Human Evolution

[the joint]

I made a comment about this in another thread and I'm somewhat shocked that nobody responded specifically to my post by calling me an idiot.

I believe in evolution in itself is true as demonstrated by an overwhelming amount of evidence, including ring species.  I would allow a caveat for something I would dub 'involution.'  Whereas evolution assumes that evolved physical states lead to evolved conscious states, involution would be the reverse, where evolved conscious states lead to evolved physical states.  I personally believe that the simultaneous occurrence of both (i.e. evolved conscious states and evolved physical states manifest in tandem) is the most likely.

But speaking in terms of evolution, I think humans are out of place.  Yes, I recognize that our genome is very highly correlated with primates' genomes.  But, I can't help but think that humans might not fit in with natural selection.

Humans are weird.  We're almost hairless, for example, and we are unlike any other species in the sense that we don't live in harmony in our niche.  We're parasites.  Yes, I know there are other parasites, but other parasites don't seem to pose a threat to virtually every living thing on this planet.

Going back to the hairless thing...

Apes, chimps, and other primates live outdoors.  Their hairy coats provide them protection from the elements and give them warmth.  So, why are we virtually hairless?  Yes, we have hair, but not in any suitable amount to protect us from the elements. 

Being virtually hairless would suggest that primates lived indoors before they lost their hair.  If primates could sustain themselves indoors long enough such that they didn't need their hair to protect themselves from the elements, then the hair would lose its necessity.  But, WTF?  Why?  It seems very implausible that a group of primates would travel to such cold environments, find and/or create shelter indoors, survive that way for so many generations and were able to sustain themselves for so long that generational intellect developed to the point where they could, for example, create fire and no longer need their hairy coats.  And, if they didn't travel to such cold environments, then why would they lose their hair anyway?  They'd be in warm enough environments where they didn't need to move indoors, didn't need to develop the intellect to make fire, etc.

The various Ice Ages that have occurred throughout history could be a possible explanation for this need to adapt.  If the world became so cold that even primates with hairy coats were threatened by the elements, then the need to move indoors would arise.  But, would they really have survived for so long (generations upon generations) that this evolved intellect would have developed anyway?

I dunno.  It all seems very weird to me.  Discuss.  All "idiot" comments are welcome.  All I know is that DNA/RNA replication is like working a copy machine.  A copy machine attempts to make an identical copy, but inevitably, every 'copy' has a few noticeable changes here and there, and when you make copies of copies, and then copies of copies of copies, these changes become more apparent over time.  And, it takes many, many, many generations (excluding something like a frame-shift in DNA) for radical changes to become apparent.

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[Electricbees]

Aquatic Ape Hypothesis?

[the joint]

Aquatic Ape Hypothesis?

Lol huh?  Haven't heard that one.

[Electricbees]

Aquatic Ape Hypothesis?

Lol huh?  Haven't heard that one.

I think it makes a little sense... Upright and hairless because ancient ancestors needed to function better in the water. For fishing, swimming, etc...

Not the best explanation, but it works.

[bb113]

I think humans look like big insects to other mammals.

[yogi]

Use it or lose it, that's the way nature works.

See.
http://en.wikipedia.org/wiki/Vestigiality

[justusranvier]

Being virtually hairless would suggest that primates lived indoors before they lost their hair.  If primates could sustain themselves indoors long enough such that they didn't need their hair to protect themselves from the elements, then the hair would lose its necessity.  But, WTF?  Why?  It seems very implausible that a group of primates would travel to such cold environments, find and/or create shelter indoors, survive that way for so many generations and were able to sustain themselves for so long that generational intellect developed to the point where they could, for example, create fire and no longer need their hairy coats.  And, if they didn't travel to such cold environments, then why would they lose their hair anyway?  They'd be in warm enough environments where they didn't need to move indoors, didn't need to develop the intellect to make fire, etc.

Hairlessness is an adaptation which allows us to cool down more efficiently. This allowed early humans to catch prey by running them to exhaustion.

