived on the ground for thousands of years before the transformation of the pelivic bone was complete. How did this species survive for long enough for the process to reach completion?

G W Pipes



One would presume because proto-human suddenly found himself in a place that lacked trees, so the choice of running up a tree for safety simply did not occur.

Could be climatic change that reduced trees; could be overcrowding that forced some apes out of the forest; or it could be some calamity that left some proto-humans stranded away from their traditional habitat.



George
 

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #13 on: 26/06/2006 20:48:57 »
Hi Gordon (nice homepage..I'll have to read that when I get a chance..but it looks fascinating !..see ?...everybody will look at it now !! :D)...oh !..call me Neil !

You ask a very good question...I just wish I had an answer to complement it :)

I just do not know......circumstance and necessity leads to invention  and evolution...something must have happened to a breed of ape that ,where ever they were located on Earth at the time, the surrounding geography must have imposed/coerced this evolutionary progress which, must have been specific to that area ..it must have dictated over time the evolution of the ability to stand upright....

without the benefit of a time machine I guess we'll never know unless irrefutable proof is discovered.

Do you have any theories on the matter ?

Men are the same as women, just inside out !
« Last Edit: 26/06/2006 20:57:15 by neilep »
 

another_someone

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #14 on: 26/06/2006 20:51:39 »
quote:
Originally posted by GordonP
2 seeing dinner is one thing, eating it another. Addtionaly climbing trees allows you to feed near the top of the tree.

G W Pipes



Rather depends upon what you consider to be dinner.

If your happy eating fruit and veg, then the top of a tree is fine, but if you want some meat in your diet, then there is a limit to what you can have at the top of the tree.

Even Chimpanzees rather like a mixed diet, although Gorillas seem to be happy with a strictly vegetarian diet, with a few insects (although, interestingly gorillas are rather large for climbing trees).



George
« Last Edit: 26/06/2006 20:58:28 by another_someone »
 

Offline GordonP

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #15 on: 26/06/2006 20:57:59 »
I don't think so George, the climatic change that affected North Africa when the sub-continent of India came into contact with Ero-Asia must have happened slowly enough for all the apes to follow the retreating trees into central Africa. We are still talking about a massively large area of jungle, big enough for all the apes.

Why did our ancestors stay behind? And how did they survive long enough to evolve into the human species?



G W Pipes
 

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #16 on: 26/06/2006 21:04:06 »
Meat eaters are, by and large, preditors. Preditors are, by and large top of the food chain. How did an ape get there?

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #17 on: 26/06/2006 21:32:42 »
quote:
Originally posted by GordonP

I don't think so George, the climatic change that affected North Africa when the sub-continent of India came into contact with Ero-Asia must have happened slowly enough for all the apes to follow the retreating trees into central Africa. We are still talking about a massively large area of jungle, big enough for all the apes.

Why did our ancestors stay behind? And how did they survive long enough to evolve into the human species?

G W Pipes



Speciation does not happen across a continent.  In order for a new species start out, it has to occur in a very small geographic area.  Even if the mass of apes were to be able to follow the retreating trees, one would expect individual communities to become separated from the mass retreat.

Nor can it be said that there is ever enough forest/jungle for all the apes.  The nature of all species is that they will expand their population to utilise all the resources at their disposal.  Since it is the nature of the ecosystem that there are times when available resources are increasing (allowing an increase in population), and times when resources reduce (causing pressure on the population).  It would thus seem perfectly normal that in one of these period of expanding resources, the population of apes would expand to utilise these resources; but then when resources started to become more restricted, some of this large population of apes suddenly found they did not have the resources to live on, and had to look for new resources.

The Indian subcontinent actually started colliding with Asia around 55 million years ago, long before the proto-humans separated from other apes.  Apes themselves only separated from other monkeys around 25 million years ago, and humans from other apes about 7 million years ago.  Over those 7 million years, there have been many changes in climate, for all sorts of reasons, many of which are not even fully understood.  I don't know what was the direction of global climate change, let alone local climate change, was at the time when proto-humans separated from other apes.



