Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 84 (8914 total)
Current session began: 
Page Loaded: 06-19-2019 3:56 AM
23 online now:
Tangle (1 member, 22 visitors)
Chatting now:  Chat room empty
Newest Member: 4petdinos
Post Volume:
Total: 854,110 Year: 9,146/19,786 Month: 1,568/2,119 Week: 328/576 Day: 3/128 Hour: 1/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Prev12
3
456
...
14NextFF
Author Topic:   why is the lack of "fur" positive Progression for humans?
RAZD
Member
Posts: 19871
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 5.3


Message 31 of 202 (449786)
01-19-2008 12:00 AM
Reply to: Message 30 by molbiogirl
01-18-2008 11:04 PM


That still doesn't address the initial reason for sexual selection. Why allofasudden is nekkid pretty?

Yet it is indisputable that bare nakedness is very integral to sexual attraction in humans.

This gillette ad for instance, "Venus - Inside Every Woman" is not about shopping for food. It's about how to be unnaturally bare in order to attract a mate.

I also don't think it was "sudden" but may have been a part of "hominid" features a very long time ago. Nor are we alone ...



(1st picture originally from http://www.bristolzoo.org.uk)
(2nd picture originally from http://www.hedweb.com/gorilfam.htm)

... it's just expressed in humans to the point of endangering survival (why we need clothes eh?), which is an indicator of Fisherian Runaway Sexual Selection, not of selection for fitness to an ecology.

Personally I think apparent bareness evolved before the savanna ecology, for reasons that I have laid out in Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution and specifically on message 65 of that thread.

quote:
The loss of long thick colorful terminal hair, typical of other apes, in favor of short thin pale vellus hair, as found on most of the human body skin areas, means that the insulation value of that hair has been lost. This insulation protects the individual from both heat and cold, modulating the extremes to provide a more constant "microclimate" for the individual. The loss of such insulation would leave the individual subject to both greater heat gain and greater heat loss without some other mechanism(s) to counteract these trends.

The savanna ecology would have greater temperature swings between day and night than a jungle-forest ecology.

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:
 Message 30 by molbiogirl, posted 01-18-2008 11:04 PM molbiogirl has not yet responded

  
MartinV 
Suspended Member (Idle past 3994 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 32 of 202 (449805)
01-19-2008 3:28 AM
Reply to: Message 15 by dwise1
01-18-2008 8:06 PM



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.

Other opinion is this: it isn't given fact that the head of child has to accomodate to the pelvis channel of mother. Because the other possibility shouldn't be excluded - it could be the pelvis channel that should accomodate during evolution to the child head. Of course there is correlation between the size of the pelvis channel and the size of the head of child. But the question is if other correspondences can be really excluded. We should take into consideration that by many "nest-runaway" species there is reversible change of pelvis-form in the time of birth.

Gorilla having weight 100kg deliver of offsprings which have weight 1,8 kg with brain weight 0,2 kg. Woman (cca 50-75kg) give birth to children having weight 3,2 kg with brain cca 0,37 kg. The proportion between legs, arms and trunk are by primates' youngs very similar to those of adults. By human children the relations are distorted and correspond more to embryo. It will last one year in extra-uterus development until it will be similar to adults.


This message is a reply to:
 Message 15 by dwise1, posted 01-18-2008 8:06 PM dwise1 has not yet responded

Replies to this message:
 Message 33 by Rrhain, posted 01-19-2008 3:55 AM MartinV has not yet responded

  
Rrhain
Member (Idle past 38 days)
Posts: 6349
From: San Diego, CA, USA
Joined: 05-03-2003


Message 33 of 202 (449807)
01-19-2008 3:55 AM
Reply to: Message 32 by MartinV
01-19-2008 3:28 AM


MartinV writes:

quote:
it could be the pelvis channel that should accomodate during evolution to the child head.

But one of those things is more malleable than the other. When you press a piece of putty to the wall, the interface between them becomes complimentary, but it isn't the wall that's adjusting to the putty.

Now, while it is true the bones of the pelvis will shift during childbirth, they aren't going to shift nearly as much the fetus will be able to. Notice, childbirth is pretty taxing on the fetus as it is. It needs to turn upside down (which happens late) and then needs to pretty much corkscrew its way out in order to make it not only through the pelvic opening but around and by the sacral curves.

If there were a pressure on the female body to make it easer for childbirth, then the pelvis would be much more accomodating than it currently is. Since it isn't, since the fetal morphology is the one doing most of the work, it would appear that it is easier to adapt the fetus to the mother than the mother to the fetus.


Rrhain

Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.
This message is a reply to:
 Message 32 by MartinV, posted 01-19-2008 3:28 AM MartinV has not yet responded

    
nator
Member (Idle past 335 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 34 of 202 (449848)
01-19-2008 12:40 PM
Reply to: Message 19 by RAZD
01-18-2008 8:56 PM


quote:
So sweating explains bare appearance in humans how?

I don't know, I'm just adressing what you said comparing dogs and horses.

If I misunderstood, oh well.


