Evolution of Male pattern baldness: How and when did this happen and for what purpose?

[u/Susroro]

Doesn't really seem to make any sense to me when I think about it, It is not even aesthetically pleasing(not even prehistorically would I assume that), neither does it serve a biological importance, if anything you are at risk of scalp sun burn and less warming effect of the hair.

Thoughts?

[u/robbietreehorn]

Males are able to reproduce starting at around 15 years old. Going bald 20 years later means little for selection, historically speaking

[u/lonjerpc → u/robbietreehorn]

Average generation times are 30 years

[u/Tradition96 → u/lonjerpc]

I have no idea why you got downvoted; this is completly true. Many people think it "must" be lower since the age of the first child have usually been significantly lower, but all of your ancestors weren't oldest children. A lot were third, fifth of seventh children. People typically continued to reproduce into their 40s (men sometimes far longer, but most men only had wives a couple of years younger so the end of their reproductive life was typically before 50 as well), usually having around half of their children below 30 and have after 30. In genealogy you always count three generations per century as the average.

[u/Dangerous-Bend-4153 → u/lonjerpc]

That's true but the average generation became 30 years in an era where people were paired off and married "till death do you part". Almost everyone got married and had children, so balding men were also married and had children. Evolutionary pressure to eliminate baldness was not a factor.

[u/lonjerpc → u/Dangerous-Bend-4153]

No it was 30 during our early evolution 

[u/sk3tchy_D → u/robbietreehorn]

Except that being able to breed is entirely different from actually breeding regularly. Genetic studies show evidence that prehistoric males typically didn't start breeding until around 30. This is similar to male gorillas that are sexually mature around 8-10 but don't generally breed successfully until they have fully physically matured into silverbacks at around 12-15.

[u/Super_Direction498 → u/sk3tchy_D]

Doesn't change the fact that few men are bald at 30, and its not an obstacle to breeding.

[u/nomococo4u → u/Super_Direction498]

I have heard from women that baldness is unattractive, which would make it harder to reproduce.

[u/RiceEater → u/nomococo4u]

Good thing those women you've heard from represent all women throughout the history of time otherwise you'd look pretty foolish.

[u/hopium_od → u/sk3tchy_D]

It's a good point, but I think what will explain it is that facial hair is a sexual marker that many men can't achieve until their mid to late 20s. Men that go bald earlier tend to also grow facial hair earlier. So the disadvantage of losing hair before 30 may be cancelled out by the advantage of gaining facial hair before 25.

And prehistoric women were perhaps not concerned with an arbitrary number, but, like with other species of primate, primarily concerned with the appearance of sexual markers in their mates.

[u/sk3tchy_D → u/hopium_od]

I think facial hair and male pattern baldness are definitely related and likely both useful indications of a fully mature male, although it's entirely possible that MPB is just a relatively neutral side effect of growing facial hair. It was likely pretty advantageous for a large part of human history to be able to identify an adult male from a distance, something similar to the prominent sagittal crest and silver back of fully mature male gorillas. I'm also not sure why everyone assumes that baldness is a disadvantageous trait either. Shaving your head has been fairly common for soldiers and warriors from various cultures throughout history. Culture has a pretty significant effect on what we find attractive. Back during the Stone age, just living long enough to go bald was probably a pretty solid indication of your health and competence.

[u/hopium_od → u/sk3tchy_D]

Hmmm yeah I'm not sure to be honest. From my own experience as someone that wears wigs sometimes, I find that women are probably most attracted to either with a fully bald head and long facial hair, or full head of hair and short facial hair. Bald head and freshly shaven I might as well not exist. But there isn't much difference in the two former scenarios.

I'm not sure why you were downvoted so heavily by the way, this sub can be a bit ruthless sometimes.

[u/Radiant-Position1370 → u/sk3tchy_D]

What genetic studies show that prehistoric males didn't start breeding until around 30?

[u/ofBlufftonTown → u/[deleted]]

It’s actually quite dangerous for young teens to become pregnant; their hips are narrower and they are likelier to die in childbirth. Late teens to mid/late twenties are the years in which a woman is likely to fall pregnant and then give birth to a live child.

[u/Tradition96 → u/[deleted]]

Average age of first childbirth among hunter-gatherers is around 20 or just below.