What prompted primitive man to become bipedal?

[BumFluff]

In saying we are not descended from apes (or monkeys), you are in a way making things worse. We are descended from apes (and monkeys). Just not today's apes (or monkeys).

 

Most creationists are Caucasians from the United States. Turn the question around on them: "I would guess that your are an American of European ancestry. If you're descended from Europeans, why are there still Europeans today?" Then say how this shows the question to be a lie, a misrepresentation of the theory of evolution. Then you can go on with "every non-emotional argument against evolution is a misrepresentation of evolution, and an intentional misrepresentation at that."

 

I don't know why we continue to argue about this. I have stated that comparing mans ancestors of yesteryear, after the separation of man and apes, are in no means comparable to the apes of today. They went through different evolutionary trends. Which is pretty factual if we in fact did come from one common ancestor, as I believe. Stating that there is no way that ancient man would want to carry food to their place of residence because the apes of today don't is like saying all our mammalian ancestors must have run and jumped off cliffs to their deaths because lemurs do it today.

 

I've also explained why this separation took place in my opinion. Because of their different areas of habitation.

[D H]

Stating that there is no way that ancient man would want to carry food to their place of residence because the apes of today don't is like saying all our mammalian ancestors must have run and jumped off cliffs to their deaths because lemurs do it today.

Don't go jumping off a cliff with a red herring! Leave the red herrings to the creationists. The way you state this implies to me that you are ascribing purpose to evolution. So, back to your original hypothesis:

 

It is my belief (Although I'm fairly certain this has been proposed before) that our ancient mammalian ancestors lived on the borders of these jungle/savanna wildernesses. To forage and hunt for food they needed to travel outside of the safety of the jungle, both armed with weapons such as sticks or clubs and in packs, to gather what they needed. Having a weapon in one hand and a pile of food in the other didn't really allow for movement on all fours. They needed to walk bipedally back to the safety of the jungle. Eventually their bipedalism grew enabling them to carry more food as well as enabling them to protect themselves better. With bipedalism becoming more common it allowed our ancestors to free up their hands which would then provide them the means of more tool use, better tools and subsequently bigger brains.

 

The final sentence of your hypothesis is pretty much in line with current thinking. Everything leading up to that is not. First and foremost, you are indeed ascribing purpose to evolution. For example, "They needed to walk bipedally back to the safety of the jungle". Evolution does not have a long-term view. It has no purpose. Having a mathematical bent, I think of evolution as being a kind of local optimization function rather than a global optimization function.

 

The knuckle walking ape and the bipedal human differ in skeletal structure, musculature, nervous systems, respiratory systems, etc. Bits and pieces of every part of our body had to change. This many changes is not the work of one mutation. Our ancestors did not switch from knuckle walking to bipedalism in one fell swoop. The changes piled on top of each other, eventually leading to full upright bipedalism. The ability to carry weapons and lug food around is an advanced skill. Something else drove the changes that lead up to these abilities. That something else conferred an immediate, local optimizer kind of advantage -- like the ability to see lions off in the distance instead of seeing the lions right before they attack.

[BumFluff]

Don't go jumping off a cliff with a red herring! Leave the red herrings to the creationists. The way you state this implies to me that you are ascribing purpose to evolution. So, back to your original hypothesis:

 

 

 

The final sentence of your hypothesis is pretty much in line with current thinking. Everything leading up to that is not. First and foremost, you are indeed ascribing purpose to evolution. For example, "They needed to walk bipedally back to the safety of the jungle". Evolution does not have a long-term view. It has no purpose. Having a mathematical bent, I think of evolution as being a kind of local optimization function rather than a global optimization function.

 

The knuckle walking ape and the bipedal human differ in skeletal structure, musculature, nervous systems, respiratory systems, etc. Bits and pieces of every part of our body had to change. This many changes is not the work of one mutation. Our ancestors did not switch from knuckle walking to bipedalism in one fell swoop. The changes piled on top of each other, eventually leading to full upright bipedalism. The ability to carry weapons and lug food around is an advanced skill. Something else drove the changes that lead up to these abilities. That something else conferred an immediate, local optimizer kind of advantage -- like the ability to see lions off in the distance instead of seeing the lions right before they attack.