Humans, he said, have several adaptations that help us dump the enormous amounts of heat generated by running. These adaptations include our hairlessness, our ability to sweat, and the fact that we breathe through our mouths when we run, which not only allows us to take bigger breaths, but also helps dump heat.

“We can run in conditions that no other animal can run in,” Lieberman said.

While animals get rid of excess heat by panting, they can’t pant when they gallop, Lieberman said. That means that to run a prey animal into the ground, ancient humans didn’t have to run further than the animal could trot and didn’t have to run faster than the animal could gallop. All they had to do is to run faster, for longer periods of time, than the slowest speed at which the animal started to gallop.

All together, Lieberman said, these adaptations allowed us to relentlessly pursue game in the hottest part of the day when most animals rest. Lieberman said humans likely practiced persistence hunting, chasing a game animal during the heat of the day, making it run faster than it could maintain, tracking and flushing it if it tried to rest, and repeating the process until the animal literally overheated and collapsed.

Most animals would develop hyperthermia — heat stroke in humans — after about 10 to 15 kilometers, he said.

By the end of the process, Lieberman said, even humans with their crude early weapons could have overcome stronger and more dangerous prey. Adding credence to the theory, Lieberman said, is the fact that some aboriginal humans still practice persistence hunting today, and it remains an effective technique. It requires very minimal technology, has a high success rate, and yields a lot of meat.

Lieberman said he envisions an evolutionary scenario where humans began eating meat as scavengers. Over time, evolution favored scavenging humans who could run faster to the site of a kill and eventually allowed us to evolve into persistence hunters. Evolution likely continued to favor better runners until projectile weapons made running less important relatively recently in our history.

“Endurance running is part of a suite of shifts that made Homo [the genus that includes modern people] human,” Lieberman said.

[cbeast]

Early manscaping led to too many infected abrasions. Man evolved the hair patterns he has to look good in leather. Women have less body hair because early waxing had too many bee stings.

[cbeast]

Aquatic Ape Hypothesis?

Lol huh?  Haven't heard that one.

I think it's sort of true, but more related to the period when Africa was isolated. Many mammals evolved into aquatic animals. Humans probably evolved from a formerly aquatic mammal that moved back inland. These traits returned quickly while migrating along the coasts and island hopping. Being semi-aquatic allows us to escape many predators. The Aquatic Ape theory is great, but probly incomplete because they are not looking back far enough for the original evolutionary ancestors. Finding human fossils without these traits would be more difficult because there was a smaller evolutionary window to return the traits.

[Raoul Duke]

Aquatic Ape Hypothesis?

Damn, you're the first person I find that knows about that theory.
I used to mention it to my friends, but after doing it 4 or 5 times and "get the look" I stopped 

EDIT: And cbeast also knows it.

What I find particularly interesting in that theory is the explanation for why the human brain evolved so much.

[cbeast]

Aquatic Ape Hypothesis?

Damn, you're the first person I find that knows about that theory.
I used to mention it to my friends, but after doing it 4 or 5 times and "get the look" I stopped 

EDIT: And cbeast also knows it.

What I find particularly interesting in that theory is the explanation for why the human brain evolved so much.

It's amazing that there are a lot of brain and other physiological similarities we share with other aquatic mammals and birds. I just don't think that any apes were aquatic before our ancestors. The 98% DNA we share with Chimpanzee probably means that they probably also descended from an aquatic mammal, but adapted to forests instead of savannas and shorelines.

[bb113]

Aquatic Ape Hypothesis?

Damn, you're the first person I find that knows about that theory.
I used to mention it to my friends, but after doing it 4 or 5 times and "get the look" I stopped  

EDIT: And cbeast also knows it.

What I find particularly interesting in that theory is the explanation for why the human brain evolved so much.

It's amazing that there are a lot of brain and other physiological similarities we share with other aquatic mammals and birds. I just don't think that any apes were aquatic before our ancestors. The 98% DNA we share with Chimpanzee probably means that they probably also descended from an aquatic mammal, but adapted to forests instead of savannas and shorelines.