This message is a reply to:
 Message 19 by RAZD, posted 01-18-2008 8:56 PM RAZD has responded

Replies to this message:
 Message 35 by RAZD, posted 01-19-2008 6:52 PM nator has not yet responded

    
RAZD
Member
Posts: 19871
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 5.3


Message 35 of 202 (449908)
01-19-2008 6:52 PM
Reply to: Message 34 by nator
01-19-2008 12:40 PM


I was using horses to show that sweating and running are not necessarily linked.

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:
 Message 34 by nator, posted 01-19-2008 12:40 PM nator has not yet responded

  
Doddy
Member (Idle past 4075 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 36 of 202 (450642)
01-22-2008 11:35 PM
Reply to: Message 30 by molbiogirl
01-18-2008 11:04 PM


Armchair speculation
molbiogirl writes:

That still doesn't address the initial reason for sexual selection.


I guess I can speculate as to why this form of sexual attraction would be kept and become mostly dominant in the population.

One reason, using the Handicap principle, may be that, like the peacock's tail, not having hair is selected for because it is disadvantage. A female that can stand the temperature changes is obviously very healthy (or very capable of making clothing, shelter or fire), and hence would be a good potential mate.

One other hypothesis could be that Homo sapiens was less hairy than [/i]Homo neanderthalensis[/i]. Interbreeding may have occurred between the two, but the Neanderthals might have been incompatible with the humans. So, a human seeking a less hairy human would be more likely to have mating efforts rewarded with offspring. But why would the women be less hairy than the men, you may ask? Perhaps it was the case that women had little choice in a mate, or maybe just luck that the mutation for this type of sexual attraction happened to affect the male brain more so.

Lastly, perhaps hairlessness was in fact an advantage for males to be running or some other such activity, but sexual selection occurred in addition to this. That is, a mutation that cause a male to prefer hairless females results in that male having sons who are better at hunting. Why should such a mutation be selected against once it had occurred?


Help to inform the public - contribute to the EvoWiki today!

This is what we are up against. There are thousands around the world more being (home-)schooled in the same way. But the internet is far reaching! Teach evolution by joining the Evolution Education Wiki today!


This message is a reply to:
 Message 30 by molbiogirl, posted 01-18-2008 11:04 PM molbiogirl has not yet responded

Replies to this message:
 Message 37 by RAZD, posted 01-23-2008 7:51 AM Doddy has not yet responded

    
RAZD
Member
Posts: 19871
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 5.3


Message 37 of 202 (450683)
01-23-2008 7:51 AM
Reply to: Message 36 by Doddy
01-22-2008 11:35 PM


Re: Armchair speculation
Small point\quibble

Lastly, perhaps hairlessness was in fact an advantage ...

We are not hairless nor even have fewer number of hairs than an ape our size should have, what we have are less developed hairs. Where we see apparent bareness the skin is covered with vellus hair instead of terminal hair, especially on the female

One reason, using the Handicap principle, may be that, like the peacock's tail, not having hair is selected for because it is disadvantage. A female that can stand the temperature changes is obviously very healthy (or very capable of making clothing, shelter or fire), and hence would be a good potential mate.

Or because the female looks younger, more like a child than an adult capable of reproduction, they are more protected and cared for, thus giving their offspring an advantage.

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:
 Message 36 by Doddy, posted 01-22-2008 11:35 PM Doddy has not yet responded

Replies to this message:
 Message 53 by dogrelata, posted 08-29-2008 1:38 PM RAZD has acknowledged this reply

  
macaroniandcheese 
Suspended Member (Idle past 2093 days)
Posts: 4258
Joined: 05-24-2004


Message 38 of 202 (450727)
01-23-2008 11:46 AM
Reply to: Message 15 by dwise1
01-18-2008 8:06 PM


i wonder if there has been an increase in maternal mortality due to large-headed babies since the invention of the c-section. i.e. large-headedness can survive sometimes, but when a c-section isn't available, the mother is more likely to die.
This message is a reply to:
 Message 15 by dwise1, posted 01-18-2008 8:06 PM dwise1 has not yet responded

Replies to this message:
 Message 39 by Jaderis, posted 01-23-2008 2:07 PM macaroniandcheese has responded

  
Jaderis
Member (Idle past 1590 days)
Posts: 622
From: NY,NY
Joined: 06-16-2006


Message 39 of 202 (450753)
01-23-2008 2:07 PM
Reply to: Message 38 by macaroniandcheese
01-23-2008 11:46 AM


i wonder if there has been an increase in maternal mortality due to large-headed babies since the invention of the c-section. i.e. large-headedness can survive sometimes, but when a c-section isn't available, the mother is more likely to die.

I've had similar thoughts, but I think that that larger head size being passed along would only occur (or much more frequently) in those areas with c-sections readily available. The mortality rate would probably only increase in the relatively rare instances where the mother was not able to reach a hospital or chose/was forced not to utilize hospital services even in an emergency.

In areas where c-sections are not readily available, large-headedness would not be passed along as much and therefore the mortality rates would probably remain much the same as it ever was.

I could be completely wrong, of course.


