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Author Topic:   Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
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Message 37 of 131 (205874)
05-07-2005 4:19 PM
Reply to: Message 36 by EZscience
05-05-2005 3:42 PM


Re: Endosymbiosis
yep, thats the one.
perhaps that was the first "sex" ?
if you consider sex to be a sharing of DNA between two parents to make an offsring with features that come from both parents ...
the question left for me, though, is whether the {mitochondrial donor} was a willing (injecting?) participant or an unwilling (consumed) participant, and one that evolved a defence against being digested.

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 40 of 131 (206971)
05-11-2005 7:22 AM
Reply to: Message 39 by EZscience
05-11-2005 5:59 AM


Re: Fisherian 'runaway' sexual selection example
Good stuff again. Doesn't seem to be on the PNAS (Proceedings of the National Academy of Sciences) website yet.
I am still waiting to see if any IDist (like Jerry) can identify a specific {just created} stage in the fossil record and then demonstrate devolution from that point on. But that's another thread.
{{edited to correct typo ... wegsite? perhaps a freudian link to wigsite? lol}}
This message has been edited by RAZD, 05*13*2005 08:24 PM

we are limited in our ability to understand
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RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 41 of 131 (207252)
05-11-2005 10:04 PM


Addendum #1, Human Body Hair and Female Pattern 'Bareness'

Addendum #1

In the original post on this thread I introduced a number of features that I felt fit the pattern of run-away sexual selection.
Possibly the most contentious of these was the Skin hair thinness issue at the end.
Let's look at this issue in a little more detail.
From Human Thermoregulation and Hair Loss (click)
Body hair is one of the most important features of the mammal thermoregulatory system. Hair can act as an important heat retention and heat prevention device in mammals. By trapping a layer of dead air against the skin, a layer of hair can act as an extremely efficient insulation, reducing the rate of convective heat loss to the environment. However, this exact same system acts as a way to prevent heat gain from the environment by the same principle; by using this layer of dead air to reduce the rate of convective heat gain from the environment to the skin. Besides insulation, the layer of hair on mammals is important in reducing the radiation from direct and indirect sunlight, and can thus act to reduce heat gain from the environment in two ways.
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:
The obvious solution to this situation is decreased body hair with increasing body size, which is exactly what is seen in anthropoids. When the number of hair follicles present in species per unit of area is compared with body size, all primates (including humans) fit along a regular log linear regression line, along which the density of hair per unit of area decreases as body size increases. Species like chimpanzees and gorillas have relatively fewer hair follicles per unit area of skin compared to the smaller monkeys. Humans fall along this line, and have a relative hair density almost the same as seen in chimpanzees, gorillas and orangutans.
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) Let's continue:
The difference between the thick pelage of the Great Apes and humans is not in terms of the density of hair, but in its length and thickness and the production of vellus hair in most humans to the exclusion of terminal hair on the body. Humans are not "hairless", but are merely covered by thinner, smaller and unpigmented hair (Schwartz & Rosenblum 1981; Schultz 1931).
This may seem like an obvious point (although 'underpigmented' might be better than unpigmented: it's not albinoism).
Now to better understand the distinction here, we need to know what vellus hair is and how it differs from terminal hair.
Types of Hair (click)
There are three types of hair:
*lanugo: fetal hair
*vellus: replace lanugo hairs in the peripartum period, unmedullated
*terminal hairs: long, coarse, medullated; typified by scalp and pubic regions
And from Hair Growth, Classification of Hair (click):
Human hair varies with respect to texture, color, and length.
*Lanugo hairs cover most of the fetal skin and shed perinatally. These lightly pigmented hairs are fine in texture.
*Thicker and darker than lanugo hairs, vellus hairs cover most of the glabrous skin surface except palms, soles, palmar and plantar surfaces of fingers and toes, inner aspect of the prepuce, and the glans penis.
*Darkly pigmented terminal hairs are long and thick and most commonly are located on the scalp and the facial areas of men. These hairs can reach a preprogrammed length based on length of the anagen phase. Ultimately, terminal hairs undergo involution and convert to catagen and then to telogen phase. The mechanism and factors that induce the hair to terminate growth and involute are largely unknown.
And from Wikipedia: Vellus hair - Wikipedia
Vellus hair is a very soft and short hair that grows in most places on the human body in both sexes. In Caucasians it is often colourless, or blonde. It is best seen in women and children, as they have less terminal hair to obscure it. Vellus hair is also found in pre-adolescents (Tanner stage 1) as well as in male pattern baldness.
Vellus hair is juvenile hair that is best seen in women? Other than facial hair, is there really that much difference in hair patterns between males and females? See information about a medical 'condition' called Masculine Hair Distribution (in a female):
This is excessive hair growth in an androgen dependent pattern. It is applied to females who complain of hair growth in the beard area, around the nipples and in a male pattern on the abdomen. Androgens induce the transformation of fine vellus hair into coarse terminal hair.
Female vellus hair that is transformed into terminal hair in a male pattern. As a bad thing.
Put this together with the "baby-faced-ness" and the issue of run-away sexual selection of
Human Skin hair thinness is seen as two results of the same process: juvenile features selected for in the female of the species. And considering that the bareness of the human female could not get much further developed without some mutation to actually decrease the numbers of hairs on the human body, I would say that it has been carried to the extreme condition that is characteristic of a fully developed run-away mechanism.
Enjoy.

