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Author | Topic: Is body hair a functionless vestige? | |||||||||||||||||||||||||||||||||||||||||||
greyseal Member (Idle past 4059 days) Posts: 464 Joined: |
ken fabos writes: Greyseal - I don't see how mutations can derive from anything except individuals - whilst a specific mutation can occur independently the chances of that aren't high wheras a mutant gene will be passed to descendents and, as long as that line doesn’t die out, will almost certainly become part of the gene pool. Hi Ken, I don't think you understand what I mean. Firstly, mutations happen all the time. Every single child is a mutant since no child is an exact copy of one of the parents (at least not in humans). In addition to pure hereditry, mutations occur as well. Finally, a particular (beneficial) mutation may originate with one individual, but for that mutation to become general it has to a) propagate (i.e. there need to be descendants who can carry it hereditarily)b) be advantageous or at least not disadvantageous whilst doing so. if you take humans (and this is my interpretation of the history of humans according to my limited understanding of the facts) then at some point there was a population of ape-like creatures. They separated into at least two groups. One group set off for the plains of Africa, the other stayed in the jungle. We will focus on the plains-group - mutations happened continuously by chance to individuals within this group (well, in the process of their conception). Those which were less hairy (either because or inspite of this!) faired in general better. I think you agree with me there. If that's what you meant, you may as well stop here, because you are correct - although there is no reason that a mutation MUST occur in only one individual. The same random change could occur multiple times - certain changes are small enough, or the population big enough - or the same result could occur in more than one way. unless they were immediately bald like us, chances are there will be further mutations reducing hairiness, which would again confer better survivability, which would once again mean that more and more of the population (over time) has this new-new gene change. ...and so on. Now, my method is, to my understanding, what happened. The changes are random, and natural selection working on those changes favour, over time, certain mutations over others. What's your version?
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Ken Fabos Member (Idle past 1438 days) Posts: 51 From: Australia Joined: |
Greyseal - whilst I don't fully understand evolutionary processes, I don't think you do either although I have to say thanks for making me think about this more deeply than I otherwise might have.
To start, the offspring of parents aren't mutations even though they aren't exact copies; the differences would be a result of recombination not mutation. Just what role recombination plays in producing traits that have not existed previously is something I admit to not fully understanding but mutation is when genes replicate with ‘mistakes’. These mistakes are random and won’t appear in response to environmental or other factors, just get carried, replicated or lost according to the fitness (reproductive success) of the random individuals that carry them. Past the initial occurance they probably shouldn’t be called mutations but the changed gene in later generations seems to be called that for the sake of convenience. My understanding (mostly from Colby’s Introduction to Evolutionary Biology ) is that, whilst the same mutation can occur independently, it's an extremely low probability random event. This fits with my own thinking about the size of a genome and the random nature of mutations. The same beneficial (or at least not seriously deleterious) mutation occurring independently across a larger population is very unlikely. Should similar traits arise out of different genetic changes, I doubt they would be carried universally or breed true. Having a mutation arise in an individual, be inherited by descendents and spread through the gene pool through successive generations looks both reasonable and much more likely than arising independently. As Colby concisely puts it - genes mutate, individuals are selected and populations evolve. I can only refer back to Colby's online article which refers to mutations several times as occuring first within individuals. I can only believe he does correctly summarise evolutionary processes; natural selection selects between existing traits, those traits arose from mutations in individuals and were spread through following generations by inheritance. He refers to the equation 4*N for the number of generations for a mutation to reach fixation, where N is the effective breeding population. For a small tribe of proto humans (below 100), that rarely mate outside it that would be in the hundreds generations — multiplied by 20 years per generation ( which is probably overgenerous) we’re talking around 100,000 years or less. That is the time before that population all had that common ancestor. This would be even faster when mating choices aren’t random as that would reduce the effective breeding population that carry that changed gene — and for homo sapiens we know that mating options are ‘assortative’ as in we tend to mate with people like us. Less hairy with less hairy? That would lead to a sub-sub- population with that trait. If it’s associated with greater fitness (reproductive success) the relative numbers of furry to furless would shift in favor of the latter. I think that traits that are common to our entire species have to predate it's major diaspora and even if some traits could have developed independently within reproductively isolated sub-groups, having them develop within all sub-groups would be so unlikely as to be effectively impossible. So I believe that furlessness predated our species spreading far and wide. You said - "unless they were immediately bald like us, chances are there will be further mutations reducing hairiness, which would again confer better survivability, which would once again mean that more and more of the population (over time) has this new-new gene change." I suppose that could occur except that I think 'further mutations reducing hairiness' would not be likely; all mutation is random and beneficial mutations rarer than neutral to deleterious ones. Chances are the appropriate mutations will not happen when or because it’s needed. I suppose that would lead to slow development of this trait, but would an incremental change to hairiness really provide better survivability or reproductive success? I have to admit that how far natural selection can take a trend such as toward reduced hairiness is a valid question and I’m still uncertain about it; selection of the least hairy from each generation might continue that trend further than I might initially expect. But that depends on that trait providing clear advantage - or more strictly speaking having natural selection favour the reproductive success of those with less hair over those that don't. What I don’t think is clear is that incremental changes to reduced hairiness would have enough benefit, generation to generation, to give greater reproductive success; heat dissipation — the most established advantage that is claimed for reduced hairiness - is a result of two significant changes; more watery and abundant sweat as well as reduced hairiness. (Tougher skin is also a related trait that humans appear to possess, but I don’t want to complicate this too much). Each trait by itself may not have conferred great advantage and it was when the two combined that this gave significantly better heat dissipation, thus greater endurance in hot conditions and consequently gave those with them superior hunting and gathering range and ability. When the benefits of changes to hairiness without change to sweatiness are pared down even further by occurring as small incremental ones they are even less likely to result in selection in favour of them. Gene flow - mixing of previously separate gene pools - would, if these separate traits evolved within separate groups, result in less fur and more watery sweat being combined and again that clear advantage would first appear in individuals and siblings, not across the population over a long time. But prior to more abundant perspiration the impacts of thinned fur, even if arising rapidly, may have been marginal or even detrimental if severe cold, was still a limiting factor. Similarly, had greater perspiration come first there may have been disadvantages since greater water loss without much better heat dissipation would have limited, not extended, their range for hunting and foraging. Reduced parasite loads from thinned fur also has it's complications - thick fur can protect against some kinds (e.g. mosquitos and small biting flies) whilst providing better habitat for others (lice or fly maggots in wet matted fur) or change how easy they are to locate and remove (ticks). Also the disease carrying aspects can make specific parasites more and less significant; as long as mosquitos don’t carry disease we can tolerate more of them but when they do —and the disease is serious — that can heavily impact a population and do so quickly. So, by having more of the body more easily scrutinised visually, some parasites are made easier to physically remove whilst we could be more vulnerable to others. Still, shorter thinner hair's finer sensitivity to low threshold tactile sensation gives greater sensory awareness of the presence of some kinds of parasites, so, depending on which parasites and diseases, being thin furred could have mattered greatly to the health and consequently the reproductive success of the individuals who became the foundation parents of our species. Insects are well known for being able to adapt quite quickly so slow, incremental changes in our ancestors may not confer much advantage given that parasites can adapt quickly enough to keep up. In this respect rapid change could confer more advantage than incremental change to hairiness. So we get back to luck and chance. Chance as it effects individuals (individuals are selected both by the relative advantage and disadvantage of the traits they carry as well as by life's chances) would play an important part. A beneficial mutation that might go on to have enormous advantage could easily be lost if the initial individual carrying it meets random misfortune. Harmful mutations, at least the most serious ones, by their nature, tend to die out and not get passed on. And those are still more common than mildly deleterious through to beneficial mutations. That's why I see chance and luck in both the right mutations arising and the individuals with them surviving as playing a crucial role in us being the way we are. PS I wonder if some of this discussion has relevance to The common ancestor thread? I've been a bit busy to get involved in it.
