r/evolution • u/Susroro • 7d ago
question Evolution of Male pattern baldness: How and when did this happen and for what purpose?
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?
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u/Sanpaku 7d ago
Pleotropy. MPB is associated with genes for earlier puberty, increased bone mineral density and pancreatic β-cell function. Those may have provided enough of a reproductive fitness benefit to overwhelm any detriment from late age sexual attractiveness, cold tolerance or melanoma.
Yap et al, 2018. Dissection of genetic variation and evidence for pleiotropy in male pattern baldness. Nature communications, 9(1), p.5407.
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u/Swellmeister 7d ago
Humans are social animals though. Parents and grandparents remain actively present in their descendants life.
Baldness is a fairly honest signal sign of testosterone expression and reception in the male lineage.
Theres a reason why baldness is frequently a cultural symbol indicating maturity, wisdom, even warrior status, really anything youd expect to use to describe a desirable male leader.
Reproductive fitness isnt about you. Its about your genes. Benefiting your children is still a straight forward beneficial gene.
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u/NonSequiturDetector 7d ago
Your comment is written like it's correcting a statement in the preceding comment but your comment isn't correcting anything in the preceding comment.
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u/Swellmeister 7d ago
Its pointing out pleiotropy in a post reproductive trait is not a good explanation because human adult males haven't actually stopped being relevant in a reproduction just because they stopped breeding.
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u/nihilism_squared 7d ago
male pattern baldness is not a detriment. people have had widely different opinions on it throughout time
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u/torontopeter 7d ago
This is a fundamental misunderstanding of evolution. People have this misconception that evolution always acts in a positive way. But often there is no “purpose” behind an observed trait.
In the absence of positive selection (ie a trait is required to exist or to be removed, to increase fitness for a specific niche or for reproduction), traits can experience neutral evolution (it doesn’t matter to fitness or reproduction if a trait is there or not).
Not all observed traits went through positive selection, and as others have mentioned, baldness doesn’t play an active role in fitness or fertility, and often occurs after sexual reproductive age anyway.
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u/ognisko 7d ago
Also some traits are byproduct and unintended consequences of something else. Like heightened hormones which might serve a positive purpose but means that your hair falls out. Nature chose the hormones.
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u/RandomNick42 6d ago
This. Isn't baldness correlated with higher levels of testosterone? Which could result in a bunch of positive pressures on its own.
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u/lonjerpc 7d ago
But it does play a role in both survival fitness and firtility. It also happens well within human generation lengths in a significant part of the population. Its evolution is actively studied by evolution biologists
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u/Certain-Anxiety-6786 6d ago
Lots of things play roles in survival but that is different than being under active selection pressures.
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u/lonjerpc 6d ago
But it would have been under active selection pressure. This is why it's such an interesting trait in evolutionary biology
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u/Certain-Anxiety-6786 6d ago
Why?? Can you prove that this trait is a departure from Hardy-Weinberg equilibrium? Active selective pressure isn’t vibes. It’s a well studied field and male pattern baldness has not yet been shown to not be under HW equilibrium. That’s what you need to show me
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u/lonjerpc 6d ago edited 6d ago
No it's your responsibility to show that it doesn't. Otherwise it's still an interesting thing to research. Maybe it's not under active selection pressure or maybe it's under pressure because it's attached to another trait. But the burden of proof to stop research is showing that it's not under selection pressure.
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u/Certain-Anxiety-6786 6d ago
This is the only good answer in these comments. Not everything evolved for _a reason_
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u/Proper-Marsupial-786 7d ago
If it was a matter of hair just getting old / damaged i might agree. But MPB is directly activated by DHT - the same hormone that orchestrates puberty in male teens. There’s no reason why head hair should wither in the presence of DHT. It feels like it’s been selected for on purpose to signal something socially.
