Evolutionary speaking, why does a non-reproductive trait persist in humans?

[LaFemmeFatale_1]

Wouldn’t a trait that made people less likely to reproduce die out?

Unless it served a higher purpose of helping in survival and reproduction of other people… What are your thoughts?

Updates

+1 y

For example, if homosexuality (which can’t give out an outcome of giving an offspring) doesn’t serve the best interests of population why would it survive and persist in so many living species.

It either benefits the survival of the individual, either balances out the population’s number or helps with the reproduction of other humans/animals in the population.

I think there’s a reason it exists and that reason is beneficial for the rest of the population. But I wonder what’s that reason.

[Malcom_Reynolds]

There's an entire book about this called The Selfish Gene. Basically the idea is that it's the genes that benefit from natural selection not the individuals.

How might this apply to something like homosexuality? It can result in better care being given to raising of young in a tribe like environment. Where a homosexual individual might not benefit in a reproductive way, but a tribe that carries genes that sometimes result in homosexuality could benefit in the long run.

I don't know if I explained that very well but if you're interested in that, I recommend the book

[NaultD]

We make tools that is outside of biology. We have glasses, asthma medicine, cesarean section that creates life that would be impossible in a stone age in a Darwin evolutionary stand point. Therefore way more people survive.

With more people surviving trivial medical issues more people grow up and push the boundaries of science and our understanding of the universe.

https://www.youtube.com/embed/6qZWMNW7GmE

[OlderAndWiser]

Do you have a specific trait in mind?

[OlderAndWiser]

I believe your initial thought is correct; there is a beneficial consequence of traits which survive the selection process. An example which I understand is colorblindness.

Colorblindness is primarily a "defect" present in males, as it is carried on the Y chromosome. There are 6 different types of colorblindness; one type results in seeing everything in black and white, while the other types have great difficulty in distinguishing certain colors.

You have two types of cells in your eyes which convert light to electrical signals that are sent to your brain. Rods produce a binary signal which is interpreted as black or white. Cones convert light to a signal which is interpreted as specific colors.

Color perception requires a fair amount of light saturation, so people with normal vision easily perceive colors during the day, but under the dim illumination of night, most vision depends on the rods and black/white perception.

[OlderAndWiser]

People with a color defect depend on their black/white perception, and other visual cues for distinguishing objects in the visual field. They compensate for their color defect by noticing subtle movement, shadows, increased ability in depth perception, etc.

There are two non-obvious advantages for men with color defects. First, they have better night vision, since their black/white perception is more developed. Second, animals have adapted for survival by having colors which camouflage them in wooded areas. However, those color cues are not perceived by colorblind individuals and animals are more obvious; therefore, colorblind individuals are better hunters.

Neither of these traits gives a man a direct advantage in the process of mating and reproduction, but they do help colorblind men to survive a sufficient time to reproduce. And colorblindness does not seem to have any significant adverse offsetting impact on survival and reproduction.

I have a colorblindness called extreme deuteranomaly, so I have experienced being in the woods and spotting wild turkeys and deer that others did not see. It is a very real phenomenon.

[RavVid]

It's a good question. My understanding of gay guys is it is due to hormonal balances in the womb. It is something that goes slightly wrong not badly wrong.

But there are a number of sexual traits which you could question. Any outercouse activity is not fit for reproduction purposes. Fellatio isn't but it wasn't invented in Portnoys Complaint circa 1970. It has been depicted for a long time in art.

As a guy, it feels like an entire games package was installed at puberty. Everything in the games package feels so right it cannot be wrong. Fellatio feels as right as inserting your penis into a vagina.

Given the endurance of fellatio then it is not some flash in the pan penchant, like a stiletto fetish. I think we have to assume Homo Erectus man made Homo Erectus girl bob her head back in 2 Million years BC.

It is really hard to see how cuming in a girls mouth helps reproduction - her ovaries are elsewhere

Except perhaps as playfulness. We are a playful species. Skiming stones across water has no point to it other than it is fun. Picking up sticks and throwing them for fun could be the glimmerings of spears, boomerangs and throwing axes/cudgels.

