Causes of MPB

[Buy The Ticket]

As a personal suspicion, i speculate hair loss could be an index of health and reproductive viability for women. If that was true, then hair loss would signal to women when a partner, appearing otherwise healthy, actually possesses a weak metabolic fitness, such as during old age.
The evolutionary advantage would be enormous in this case, with women instinctively knowing which males are the strongest and most fertile (MPB is correlated to low testosterone and perhaps associated to muscular wastage and weakness), while confirming that premature baldness is a disease with an external cause.

I think this is a bit ridiculous to be honest.

[Davey Jones]

I think this is a bit ridiculous to be honest.

And it likely is. To specifically evolve to show that you are NOT fit doesn't mesh in with natural selection at all. Aston always has been a bit of an oddball though, and science needs off the wall theories, 'cause a few of them inevitably end up true. This one, however, seems caused more by an all to common problem: for some reason, people just don't get how evolution works.

[Aston]

And it likely is. To specifically evolve to show that you are NOT fit doesn't mesh in with natural selection at all. Aston always has been a bit of an oddball though, and science needs off the wall theories, 'cause a few of them inevitably end up true. This one, however, seems caused more by an all to common problem: for some reason, people just don't get how evolution works.

I don't particularly like my own speculation, however it trumps, in my eyes, any other theory of the cause of male pattern baldness i have studied, and i would be happy if it could be proven wrong on a logical basis alone.
"It is ridiculous" doesn't mean it is wrong, for instance, and thus such a claim doesn't represent a challenge.

"To specifically evolve to show that you are NOT fit doesn't mesh in with natural selection at all."

A male born with a gene to manifest baldness in case of nutritional/developmental deficiency, yet NOT manifesting it, will be actually manifesting fitness proportionally to the strength of the gene.
If this is how it actually works, then between two males, both having the same MPB genes, the most nutritionally fit one will have the most hair. If this makes him also more attractive to females, then doesn't it mean that the most fit male (thus probably with better genes/resources overall) will have better reproduction chances? Isn't that perfectly compliant to the natural world?

Most species of mammals, including many primates, reproduce through the dominance of a single alhpha male (or a restricted group of alphas) based almost entirely on physical fitness. Strength and size are the primary indicators of such fitness for females.
You may notice that human males do not usually physically fight each other to assert dominance over a female. While our size and physical fitness still matters in conquering a mate, we live in societies where food is abundant and achieving maximum physical size is expected. What if nutrient rate of a diet, rather than energy density, determines the physical fitness/health of a mammal? Wouldn't that mean women have lost their ancestral way of choosing the fittest mate with the advent of modern societies?
If we assume nutrient fitness affects DHT metabolism and therefore MPB, then MPB becomes an indicator of metabolic fitness much more precise than physical size and strength or any other visual clue a woman could have. This would also explain why MPB would increase with the increase of energy-dense, nutrient-poor foods worldwide.

About the diffusion of energy-dense, nutrient-poor foods: http://www.dailymail.co.uk/sciencete...ing-blame.html

Is it a far-fetched, ridiculous theory? Probably. Is it worse than saying MPB exists to give us more surface skin to metabolize vitamin D or is just a "casual" mutation that seems to affect the vast majority of men in the developed world? I wonder. It's just speculation, after all.

[Davey Jones]

I don't particularly like my own speculation, however it trumps, in my eyes, any other theory of the cause of male pattern baldness i have studied, and i would be happy if it could be proven wrong on a logical basis alone.
"It is ridiculous" doesn't mean it is wrong, for instance, and thus such a claim doesn't represent a challenge.

"To specifically evolve to show that you are NOT fit doesn't mesh in with natural selection at all."

A male born with a gene to manifest baldness in case of nutritional/developmental deficiency, yet NOT manifesting it, will be actually manifesting fitness proportionally to the strength of the gene.
If this is how it actually works, then between two males, both having the same MPB genes, the most nutritionally fit one will have the most hair. If this makes him also more attractive to females, then doesn't it mean that the most fit male (thus probably with better genes/resources overall) will have better reproduction chances? Isn't that perfectly compliant to the natural world?

Most species of mammals, including many primates, reproduce through the dominance of a single alhpha male (or a restricted group of alphas) based almost entirely on physical fitness. Strength and size are the primary indicators of such fitness for females.
You may notice that human males do not usually physically fight each other to assert dominance over a female. While our size and physical fitness still matters in conquering a mate, we live in societies where food is abundant and achieving maximum physical size is expected. What if nutrient rate of a diet, rather than energy density, determines the physical fitness/health of a mammal? Wouldn't that mean women have lost their ancestral way of choosing the fittest mate with the advent of modern societies?
If we assume nutrient fitness affects DHT metabolism and therefore MPB, then MPB becomes an indicator of metabolic fitness much more precise than physical size and strength or any other visual clue a woman could have. This would also explain why MPB would increase with the increase of energy-dense, nutrient-poor foods worldwide.

About the diffusion of energy-dense, nutrient-poor foods: http://www.dailymail.co.uk/sciencete...ing-blame.html

Is it a far-fetched, ridiculous theory? Probably. Is it worse than saying MPB exists to give us more surface skin to metabolize vitamin D or is just a "casual" mutation that seems to affect the vast majority of men in the developed world? I wonder. It's just speculation, after all.