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Ken Fabos Member (Idle past 1438 days) Posts: 51 From: Australia Joined: |
I recall reading - just a reference in comments on another forum but unfortunately can't find it again - to speculation that the earliest function of hair was sensory. It seems to be a universal characteristic of hairs to transfer tactile impulses to sensory nerves within the skin. Presumably hairs existed before their role as insulation; did they transmit tactile impulses before then? Did they have muscles to hold them erect? Goosebumps may have had the role of extending the reach of tactile hairs long before they acquired the role of signaling to predators. It would mean that they are not vestigial, as they still perform this function.
(Edit p.s. - Since found the reference to this article - Just a moment... although it doesn't really explore sensory function prior to (or during or after) hair/fur as insulation, rather sees a mechanoreceptor role as an early intermediary step to hair as we recognise it. It looks like the author is one more academic of evolution of hair that fails to recognise the near universal tactile sensory function of hairs. That seems implicit in this sentence... "Later, as endothermy was gradually perfected in early mammals, perhaps a Jurassic event when they occupied the nocturnal niche (11), an insulatory boundary was further improved by multiplication of nontactile hairs." ... which I take as differentiating hairs that are clearly specialised for tactile function - such as Vibrissae hair (whiskers) - from those that aren't. One more who should know better that has failed to notice that even the non-specialised ones retain a tactile sensory function.) Edited by Ken Fabos, : Added p.s.
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DMJY510 Junior Member (Idle past 4941 days) Posts: 3 Joined: |
I don't know whether it is true ,maybe we can have a rearch ,we are curious about.
Edited by AdminModulous, : No reason given. I like whale snot |
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Robert Byers Member (Idle past 4566 days) Posts: 640 From: Toronto,canada Joined: |
This yEC creationist has a more likely answer to why humans have hair.
of coarse it all starts from biblical boundaries of men after the flood needing to deal with a new kind of world. Our bodies are entirely covered with hair save our palms etc. yet this hair is not to keep us warm. We are not in need like animals. rather the hair is simply a reaction to keep us dry. yet its not actually needed. So our having hair is a wrong over sensitive reaction of the inate powerful abilities of bodies to adapt to the local areas we migrated to. The good evidence hair is just a reaction for dryness is where it comes upon puberty. Its then that under the arms etc where the most sweating takes places that hair grows in a useless attempt to keep the area dry. The excess hair is from excess sweating that the body remebers genetically. Again its worthless but indicates hair is just a reaction to keep one dry. In the animal kingdom hair is also to keep one dry and often creatures only have more hair in order to have special protection. like beacers or musk ox. The hair itself doesn't keep them warm but instead yiny air sections created by the hair are what keep them warm. With some creatures great amounts of hair do just keep them warm.
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Jon Inactive Member |
This yEC creationist has a more likely answer to why humans have hair. of coarse it all starts from biblical boundaries of men after the flood needing to deal with a new kind of world. Our bodies are entirely covered with hair save our palms etc. yet this hair is not to keep us warm. We are not in need like animals. rather the hair is simply a reaction to keep us dry. yet its not actually needed. So our having hair is a wrong over sensitive reaction of the inate powerful abilities of bodies to adapt to the local areas we migrated to. The good evidence hair is just a reaction for dryness is where it comes upon puberty. Its then that under the arms etc where the most sweating takes places that hair grows in a useless attempt to keep the area dry. The excess hair is from excess sweating that the body remebers genetically. Again its worthless but indicates hair is just a reaction to keep one dry. In the animal kingdom hair is also to keep one dry and often creatures only have more hair in order to have special protection. like beacers or musk ox. The hair itself doesn't keep them warm but instead yiny air sections created by the hair are what keep them warm. With some creatures great amounts of hair do just keep them warm. As these are the Science Forums, you'll need to provide scientific evidence to support these assertions. Jon Check out No webpage found at provided URL: Apollo's Temple! Ignorance is temporary; you should be able to overcome it. - nwr
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NoNukes Inactive Member |
Robert Byers writes: So our having hair is a wrong over sensitive reaction of the inate powerful abilities of bodies to adapt to the local areas we migrated to. Why do whales have hair? Surely it is not to keep them warm or dry.