George
 

another_someone

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #18 on: 26/06/2006 21:41:15 »
quote:
Originally posted by GordonP
Meat eaters are, by and large, preditors. Preditors are, by and large top of the food chain. How did an ape get there?



So fasciitis necroticans or Clostridium botulinum are at the top of the food chain?

I think it is a little simplistic to look at the 'food chain' as a structure that has a clear top and a clear bottom.

This is ofcourse even further complicated by animals that indulge in cannibalism (which includes both some human tribes and chimpanzees).  Are animals who eat their own kind above or below themselves in the food chain?



George
« Last Edit: 26/06/2006 21:41:49 by another_someone »
 

Offline GordonP

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #19 on: 26/06/2006 22:14:40 »
Hi again George
Where ever, or when ever, apes began to walk upright, it happened. Even Darwin couldn't tell us why. In 2006 one-one else can.

How does an ape, so dependent on trees for survival, suddenly survive on the open grasslands?

One possible answer to this question is so politically incorrect, so soaked in sex and violence, that I hesitate to offer it before properly examining other explainations.

Please help me out, offer me an explaination.

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #20 on: 26/06/2006 22:49:18 »
quote:
Originally posted by GordonP
How does an ape, so dependent on trees for survival, suddenly survive on the open grasslands?



Animals can change there decencies and relationships quite dramatically.

Giant pandas are related to bears, and yet bears are carnivores while Giant Pandas have a very close dependence upon bamboo.  How is this change of dependency any less unusual than the change of ape from forest dwelling to living on a savannah or in a coastal area (both of which have been suggested as possible environments for proto-humans)?

We don't know exactly what the change in environment allowed the change in proto-human physiology, but there is nothing so unusual in such a change that it has not been seen in many other species.

What the exact dependency between pre-human apes and the forest were is itself not totally certain.  Gorillas, although they are forest dwellers, are not themselves tree climbers, although most other apes are.

http://en.wikipedia.org/wiki/Mountain_Gorilla
quote:

Mountain Gorillas have longer and darker hair than other gorillas, enabling them to live at high altitudes and travel into areas where temperatures drop below freezing. They have adapted to a life on the ground more than any other non-human primate, and their feet most resemble those of humans. Gorillas can be identified by nose prints unique to each individual. Researchers often use photographs and illustrations of noses for identification and monitoring.



http://en.wikipedia.org/wiki/Sahelanthropus%5Ftchadensis
quote:

The fossil skull TH 266, nicknamed "Toumaï" ("hope of life" in the local Goran language of Chad), may be a common ancestor of humans and chimpanzees; most molecular clocks suggest humans and chimps diverged 1–2 million years after S. tchadensis (5 mya). The original placement of this species as a human ancestor but not a chimpanzee ancestor complicated the picture of the human family tree. In particular, if Toumaï is only a direct human ancestor, its facial features bring the status of Australopithecus into doubt because the thickened brow ridgers are similar to later hominids, but not earlier ones. Another possibility is that Toumaï is anatomically related to both humans and chimpanzees, but the ancestor of neither. Brigitte Senut, the discoverer of Orrorin tugenensis, claims that the features of S. tchadensis are consistent with a female proto-gorilla.
If Senut's claims are true the find would be especially significant; there have been no chimp or gorilla ancestors to be found anywhere in Africa and light would be shed on their family trees. What the find does show is that the last common ancestor of humans and chimpanzees is unlikely to resemble chimpanzees very much, as had been previously supposed.



The emphasis on the last paragraph is mine, but I think it is important to remember that our common ancestor with the other great apes was no more chimpanzee, or gorilla, than it was human; but was another animal altogether.

quote:
Originally posted by GordonP
One possible answer to this question is so politically incorrect, so soaked in sex and violence, that I hesitate to offer it before properly examining other explainations.