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u/Certain-Anxiety-6786 6d ago
“No reason why head hair should wither in the presence of DHT” why is this? DHT is a signaling molecule - signaling going awry is the hallmark of biology. This is why we have allergies, issues with menopause, autoimmune disorder etc. these are all signaling systems gone awry. It’s possible that’s a random mutation that didn’t have much actually fitness cost and so was never selected against is why DHT leads to hair loss.
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u/Proper-Marsupial-786 6d ago
It’s a near universal effect across all men (to varying degrees) localized specifically to the scalp and almost exclusively begins in the late 20s to early 30s which coincidentally is the tail end of reproductive age for early humans. All of which is orchestrated by a hormone already known to signal the transition from one stage of life to the next in puberty. I’m sorry but that doesn’t sound like a coincidence to me.
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u/Certain-Anxiety-6786 6d ago edited 6d ago
Okay you’re a bad biologist. That’s fine. Can you show me that it’s under active selective pressure? Do you have evidence showing it’s not in Hardy-Weinberg equilibrium? Evolutionary bio isn’t vibes it’s a well studied field
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u/bcopes158 7d ago
Be careful about assuming that what is esthetically deairable in one time and place tells us anything about what is what is esthetically pleasing generally. It varies dramatically with time and place.
Secondly traits that occur later in life rarely effect fitness to reproduce to a large degree. Most men especially in early human populations already had kids before they would start going bald. Assuming that would have made them less likely to breed.
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u/This_is_me2024 7d ago
Male pattern baldness is something that happens after you have reached peak breeding age. Evolution doesnt give a damn if you become an ugly busted bastard in your 30s, just that you are a viable mate as a sexually mature life form.
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u/Inevitable-Copy3619 7d ago
Hey, tell us what you really think of bald men :)
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u/This_is_me2024 7d ago
Sure, I'll tell you after my shower, I need to re up my queball head (I have male pattern baldness and just bic it)
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u/Inevitable-Copy3619 7d ago
Ah then you can call us ugly hahha I wish I had hair but it is what it is and I’m not too bent out of shape.
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u/Strive_to_Thrive 7d ago
I just wish mine would stop needing to be shaved. If I'm gonna lose it, at least have the courtesy to require no upkeep.
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u/This_is_me2024 7d ago
The day three stubble is the worst for me. Day 1 and 2 I can deal, I can put a hat on. Day 3, shits like velcro.
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u/Tradition96 7d ago
Evolution DOES give a damn about you becoming an ugly bastard in your 30s, since most men can continue to reproduce long after that. Any feature that appears before age of 50 can impact reproductive success.
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u/FrameworkisDigimon 6d ago
Sure but if you've already reproduced the children pre baldness and post baldness carry the same genes.
This point would be relevant if there was a "bald person cannot reproduce until they became bald" factor but there isn't.
By the time you're thirty you've had the better part of twenty years to already have children and, at least in the recent past, would generally already have had children.
It could be the case that there's selection pressure to find baldness to not be a deal breaker. Imagine, for example, Uggina and Ugga both find that their respective partners Ugg and Ogg go bald. Whose children are more likely to survive to reproduce, Uggina's after she abandons the unit because Ugg's baldness is so horrifying to her or Ugga's who stays with the family unit because Ogg's baldness is no big deal to her?
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u/Tradition96 6d ago
Selection pressure isn’t just about having zero children vs having children. A man who continues to have children throughout his 30s and 40s is much more reproductively successful than a man who stops having children at 30 (the difference between 3 and 8 children are for example very large).
I don’t think baldness effects reproductive succesfulness, not because of the age where it manifests, but because women have, on a group level, not found it particularly unattractive.
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u/Endward26 7d ago
That argument doesn't work.
We need to understand the reproduction patterns of early humans in evolutionary history. When we consider observations from different societies and other primates, the concept of a "peak breeding age" becomes much more blurry.
There is a trade-off between skill, social position, experience, etc., and actual reproduction.7
u/roryclague 7d ago
As far as changes in gene frequency, all that matters is whether baldness occurs after children have been born (assuming the bald phenotype prevents reproduction and birth of a first child, itself a shaky assumption not born out in the data). If so, genes leading to MBP will stay in the population.