I think you are making a very subtle mistake. Yes, genes that show a more fit mate certainly exist, but it isn't as a matter of the showing inferiority developing, but the showing of superiority. What I mean to say is that a way to show you're worse doesn't evolve naturally. Based on the inheritability of MPB, we can say with relative certainty that there is a genetic component found exclusively in some individuals. If it's cause was to JUST single out individuals who were not getting the nutrition to develop hair despite the genes, it wouldn't have developed, because natural selection does not care about the fitness of groups as a whole. It only cares about the individual.

Take pea****s as an example. There was a time when pea****'s feathers (on males) indicated good health. The bigger the feathers, the more the pea**** was eating. Basically, at least. Which meant that the ones with smaller or no feathers would not be selected (much like baldness). But! Evolution came into play and started allowing for the development of feathers despite poor nutrition. The environment essentially started to favor pouring any resources into feathers instead of into anything else, because that's what got a bird laid. Now the feathers have nothing to do with the actual fitness of the male, but because they still help acquire mates, they have everything to do with the genetic fitness.

See, what you're suggesting is that the inability to grow feathers would have been stressed (instead of the ability to) so that females could identify poor mates, but those genes would never survive, as the ones with them would not have mated and would have died off.

I hope this is clear. It's pretty complex idea, and it might be simplified too hard. But yeah, the way you're suggesting genes are selected seems to assume that evolution takes into account populations in ways that it does not.

The presence of MPB in the gene pool implies that it was either beneficial to mating at some point, associated with other factors that were more beneficial to mating than balding was negative to mating, or that MPB had no effect on mating at all and stayed as a non-affective mutation.

Each is possible.

1. Beneficial to mating: In gorilla groups, males that have larger foreheads have more promenence and access to mates. Thus, any hair that can recede increases the appearance of the forehead, and thus status. This could have been true at some point for humans too, since we fairly likely had primate ancestors.

2. Associated with other factors: If whatever causes balding exactly makes you a MORE fit mate otherwise, balding would remain in the gene pool. For instance, if whatever causes MPB also makes you smarter, it would remain. I think we know so little about MPB that this is at least possible.

3. Since balding happens after mating would typically take place (at least in the early days of man), it likely had no effect on mating at all, and still doesn't. Think of how many bald men you know with children. And how many daughters of bald men you know that have children.

I'm not really that good of a science writer, so this may not be clear. And I wouldn't expect you to just take my word for it, but I promise: the way you think evolution works is a little off. And I'd be happy to try to explain why more if you have specific questions I could answer a little at a time.

[Aston]

See, what you're suggesting is that the inability to grow feathers would have been stressed (instead of the ability to) so that females could identify poor mates, but those genes would never survive, as the ones with them would not have mated and would have died off.

No, according to my speculation the ability to grow feathers would have been stressed, but poor fitness would have caused pea****s to still have no tails or grow smaller tails.
This is what actually occurs to pea****s.
They don't grow tails of the same size across the board. You are assuming that pure sexual selection alone justifies the presence of sexual dimorphisms, but that theory isn't the most popular, in my view.

The Handicap Principle, for instance, supports my speculation, with a famous study proving that pea****s born from males with bigger tails have better survival rates. Thus, tail size correlates to fitness. Females also choose males with bigger tails preferentially. In fact, the pea****'s case is often quoted by the proponents of the Handicap Principle as exemplar: http://en.wikipedia.org/wiki/Handicap_principle

The genetic structure that allows some pea****s to have smaller tails than others is consequently a positive trait, because females can choose the males with the biggest tails and be sure that such males are more fit than the ones with smaller tails. The difference in tail size is influenced by the capacity of the male pea****s to adapt to their environment, which is what we call "fitness". This is even more evident in deer antlers, which serve as ritualistic weapons in male-to-male combat, yet are proportional in size to deer nutrition.

Therefore, if pea**** tail size (only the male birds have such tails) represents fitness, then human males' hair could represent fitness in the same way.

Furthermore, if we consider DHT metabolism, an excess of DHT causes excess body hair and hair loss on the head. Women across the globe have an overwhelming preference for men with a head full of hair and low body hair. (Apparently, only 20% of women preferred men with chest hair, in a cross-country study.)
Increased DHT metabolism thus correlates negatively with reproductive chances, and is typical in old age, which corroborates my speculation further about hair loss being correlated to fitness, or rather, that the presence of hair is a sign of fitness, thus also playing a negative role in its absence, like the smaller tails of male pea****s.

There are always fitter individuals who manifest better traits than less fit individuals and if males evolve ways to "look" fit regardless of actual fitness, females evolve new ways to distinguish fitness in males independently. I believe you may be mistakenly assuming evolution always achieves the ideal case scenario, while it never does so and is in fact a very imprecise, tentative mechanism, which has unarguably doomed countless species to extinction for every currently living one.

As i said before, the recent evolutionary disappearance of energy intake as a fitness indicator (thanks to agriculture) could very well have masked a widespread micronutrient fitness deficit to females, causing them to use a previously positive or minor trait like the absence of hair loss as a major fitness determinant. How? Simply, those with hair loss genes yet no hair loss would indicate fitness and produce statistically better offspring of those without baldness genes. The daughters of the women who preferred men with hair would therefore tend to inherit better genes, survive better and diffuse such trait.

I won't say this theory "must" be correct, but i believe it currently can't be denied with our knowledge of evolutionary biology.