So I am going to argue our playfulness is the mother of our inventiveness and our playfulness combines with sexuality for sexual playfulness. Homo Erectus man thought I wonder what it would feel like to put my penis in my girls mouth. Or what will it feel like if I hump her ass. Turned out to be quite nice.

Just as now, it might have revved up Homo Erectus man and ended with a couple more babies being born.

That's the best I can get to.

[love_conquers_lust]

Humans are closely related to Bonobos as well as Chimpanzees. Bonobos are polyamorous and use sex to neutralize tension. So, that's one possible explanation for it in human behavior if you subscribe to evolution.

You could also look at it from population dynamics. It's there to protect humans from overpopulation if a carrying capacity is unsustainable. A better alternative than high infant mortality rates or warring for limited resources.

Another explanation that's more roundabout but still viable. Consider that hunters would sometimes be away from days at a time. This also might have put evolutionary pressure on females within a species to become that much more attractive to incentivize hunters to return from treks as opposed to abandoning their tribes.

Genetically, not all traits are simply dominant and recessive. There’s also codominance and incomplete dominance of phenotypes. There’s also the Hardy-Weinberg equation that says just because a dominant trait becomes the majority, doesn’t mean the recessive trait will disappear.

[EricSummer]

Homosexuality is part of a mechanism to be attracted to one gender only. From evolutionary perspective this is better than being attracted indiscriminately to all genders. However, as humans are terribly comokex, this mechanism occasionally goes the wrong way round. This is still better than not having it at all in the population.

In addition, it has been found that female siblings of homosexual males are more fertile. So there is some genetic trait that helps their fertility while at the same time making their brother gay. This offsets some of the evolutionary burden of this trait.

[richardcory]

There is some kin-selection effect. For example having some percentage of people willing to sacrifice themselves for others, will allow the community, and therefor those people's relatives, to survive and pass on their genes.

[msc545]

What is an example of a non-reproductive trait?

There is a lot of genetic material that persists in the gene pool that has no obvious function - the traits you are talking about might be controlled there.

[LaFemmeFatale_1]

For example, if the homosexuality (which can’t give out an outcome of giving an offspring) doesn’t serve the best interests of population why would it survive and persist in so many living species.

It either benefits the survival of the individual, either balances out the population’s number or helps with the reproduction of other humans:animals in the population.

I think there’s a reason it exists and that reason is beneficial for the rest of the population. But I wonder what that reason is…

[msc545]

There is no obvious reason for homosexuality from an evolutionary standpoint. I've been thinking about that a lot since you mentioned it and I'm coming up with essentially nothing. Sorry.

[richardcory]

I can imagine that men and women who do not have their own families might find it easier to act for the common good of he group rather than for their own children. They would also not be part of what might be a competitive process to find mates.

Another possibility is that if the women tended to stay in a safe location to raise children, and needed men for protection, then other men might be more comfortable with that protection being provided by a man who was known to not be attracted to women. (this is making a big and possibly incorrect guess at gender roles in the paleolithic.)

[Anonymous]

It could be that it's helpful to the lineage of genes, while not being beneficial to the genes of the homosexual individual. So for example, if a couple has many kids and it turns out that one of them is gay, that guy can provide extra help when it comes to raising the others' kids or could provide material support.

[Adaeva]

Certain combination of recessive genes can be beneficial. For example, resistance to malaria. However, when someone inherited a combination of the recessive genes from both parent the combination can be deadly. However, that is more rare so overall the genes are beneficial.

[BeMuse]

Essential genes for survival are protected more heavily, were as the rest of the genome is less so protected and more vulnerable to mutations. Apparently which hole you stick your dong in isn't as important as say gene expression or cell growth. Thus mutations that mess with your higher order thinking and mess up your sexual reduction might reoccur as some low frequency, especially if there are persistent mutagens say in the water supply that people consume on a regular basis.

[BeMuse]

*at...

[Billlewis]

I think you have to take into account the skyrocketing cost of living. Also, many people, myself included, believe that liberalism, groupthink and technology have become so all consuming that they wouldn't want to bring a child into this world any longer, even if they could afford it.