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u/Endward26 7d ago
The problem is that, at least in theory, there is no age at which a man cannot reproduce.
From a pure evolutionary point of view, the question remains open.
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u/Tradition96 7d ago
Average age of onset of male pattern baldness is 30, when a man is often in his physical peak.
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u/Ok_Writing2937 7d ago
all that matters is whether baldness occurs after children have been born
Not really. A male still pumping out children at age 80 will be outperforming one who stops at age 30. More offspring = greater genetic contribution.
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u/pastaandpizza 7d ago
a "peak breeding age" becomes much more blurry. There is a trade-off between skill, social position, experience, etc., and actual reproduction.
A social construct of peak breeding age and a biological/evolutionary peak breeding age can surely be untangled? Onset of puberty provides the lower bounds of breeding age obviously (and that age shifts with environment) and then onset of sperm quality decline (starts around age 35 for modern men) and biological complications from mother (around the same age for modern women) give an upper bounds.
This seems like when biology/evolution has decided the peak breeding age is to manage our reproductive systems optimally. Our culture baggage can and does shift this range a few years in one direction or another - but it's not going to overcome OP's suggested that male pattern baldness currently coincides with the end of what evolution has decided is peak breeding age?
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u/Endward26 7d ago
and then onset of sperm quality decline (starts around age 35 for modern men)
That doesn't prevent the males from reproducing.
It could be selected against but from the viewpoint of a single organism and their genes, it could still successful recreate the genes.
As strange as it may sound, an organism would have an interest in recognizing signs in others that indicate successful reproduction with those others is less likely. Conversely, it would have an interest in ensuring that it does not emit those very signs itself under any circumstances.
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u/pastaandpizza 1d ago
That doesn't prevent the males from reproducing. It could be selected against but from the viewpoint of a single organism and their genes, it could still successful recreate the genes.
It does decrease their fertility rate. It doesn't prevent, but fertility rate absolutely drops during this age period and beyond. If a woman has to chose a mate, males in this age range have physical signals that coincide with this drop in fertility and she could chose another, and the women who choose the most fertile mates are more likely to have more offspring Hell, or it could mean the opposite, the signals say hey he made it this long he's obviously done something right, maybe he is a good mate. Either way it's signs of aging being selected for, and that dual-use for the signals could be why it's kept around instead of everyone looking ageless.
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u/robsc_16 7d ago
It can happen at really young ages too. I probably started losing mine at 16-17 and it's not like I was unable to have children.
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u/hopium_od 7d ago
I was 12 lol
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u/Tradition96 7d ago
That was probably not male pattern baldness but some other form of hair loss. Male pattern baldness is triggered by testosterone, which needs to be above a certain threshhold to kick in. A 12-year old having enough testosterone to trigger male pattern baldness would be extremly unusual.
There are, however, many other causes of hair loss that can happen to a person.
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u/FitzCavendish 7d ago
Can I just say that there is a lot of negativity and prejudice here. "Negative trait", yada yada yada. Bald people are a community.
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u/jnpha Evolution Enthusiast 7d ago
Please read this: https://evolution.berkeley.edu/misconceptions-about-natural-selection-and-adaptation/defining-adaptation/
Not every thing is an adaptation or is there for a "purpose".
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u/ah-tzib-of-alaska 7d ago
aesthetics are mostly cultural so your aesthetics as a judge for a traits possibility for sexual selection is not good data
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u/Helmdacil 7d ago
Hair loss in aging is not human-specific, it is present in most mammals. Mice for example get patchy hair and greying at 12-18 months.
Hair loss in general has something to do with testosterone, thats why we have daily medications one can take to prevent hair loss (but its a lifelong thing, and it also potentially screws with male fertility). So if you are wondering how the Elon Musks do it, the guy was balding at age 30, got a hair transplant, and started taking pills.