Its then that under the arms etc where the most sweating takes places that hair grows in a useless attempt to keep the area dry. Given your explanation, it is difficult to imagine why humans have hair at all. According to you human hair does not work to keep us warm or dry, is apparently completely useless and presumably always has been. Why do men grow hair on their faces some time after puberty? In fact, hair seems to grow faster on the head and face than under the arms. Why is that? Edited by NoNukes, : No reason given.
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Robert Byers Member (Idle past 4566 days) Posts: 640 From: Toronto,canada Joined: |
NoNukes writes: Robert Byers writes: So our having hair is a wrong over sensitive reaction of the inate powerful abilities of bodies to adapt to the local areas we migrated to. Why do whales have hair? Surely it is not to keep them warm or dry.
Its then that under the arms etc where the most sweating takes places that hair grows in a useless attempt to keep the area dry. Given your explanation, it is difficult to imagine why humans have hair at all. According to you human hair does not work to keep us warm or dry, is apparently completely useless and presumably always has been. Why do men grow hair on their faces some time after puberty? In fact, hair seems to grow faster on the head and face than under the arms. Why is that? As i said the body is over sensitive or powerful and so over reacts to triggers.hair is useless under the arms etc but is useful on the head. In fact i would say its logical that women have greater hair on the head relative to their body size because they need to keep the head dryer because of lesser body heat. Wet hair threatens them more then big guys. Now perhaps again its useless but it might be usefull. anyways its just a more likely interpretation to see hair as a attempt of the body to keep it dry. In nature getting wet is quite dangerous as anyone who deals with cold cAnadian lakes will tell you. Therefore our bodies simply grow trivial hair because of a past of being a little more wet. Special areas on our body just make this equation more obvious.
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ZenMonkey Member (Idle past 4708 days) Posts: 428 From: Portland, OR USA Joined: |
Robert Byers writes: In fact i would say its logical that women have greater hair on the head relative to their body size because they need to keep the head dryer because of lesser body heat. Wet hair threatens them more then big guys. Now perhaps again its useless but it might be usefull. More head hair for women is good because they have less body mass and more hair keeps them warmer. More head hair for women is bad because it retains more water and makes them colder. I see. I have no time for lies and fantasy, and neither should you. Enjoy or die. -John Lydon What's the difference between a conspiracy theorist and a new puppy? The puppy eventually grows up and quits whining.-Steven Dutch I never meant to say that the Conservatives are generally stupid. I meant to say that stupid people are generally Conservative. I believe that is so obviously and universally admitted a principle that I hardly think any gentleman will deny it. - John Stuart Mill
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Coyote Member (Idle past 2304 days) Posts: 6117 Joined: |
As i said the body is over sensitive or powerful and so over reacts to triggers. hair is useless under the arms etc but is useful on the head. In fact i would say its logical that women have greater hair on the head relative to their body size because they need to keep the head dryer because of lesser body heat. Wet hair threatens them more then big guys. Now perhaps again its useless but it might be usefull. anyways its just a more likely interpretation to see hair as a attempt of the body to keep it dry. In nature getting wet is quite dangerous as anyone who deals with cold cAnadian lakes will tell you. Therefore our bodies simply grow trivial hair because of a past of being a little more wet. Special areas on our body just make this equation more obvious. Sorry, this is absolute nonsense. You can't just go making thing up that sound good to you, but which are supported by no evidence--or actually contradicted by the evidence--and expect to get away with it. Can you support any statement that you have made with peer-reviewed data? If not, why don't you just stop spouting off that nonsense. You only make your side of the debate look foolish when you come up with these kinds of statements. Haven't you read St. Augustine's comments that pertain to this kind of nonsense? Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
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Robert Byers Member (Idle past 4566 days) Posts: 640 From: Toronto,canada Joined: |
The body doesn't react to water soaked hair. it just reacts to a need to keep the body dry.
