Scientific question: why do men have DHT resistant hair?

[Acrobaz]

I recognise in advance that this is a rather technical question that is of limited practical application to hair restoration.

 

We now know that, even in the most extensive cases of hair loss, men commonly retain hair, in a horseshoe shape around the bottom of the head, containing follicles that are genetically programmed to resist the effects of DHT. Hence its use as a donor area for HT procedures.

 

My question is this: have any of the scientists out there offered any theories as to why there is an evolutionary advantage in having DHT resistant follicles in that particular location?

 

I know. I am a geek.

[Bill - Seemiller]

Acrobaz,

 

This is a great question. Unfortunately, I'm not sure that anyone fully knows the answer to this, since answering this very question is a huge part of unlocking the mystery of finding a cure.

 

I too would like to hear what others have to say on this topic.

 

Best wishes,

 

Bill

[TC17]

I'm not a scientist, but I did major in biological anthropology as an undergrad. With my (limited) knowledge of evolution, I would say that there is no evolutionary reason for the DHT resistant rim of hair. I say that solely because such a pattern exists only in extremely bald men, who are almost always relatively old. It is a fundamental principle of evolution that nature doesn't care about you past your peak reproductive period, so any characteristics that would manifest themselves that late in the game are not naturally selected for. It is probable that the men who will now become Norwood 7's, would have died years before the pattern would ever show itself years ago. That's the only guess I could give you, but it should be noted that our closest animal relative (the bonobo chimpanzee) is a sufferer of hair loss as well.

[Dr. William Lindsey]

I recall hearing a talk somewhere about some Pacific island population that didn't make DHT; and were "reassurance" that propecia use didn't hurt folks over long terms, as this population they referenced didn't have the enzyme that propecia blocks.

 

 

Now that doesn't answer your question I know but it does suggest that making DHT and losing hair is normal, and that population is the unusual or deviant gene compared to us lucky guys losing hair with age.

 

Ask God when you meet Him is probably the only way we will really find out. There are lots of weird things in human physiology that I want to ask about too.

 

Dr. Lindsey McLean VA

[Abedogg]

Dr. Lindsey,

 

It is an interesting question. I'm no scientist either but here's my guess...

 

I think the general thought is that species evolve (change) to survive. And generally they do. but this happens by sheer luck.

 

For instance, a monkey is born with a freak gene that makes his hips more adaptable to upright walking. This allows him to pick fruit where he couldn't before or allows him to run faster and tackle more female monkeys and impregnate them (whatever the reason it gives them some sort of advantage).

 

 

Unfortunately, I think the hairloss gene, which was probably due to a freak gene mutation, has no evolutionary benefit.

 

If hairloss did have a benefit - let's say it kept us cooler as the earth gets hotter and we are able to live more reprodcutive years than men with a full head of hair - more women would mate with men that carried the gene and possibly, the horeshoe pattern would get lower and lower through selective breeding until eventually we all would just go bald!

 

So, I believe the hairloss gene just happened to be a freak mutation that only affects certain areas of the head, that has carried down through generations.

 

Maybe global warming will be good for us.

 

 

Abe

[Abedogg]

Reading your post I really didn't answer your question at all.

 

Here is my guess why pacific islanders have dht resistant hair.

 

Because having hair on the top of the head blocks out intense sun that is abundant where they live. This sun would cause cancer on a bald head.

[Leeson]

Abe,

Not DHT resistant, they lack the enzyme that converts testosterone into DHT. Also those born w/o the type 2 alpha reductase enzyme (kind propecia blocks) and weren't affected by MPB, although they had the type 1 enzyme for DHT (avodart blocks also).

[MrJobi]

Genes , genes , genes

 

It would be the same reason for other characteristics found in people. Evolution is a tricky subject

[Marvin]

Just because a trait exists in the gene pool does not mean that it must confer a biological advantage. Baldness seems to be something that has neither positive nor negative consequences from a biological perspective.

 

Variations between different ethnic groups could very well just be the founder effect.

[Acrobaz]

A belated thanks to all that contributed to this topic. I've been reading up on evolutionary theory recently (what else was there to do during my three-week post-op downtime!?) and I think TC17 nailed it. It seems that the "horseshoe" confers no evolutionary benefit because it generally happens once (in evolutionary terms) men pass their reproductive peak. Oh well. And there I was hoping that someone would say that bald men have evolutionary advantages!

 

There has been some interesting stuff recently about how the decreasing number of older men reproducing is reducing the number of genetic mutations that power evolutionary change in humans, but I can't find any link between that and the question I posted.

 

I thought Abe's link with sun and cancer was interesting - I wonder if there has been a study of the geographical distribution of hair loss (or, rather, DHT resistance) according to climate?

 

I also saw a reference somewhere (and - grrrr - can't find it now) to the effect that while hair on the top of the scalp is genetically encoded to be adversely affected by DHT, by contrast moustache and beard growth are promoted by DHT. That might suggest that the presence of the resistant "horseshoe shape" around the lower part of the head is somehow linked to the evolutionary role of facial hair - namely that its growth in puberty signified, in evolutionary terms, that a male was ready to mate. The suggestion seemed to be that the hormones necessary to promote beard growth ensure - perhaps as an unintended by-product - that the horseshoe, which is proximate, remains DHT resistant. An interesting thought, just wish I could find the reference.

 

Final point: when I did some internet searching on the topic (hmm, not exactly hard science), I found this:

http://www.guardian.co.uk/note...y/0,,-192228,00.html

For those that don't know, the Guardian is a UK broadsheet newspaper that runs a well-known "notes & queries" column for people to ask questions on the rather trivial. My favourite response - almost Pythonesque - is the suggestion that men evolved so as to become less hairy, in order to make them less flammable after the discovery of fire!!

 

Regards.