(1) -- This is for those that followed the {evolution of clothes) thread or that have seen a particular message of mine referring to sexual selection "blocking" the selection of a mutation for less hair in non-human species. I had claimed that a mutation was not necessary to explain the apparent bareness, just selection of already occurring variations within the population.
Jar please take note, as this specifically addresses the point you raised in msg 86 (click) of that thread: mutation is not needed to explain human body hair.
But I also could have been clearer on what was being "blocked" and why: normal sexual selection revolves around the 'norm' of the species (tendency for stasis) and abnormalities are rejected, sometimes viciously, sometimes just by refusal to mate. Albinism is a recurring condition due to a recessive gene mutation. Usually albinos do not have high success in mating. A similar mutation in a dominant gene is not observed, although it has likely occurred in the past: failure to observe it is possible evidence of acute selection against it in mating success. You also have the Greenish Asian Warbler ring species where two subspecies do not mate (even though each other subspecies does around the ring) because they are viewed as just too different.
Any randomly occuring mutation for bareness would run into this problem. And such mutations do occur: we have the hairless cat (click) as a result of such a mutation and selective breeding by humans.
{{edited subtitle and first line to make room for a followup addendum, added line above footnote}}
Enjoy.
{{added by edit: the next addendum is
Addendum #2 Message 65- Enabling Mechanisms
end edit}}
This message has been edited by RAZD, 06*02*2005 07:57 AM

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

Replies to this message:
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 42 of 131 (207899)
05-13-2005 8:39 PM
Reply to: Message 4 by AdminJar
04-23-2005 8:09 PM


Still too long for an OP?
btw jar, no offense, but I felt that because you were involved in the other discussion(s) that another view would be appropriate. I have also added an addendum that would have made the OP even bigger, and have another one planned to finish my presentation on this topic.
Please note that I also address your question about mutations in the addendum in greater detail (see the footnote).
cheers.

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 44 of 131 (207926)
05-13-2005 10:41 PM
Reply to: Message 43 by EZscience
05-13-2005 10:31 PM


Re: Addendum #1, Female Pattern 'Bareness'
put the shoe on the other foot: the females are being selected for mating based on their bareness, not the males.
the evidence is (1) greater expression of the feature in females than in males and (2) greater consistency of expression in females than in males
if males are not being selected for bareness (while females are) then they should exhibit more variation in hairiness than females: they do.
this also correlates with babyfacedness being selected for in females but not in males.
this was part of my point on sexual dimorphism in the OP, if you remember.
the next question on whether Fisherian Runaway is involved is if any disadvantage can be identified and whether any possible compensatory mechanisms become involved (the answer here is yes, but that is the next addendum...)

we are limited in our ability to understand
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RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

This message is a reply to:
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 46 of 131 (207928)
05-13-2005 11:01 PM
Reply to: Message 45 by EZscience
05-13-2005 10:49 PM


Re: Addendum #1, Female Pattern 'Bareness'
heh
I saw that as I was signing off again.
answers (a little short as my brain is already in bed)
1 - vary significantly against what background? we now have clothes that hide this feature and the possibility that we have already reached the extreme possible. see article on male hair pattern (in women) cited above for some evidence of this still operating. and current mating patterns are not necessarily ones in practice when the issue was selectively involved.
2 - a male could also be dominant in a group and choose who to mate with -- look at the difference in "age" of genetic "adam" versus genetic "eve" -- while restricting other males activities. his dominance gives his offspring advantage.
more tommorrow. must. sleep.

we are limited in our ability to understand
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RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 47 of 131 (208066)
05-14-2005 12:37 PM
Reply to: Message 39 by EZscience
05-11-2005 5:59 AM