 

You seem to be saying that bipedalism grew of chance. No I don't believe evolution has an all out purpose. Evolution doesn't work to achieve an ultimate goal. It works as with little evolutionary steps through sexual, natural or ecological selection. Bipedalism took a long time to occur, it didn't occur overnight. You misunderstand what I'm saying. What I am saying is that, because of the environmental impact, our ancestors needed to adapt to their surroundings which would eventually lead to bipedalism. Desertification of Africa didn't occur overnight. There wasn't some great God in the sky that said "Let it be!". It took a long long time and humans were adapting to this over a long period of time. The local optimization functions are the reason, in the theory I posted, why one group remained apes and the other group evolved into humans.

 

I've been reading theory after theory of why bipedalism occurred in humans but I have not read anything stating why one group of ancestor evolved one way while the other evolved the other way. What do you propose is the 'correct' theory of why this occurred?

[iNow]

Some object to saying that we are descended from apes on religious grounds. These religious objections have made some who do ascribe to evolution reject the claim that we are descended from apes. These non-religious objections are based on invalid of the claim by those who believe in creationism. One such objection with saying that we are descended from apes implies we are no longer apes. We are apes. End of story.

 

Another objection is that saying that we are descended from apes implies we are descended from the apes extant today. This is the stupid "if humans are descended from monkeys, why do monkeys still exist" non sequitur. The only way to answer this question is "it is said most Americans are descended from Europeans, so why do Europeans still exist?"

 

Another one which I think captures the issue helpfully is this:

 

If amphibians descended from fish, then why are there still fish?

 

 

One more easily realizes how silly the objection is when it's taken away from the context of humans. The change in context helps when dealing with those who have a mental wall around this concept due to their desire to see humans as somehow special and different from all other life.

 

 

 

 

I've been reading theory after theory of why bipedalism occurred in humans but I have not read anything stating why one group of ancestor evolved one way while the other evolved the other way. What do you propose is the 'correct' theory of why this occurred?

 

That the groups had slightly different environmental factors acting on their selection.

Edited July 5, 2008 by iNow
multiple post merged

[BumFluff]

That the groups had slightly different environmental factors acting on their selection.

And that is exactly what I said. But what environmental factors would cause

one group to become bipedal while the other not to?

[iNow]

I think it is a mistake to consider some small subgroup of factors and call it a day. In reality, it's all factors aggregated together which led to the differing outputs.

[BumFluff]

I think it is a mistake to consider some small subgroup of factors and call it a day. In reality, it's all factors aggregated together which led to the differing outputs.

 

I'm trying to understand what theories could lead to man becoming bipedal and apes not to. Every theory I've read does in no way describe why one group became bipedal and the other didn't. One of the major contributing factors, in my opinion and as stated above, is that desertification at that time attributed to it significantly.

[foodchain]

I'm trying to understand what theories could lead to man becoming bipedal and apes not to. Every theory I've read does in no way describe why one group became bipedal and the other didn't. One of the major contributing factors, in my opinion and as stated above, is that desertification at that time attributed to it significantly.

 

why do all apes have to have the same evolutionary history, as in why would they all have to become like people? Do all people have to be exactly alike?

[BumFluff]

why do all apes have to have the same evolutionary history, as in why would they all have to become like people? Do all people have to be exactly alike?

If they went through the same environmental evolutionary trends then yeah I think we do. I highly doubt that if an evolutionary change occurred in one small portion of a population that it wouldn't spread to other members of exactly the same population. I believe that is one of the foundations of the evolutionary theory. Therefore they must have been in different populations more likely in different types of environments.

[arnoldschwartz]

Thanks for all the info, this something that I have been curoious about for a while

[CDarwin]

CD Dawin,

 

I have seen that anti AH website before. It is full of strawman arguments, and inaccuracies. Your point about most aquatic mammals being 'haired' is interesting, but not actually that important. Most aquatic mammals have short or no legs but frogs have long legs - it all depends on what the starting point is and what evolutionary processes then come into play. Maybe we were living in muddy waters or boggy areas where hair was a disadvantage. Also cetaceans have no hair, as do hippos, elephants, rhino's, all of which are either semi aquatic or have had semi aquatic ancestors.