As for why hair loss occurs, Yeah that is a good question. If there were strong enough selection upon the trait you'd imagine that hair loss could be prevented, there is a lot of variation within the human population and there is variation due to stress as well. Basically selection has not been strong enough to weed out the trait, and its a byproduct of how our gene expression profiles are wired.
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u/LunarPrincessSophie 7d ago
It's a hormonal side effect of the metabolism of testosterone - with dihydrotestosterone being the culprit. It sets in after reproductive age and doesn't cause a significant disadvantage so there is no selective pressure against it
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u/Shadowratenator 7d ago
Not everything that happens has a direct distict purpose. It appears to be a side effect of testosterone.
It could be that the purpose is the levels of testosterone to make attractive 20 something males just doesn't pan out as well later in life. It's possible that knocking older males down a notch by making them go bald improves the mating chances for the up and coming males, thereby increasing genetic diversity.
Other apes also display male baldness. it doesn't seem to carry stigma for them. it could be that our non human ancestors found a bald male quite attractive so this was selected for and we still have it.
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u/Ok_Writing2937 7d ago
Depending on how one interprets natural selection, male baldness might also improve fitness by helping females weed out partners who may provide less viable offspring.
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u/Shadowratenator 7d ago
The plain truth is bald dudes make great starship captains. We know it. We will be thankful we kept the genes around in a few hundred years.
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u/Funky0ne 7d ago
Despite what current male beauty standards might have you believe, I’m not sure I’ve ever seen much evidence that men with mpb historically (or even currently for that matter) have statistically significantly more difficulty finding mates or fathering children than anyone else.
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u/sk3tchy_D 7d ago
Everyone in here saying that male pattern baldness doesn't start until well after breeding age are viewing things through a fairly modern (in evolutionary terms) lens. Anatomically modern humans diverged from other Homo species around 2 million years ago. Genetic evidence seems to show that prehistoric human males typically didn't successfully breed for the first time until they were around 30, with females usually starting in their early 20s. We become sexually mature in our teens, but that does not mean that is when we typically started breeding. Our brains and bodies continue developing into our 20s. My physical peak was definitely between 28 and 33. Both gorilla and chimp males reach sexual maturity at around 8-10, but don't generally reproduce successfully until they are 12-15. We live longer and mature slower, so it makes sense that we would have a longer gap. It's entirely possible that male pattern baldness is a similar signal to the silver backs that fully physically mature gorillas develop.
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u/Mr-DolphusRaymond 7d ago
I agree with you point but I think the numbers need some context.
The evolutionary average generation time is like 31 for human males, but that would be the average middle kid who survived childhood, not the first kid, which would be at a younger age on average. The 31 figure is also skewed high since many men can continue to have kids until much later than most women. Average first kid cannot be deduced from the same calculations but we might expect a median or modal age of first concieved kid for men well under 30 and possibly under 25.
For reference, Hadza women marry at 17-18 and men at 20, and they generally don't delay consummation
https://pmc.ncbi.nlm.nih.gov/articles/PMC2781963/
This linked study also points out that Hadza breeding strategies do not conform to Western standards in multiple ways e.g. women favouring taller men, assortative mating for weight/bmi
It's easy to imagine that male pattern baldness was not considered extremely important to most of our ancestors. Somebody got Herpes from Paranthropus for example
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u/Idoubtyourememberme 7d ago
It simply happened randomly, and since it doesnt give a survival or reproductive disadvantage, it jsut sort or stayed around.
Even if it is not aesthetically pleasing, by the time it shows up, the man is past his reproductive prime, so it lowering his chances is a non-issue (biologically speaking)
Not everything that evolves and stays around needs a benefit, "net neutral" is all that is needed. Positive traits simply spread around faster
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u/nihilism_squared 7d ago
baldness is not inherently ugly nor beautiful. opinions on beauty, especially of human bodies, are extremely variable across time. maybe paleolithic people thought it was hot. there's a good chance that armpit hair exists to make people smellier, because paleolithic people found it hot
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u/Hivemind_alpha 7d ago
Any trait that is expressed after most examples of the population have had their children is almost completely invisible to evolution. Think of susceptibility to dementia, heart failure, arthritis, susceptibility to cataracts, even male pattern baldness. What keeps you alive and fit and attractive to mates in order to breed is subject to natural selection. After that point, it doesn’t matter what your genes do to your body, because the next generation is already fixed; selection has judged your genome and passed it on. What happens to the shell those genes were delivered to your offspring in is almost totally irrelevant.