What similarities do we share with birds? Their brains are structured completely differently from ours (although I guess there are similar circuits if I remember correctly), and their bodies... well they have wings and beaks, etc.

And to OP: It takes energy to grow hair, if it offered no advantage (wearing clothing, living indoors) it would slowly be selected out. Young mammals are mostly (all?) born hairless, so this would not even be a difficult mutation, just turn on/off some genes in skin cells to make the hair thinner in response to the same growth factors that make arms, arms and legs, legs, etc. It may have even been advantageous to go without body hair in the context of wearing animal skins as clothes since you could choose to radiate excess heat better when beneficial.

Also this made me think you would like this book: http://www.amazon.com/Origin-Consciousness-Breakdown-Bicameral-Mind/dp/0618057072

It's not so much scientific as a really interesting narrative.

edit:
Other advantages of reduced body hair:
1) Less insect infestation
2) Less time/energy spent grooming (related to 1)
3) More sensitive to tactile stimuli in areas you have thinner, less curly hair (insects again)
4) Makes it easier for humans to assess the sex of one another

[the joint]

Regarding the aquatic ape hypothesis:

Bears seem to do very well in the water.

[the joint]

And regarding advantages of hair:

These are good points.  However, this still begs the question...why hair to begin with, then?  Reptiles had scales.  Amphibians have smoother skin which allow for efficiency in the water.  So, why did mammals have hair?  If being hairless was more efficient, wouldn't that have been the next step?  Clearly having hair became a dominant characteristic in primates.  That characteristic "won," and it likely won for a reason.

It still seems to boil down to protection from the environment.  I think this still suggests that intellect would have need to have evolved to the point where primates were capable of surviving indoors, and when hair became less of a necessity, then it lost its prominence.

Besides, humans do NOT really have the speed or endurance to catch anything faster than a rabbit with bare hands, and that's if you're very, VERY quick.  I would imagine that humans did require heat dissipation to chase prey, but only when they had something like a spear to throw at it.  I.e. a human would run to get close enough to its prey to get off a good shot.  This still seems to mean that the evolved intellect preceded the hairlessness.

Still seems backwards to me.

[bb113]

Hair keeps you warm. My understanding is that humans do have the endurance and intelligence to track a gazelle, keep it running until it is worn out, then get it.

random link:

http://effectivenm.blogspot.com/2009/07/humans-runners.html

Also using clothing would have been more important than living indoors, in my opinion. Maybe I am missing something, is there a reason you think humans must have been "hairless" before developing tool use?

[Nachtwind]

Hailressness: Aquatic Ape theory.

Human migration to Europe began some 40k years ago at the end of the Weichsel glacial.. climate wasnt that bad anymore. In areas as the levant (Near east) as well as southern Spain agriculture was possible already.
So those hairless apes started migrating into the "colder" areas when they had the technology to survive there.

Problem solved

[cbeast]

Aquatic Ape Hypothesis?

Damn, you're the first person I find that knows about that theory.
I used to mention it to my friends, but after doing it 4 or 5 times and "get the look" I stopped  

EDIT: And cbeast also knows it.

What I find particularly interesting in that theory is the explanation for why the human brain evolved so much.

It's amazing that there are a lot of brain and other physiological similarities we share with other aquatic mammals and birds. I just don't think that any apes were aquatic before our ancestors. The 98% DNA we share with Chimpanzee probably means that they probably also descended from an aquatic mammal, but adapted to forests instead of savannas and shorelines.

What similarities do we share with birds? Their brains are structured completely differently from ours (although I guess there are similar circuits if I remember correctly), and their bodies... well they have wings and beaks, etc.

And to OP: It takes energy to grow hair, if it offered no advantage (wearing clothing, living indoors) it would slowly be selected out. Young mammals are mostly (all?) born hairless, so this would not even be a difficult mutation, just turn on/off some genes in skin cells to make the hair thinner in response to the same growth factors that make arms, arms and legs, legs, etc. It may have even been advantageous to go without body hair in the context of wearing animal skins as clothes since you could choose to radiate excess heat better when beneficial.