 

I think you were responding to Lucaspa there, not me, which might be why you answered none of my objections.

 

The real problem with aquatic ape is that it's simply not necessary with respect to the fossil record. If an aquatic stage happened, it left no trace in any of our fossil ancestors. Basically, it's one giant "just so" story with questionable internal consistency that more importantly has absolutely not one shred of evidence from the period of human evolution it purports to explain supporting it.

 

 

Uhm... a lot of other things have been posted here since I've been on a computer. Sorry if the discussion has moved totally beyond what I'm talking about. I'll catch up tomorrow when I'm not exhausted.

[bombus]

To Bumfluff

Second ; Relating to hairlessness. Your theory is not new. Loss of hair as a cooling mechanism has been proposed many times. In fact, one of the few special physical attributes humans have is extreme stamina - if you are young, male, and physically fit - and at least some in each tribe fit that description. This permits a special kind of hunting. To chase a gazelle or similar prey animal until it keels over from exhaustion. This is still done by some African tribes. One reason humans can do this is due to lack of hair and a cooling system that is far superior to most terrestrial mammals.

 

I've seen a film of that - african's hunting a elan I think. However, what struck me was that it was only possible because the humans could carry their water with them. Does this suggest that we started carrying water with us before we lost our hair? Else, surely we'd have suffered from dehydration. Sweating in hot dery places aint a good idea unless water is readily available. This is why I tend towards the AAH prior to us living on the savannah. i.e., we'd already lost our hair.

[BumFluff]

I've seen a film of that - african's hunting a elan I think. However, what struck me was that it was only possible because the humans could carry their water with them. Does this suggest that we started carrying water with us before we lost our hair? Else, surely we'd have suffered from dehydration. Sweating in hot dery places aint a good idea unless water is readily available. This is why I tend towards the AAH prior to us living on the savannah. i.e., we'd already lost our hair.

 

That's a good point. However regardless if we lost our hair because of AAH or we lost it due to cooling we would still need to carry the water with us or migrate to where the water was. That's why I think that our ancestors were nomadic. They scavenged and hunted for food, storing which they could, until they had to move on when the water sources began to dry up and the desert began to overtake them.

 

Why would man have lost their hair because they were partly aquatic and what prompted them to become partly aquatic? Why would we have lost that aquatic ability? The only reasons I could think of why man would become partly aquatic is to get food, fishing without rods, or to get away from predators.

[Mr Skeptic]

Carrying water is particularly difficult, as it would have required them to be smart enough to make a water bottle. That would require significant tool use. Perhaps enough tool use to have required carrying tools. I'd say it is most likely that the first carrying involved tools and extra food. Most animals carry water and as much food as they can eat inside their bodies.

[arnoldschwartz]

Carrying water is particularly difficult, as it would have required them to be smart enough to make a water bottle. That would require significant tool use. Perhaps enough tool use to have required carrying tools. I'd say it is most likely that the first carrying involved tools and extra food. Most animals carry water and as much food as they can eat inside their bodies.

 

Yes this makes sense as carrying tools they would need to be bipedeal to have two hands free to carry things

[SkepticLance]

Carrying water is not that difficult.

The San people of the Kalahari used to do it using the shell of an ostrich egg. The Maori people of my country used the dried shell of the gourd fruit, which I believe is also widespread in Africa. In the Pacific they used coconut shells. There are probably lots of other ways that I do not know about.

[bombus]

That's a good point. However regardless if we lost our hair because of AAH or we lost it due to cooling we would still need to carry the water with us or migrate to where the water was. That's why I think that our ancestors were nomadic. They scavenged and hunted for food, storing which they could, until they had to move on when the water sources began to dry up and the desert began to overtake them.

 

Why would man have lost their hair because they were partly aquatic and what prompted them to become partly aquatic? Why would we have lost that aquatic ability? The only reasons I could think of why man would become partly aquatic is to get food, fishing without rods, or to get away from predators.

 

I think it should really be 'the swimming ape', rather than 'the aquatic ape'. I imagine we started living near coastal waters and fed on shellfish, fish and other stuff available in that habitat, and were safe from predators in the water (shark attacks are pretty rare in coastal waters) so hung about in it most of the time. As we probably didn't sleep in the water losing our hair would have aided drying out (and so warming up). Also, maybe improved our swimming ability but to a lesser extent?