I keep saying ‘almost’ because in some species, there’s an infant care and cultural repository role by seniors. In that case, an attentive grandparent improves the survival chances of the offspring, so the characteristics that make them effective in that role are still subject to selection.
Imagine a new human mutation that made the carrier drop dead at 50, but was invisible before then. Would it stop you having children? No. Would it harm those children before they can breed? No - we’re a social species with a community safety net, and any advantage you might claim they miss out on could equally be balanced by a disadvantage they no longer suffer (elder care draining resources, increasing risks etc). So what makes the frequency of that gene drop in the population over generations ? Nothing. It drifts.
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u/Think-Photograph-517 7d ago
Some things don't evolve due to being an advantage. They are just a side effect of something. Or just don't matter one way or the other.
Male pattern baldness is caused by high testosterone levels, which can have various advantages. Baldness is a side effect that doesn't seem to have advantage or disadvantage from an evolutionary standpoint.
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u/Lorelessone 7d ago
It tends to come in after a mans prime reproductive years so is irrelevant to sexual selection.
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u/joedenowhere 7d ago
A genetic change can spread through a population not because it directly increases fitness or survival, but because the opposite sex has some reason for preferring it. (Called sexual selection.) Male baldness may be a way for a male to indicate to females that he has managed to survive early adulthood, so he would make a good partner. Also possible that it's a consequence of some unrelated genetic change that was selected for fitness or survival reasons.
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u/pastaandpizza 7d ago
Everyone here is saying "just cause happens doesn't mean it's advantageous/natural selection" I think is ignoring that fact that balding can be advantageous - to tell other humans you're at the end of your peak fertility.
Male sperm quality drops around the same time many men experience pattern baldness. Just like puberty grows body hair as a signal of fertility, male pattern baldness can be the opposite cue to steer women towards younger mates.
I doubt we'd ever find evidence to support that hypothesis, but it's just as valid a hypothesis as valdness being an unselected byproduct of male biology.
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u/nihilism_squared 7d ago
there's no reason an animal would evolve a "hey, don't mate with me!" signal
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u/Mr-DolphusRaymond 7d ago
A more logical reason might be it forces fathers to focus on their kids since they can no longer convince other women to sleep with them.
I highly doubt that's the case but a lot of people in this thread are invoking group selection type stuff which makes no sense to me either
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u/nihilism_squared 6d ago
there's no evidence baldness was considered unattractive in paleolithic society. you're assuming it's always been seen as ugly which is simply not true
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u/Mr-DolphusRaymond 6d ago
Should have put a /s
I'm just trying to affirm that no trait is positively selected as a signal to lower fitness.
Even my tongue in cheek explanation based on a faulty assumption is a better hypothesis than this "take one for the team" understanding of baldness evolution some people are endorsing
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u/pastaandpizza 5d ago
In that case signs of aging would be significantly better hidden. Gray hair / balding / whatever. Those signs show age, and fertility decreases during this time, if signals that showed you were less fertile were a hinderance to selection (hey don't mate with me!) then the opposite would be selected for - signs of aging would be better consealed.
My point was signs of aging limiting your old age mating may for you to focus on already established familial connections, kind of like the "gay uncle hypothesis".
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u/corobo 7d ago edited 7d ago
Being bald never made anyone die or become impotent so it's never had an opportunity to leave the gene pool.
Why bald in the first place? Probably a continuation of losing our fur from the ape days - helps keep us hunting by making our sweaty new cooling system more effective
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u/Hastur13 7d ago
As a balding man with an interest in evolutionary biology, I have given this a lot of thought. I think it might be less of an adaptation, as it is a function of clothing. There are fewer bald and balding men being selected out of the gene pool by extreme sun exposure.