Also this made me think you would like this book: http://www.amazon.com/Origin-Consciousness-Breakdown-Bicameral-Mind/dp/0618057072

It's not so much scientific as a really interesting narrative.

edit:
Other advantages of reduced body hair:
1) Less insect infestation
2) Less time/energy spent grooming (related to 1)
3) More sensitive to tactile stimuli in areas you have thinner, less curly hair (insects again)
4) Makes it easier for humans to assess the sex of one another

I first read Julian Jaynes work in the early eighties. It changed the way I think about brain evolution, development, intelligence, and communication. Elaine Morgan's work on AAH disrupts the over simplified Monkey's Uncle Hypothesis. There are still a lot of question about human evolution that are unanswered and some have even more controversial hypotheses. There is still a lot of science to do before we get cake.

[Phinnaeus Gage]

I wonder if any of the above has something to do with French women regressing back to their former Roots.



This also begs the question as to why theymos opted for French 101. Surely it wasn't to learn pickup lines.

~Cackling Bear~

[yogi]

The fossil record does not support the aquatic ape hypothesis.

[punningclan]

I made a comment about this in another thread and I'm somewhat shocked that nobody responded specifically to my post by calling me an idiot.

I believe in evolution in itself is true as demonstrated by an overwhelming amount of evidence, including ring species.  I would allow a caveat for something I would dub 'involution.'  Whereas evolution assumes that evolved physical states lead to evolved conscious states, involution would be the reverse, where evolved conscious states lead to evolved physical states.  I personally believe that the simultaneous occurrence of both (i.e. evolved conscious states and evolved physical states manifest in tandem) is the most likely.

But speaking in terms of evolution, I think humans are out of place.  Yes, I recognize that our genome is very highly correlated with primates' genomes.  But, I can't help but think that humans might not fit in with natural selection.

Humans are weird.  We're almost hairless, for example, and we are unlike any other species in the sense that we don't live in harmony in our niche.  We're parasites.  Yes, I know there are other parasites, but other parasites don't seem to pose a threat to virtually every living thing on this planet.

Going back to the hairless thing...

Apes, chimps, and other primates live outdoors.  Their hairy coats provide them protection from the elements and give them warmth.  So, why are we virtually hairless?  Yes, we have hair, but not in any suitable amount to protect us from the elements. 

Being virtually hairless would suggest that primates lived indoors before they lost their hair.  If primates could sustain themselves indoors long enough such that they didn't need their hair to protect themselves from the elements, then the hair would lose its necessity.  But, WTF?  Why?  It seems very implausible that a group of primates would travel to such cold environments, find and/or create shelter indoors, survive that way for so many generations and were able to sustain themselves for so long that generational intellect developed to the point where they could, for example, create fire and no longer need their hairy coats.  And, if they didn't travel to such cold environments, then why would they lose their hair anyway?  They'd be in warm enough environments where they didn't need to move indoors, didn't need to develop the intellect to make fire, etc.

The various Ice Ages that have occurred throughout history could be a possible explanation for this need to adapt.  If the world became so cold that even primates with hairy coats were threatened by the elements, then the need to move indoors would arise.  But, would they really have survived for so long (generations upon generations) that this evolved intellect would have developed anyway?

I dunno.  It all seems very weird to me.  Discuss.  All "idiot" comments are welcome.  All I know is that DNA/RNA replication is like working a copy machine.  A copy machine attempts to make an identical copy, but inevitably, every 'copy' has a few noticeable changes here and there, and when you make copies of copies, and then copies of copies of copies, these changes become more apparent over time.  And, it takes many, many, many generations (excluding something like a frame-shift in DNA) for radical changes to become apparent.

Don't forget that preference plays a part in evolution in the choice of a mate for example, it's highly likely that chimps behinds are hairless because of the increased sex drive derived from this by both the male and female of the species especially given increased blood flow there. I don't believe there is any reason to restrict this particular trait to the immediate desire for sex especially when combined with a greater need for communication with ever larger brains, it's easier to see how a mate or another member of the species is feeling with less hair for example blushing or the incredibly nuanced human face.