No doubt sex and violence comes into it somewhere – these are forces that are very prevalent in the world around us, and play no small part in evolution.



George
« Last Edit: 26/06/2006 23:20:56 by another_someone »
 

another_someone

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #21 on: 27/06/2006 00:19:25 »
You might wish to have a look at another similar discussion about the separation of human from ape, although not singling out the issue of the upright stance, but may have some bearing on it.  It included a very highly speculative story by me as to how a hypothetical situation could have arisen that would have created such a division, including different physiology and very different adaptations to different environments.  It does not claim to in any way be a definitive answer to the question, merely a speculation about a possible (and grossly simplified) scenario that could be regarded as a model for the type of thing that could have lead to that outcome.

http://www.thenakedscientists.com/forum/topic.asp?TOPIC_ID=2811#28058




George
 

Offline GordonP

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #22 on: 27/06/2006 20:31:35 »
Interesting discussion. Try this for another hypothetical senario.

The climate in North Africa starts to change, as the years pass the forest retreats to central Africa and all the apes, dependent on the trees for safe haven, retreat with the forest.

One particular species begin to spend most of their time on the fringes of the forest, already a user of tools (they use stones to break open nuts)they begin to scavenge on the remains of kills left by the preditors that now inhabit the open areas, using their tools to break open the bones which remain behind in order to get at the bone marrow.

They live in small family groups led by a dominant male, usually the biggest and strongest male. The groups comprise, the dominant male, several adult females, the young and several adult subordinant males. The dominant male regards the adult females as his wives and guards them from the other males. They are still reliant on the trees for safe haven from preditors and only venture onto the open ground while one of the group is in position high in the trees as a watchout.

So far nothing has happened to effect the evolution of the species.

One day a male is born with a slight mutation, nothing spectacular, just a deformation of the pelvic bone. He still moves about most of the time with his knuckles almost brushing the ground but he can do something none of the rest of the group can do, he can take many steps in an almost upright position, the rest of the group can manage only three or four steps in this position before dropping their hands to the ground. (As with many apes today).

Eventually he approaches maturity and driven by testosterone challenges the dominant male. Not yet fully mature his chances of success are practically nil and being something of a lightweight will probably always remain so.

As the two face each other he does something that has never been done before, he picks up a short stout piece of broken branch, stands almost upright and closes in on the dominant male who also stands almost upright in defiance. After a very short while dancing around the dominant male can stand upright no longer and drops his hands to the ground, he is now defenceless. The young male knocks seven bells out of him and takes over the harem.

Something new has happened, an ape has used a tool as a weapon, and changed the path of evolution. Now it is not the biggest and strongest who rules but the one who can stand upright the longest. As the ruler of the group has the females to himself his genes will predominate the next generation and so on and so forth.

G W Pipes
 

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #23 on: 28/06/2006 17:43:16 »
quote:
Originally posted by GordonP

Interesting discussion. Try this for another hypothetical senario.

The climate in North Africa starts to change, as the years pass the forest retreats to central Africa and all the apes, dependent on the trees for safe haven, retreat with the forest.

One particular species begin to spend most of their time on the fringes of the forest, already a user of tools (they use stones to break open nuts)they begin to scavenge on the remains of kills left by the preditors that now inhabit the open areas, using their tools to break open the bones which remain behind in order to get at the bone marrow.

They live in small family groups led by a dominant male, usually the biggest and strongest male. The groups comprise, the dominant male, several adult females, the young and several adult subordinant males. The dominant male regards the adult females as his wives and guards them from the other males. They are still reliant on the trees for safe haven from preditors and only venture onto the open ground while one of the group is in position high in the trees as a watchout.

So far nothing has happened to effect the evolution of the species.

