Anyone got any evolutionary theories for hairloss?

[Bryan]

I don't know. Evolving in such a way just to remove heat seems like overkill for the body. Why would the body change the gene structure of a receptor just for that purpose and yet keep hair in the axillae and the groin?

The change in the gene structure of the androgen receptor wouldn't be the first and primary evolutionary change to keep the brain cooler. The change in the fundamental design of scalp hair follicles to make them sensitive to androgens in the first place (in the sense of having their growth suppressed) undoubtedly was.

Bryan

 

[Bryan]

Bryan,

Forgive me if Im wrong, but arent sweat glands stimulated by androgens? If so, should they not be overstimulated when hairs are missing and the circulating androgens have so little hair receptors to bind to, thus stimulating the sweat and sebaceous glands instead?

Maybe, in theory. What are you driving at, Michael? Are you hinting at a possible alternative explanation for the findings in that study?

Snow monkeys in Japan dont bald much and have comparatively low hairlines, while Orangutans and some other apes bald much more frequently closer to the equator in hotter climes.

Which would seem to support the "cooling" theory.

Bryan

 

[powersam]

the one very important point you are all missing is that up until very recently, a man would have fathered most of the children he was going to father before he even turned 20. so it doesnt really enter into the evolutionary context as the breeding part of your life would be over before hair loss presented itself.

so it could in fact have absolutely no use whatsoever, yet it could not be bred out because it would manifest after the breeding part of your life was mostly over.

 

[Bryan]

the one very important point you are all missing is that up until very recently, a man would have fathered most of the children he was going to father before he even turned 20. so it doesnt really enter into the evolutionary context as the breeding part of your life would be over before hair loss presented itself.

Nope, that's not necessarily true. Stumptailed macaques begin balding right during or after puberty.

Bryan

 

[DammitLetMeIn]

[

Nope, that's not necessarily true. Stumptailed macaques begin balding right during or after puberty.

Bryan

aah, but the stumptailed macaque is a little different. Baldness is a strength of the male mate in that species, i.e. it attracts females and is part of the selection process. I don't feel it is an adeaute model upon which to judge the human position.

 

[DammitLetMeIn]

the one very important point you are all missing is that up until very recently, a man would have fathered most of the children he was going to father before he even turned 20. so it doesnt really enter into the evolutionary context as the breeding part of your life would be over before hair loss presented itself.

so it could in fact have absolutely no use whatsoever, yet it could not be bred out because it would manifest after the breeding part of your life was mostly over.

is this true?

it would certainly make a lot of sense

 

[DammitLetMeIn]

I think it's an indirect effect. Baldness is obviously linked to androgens, and those other health issues are also linked to androgens in some way. Baldness doesn't directly cause (or is caused by) those other health issues. At least, as far as I know!

Bryan

I personally believe there is a bodily process which links these diseases to baldness.

my gut instinct is insulin.

 

[Bryan]

I personally believe there is a bodily process which links these diseases to baldness.

my gut instinct is insulin.

Why am I not surprised to hear that?

 

[DammitLetMeIn]

I personally believe there is a bodily process which links these diseases to baldness.

my gut instinct is insulin.

Why am I not surprised to hear that?

well ok, i'm willing to be persuaded otherwise tho, my mind is not closed.

 

[powersam]

the one very important point you are all missing is that up until very recently, a man would have fathered most of the children he was going to father before he even turned 20. so it doesnt really enter into the evolutionary context as the breeding part of your life would be over before hair loss presented itself.

so it could in fact have absolutely no use whatsoever, yet it could not be bred out because it would manifest after the breeding part of your life was mostly over.

is this true?

it would certainly make a lot of sense

completely true, in regards to humans. hadnt thought about other species. i had assumed by reading the thread that we were primarily discussing human evolution.

 

[docj077]

I don't know. Evolving in such a way just to remove heat seems like overkill for the body. Why would the body change the gene structure of a receptor just for that purpose and yet keep hair in the axillae and the groin?