Re: Fisherian 'runaway' sexual selection example
EZ:
I am further answering your last post with an answer to this one, as the concept is linked: you quote the Globe and Mail article with:
EZscience, msg 39 writes:
"A study of mosquitofish guppy-like creatures that feed on mosquito larvae shows that females definitely prefer well-endowed males to their shrimpier brothers."
"But sex aside, being bigger isn't necessarily better. Male mosquitofish with large genitalia have a greater risk of dying even if it is with a smile. That's because mosquitofish with large genitalia known as a gonopodium can't swim as quickly..."
"All females had the same preference..."
Let me augment that with a larger quote:
To test for mating preference, 50 female mosquitofish were placed in separate aquariums, which were each furnished with side-by-side video screens showing the same male mosquitofish: on one screen he was life-sized, on the other his genitalia had been digitally enhanced by 15 per cent.
They chose the larger one over and over. All females had the same preference, Mr. Langerhans said, noting that they spent 80 per cent more time at the end of the tank with the screen showing the more amply endowed male.
Now the question arises, is female bareness similar. your last post asks
1. Females would have to vary significantly in reproductive success based on degree of hairiness (No evidence, I suggest)
And I would say that we have the same kind of evidence as provided for the mosquitofish, and it is readily available to anyone on the internet (well anyone without netnanny ...)
I submit to you that internet porn demonstrates extreme and continued attraction to and selection for bare females, exactly like that displayed by the female mosquitofish to the fish porn movies.
That even if you google "hirsute women pictures" that what you will get is not sites of women with hairy chests, beards, backs and the like, but just pictures of currently "normal" bare women that are not shaved.
And most porn sites show unnaturally bare women, just as ads and magazines promote the extra baring of the female body with creams, surgical procedures and thousands of kinds of razors to remove "unwanted" hair. From this article in USA today:
"More attention is being paid to the leg, which means more attention is being paid to hair removal and the razor and technology," says Marshal Cohen, trend watcher for fashion and retail tracker, The NPD Group. "The whole shaving and hair removal business has just begun. We haven't even gotten to the root of the business."
I also refer you (again) to the medical "condition" called Masculine Hair Distribution (in a female):
This is excessive hair growth in an androgen dependent pattern. It is applied to females who complain of hair growth in the beard area, around the nipples and in a male pattern on the abdomen. Androgens induce the transformation of fine vellus hair into coarse terminal hair.
I would say this selection is so prevalent that even women are actively engaged in it (as well as men) in order to attract mates, and that they seek to {remove\suppress} their body hair growth to an unnatural level (and get depressed if they cannot).
Remember that one of the criteria is that features selected for have reached a point where they can not occur normally: even longer tail feathers, even bigger gonopodium, even more babyfaced-ness, etc.
And I would close by saying that the variance of hairiness in the population is not from hirsute male type hairiness, but from almost bare to nearly almost completely bare appearance, so the female population is already highly skewed.
What say?

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

This message is a reply to:
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 49 of 131 (208107)
05-14-2005 4:08 PM
Reply to: Message 48 by EZscience
05-14-2005 2:04 PM


Re: Human female hairlessness - a function of male choice ?
I'm not convinced that strict monogamy is (1) all that traditional and (b) required. Polygamy with more successful males being able to choose mates and more of them will also work, allowing more of his genes to be dispersed into the {more select} females thus spreading both the (xx) bareness genes and the (xy) preference for them. This also leaves the {less select} females to be divided between the remaining males with a more random result. Trickle down theory?
Certainly before 'marriage' was {codified}, behavior along these lines could reasonably be expected: we see similar behavior in chimpanzees (Pan troglodyte, Bonobos behavior is ... special ...), and it is rampant in Gorillas: but where the dominant male mates with (virtually) all females there is not much benefit to more attractiveness.
There is probably a small range of group dynamics that would allow such sexual selection, but one that includes known human behavior (consider successful men and attractive women and the propensity for human "affairs").
(2,3) I also think all the male needs to have done is provided a protected environment for his offspring and mate(s) and a ready supply quality food stuffs, to ensure their health and survival. But I think you are "right on" with the quality over quantity argument, especially in a species with limited offspring compared to the more fecund species (ie - the "choice" for quality is already selected).
Thanks for your insights.

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

This message is a reply to:
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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 51 of 131 (211625)
05-26-2005 9:56 PM
Reply to: Message 50 by EZscience
05-14-2005 8:00 PM


Re: Human female hairlessness - a function of male choice ?
ps - did you see this article?
http://biology.plosjournals.org/perlserv/?request=get-doc...
some evidence of sexual selection in males.