One day a male is born with a slight mutation, nothing spectacular, just a deformation of the pelvic bone. He still moves about most of the time with his knuckles almost brushing the ground but he can do something none of the rest of the group can do, he can take many steps in an almost upright position, the rest of the group can manage only three or four steps in this position before dropping their hands to the ground. (As with many apes today).

Eventually he approaches maturity and driven by testosterone challenges the dominant male. Not yet fully mature his chances of success are practically nil and being something of a lightweight will probably always remain so.

As the two face each other he does something that has never been done before, he picks up a short stout piece of broken branch, stands almost upright and closes in on the dominant male who also stands almost upright in defiance. After a very short while dancing around the dominant male can stand upright no longer and drops his hands to the ground, he is now defenceless. The young male knocks seven bells out of him and takes over the harem.

Something new has happened, an ape has used a tool as a weapon, and changed the path of evolution. Now it is not the biggest and strongest who rules but the one who can stand upright the longest. As the ruler of the group has the females to himself his genes will predominate the next generation and so on and so forth.

G W Pipes



As far as it goes, it does not seem impossible, but it does leave a good number of questions unanswered.

You have said that “Now it is not the biggest and strongest who rules but the one who can stand upright the longest“.  This seems fine, but does not explain why this was true of proto-humans, but not other apes.

Although it is true that over recent times, the advantage of human tools has been so overwhelming that other species of apes are now endangered species, but it does not explain why for so many millions of years the other apes continued to thrive in the face of these upright toolmakers.  One must assume that these other apes must have had their own advantages to their own way of life that undermined much of the advantage the upright toolmakers had (at least until very recently).  These advantages/disadvantages would have to be environmentally dependent, so the upright toolmakers thrived in one environment, while failing to make major inroads into the environment of the other apes.

Ofcourse, the obvious answer to this is that there is very little advantage to being able to run a long way while upright when the distance between trees is only a few steps away, and this may well have been why the toolmakers never (until recently) came to displace the non-toolmakers within the bounds of the forest itself.

The second issue is the difference between genetic drift and speciation.  In order for speciation to occur, you need a separate breeding population.  If the populations are not separated, then there will be interbreeding between populations before they have become sufficiently separated to form distinct and and separate species.  Ofcourse, one could add to your scenario that, not only has this tribe of apes moved to the edge of the forest, but this was not the main body of the forest, but a small island of forest in a sea of savannah; and as the forests retreat, so the island forest is shrinking, and the tree climbing apes are finding it ever more difficult to survive, and thus leaving the walking apes isolated.  Because most of these apes have been killed off, leaving only a very small residual population, you in fact have exactly the kind of genetic bottleneck that allows a new species to quickly take hold (i.e. the same situation that allows large numbers of genetic faults in a population to develop as the population inbreeds, so this is also the same mechanism that creates new species).





George
 

Offline thebrain13

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #24 on: 29/06/2006 01:29:20 »
I think the key issue is defense. It's been brought up that taller creatures can see more prey, but on the flip side more predators can see you. if you look at when the dinosaurs roamed the earth you might notice that most of the carnivores walked upright, while most of the herbivores walked on all four. It makes since that a trex or a pack of velociraptors would trade being seen for the ability to find more prey, because what crazy creature is going to attack a pack of raptors or a trex. The diet is another advantage to walking upright. Herbivores need to eat a lot more then carnivores so they have more weight to carry around. If cows walked upright they would look like rosie odonell, and that is clearly not an efficient design. Herbivores can more adequatley defend and carry their weight around on all fours, where the more slender carnivores can afford walking upright. So my guess for the evolution of humans would be that somewhere down the line people seperated themselves from apes with intelligence first. With their bigger brains they were able to defend themselves better and could afford being seen more by other predators in exchange for being able to see more prey which led to developing the ability to walk upright. And with their new diet they could avoid looking like rosie.[xx(]
 

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Re: EVOLUTION OF THE HUMAN BODY POSTURE
« Reply #24 on: 29/06/2006 01:29:20 »

 

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