The change in the gene structure of the androgen receptor wouldn't be the first and primary evolutionary change to keep the brain cooler. The change in the fundamental design of scalp hair follicles to make them sensitive to androgens in the first place (in the sense of having their growth suppressed) undoubtedly was.

Bryan

Hmm...then, I'd still have to question the process. It would make sense to have this process occur in males that can trace their ancestry to groups that inhabit the region around the equator. But, people from the far North and South shouldn't even have a hint of male pattern baldness.

The brain has an incredibly complex venous drainage system that covers its surface. I seriously question how much difference the loss of hair can change the internal temperature. The surface temperature of the scalp may be decreased, but the change in the core temp will be minimal as a constant flow of blood with a temp at 98.6 will constantly prevent any cool down. The brain is a highly metabolic area and is very greedy in terms of blood flow. In terms of thermoregulation in the brain, the body would have found something better. Plexiform venous structures or a thinner calvarium would be the way to go.

That's just my opinion.

 

[Beethoven]

Hmm...then, I'd still have to question the process. It would make sense to have this process occur in males that can trace their ancestry to groups that inhabit the region around the equator. But, people from the far North and South shouldn't even have a hint of male pattern baldness.

Maybe the anwer for that is that the mutation occured before ancient humans spreaded from Africa in the period about 500,000 - 1,000,000 years ago(in that period they still hadn't been humans exactly... main difference was the brain size which grew alot in the last few hundreds thousand years). Since balding occurs also in some of our ancsetors-related species it also make some sense that the mutation appeared when all semi-humans-semi-monkeys (sorry for the silly term I don't remember right now all the terminlogy in the evolution of man kind...) were still in Africa.

 

[docj077]

Hmm...then, I'd still have to question the process. It would make sense to have this process occur in males that can trace their ancestry to groups that inhabit the region around the equator. But, people from the far North and South shouldn't even have a hint of male pattern baldness.

Maybe the anwer for that is that the mutation occured before ancient humans spreaded from Africa in the period about 500,000 - 1,000,000 years ago(in that period they still hadn't been humans exactly... main difference was the brain size which grew alot in the last few hundreds thousand years). Since balding occurs also in some of our ancsetors-related species it also make some sense that the mutation appeared when all semi-humans-semi-monkeys (sorry for the silly term I don't remember right now all the terminlogy in the evolution of man kind...) were still in Africa.

If that's true, I fail to see why male pattern baldness is a plague of western society and an anomaly in Eastern society. Granted, diet has a lot to do with it. Especially, the recent removal of many of Eastern societies male pattern baldness protective substances in exchange for a more western diet.

Also, if the mutation has existed that long, then why aren't there more men with androgen insensitivity?

 

[S Foote.]

If any of you want to read that whole study, here's the full citation: "Beards, baldness, and sweat secretion", M. Cabanac and H. Brinnel, Eur J Appl Physiol (1988) 58:39-46. An irony of this is that Stephen Foote was the one who first brought that study to my attention. For some reason which I don't even remember anymore, he thinks that it supports his own eccentric theory about contact inhibition and balding! :wink:

Bryan

OK Bryan, enough of this.

If you are going to keep on calling my theory eccentric, i demand you prove it in scientific terms!

Every aspect of my theory can be shown to have both purpose in evolution, and precedent in already recognised phisiological mechanisms.

On the other hand the idea that there is some kind of evolutionary purpose in a "direct" action of androgens on hair, makes no sense at all!

Tell us all the purpose of androgens "directly" growing armpit hair?

In fact the only hard in-vitro evidence we have, clearly shows that androgens do "NOT" directly change any pre-existing kind of hair growth. Androgens do "NOT" directly convert normal scalp follicles into male pattern baldness follicles!

In order to try to get around this hard proven fact, completely unprecedented hormone "time delay" mechanisms are invented by unscientific people :wink:

And you dare to call my theory "eccentric" Bryan :roll:

If as you claim here, follicles in the male pattern baldness area have evolved to be directly shrunk by androgens for cooling purposes along with beard growth, why aren't "ALL" men capable of growing a beard then bald??

