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Author Topic:   why is the lack of "fur" positive Progression for humans?
LouieP
Junior Member (Idle past 5328 days)
Posts: 12
From: Schererville, IN
Joined: 01-02-2008


Message 1 of 202 (448829)
01-15-2008 12:27 PM


hello guys i have a couple of questions that i would possibly like to see ideas on.
one is, how is the lack of "fur" a positive thing in our evolution separating us from modern day ape "cousins" what did we gain from the loss of fur that allowed the less hairy ancestors more able to survive.
Edited by LouieP, : not specific enough i hope this fixes it

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AdminNWR
Inactive Member


Message 2 of 202 (448840)
01-15-2008 12:45 PM
Reply to: Message 1 by LouieP
01-15-2008 12:27 PM


Needs a better title
We like to keep topics reasonably focussed. Your title is overly broad. If you can find something more specific ("human frailty and loss of fur" comes to mind as one possibility), then I will promote your topic.
Simply edit your opening post, and change the title to your improved choice. If other changes are appropriate, make those at the same time. Then reply to this message so I will know that your are ready to have the topic reconsidered.


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AdminNWR
Inactive Member


Message 3 of 202 (449621)
01-18-2008 2:23 PM


Thread moved here from the Proposed New Topics forum.

  
dwise1
Member
Posts: 5558
Joined: 05-02-2006
Member Rating: 2.9


Message 4 of 202 (449629)
01-18-2008 2:43 PM
Reply to: Message 1 by LouieP
01-15-2008 12:27 PM


Ever try to run long distances in a fur coat?
We're runners. One hunting strategy is to chase the animal until it collapses. We can run over long distances whereas animals with fur coats overheat and drop from heat exhaustion. They might be able to sprint faster than us, but over the long haul they just cannot keep up with our pace. Even if it takes a few days (and I have heard accounts of such hunts by bushmen), we can run just about any other animal into the ground.
Ever see someone out jogging with their dog? The jogger sweats over the entire surface of his body and is thus able to throw off excess body heat over the entire surface of his body. The dog can only throw off excess body heat through his tongue and the pads on his feet. If the jogger isn't careful, he could easily run his best friend to death, especially on a hot day.
Edited by dwise1, : No reason given.

{When you search for God, y}ou can't go to the people who believe already. They've made up their minds and want to convince you of their own personal heresy.
("The Jehovah Contract", AKA "Der Jehova-Vertrag", by Viktor Koman, 1984)
Humans wrote the Bible; God wrote the world.
(from filk song "Word of God" by Dr. Catherine Faber, No webpage found at provided URL: http://www.echoschildren.org/CDlyrics/WORDGOD.HTML)
Of course, if Dr. Mortimer's surmise should be correct and we are dealing with forces outside the ordinary laws of Nature, there is an end of our investigation. But we are bound to exhaust all other hypotheses before falling back upon this one.
(Sherlock Holmes in The Hound of the Baskervilles)
Gentry's case depends upon his halos remaining a mystery. Once a naturalistic explanation is discovered, his claim of a supernatural origin is washed up. So he will not give aid or support to suggestions that might resolve the mystery. Science works toward an increase in knowledge; creationism depends upon a lack of it. Science promotes the open-ended search; creationism supports giving up and looking no further. It is clear which method Gentry advocates.
("Gentry's Tiny Mystery -- Unsupported by Geology" by J. Richard Wakefield, Creation/Evolution Issue XXII, Winter 1987-1988, pp 31-32)

This message is a reply to:
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nwr
Member
Posts: 6227
From: Geneva, Illinois
Joined: 08-08-2005
Member Rating: 3.6


Message 5 of 202 (449632)
01-18-2008 2:55 PM
Reply to: Message 1 by LouieP
01-15-2008 12:27 PM


socialization
I'll give an opinion.
The loss of fur, particularly for a child, makes the child more dependent on the community. This dependence makes it easier for the child to learn to be a cooperative member of the society. It is the fact that humans are social (live in societies and mutually cooperate) that distinguishes humans. Sure, apes are also social, but not to nearly the same extent as humans.