[KingslayerC]

In general, sure, but you point out a good exception. Other exceptions are things that were socially condemned, then hidden, so they continued on, genetically. Homosexuality and pedophilia are some examples. We basically made them hide it so they continued to pretend to be attracted to opposite sex people and adults, so they kept making babies.

[Berethor]

Because of birth defects? and Japan is dying out because of having a low birth rate.

https://www.washingtonpost.com/world/2022/06/03/japan-low-births-population-decline-2021/

[genericname85]

do you have a particular thing on mind? if you're talking about being gay, i think that's more a fluke/error than an "inherited traid". cause how could a gay person possibly pass on their genes if they didn't fuck someone they could reproduce with?

[shortster]

It is fairly common for recessive traits to have a benefit in the gene pool. The best example of this is sickle cell anemia. As it offers anyone who has the gene protection from malaria. So populations in areas where malaria still persists have a high incidence of the gene. Whereas areas that eradicated malaria; sickle cell anemia is almost completely gone.

[shortster]

Homosexuality in animals occur for one of two reasons. Either there isn't enough males or females in a group for everyone. Or in order to trick other males into copulating with a male pretending to be female; then that male can mate with the female without any competition. Whereas in humans there isn't a genetic component to homosexuality. If there was the eugenics movement would have wiped it out.

[BoopBoopBeep]

Depends on the trait maybe... your question is pretty vague, but maybe it just hasn't worked it's frequency down to zero yet.

Did you have a specific one in mind?

[BoopBoopBeep]

After update... there's 8 billion people and rising in a world that was once estimated to be optimized for 5 billion. Maybe evolution is smarter than us.

[LaFemmeFatale_1]

I totally support homosexuality and feel that it exists because it serves a purpose.

That might be one of the reasons I was thinking about…

Anyway, isn’t it silly of people to judge other people for something that is potentially beneficial for the rest of the people?

[BoopBoopBeep]

People get on my nerves. I can usually find a legitimate reason to dislike them. Who they stick their junk in doesn't even fall in the top ten things I care about as long as it's not an animal or minor.

[Siri137]

You believe in the theory of evolution. Oh dear.

[LaFemmeFatale_1]

I don’t believe in anything. I don’t even believe in God, I think of various different possibilities and discuss them.

[Siri137]

Okay. My mistake.

[slatyb]

It's complicated but games that don't reproduce eventually suspect from the gene pool. Of course they may reappear due to mutation.

[strateguy632]

i think you just brought a valid indication not genetic?

[Grond21]

Given an evolutionary framework, it could happen if it wasn't a loss to keep it around, or if it would only kick in after children were born

[loveslongnails]

Some people NOT reproducing IS part of evolution.

[Amur8711]

It only exists because of how complicated human society, which creates mental illness.

[LaFemmeFatale_1]

I disagree. I don’t think homosexuality is mental illness… It’s totally natural in other species not only in humans.

[Amur8711]

Oh? Really, it's natural? Says who? And what species?

[LaFemmeFatale_1]

Homosexuality is noticed is penguins, dolphins, bonobos, macaques, swans, bisons, giraffes and so on and on…

[Amur8711]

Says who? Because this has only been a thing in recent years. With the big push in the pride movement. Coincidence? I think not.

[LaFemmeFatale_1]

Why do you worry about it? If men sleep with each other, it means more women for you, right?

[Amur8711]

Im amazed at how you don't see that doesn't work.

[LaFemmeFatale_1]

I know one thing for every 100 women in my country there are 91 men. You will often see men being very picky about women there and women throwing themselves at men and competing over the type of men I would never give a 2nd thought. So in a way, it’s true, the less competition the better for you, the higher chances for you.

[Amur8711]

Women will also be homosexual so it didn't chane the ratio at all, actually its far more common for women to be homo or bi than men

[LaFemmeFatale_1]

Women are more flexible about their sexuality.

[nolabels]

We're not done evolving.

[es20490446e]

Cause it what is proved to work, efficient or not.

[LaFemmeFatale_1]

Could you give an example, as to which traits do you refer?

[es20490446e]

I don't refer to any specific trait.

[Rangers]

Because God has to give bad hands to someone

[Z1pTD]

You have a point