How come beard developement in men is not directly corelated with scalp hair loss? If it's evolved because it is important in human survival, brain cooling wise, there would be a clear link in the timeframe!

As it is many men who can grow beards, do not suffer from male pattern baldness. Even in the men who do develope male pattern baldness, the vast majority show a considerable time lag between beard growth and onset of male pattern baldness. The average male pattern baldness onset is around mid to late 20's, and it can even be as late as 40's and 50's in some!

So the idea of male pattern baldness as an evolved brain cooling mechanisn, just doesn't wash. There is more than enough bare skin on the human body to radiate heat collected by the blood flow.

The important thing about Cabanac's study is not what any intepretation in terms of human evolution is, but the "actual" androgen related physiology it "PROVES".

It proves that where androgens reduce hair growth sweating capacity is increased, and where androgens increase hair growth sweating capacity is reduced.

The only mechanism that makes sense of this in terms of mammalian evolution, is that androgens are changing the local tissue "Hydraulics" in line with the dermal model in my early paper.

http://www.hairsite2.com/library/abst-167.htm

Your direct action needs yet more mechanisms to explain the sweating link as well as even more nonsense "opposite" fantasy mechanisms Bryan!

In my opinion, there is no significance whatsoever in evolution for the human hair patterns we see today. These are just an unimportant "side effect" of increased levels of DHT.

Everone knows now that reducing systematic levels of DHT with finasteride or dutasteride, effects sexual performance. Libido is down erections are not as good, and sperm quantity and quality is lowered.

Most primate societies have evolved sexual advantages because the females mate with many males. Increased androgen levels in general would be an advantage. In particular in such early human conditions, increased DHT would have offered a big advantage in both getting your sperm to the target, and "flooding" out your competition!

http://www.cambridge.org/catalogue/cata ... 384&ss=exc

The hair pattern changes mean nothing in terms of any mating advantage or disadvantage. As some of the more inteligent posters have already said, male pattern baldness would not have been an issue in early humans as they just didn't live that long.

S Foote.

 

[Bryan]

Also, if the mutation has existed that long, then why aren't there more men with androgen insensitivity?

Doctor, I don't understand what you're implying. Can you elaborate on that a little?

Bryan

 

[bubka]

Why would humans have needed a bald head for survival? perhaps they didn't?

I've read a few theories:

one was that its to allow more sun to enter the body in cold northern climates...

or is it simply the sign of illness? given that its associated with so many maladies and imbalances...

u got any ideas?

it's not always about "survival" again, showing what you don't know about evolution, it was a sexual preference type of selection for mating, like most species exhibit

 

[docj077]

Tell us all the purpose of androgens "directly" growing armpit hair?

Shave your armpits and prevent sebum production with a topical anti-androgen for a few weeks. Then, you'll see the purpose of sebum production and underarm hair. I have to warm you. Make sure you have some lotion on hand for the chafing.

In fact the only hard in-vitro evidence we have, clearly shows that androgens do "NOT" directly change any pre-existing kind of hair growth. Androgens do "NOT" directly convert normal scalp follicles into male pattern baldness follicles!

This is something that is well known and numerous studies have been posted on this site that refute what you say. Growth inhibition requires androgen binding at the level of the dermal papillae, as well as, at the level of the dermal fibroblasts at concentrations that are equivalent to body growth factor and hormone levels in individuals with male pattern baldness. Increasing testosterone levels incrementally will eventually lead to growth inhibition of hair follicles from areas that are considered to be immune to such processes such as follicles taken from the back of the head.

The only mechanism that makes sense of this in terms of mammalian evolution, is that androgens are changing the local tissue "Hydraulics" in line with the dermal model in my early paper.

S Foote.