Our hair grew to be on the top of our heads and cover our shoulders in order to prevent overexposure in those areas while walking uprights. We lost the hair elsewhere so that we could more effectively cool ourselves.
Basically, I think balding is a random mutation that isn't catastrophic, and over time has become even less detrimental than it was in the past. Therefore, even with sexual selection, it's not really being bred out of the gene pool. It also doesn't tend to show itself until just after men are most sexually active. So that's another thing that keeps it pretty safely in a lot of our genes.
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u/Party-Cartographer11 7d ago
I heard it was more common in northern Europe, kind of like having less pigment in skin, and thinner hair to allow for more exposure to sunlight for vitamin D. No hair on the surface directly facing the sun compensates for low sunlight hours in the winter.
Also, I think different than below that male reproductive age goes well beyond when mail pattern baldness onsets (20s and 30's) especially in non-puritanical societies. I also think that due to the horrible horrible treatment of women over the ages than the attractiveness of men as a trait for higher reproductive ahhh, episodes, may not be important due to lack of consent.
I have no data other than loosely historical observation and of course there are counter examples like people with high pigment skin and baldness
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u/After_Ad9425 7d ago
For one baldness doesn’t really have any..negative traits. Maybe perceived attraction in society, but that’s not enough to stop people from breeding. I mean, there are a lot of dads that have or are going bald right now right? Mutations are not strictly good or bad, they are just carried over generations, what is or isn’t considered a bad gene depends entirely on whether or not those bad genes can be statistically passed down. And while maybe people with hair breed more then people without, that gene is still being passed down well enough to not get lost.
It also probably helps that most pattern baldness occurs later in life then the average time it takes for them to have a kid.
There’s also the uh…non consensual method which while absolutely fowl and disgusting does it happen and probably happened a lot more in the past.
I also want to specify male pattern baldness as societal attraction because what is and isn’t attractive to people varies on both an individual level and a societal level, which also means the average attraction or unnattractrion of a trait changes with the time period. I don’t think we even have much idea what prehistoric people thought of as attractive or attractive enough.
Also statistically speaking there is likely at least a small minority of women that find it attractive or at least don’t care so much about it.
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u/war_ofthe_roses 7d ago
One of the most common fallacies about evolution is that everything in existence has an evolutionary purpose.
This is false.
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u/sisconking132 6d ago
There is a term for problems that arise later in life, after most individuals stop having children. It’s basically an evolutionary blind spot.
Natural selection can only select for traits that improve one’s ability to have offspring and one’s offspring to have offspring. Issues that arise mostly later in life such as arthritis, dementia, and other age related illnesses essentially cannot be weeded out effectively by natural selection because these problems arise after individuals stop having offspring.
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u/CaptainONaps 7d ago
I'd marry a balding chick if she paid all the bills, calmed me when I was stressed, dealt with thuds in the night, answered all my questions about the world, held me gently and made me feel special.
So fast. I'd marry her so fast.
That's why there's bald guys. Evolution.
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u/Fit_Rate7093 7d ago
I blame the arm pokes...
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u/strumthebuilding 7d ago
For enabling people to live long enough for “negative traits” (I baldly reject this framing fwiw) to emerge post-reproductive-age?
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u/Fit_Rate7093 7d ago
Says the people making bank from them. Gates said himself they are very lucrative. Let's say they are a money making scam at best. How long did humanity survive without them. Was it thousands or millions of years?
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u/strumthebuilding 7d ago
“lucrative”
The thing I love about anti-vaxxers & other opponents of medicine is that none of them are trying to make any money.
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u/Fit_Rate7093 7d ago
I never paid a penny to anyone regarding their position on vaccines. Name one person.