Let's end the political smears

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molbiogirl
Member (Idle past 2129 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 6 of 202 (449645)
01-18-2008 3:31 PM
Reply to: Message 4 by dwise1
01-18-2008 2:43 PM


Ever try to run long distances in a fur coat?
Yup.
Dissipation of heat is the function that most conspicuously distinguishes human skin from that of all other animals. Removal of excess heat is greatly facilitated by the loss of body hair because it increases thermal conductance and permits additional heat loss through sweating.
A strong case can be made for the evolutionary loss of apocrine sweat glands in humans because these sweat glands are most common in heavily furred animals. The African apes exhibit a ratio of approximately 40% apocrine sweat glands to 60% eccrine; the great preponderance of eccrine sweat glands in modern humans probably evolved under the strong influence of natural selection, following the loss of the apocrine glands.
This process was probably propelled by increases in body size and activity levels associated with modern limb proportions and striding bipedalism.
And you very nearly nailed the title of a paper, dwise!
The Energetic Paradox of Human Running and Hominid Evolution
Current Anthropology, Vol. 25, No. 4 (Aug. - Oct., 1984), pp. 483-495
There is also this:
A naked ape would have fewer parasites
Proceedings of the Royal Society
Volume 270, Biology Letters Supplement 1 / August 07, 2003
According to this paper ...
Evolution of nakedness in Homo sapiens
Journal of Zoology 273 (1), 1-7.
... there are a dozen different hypotheses.
The cooling device hypothesis
The hunting hypothesis
The bipedality hypothesis
The allometry hypothesis
The clothing hypothesis
The vestiary hypothesis
Neoteny hypothesis
Carrion-eating hypothesis
Sex-related hypothesis
Aquatic ape hypothesis
Adaptation-against-ectoparasites hypothesis
The author kicks the snot out of all of them -- except parasites and ornamental.
As the ectoparasite burden on hominids increased, having fewer parasites may have become more important for survival than a warm fur coat. Natural selection may have started to favour shorter-haired and less parasite-ridden individuals, leading to the naked ape of today (Rantala, 1999). Selection pressure towards nudity may have been enforced by the many lethal diseases that are carried by blood-sucking ectoparasites. For example an outbreak of typhus, various forms of spotted fever, bubonic plague or any similar pandemic could have wiped out an entire fur-bearing segment of the human population (Olson, 1966).
This ”naked skin’ makes humans more vulnerable to UV radiation and to both high and low temperatures (Amaral, 1996). Furthermore, fur would protect humans from wounds, sores and insect bites, which may cause serious inflammations. A hairy individual also looks larger, which confers an advantage especially in sexual selection and in defence against predators. Thus, nakedness causes many clear costs for the naked ape.
In The Descent of Man, and Selection in Relation to Sex, Darwin argued that man, or rather primarily woman, became divested of hair for ornamental purposes and that women subsequently transmitted the sexual advantage of nakedness almost equally to their offspring of both sexes. Darwin (1871) had also collected evidence that many species had evolved features that were in themselves inconvenient or injurious, but that were retained because they were attractive to the opposite sex.

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MartinV 
Suspended Member (Idle past 5316 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 7 of 202 (449675)
01-18-2008 6:18 PM
Reply to: Message 1 by LouieP
01-15-2008 12:27 PM


Very intereting question. I am afraid neodarwinism have no coherent answer to it - there would be probably many untestable stories of evolution of it. I don't know when the fur evolves during embryonic development of apes. I would bet on late stages. In that case I guess the neoteny would be probably the answer of my taste. Human morphological development is so to say interrupted and people look most embryo-like comparing other primates. People are also so to say born prematurely, they should have been in uterus for one year more.
(and there is no physiological explanation why they are not. Those mothers who bear children longer should have had some survival advantage)
So the first year of their life they are totally dependent on their mothers and we can speak about social-uterus development. It coincides with following development of language, stance etc which cannot be reduced and compared to other primates. Human are special and on my opinion their evolution cannot be explained by evolution of primates.

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RAZD
Member (Idle past 892 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 8 of 202 (449688)
01-18-2008 6:56 PM
Reply to: Message 4 by dwise1
01-18-2008 2:43 PM


We're runners. One hunting strategy is to chase the animal until it collapses. We can run over long distances whereas animals with fur coats overheat and drop from heat exhaustion.
Which explains why all the animals in Africa are covered in fur, and the male human is hairier than the female. Or are you saying that humans can run faster than animals and women did all the hunting??
Ever see someone out jogging with their dog? The jogger sweats over the entire surface of his body and is thus able to throw off excess body heat over the entire surface of his body. The dog can only throw off excess body heat through his tongue and the pads on his feet. If the jogger isn't careful, he could easily run his best friend to death, especially on a hot day.
Ever tried that with a horse?
Sorry but this "explanation" just does not add up.
Enjoy.
Edited by RAZD, : dimorphism is part of the equation
Edited by RAZD, : .