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 53 of 131 (211735)
05-27-2005 7:27 AM
Reply to: Message 52 by EZscience
05-26-2005 10:15 PM


Re: Human female hairlessness - a function of male choice ?
good. then you can help me understand why they say
We also tested if any chromosomes show an excess of genes with evidence for positive selection. The only chromosome enriched in genes with small p-values from the likelihood ratio test for positive selection is the X chromosome (p = 0.0049; MWU). Several factors influence the contrast between the X and autosomes in tests of selection, including hemizygosity of the X in males, resulting in more effective selection against deleterious recessive and in favor of positive recessive mutations [25]. Male hemizygosity also results in mutations, with male-specific effects being more readily fixed by selection on the X [26]. This increased efficiency of selection for male-specific genes on the X may explain the excess of X-linked genes expressed in spermatogonia [27]. The observation that reproductive proteins generally evolve at a greater rate, coupled with the overrepresentation of male-specific genes on the X, could produce the excess positive selection seen on the X. However, after eliminating all genes with highest expression levels in the testis, or annotated as functioning in spermatogenesis, there is still an excess of putatively positively selected genes on the X chromosome (p = 0.0131; MWU). Thus, it appears that the elevated positive selection on the X is likely due to the general tendency of mutations to be recessive, regardless of their tendency to be male-limited in expression.
and only talk about male fixing ... when they are also talking about the X chromosome (not the Y)? (it wouldn't have anything to do with 11 male and 2 female authors ...)

we are limited in our ability to understand
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RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 54 of 131 (211741)
05-27-2005 7:51 AM


for Catholic Scientist
from
EvC Forum: Trait changes in a species.
Catholic Scientist, {Trait changes in a species} thread, msg 12 writes:
Is it assumed that we only became hairless after we became human?
(probably could be worded better but I hope you understand the question)
Not necessarily, hair thinning could have occured earlier. One thing to note is that the eccrine glands are distributed over the body with the same pattern and density in Gorillas, Chimpanzees and Humans (in these two apes they are (possibly) linked with sexual pheromones). Only in Humans have these glands developed into sweat glands (necessary for overheat regulation). The eccrine glands on other apes are limited to the pads of {hand\feet}.

we are limited in our ability to understand
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RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 57 of 131 (212025)
05-27-2005 11:53 PM
Reply to: Message 56 by New Cat's Eye
05-27-2005 5:51 PM


Re: for Catholic Scientist
I'll get into this in greater detail later (I hope), but I think it (reduced hair) had to be spread over several generations as a minimum.
The problem with the hairless chimp is that it would likely have a very low survival rate in the wild (as opposed to a {temperature\climate} controlled enclosure) because the sudden loss of hair presents two simultaneous problems:
Too much exertion on a windless hot sunny day: in the absence of any mechanism to {shield\protect\divest} a body of excess heat, hyperthermia becomes a foregone conclusion, and likely to be fatal if no counteraction is taken. This happens to humans who lose the ability to sweat (or have maxed out their sweat-ability). See Hyperthermia - Wikipedia:
Body temperatures above 40C (104F) are considered life-threatening. At 41 C (106 F), brain death begins, and at 45C (113 F) death is nearly certain. Internal temperatures above 50 C (122 F) will cause rigidity in the muscles and, therefore, certain immediate death.
Signs include increasing body temperature (hyperpyrexia), dehydration and lack of sweating, seizures, collapse and decreased consciousness which proceeds rapidly to multi-organ failure and death as the brain 'cooks'.
On the opposite side is the problem of surviving cold windy rainy nights, with activity at a minimum, for then hypothermia becomes a foregone conclusion. This happens to humans that get wet when it is cool and windy. See Hypothermia - Wikipedia:
If body temperature falls below 32 C (90 F), the condition can become critical and eventually fatal. Body temperatures below 27 C (80 F) are almost uniformly fatal, though body temperatures as low as 14 C (57.5 F) have been survived.
If you've ever had your skin turn blue with goose-bumps and your teeth chatter when swimming on a summer day, you've experienced hypothermia (and "goose-bumps" are the retained muscle reaction to cold which made the body hairs stand on end to increase insulation value).
From 90 F to 104F is a pretty narrow window for acceptable body temperatures, and to expect any natural (uncontrolled) environment to always remain within those parameters for a body unable to adjust to changing conditions is very shortsighted. And this true for humans that evolved to have finer hair than all other apes at some distant pre-historic, pre-human art recorded time (if not a time millions of years ago).
The Serengeti Plain in Tanzania, home to Olduvai Gorge, is thought to be one of the ranges of early {hominids\humans}, and from Serengeti:
With altitudes ranging from 920 to 1,850 metres - higher than most of Europe - mean temperatures vary from 15 degrees to 25 degrees Celsius. It is coldest from June to October, particularly in the evenings.
That's 60F to 75 (F59F to 77F), and the "rainy season" lasts for months.
There are some things you can do to stave off the effects of {overheating\underheating}, but it would be virtually impossible to maintain them for months on end.
This makes a sudden change (by mutation or {medical\environmental} aberration) to a {thin\short} hair condition highly unlikely to survive long enough to breed a second generation without intervention of some kind.
I would not be surprised to find that the medical condition of the hairless chimpanzee is not any more uncommon than the condition is in humans, where it occurs in:
... approximately 1.7 percent of the population overall, including more than 4.7 million people in the United States alone according to the National Alopecia Areata Foundation.
But that it has not been observed before due to the poor individual survival prospects.
Enjoy.