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u/Top-Needleworker-516 7d ago
I believe it is a long genetic trait that possibly goes back hundreds of years to when many humans remained in caves or underground. And obviously what’s something you couldn’t get in the shade back then? The sunshine vitamin, Vitamin D specifically. So possibly it was the bodies resilience response to obtain such Vitamin since it is at the highest point of the body and in such pattern.
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u/Tombobalomb 7d ago
It's been around for a very long time and is widespread, ironically, because of sexual selection which favours it
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u/SevenIsMy 7d ago
Peacock females are attracted to long feathers, a peacock male with long feathers is an indicator for good health.
Good health is an evolutionary advantage, and selection favours the steps which leads to it.
Being old is an indicator for good health. So all the signs of old age may drive this selection.
The disadvantages are less severe, than the benefits.
You might then think why do then Man not get bolder earlier and earlier?
Maybe it has something to which the fact that Men and Woman share the same gens, and for reproductive selection it an advantage to be attracted to young features on women.
So woman ending up with 2 sets of preferences selections.
Do woman who have high testosterone levels preference younger looking man?
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u/Healthy_Article_2237 7d ago
I think getting old enough to have baldness or gray hair wasn't a huge concern for millennia. Animals in captivity show similar aging with gray hair but you never see it in the wild because they don't live as long.
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u/NoGoat3930 7d ago
No idea, but I have so many fewer lice, so much more blood, and so much less typhus, ever since I went bald.
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u/nihilism_squared 7d ago
there is no inherent reason for it to be aesthetically pleasing or displeasing. there's a decent chance our ancestors found it really hot
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u/UnholyShadows 7d ago
Honestly id say most men dont want to go bald and will do anything to not go bald. Some guys just accept their fate and go bald where as others try to fight it.
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u/LadyAtheist 7d ago
It's neutral, not adaptive, unless signaling "I have sperm with mutations" is adaptive.
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u/shadowmastadon 7d ago
you won't see this comment since it's buried but this is my take; if you look at where the gene is most expressed, it's in Africa/Middle east. If you've noticed, African men generally look very good even dominant when they go bald. I suspect this gene started mixing with the more middle eastern and then caucasian populations unfortunately, causing us with ancestors in Europe and the rest of Asia to look not so awesome/dominant
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u/willienwaylon11 7d ago
I think the spandrels of San Marco should be required reading for like high school biology. I get the critiques of the paper and SJG but we really need the general public to chill with adaptationist story telling
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u/lightspeeed 7d ago
I’m wondering whether population differences in male-pattern baldness could partly reflect different evolutionary histories. In hot, open environments, keeping more scalp hair may have offered practical benefits such as sun protection and heat management. As human groups moved into different climates and habitats, that pressure may have changed.
Male-pattern baldness is strongly influenced by how hair follicles respond to hormones—especially DHT, a derivative of testosterone. Genetic variants associated with greater DHT sensitivity appear at different frequencies across populations, which could help explain why average rates of baldness vary between ancestry groups. That does not mean there is one “baldness gene” or that ancestry determines any individual person’s outcome; it means inherited risk factors are distributed unevenly.
Baldness itself may also carry social signals. Some research on first impressions suggests that bald men can be seen as older, less conventionally attractive, and sometimes less dominant or intimidating. This lines up with other findings showing that women tend to be more drawn to dominant or aggressive traits when thinking about short-term sexual partners, but often prefer kinder, less threatening qualities in men they see as long-term partners or fathers. That doesn’t prove baldness evolved specifically to signal nurturing, but it raises the possibility that it may have had different social tradeoffs depending on the context.
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u/Taxibl 7d ago
It comes from our ape ancestors. At one point it was a reproductive advantage for makes to look mature ugly and mean to scare off younger males.
Chimps also go bald and sometimes just not on their heads. Juvenile chimps are cute and fuzzy. Full grown male chimps are aggressive, uglier and have patchier fur.
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u/Good_Ask_2299 7d ago
you just know ancient japanese dudes had to start cutting their hair like that cause one emperor sometime long ago was balding
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u/MentalPlectrum 7d ago
neither does it serve a biological importance, if anything you are at risk of scalp sun burn and less warming effect of the hair.