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Robert Byers Member (Idle past 4566 days) Posts: 640 From: Toronto,canada Joined:
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Coyote writes: As i said the body is over sensitive or powerful and so over reacts to triggers. hair is useless under the arms etc but is useful on the head. In fact i would say its logical that women have greater hair on the head relative to their body size because they need to keep the head dryer because of lesser body heat. Wet hair threatens them more then big guys. Now perhaps again its useless but it might be usefull. anyways its just a more likely interpretation to see hair as a attempt of the body to keep it dry. In nature getting wet is quite dangerous as anyone who deals with cold cAnadian lakes will tell you. Therefore our bodies simply grow trivial hair because of a past of being a little more wet. Special areas on our body just make this equation more obvious. Sorry, this is absolute nonsense. You can't just go making thing up that sound good to you, but which are supported by no evidence--or actually contradicted by the evidence--and expect to get away with it. Can you support any statement that you have made with peer-reviewed data? If not, why don't you just stop spouting off that nonsense. You only make your side of the debate look foolish when you come up with these kinds of statements. Haven't you read St. Augustine's comments that pertain to this kind of nonsense? This is rock solid analysis upon data .If you disagree then say why and say why you have an alternative. I don't asks for peer review jazz. Intelligent ideas have the force of persuasion qwithin them based on facts and reason. Don't need anyone else to give legitimacy.
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Blue Jay Member (Idle past 2895 days) Posts: 2843 From: You couldn't pronounce it with your mouthparts Joined: |
Hi, Robert.
Robert Byers writes: This is rock solid analysis upon data. Please spend some time looking up and studying the words "analysis" and "data," with particular emphasis on how they are used in science. Then, do some careful thinking about what the phrase "rock-solid" means. If, after you've done this, you still believe that the quoted sentence accurately represents the crap you keeping putting out here, please tell us again, so that we can all know that engaging you in further conversation is completely futile. But, make sure you post it publicly so that we have the documentation. Thanks. -Bluejay (a.k.a. Mantis, Thylacosmilus) Darwin loves you.
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bluescat48 Member (Idle past 4387 days) Posts: 2347 From: United States Joined: |
This is rock solid analysis upon data . If you disagree then say why and say why you have an alternative. You are making the claim, therefore you must back it up with evidence. The burden of proof is on the claimant. There is no better love between 2 people than mutual respect for each other WT Young, 2002 Who gave anyone the authority to call me an authority on anything. WT Young, 1969 Since Evolution is only ~90% correct it should be thrown out and replaced by Creation which has even a lower % of correctness. W T Young, 2008
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NoNukes Inactive Member |
Robert Byers writes: As i said the body is over sensitive or powerful and so over reacts to triggers. Why do whales have hair? Why do men grow facial hair? Your explanations don't deal with either. Are you ducking the hard questions?
hair is useless under the arms etc but is useful on the head. In fact i would say its logical that women have greater hair on the head relative to their body size because they need to keep the head dryer because of lesser body heat. Do women have more hair on their head than men for any reason other than not getting hair cuts? My own hair was quite long in the 70s. Do we really have more hair on our underarms than elsewhere? I don't.
Wet hair threatens them more then big guys. Now perhaps again its useless but it might be usefull. The correct way to express your state of knowledge about why humans have hair would be "I don't know". If wet hair is dangerous, then why grow hair? Is there any field of human endeavor that you know enough about so that you don't have to just make stuff up?
Therefore our bodies simply grow trivial hair because of a past of being a little more wet. Special areas on our body just make this equation more obvious Really. So at some point in the past, men got their chins and upper lips wet but not their foreheads? Women exhibited a different pattern of getting wet? When did this evolution take place? Edited by NoNukes, : bad apostrophe removed
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