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 59 of 131 (212099)
05-28-2005 10:26 AM
Reply to: Message 58 by New Cat's Eye
05-28-2005 12:43 AM


Re: for Catholic Scientist
bold added for emphasis
but, a lot of the evolutionary advances that I've learned about seem highly unlikely, so perhaps we can't rule this possibility out all toghether.
No highly unlikely or improbable event can be ruled out, especially where the evidence is thin. Like you say, {hair\fur} does not usually fossilize: but occasionally it does and we may get a surprise when that happens.
But in the case of hairless (which we aren't) apes evolving from a single individual, that individual has to survive from birth the breeding: one day of {fatal\extreme} enough weather in 10-11 years is within the experience of most people (check the coldest day on record, the hottest day on record, in the last 10 years).
Not to belabor the point, but those temps before were the means. From Page not found - Kabiza Wilderness Safaris
Extreme temperatures in Nairobi range from 50 degrees to 90 degrees.
and those are still not record 10 year extremes.
The essential difference between humans and the hairless chimpanzee however, is that we are not bare, and that in fact we have virtually the same numbers of hairs as chimpanzees. As noted in the Message 41
From Human Thermoregulation and Hair Loss (click) ...
When the number of hair follicles present in species per unit of area is compared with body size, all primates (including humans) fit along a regular log linear regression line, along which the density of hair per unit of area decreases as body size increases.
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.
The difference is not in the numbers of hairs but in the {types\length\diameter} of hairs. And we are not the only apes with thinly haired areas:
We just have taken the {apparent bareness} to the greatest extreme (see reference to run-away sexual selection in the original post)
Enjoy
Edited by RAZD, : update picture links and sig

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 60 of 131 (212101)
05-28-2005 10:31 AM
Reply to: Message 55 by EZscience
05-27-2005 11:47 AM


Re: Human female hairlessness - a function of male choice ?
Thanks, that makes sense. The other positively selected mutations on the X gene though -- they don't talk to much about them, would they likely be {ones\areas} more related to females?
I also found this interesting (same article):
Other genes show an apparent deficiency of polymorphisms. SCML1 has 16 substitutions (of which 15 are nonsynonymous) and zero polymorphisms. Such a pattern is consistent with repeated selective sweeps driving divergence between species, while eliminating variation within species. SCML1 is a repressor of expression of Hox genes and may play an important role in the control of embryonal development [43]. This gene may be a prime candidate for explaining developmental differences between humans and chimpanzees.
It would seem possible from this kind of specific selection to diverge a species with very little difference in overall genetics. One would expect a high correlation in just diverged species on all but genes like this one.

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

This message is a reply to:
 Message 55 by EZscience, posted 05-27-2005 11:47 AM EZscience has replied

Replies to this message:
 Message 61 by EZscience, posted 05-30-2005 1:28 PM RAZD has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 62 of 131 (212659)
05-30-2005 2:24 PM
Reply to: Message 61 by EZscience
05-30-2005 1:28 PM


Re: Selected genes and polymorphisms.
yes. I am aware that the absence of testosterone during development of a genetically male child causes the individual to grow up for all intents and appearances as a female, just absent the uterus and internal female organs (the testes never descend).

This message is a reply to:
 Message 61 by EZscience, posted 05-30-2005 1:28 PM EZscience has not replied

  
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