Evolutionary reason for male pattern baldness?

Well, thats about it? Is there any evolutionary/survival advantage that would explain male pattern baldness? It seems rather universal and, based on modern, Western perceptions, likely to reduce the chances to reproduce instead of enhance?

Biologists? anyone?

Just a WAG but might it be something to do with the relatively recent increase in life expectancy amongst men? Perhaps back when people used to be lucky to see 50 baldness was not so much of an issue but with advances in medicine and living standards people live longer but hair stops being produced at the old “expected time of death”.

There doesn’t have to be an “evolutionary advantage” for any given characteristic; merely the lack of a disadvantage related to survival and reproduction. As mittu notes, reproduction typically occurs/occurred before male pattern baldness has its impact.

I’ll disagree with that. I am under 40 and am going bald. Of course, there are people who start losing their hair in their 20s.

I suppose we could start graphing amount of hair missing versus lessened likelihood of finding a mate (this is assuming there is real data confirming that balding men are indeed less likely to reproduce) over time, but I’m assuming that men with just a bit of thinness wouldn’t be at much of a disadvantage. Thus it pays to start hunting for that mate when young - get that done with before your hair starts falling out and she starts looking askance at you?

Everyone seems to be implying that the absence of hair would be a detriment to mating. While this may or may not be the case now, I don’t see how an earlier human species would necessarily have negative feelings about hair loss. Humans are not the only primates in which baldness happens naturally at maturity. Many orangutans and chimpanzees of both sexes show some signs of baldness when they reach maturity.

The OP asked about,

To this I would suggest that it indicates maturity and fortitude, like graying of the hair. Other males would be able to discern the older dominate males. A proposed mate would look for a mate that has shown evidence of resilience. By mating with one that has lived a long life, they would ensure that their offspring might share in this genetic advantage.

It doesn’t have to be an advantage as long as it isn’t a significant detriment. I can’t imagine that early humanoid females would shun an otherwise healthy male just because he was a little thin on top. That’s a luxury for modern women, and many of them don’t seem to care much either. I suspect most of the negativity about baldness comes from men themselves, who see it as a sign of aging.

I believe MPB is a side-effect of testosterone levels. If that is the case, and it’s neutral for sexual selection, there’s no reason for it not to be in the gene pool. Not every trait needs to be a positive, it just doesn’t have to be a negative or could be tied to another positive result.

I’m over 50 and the stuff grows everywhere.

I just keep it mowed.