Counterpoint - can't get head lice any more.
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u/Ghastly-Jack 6d ago
To enable bald cavemen to hide in pterodactyl nests by pretending to be eggs. What? You're saying old-timey cartoons are not legitimate science?
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u/MarkTony87 6d ago
Mutation doesn't happen for a purpose. It's random. But traits that prevent survival to reproductive age are selected out of the population. It seems that being bald doesn't prevent very many persons from reproducing and passing on those genes.
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u/ValuableLatter6913 6d ago
Baldness isn’t an evolutionary failure! We just as a society have decided balding is unattractive, it wasn’t always this way. Ancient Christian art depicts balding as a sign of wisdom or authority.
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u/Typical-Tax1584 6d ago
Cause if we started out bald, we'd be way too sexy from an earlier age and it just wouldn't be fair.
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u/FrameworkisDigimon 6d ago
Three basic points.
Firstly, natural and sexual selection happen at the level of reproduction so anything that happens post-reproduction isn't subject to selection pressure. By the time baldness comes in, men will traditionally have already reproduced.
Secondly, something things just are. Evolution has no destination in mind (it has no mind) and it can also be the case that something subject to selection pressure just so happens to have a side effect.
Thirdly, attraction is frequently thought to be largely cultural. I think the famous evidence for this is logically dubious (e.g. demonstrating cross cultural differences in breast fetishisation -- a real result -- isn't the same as demonstrating cross cultural difference in the presence of attraction to breasts*) but the basic claim is sound. Consider tans. The prevailing beauty standard among white people in the English speaking west has been to be tanned for decades. Two hundred years ago? Not the case. The reverse was true. In China, and for most Chinese people being pale or tan are both generally achievable outcomes, they are still anti-tan. So when you say:
It is not even aesthetically pleasing(not even prehistorically would I assume that)
that's not really something that can be assumed.
However, it is probably irrelevant because of the first point. Just something to keep in mind, though.
*For example, we don't fetishise faces but does that mean attractive faces don't exist? No-one ever or would ever claim this, so why is the one given as evidence for the other with breasts? (This could easily be a pop science thing where the popular literature I've encountered is misunderstanding the actual research explanation.)
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u/WazuufTheKrusher 5d ago
Not everything that is the way it is exists because it is beneficial, it exists because it didnt reduce the ability of the population to grow, and maybe even help.
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u/Ravenous_Goat 20h ago
I heard it was because of the intense activity of the male brain… Similar reason as to why women don’t grow hair around the mouth…
Just Kidding, sheesh!!! 😁
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u/SeekingTheTruth 7d ago
To those who say that evolution doesn't care about how you look after the reproductive age in the 30s, two things to remember:
- Men's reproductive age doesn't really end at 30 or 50 or even 70.
- The hairstyle is more of a characteristic that influences sexual selection. That means a fertile female may make a decision to mate based on it. So it has strong selection pressure, not weak. Why the head? Probably because it is hard to cover up. Probably why you don't go bald in your genitals (covered up - not an obvious characteristic)
Male pattern baldness differentiates older males from younger males. I believe it exists because it is evolutionarily beneficial for the species for the women to be able to identify older verses younger.
It is not established that they will prefer younger in all societies including historical ones because that preference can be learned (beauty is in the eye of the beholder) and really depends on social structure (older men have higher status), survivors bias (older men are proven fit for surviving so long) and apparent fitness (may have more muscles than younger men).
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u/frostyfins 7d ago
Ok but hear me out: bald guys can look sooooooooo handsome.
If life gives you lemons (the bald genes), make lemonade (rock the look)!
(Maybe baldness was selected for by generations of women with great taste in properly matured men?)
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u/sevenut 7d ago
Negative traits that set in after reproductive age have no big incentive to be weeded out. It's mostly about reproduction and not so much quality of life. And being bald doesn't really impact a father's ability to take care of his children, either.