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


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RAZD
Member (Idle past 892 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 9 of 202 (449691)
01-18-2008 7:07 PM
Reply to: Message 6 by molbiogirl
01-18-2008 3:31 PM


This process was probably propelled by increases in body size and activity levels associated with modern limb proportions and striding bipedalism.
Which doesn't explain the sexual dimorphism in hairiness.
It was probably more likely propelled by sexual selection for younger more childlike appearance in mates.
See Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution for another view on this subject.
This process was probably propelled by increases in body size and activity levels associated with modern limb proportions and striding bipedalism.
I wouldn't be surprised to find that the first hominid ancestor that was "bare" appearing predates the formation of the savanna ecology in africa.
Enjoy.
Edited by RAZD, : .

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


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RAZD
Member (Idle past 892 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 10 of 202 (449700)
01-18-2008 7:40 PM
Reply to: Message 1 by LouieP
01-15-2008 12:27 PM


... what did we gain from the loss of fur that allowed the less hairy ancestors more able to survive.
It may surprise you to learn that we have as many hair follicles as a ape would have for our body size. See Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution - Addendum #1, Human Body Hair and Female Pattern 'Bareness'
quote:
If loss of hair was an important variable in thermoregulation then we would expect {evolutionary pressure \ natural selection} to show a broad trend of hair thickness variations that could be correlated with the need to {retain\dissipate} heat.
We do see this. From the same source, here discussing the need of larger bodies to {retain less \ dissipate more} heat due to the increase in volume as the cube but skin area as the square of a size dimension:
To drive this point home, the number of hairs on the human body are precisely what they should be for the human body size. We are not displaced on the scale. There is no special loss of hair required for thermoregulation, and thus there is no special mechanism needed to provide for the loss of hair: no mutation is needed for the explanation of amount of human body hair. (1)
What is different is that the hair does not mature beyond childhood (vellus) hair for almost all females and major portions of males. Mature (terminal) hair grows on the head, pubic and armpit areas on both sexes and on the face, chest, back and arms on males.
What we see is that that female skin areas are covered with vellus hair, rather than terminal hair. Male pre-pubescent youth skin areas are also covered with vellus hair, rather than terminal hair.
Sexual dimorphism points towards sexual selection being a factor.
Retention of youthful characteristics into adulthood (neoteny) is well marked in human evolution, in facial characteristics (especially jaw and teeth) compared to other apes and in the long time it takes for humans to reach maturity after becoming sexually able.
This is either another example of neoteny in humans or it is the raison d'etre for neoteny (ie sexual selection for younger appearing females).
Enjoy.
Edited by RAZD, : .

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
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nator
Member (Idle past 1657 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 11 of 202 (449703)
01-18-2008 7:48 PM
Reply to: Message 8 by RAZD
01-18-2008 6:56 PM


Ever see someone out jogging with their dog? The jogger sweats over the entire surface of his body and is thus able to throw off excess body heat over the entire surface of his body. The dog can only throw off excess body heat through his tongue and the pads on his feet. If the jogger isn't careful, he could easily run his best friend to death, especially on a hot day.
quote:
Ever tried that with a horse?
Of course, horses sweat over their entire bodies.

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dwise1
Member
Posts: 5558
Joined: 05-02-2006
Member Rating: 2.9


Message 12 of 202 (449706)
01-18-2008 7:50 PM
Reply to: Message 8 by RAZD
01-18-2008 6:56 PM


dwise1 writes:
We're runners. One hunting strategy is to chase the animal until it collapses. We can run over long distances whereas animals with fur coats overheat and drop from heat exhaustion.
Which explains why all the animals in Africa are covered in fur. Or are you saying that humans can run faster than animals?
Not faster, but farther. Take for example, the cheetah, which is the fastest land animal. In a 100-yard dash, it would beat us hands ... er ... paws-down. But who would win a 1-mile run? Not the cheetah, that's for sure. Though in the cheetah's case it wouldn't be from overheating, but rather from anoxia. As I recall, the cheetah holds its breath, or at least hardly breathes at all, when it runs. It's built for isolated sudden bursts of high speed, not for any kind of real distance. Remember, I was talking about distance running.
As Molbiogirl pointed out, there are many advantages to fur, so why shouldn't most animals in Africa have fur? Notice also that none of them are shaggy, but rather a smooth-hairs, which is in keeping with a hot climate. Notice also that we aren't the only nekkid critters out there, but there are also hippos, rhinos, and elephants.
Remember also that the excess body heat I'm talking about is generated by the act of running. Not just from walking about in the noon-day sun, but from running.
We are built for running long distances. Very few other animals are.
dwise1 writes:
Ever see someone out jogging with their dog? The jogger sweats over the entire surface of his body and is thus able to throw off excess body heat over the entire surface of his body. The dog can only throw off excess body heat through his tongue and the pads on his feet. If the jogger isn't careful, he could easily run his best friend to death, especially on a hot day.
Ever tried that with a horse?
I'm a city boy, myself. But I seem to recall that horses do sweat through their skin, whereas dogs don't. Even with its fur, the horse should have much more cooling effect from its sweating through its skin than a dog would through its "sweating" only through its tongue and paw pads.
Though that still begs the question of whether a man could out-run a horse given a great enough distance. Remember, the horse may be faster over a shorter distance, but can the horse keep up its pace for longer than a man could? That is the real question.
So what do you think doesn't "add up"?
Edited by dwise1, : can a man outrun a horse?