However, in order for your mechanism to work there is the requirement of muscle hypertrophy in the scalp, which is not a proven phenomenon. The effect must lead to lymphatic obstruction, which is not a proven phenomenon either. Looking at histological specimens from men with male pattern baldness reveals neither process. Nor, is there any evidence for edema of any kind. And, the argument that the edema is so little that it can't be seen doesn't work here. In other parts of the body where edema can lead to hair loss, the edema is always very prevalent before any other process begins.

Another problem that I have here is that there is no increase in the incidence of lymphangiosarcoma in the scalp of men with male pattern baldness. That's a big problem, because lymphatic obstruction has a tendency to lead to such processes. Just ask women that have gone through radical mastectomies.

Histologic specimens also fail to show lymphatic dilation or proliferation of any sort.

The last item that must be considered is the very mechanism that minoxidil uses to decrease blood pressure. Minoxidil is a selective arterial dilator. It would increase blood flow to the scalp, and thus, increase edema if there is indeed a failure of lymphatics.


Your theory is interesting Foote, but I have too many problems with it. Both in terms of the histology and pathology and in terms of the use of minoxidil for male pattern baldness.

Dammitletmein (bless his heart) has posted some interesting studies recently. Although his interpretations are typically misguided, his studies are rather revealing. There is an increase in IGF-1 in the scalp of men with vertex baldness. Is there a similar finding with frontal baldness? I don't know. However, it's important to realize the problem with increased IGF-1. IGF-1 promotes keratinocyte proliferation while decreasing differentiation, which will prevent keratinocyte maturation and function. Not only is this true, but TGF-beta is also increased and works synergistically in tissue to increase collagen deposition and prevent collagenase activity. Lastly, IGF-1 also promotes the function of t-cells in dermal tissue giving us an immune response and TGF-beta causes keratinocytes to undergo apoptosis. There are androgen receptors on both the dermal papillae and the dermal fibroblasts. The whole process is required for permanent male pattern baldness and the link between the dermal papillae and the keratinocytes is required for growth inhibition due to keratinocyte immaturity. So, the only studies that can be trusted that use scalp follicles are those studies that have the entire follicle present. Dermal papillae, dermal fibroblasts, and keratinocytes.

If there is indeed edema in the scalp of men with male pattern baldness, then it's a result of a much larger inflammatory process and not obstruction, in my opinion.

As with everything that I post, that's just my opinion, but there is a lot of science to back up what I say.

 

[docj077]

Also, if the mutation has existed that long, then why aren't there more men with androgen insensitivity?

Doctor, I don't understand what you're implying. Can you elaborate on that a little?

Bryan

In diseases that have triplet repeat mutations as their basis, the severity of the disease (as in protein malfunction) is associated with the accumulation of mutations through the generations. The greater the number of mutations, the earlier the onset of the disease and the more severe the disease. Huntington's Disease in an excellent example.

Granted, male pattern baldness may be an entirely different process, but if triplet repeat mutations increase in the same way they do in Huntington's, then the eventual result should be androgen insensitivity. Again, increased mutation (androgen receptor gene) leading to poorly formed and non functional protein production (androgen receptor) leads to androgen insensitivity.

Unless the mechanism has been avoided or changed in male pattern baldness, the end result of generational inheritance should lead to androgen insensitivity.

I might be thinking of this in the wrong way, however.

 

[Bryan]

I evidently misunderstood you before. When you asked why the mutation hasn't resulted in even more men with androgen insensitivity, I assumed you were talking about the mutation of scalp follicles from being stimulated by androgens to being suppressed by them. I didn't realize you were talking about the androgen receptor polymorphisms.

 

[abcdefg]

Considering science does not know for sure how life started, or what caused evolution who is to say there even is a reason? I mean it might just be some anomaly or fluke mutation that might not ever happen again or in any pattern. I mean lightning strikes in totally random places that can not be predicted in any way known to man. Who is to say that some natural processes like evolution have any predictable path? People want these things to make logical sense when mother nature just does as it wants irrespective of what we want to believe. Its funny how researchers apply math to solving problems in the human body when math makes no sense in the human body because math was really not invented to be applied to that.