"You are metaphysicians. You can prove anything by metaphysics; and having done so, every metaphysician can prove every other metaphysician wrong--to his own satisfaction. You are anarchists in the realm of thought. And you are mad cosmos-makers. Each of you dwells in a cosmos of his own making, created out of his own fancies and desires. You do not know the real world in which you live, and your thinking has no place in the real world except in so far as it is phenomena of mental aberration." -The Iron Heel by Jack London

"Hazards exist that are not marked" - some bar in Chelsea


This message is a reply to:
 Message 38 by macaroniandcheese, posted 01-23-2008 11:46 AM macaroniandcheese has responded

Replies to this message:
 Message 40 by macaroniandcheese, posted 01-23-2008 3:49 PM Jaderis has not yet responded

    
macaroniandcheese 
Suspended Member (Idle past 2093 days)
Posts: 4258
Joined: 05-24-2004


Message 40 of 202 (450761)
01-23-2008 3:49 PM
Reply to: Message 39 by Jaderis
01-23-2008 2:07 PM


the more important issue is where the parents were born, then, and not where the current pregnancy is taking place. or rather, whether the current pregnancy is taking place in an area with less access to c-sections.
This message is a reply to:
 Message 39 by Jaderis, posted 01-23-2008 2:07 PM Jaderis has not yet responded

  
Jon
Inactive Member


Message 41 of 202 (450873)
01-24-2008 2:00 PM
Reply to: Message 23 by RAZD
01-18-2008 9:30 PM


Men - from nearly bare to covered in hair, all having little trouble finding mates, trait not selected at all.

All? I do not know if I would say 'all' :o

Jon


Beware the Jabberwock, my son!
This message is a reply to:
 Message 23 by RAZD, posted 01-18-2008 9:30 PM RAZD has acknowledged this reply

  
TheTruth
Member (Idle past 4030 days)
Posts: 60
Joined: 02-11-2008


Message 42 of 202 (455821)
02-13-2008 9:55 PM
Reply to: Message 1 by LouieP
01-15-2008 12:27 PM


or it could be because God used intelligent disign and made us that way
This message is a reply to:
 Message 1 by LouieP, posted 01-15-2008 12:27 PM LouieP has not yet responded

Replies to this message:
 Message 43 by TheTruth, posted 02-13-2008 10:04 PM TheTruth has not yet responded

    
TheTruth
Member (Idle past 4030 days)
Posts: 60
Joined: 02-11-2008


Message 43 of 202 (455824)
02-13-2008 10:04 PM
Reply to: Message 42 by TheTruth
02-13-2008 9:55 PM


besides the fact if we evolved then we start reevolving in the womb am i right but funny thing we have little to no hair and if we evolved next generations would have less and less hair but that isn't true look at history dark ages long hair then we cut it hippies long hair the we cut it new age long hair it is a stretch to say that we evolved out of fur not historical finds show any evidence of excess body hair in previous years
This message is a reply to:
 Message 42 by TheTruth, posted 02-13-2008 9:55 PM TheTruth has not yet responded

Replies to this message:
 Message 44 by Vacate, posted 02-14-2008 12:22 AM TheTruth has responded
 Message 46 by Wounded King, posted 02-14-2008 12:17 PM TheTruth has responded

    
Vacate
Member (Idle past 2766 days)
Posts: 565
Joined: 10-01-2006


Message 44 of 202 (455836)
02-14-2008 12:22 AM
Reply to: Message 43 by TheTruth
02-13-2008 10:04 PM


besides the fact if we evolved then we start reevolving in the womb am i right

Sorry, you are incorrect. An individual does not evolve, populations evolve.

but funny thing we have little to no hair and if we evolved next generations would have less and less hair but that isn't true

Correct. Its not true that we must have less and less hair. Evolution is not in a specific direction, nor is it specifically taking place in each generation.

long hair then we cut it hippies long hair the we cut it new age long hair

This is not an indicator of evolution in one direction or another, what point does it serve?

historical finds show any evidence of excess body hair in previous years

Look further back. You appear to think that Shakespeare should have looked like a monkey.


This message is a reply to:
 Message 43 by TheTruth, posted 02-13-2008 10:04 PM TheTruth has responded

Replies to this message:
 Message 45 by TheTruth, posted 02-14-2008 12:10 PM Vacate has responded

  
TheTruth
Member (Idle past 4030 days)
Posts: 60
Joined: 02-11-2008


Message 45 of 202 (455885)
02-14-2008 12:10 PM
Reply to: Message 44 by Vacate
02-14-2008 12:22 AM


ok the last one was a typo it was supposed to say no historical evidence so im saying never was a man a monkey man was man and monkey was monkey there may have been a cross breed im not denying that i was saying hypotheticaly in the womb a person starts in the "fish stage" and progresses to a human by the third trimester but i don't think that i think it is a human from conception
This message is a reply to:
 Message 44 by Vacate, posted 02-14-2008 12:22 AM Vacate has responded

Replies to this message:
 Message 49 by Vacate, posted 02-15-2008 12:10 AM TheTruth has not yet responded

    
Prev12
3
456
...
14NextFF
Newer Topic | Older Topic
Jump to:


Copyright 2001-2018 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2019