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jar
Member
Posts: 33958
From: Texas!!
Joined: 04-20-2004


Message 13 of 202 (449707)
01-18-2008 7:57 PM
Reply to: Message 12 by dwise1
01-18-2008 7:50 PM


Wolves
Ever see a wolf Pack hunting? Deer running?

Anyone so limited that they can only spell a word one way is severely handicapped!

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NosyNed
Member
Posts: 8975
From: Canada
Joined: 04-04-2003


Message 14 of 202 (449710)
01-18-2008 8:02 PM
Reply to: Message 13 by jar
01-18-2008 7:57 PM


Running Farther
I have no backup but I think that humans can run down (over hours or days) anything on the African savanna. I've seen documentaries of Bushmen running in the sun for many, many hours until they have an antelope staggering and just walk up and spear it.
Wolves are only good for a shortish run (again no backup). I don' know about deer. My only source is a documentary showing a wolf after a young caribou. The claim was the wolf had to get it in the first mile.

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dwise1
Member
Posts: 5558
Joined: 05-02-2006
Member Rating: 2.9


Message 15 of 202 (449711)
01-18-2008 8:06 PM
Reply to: Message 7 by MartinV
01-18-2008 6:18 PM


People are also so to say born prematurely, they should have been in uterus for one year more.
(and there is no physiological explanation why they are not. Those mothers who bear children longer should have had some survival advantage)
So the first year of their life they are totally dependent on their mothers and we can speak about social-uterus development. It coincides with following development of language, stance etc which cannot be reduced and compared to other primates. Human are special and on my opinion their evolution cannot be explained by evolution of primates.
Suggest that to a woman, if you dare. In particular one who has given birth.
The problem with a bigger brain is that the head also needs to be big enough to accommodate it. Let a fetus mature for a year in the womb and then try to fit that huge head through the birth canal. It simply would not fit. Sure, we could to a C-section, but how long has that been an option? (hint: "C" stands for "Caesar"). Certainly not back when we were evolving a bigger brain.
In case you still don't realize what the survival advantage of giving birth to a child with a fully grown brain, the answer is zero. Those women would die in childbirth, leaving the baby, should it through some incredible miracle survive the ordeal, without a mother to care for it.
Rather, a human neonate has only a partially grown brain and a partially developed skull, just so it can squeeze through the birth canal -- and it's a very tight squeeze even then. The rest of the development of the brain and skull occurs after it is born. Yes, that means that it's much more dependent and unable to care for itself when it's born, but the survival advantages are very obvious (in case they are not obvious to you: bigger brain, survival of the mother, development of social structures to ensure care of the infant, development of marital bonds between the parents to also ensure care of the infant, continued nurturing of the child to full maturity).

{When you search for God, y}ou can't go to the people who believe already. They've made up their minds and want to convince you of their own personal heresy.
("The Jehovah Contract", AKA "Der Jehova-Vertrag", by Viktor Koman, 1984)
Humans wrote the Bible; God wrote the world.
(from filk song "Word of God" by Dr. Catherine Faber, No webpage found at provided URL: http://www.echoschildren.org/CDlyrics/WORDGOD.HTML)
Of course, if Dr. Mortimer's surmise should be correct and we are dealing with forces outside the ordinary laws of Nature, there is an end of our investigation. But we are bound to exhaust all other hypotheses before falling back upon this one.
(Sherlock Holmes in The Hound of the Baskervilles)
Gentry's case depends upon his halos remaining a mystery. Once a naturalistic explanation is discovered, his claim of a supernatural origin is washed up. So he will not give aid or support to suggestions that might resolve the mystery. Science works toward an increase in knowledge; creationism depends upon a lack of it. Science promotes the open-ended search; creationism supports giving up and looking no further. It is clear which method Gentry advocates.
("Gentry's Tiny Mystery -- Unsupported by Geology" by J. Richard Wakefield, Creation/Evolution Issue XXII, Winter 1987-1988, pp 31-32)

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