[SkepticLance]

Spending time in water does not require hair loss. Seals and otters have the most amazing fur coats. Evolution for an aquatic existence did not lead to them losing hair. Quite the reverse. They evolved fur that traps air - much denser.

 

Human hair loss is much more easily explained. We have had clothing for a long time. Development of clothing permits heat retention without having fur. And by being able to shed clothing, and having no fur, we can hunt with the major advantage over other animals of superior cooling. As I pointed out earlier, this gives hunting stamina that is extraordinarily superior.

[CDarwin]

I rather get the feeling of yelling against the wind, but everyone realizes that there's no fossil or archaeological evidence for anything being said here, right?

[BumFluff]

Spending time in water does not require hair loss. Seals and otters have the most amazing fur coats. Evolution for an aquatic existence did not lead to them losing hair. Quite the reverse. They evolved fur that traps air - much denser.

 

Human hair loss is much more easily explained. We have had clothing for a long time. Development of clothing permits heat retention without having fur. And by being able to shed clothing, and having no fur, we can hunt with the major advantage over other animals of superior cooling. As I pointed out earlier, this gives hunting stamina that is extraordinarily superior.

 

I doubt that the wearing of clothing would be the only reason why man's ancestors lost their fur. I believe it has been stated earlier in this thread that the further north you go the more clothing people wear. Heck near the equator the woman and men are almost naked even today. Do you think that a animal covered in fur would even consider wearing some sort of coat? They would easily overheat.

[iNow]

I rather get the feeling of yelling against the wind, but everyone realizes that there's no fossil or archaeological evidence for anything being said here, right?

 

I do.

[SkepticLance]

To CDarwin

 

This is one of a number of threads that are purely speculation. Speculating is a fun activity, even if it leads frequently to untruths. Not a problem if no-one can prove those speculations wrong, as in this thread. Personally, I am going to enjoy myself with these unproveable speculations, and stop when real and contrary data appears. If you try to curtail the speculating with demands for evidence, you are being a kill-joy and acting against a harmless and pleasurable debate.

[iNow]

If you try to curtail the speculating with demands for evidence, you are being a kill-joy and acting against a harmless and pleasurable debate.

Or perhaps he knows that the best way to true knowledge is to follow the scientific method and demand that assertions be supported.

 

 

If you want a harmless and pleasurable debate, then take it to General Discussion. This is the Biology forum, specifically, the Evolution, Morphology and Exobiology subforum.

[BumFluff]

Or perhaps he knows that the best way to true knowledge is to follow the scientific method and demand that assertions be supported.

 

 

If you want a harmless and pleasurable debate, then take it to General Discussion. This is the Biology forum, specifically, the Evolution, Morphology and Exobiology subforum.

 

Desertification has well been known to be occuring in Africa for some time. News Search for Desertification of Africa and recent evidence, though I can't recall where I read it, supports the theory that ancient man lived on the border between the jungle environment and the desert environment.

[bombus]

I doubt that the wearing of clothing would be the only reason why man's ancestors lost their fur. I believe it has been stated earlier in this thread that the further north you go the more clothing people wear. Heck near the equator the woman and men are almost naked even today. Do you think that a animal covered in fur would even consider wearing some sort of coat? They would easily overheat.

 

I'd agree with that. The thing is much of human evolution is actually linked to neoteny, and the selection of neotenic features. It is this that has probably lead to us having huge brains - which may have been a side effect at first! Being very clever is usually an advantage to animals - especially mammals - and is the primates primary card. BUT, what is so special about humans that made our brains grow enormously, even compared to other primates? I speculate that it is probably our selection of neotenic features over the millenia.

 

Now is it just coincidence that the other extremely 'neotenic' mammals - the cetaceans - also have huge brains? I doubt it. I think there is a link between aquatic/semi aquatic life and the natural selection of neotenic features, and it is this that put early homonids on the path to Homo sapiens. Unfortuantely, there is as far as I know, virtually no absolute proof of this, apart from reinterpretation of already exisiting information.

 

It's worth a second thought though folks...