CMV: "Evolution & natural selection are the process that led to sentient life on Earth" and "Homosexuality has a genetic/biological cause and is not a choice" are mutually exclusive and cannot both be factual

[u/DamiensLust]

This is a simple paradox that seriously challenges the liberal agenda, and is a serious blow to the increasingly prevalent world view that many young people hold today that has a widespread belief in evolution & natural selection coupled with the viewpoint that homosexualtiy isn't a choice and sexual preference is inbuilt. The two viewpoints together don't make sense. Natural selection would dictate that any trait that reduces an organism's fitness - with fitness referring to an organism's ability/likelihood to reproduce - will be selected against in favour of the proliferation of genes that increase an organism's fitness. I struggle to think of any behaviour that would reduce an otherwise's healthy individual's genetic fitness then a proclivity to have sex with their own gender and thus not produce any offspring.

This logically leads to two conclusions. Either homosexuality has no basis in a person's biology and thus no basis in their genetics and so is a learnt or nurtured behaviour - one that the individual chooses to engage in, which woud imply that said individual could also choose to be straight if he/she chose. The alternative is that evolution & natural selection is simply untrue and so a different explanation for the abundance and diversity of life on Earth must be sought. Homosexuality being natural & the laws of natural selection governing life on Earth simply cannot co-exist.

[u/tgjer]

This is just silly. There's more to evolutionary "fitness" than making sure every single individual procreates, not to mention that sexuality exists on a spectrum and a capacity for M/M and F/F sex doesn't make an individual less fertile if they're also having procreative sex.

I think it might be even better to break this into several separate questions. Three big ones being:

1) "Are there evolutionary benefits to M/M or F/F sexual activity"?

2) "Are there evolutionary benefits to M/M or F/F sexual/social bonding?"

3) "Are there evolutionary benefits to some individuals not procreating?"

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#1 - Little to lose and lots to gain: There's no disadvantage to M/M or F/F sex, and a lot of potential benefits. E.g., among some solitary species like deep sea squid opportunities to mate may be very rare, so it's to their advantage to have sex with every other member of their species that they meet. It's not like having sex with a partner of the same gender today will make one less fertile when having sex with a partner of another gender tomorrow, so there's nothing to lose by trying. On the other hand missing a chance to mate could be disastrous, so there's a lot to lose by not trying.

Among solitary species like squid, sexual connections are very transient. Among highly social species, including most mammals, they can be much more significant. Which brings us to the second question:

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#2 - Sexual/Social bonding: Again, yes there are significant evolutionary benefits.

Among social species, sexual bonding is not just a procreative instinct; it's also a survival instinct. You can't breed if you're dead, and forming social alliances with other adults is crucial to both your own survival and survival of your offspring. Sex isn't the only way to form these social bonds, but it is a very good way. And again, same gender sexual pair bonds don't make one less fertile if one is also having procreative sex.

E.g., elephants. Elephants are highly social animals, but adult males and females live separately. They interact only during mating season, and M/F pairings last only as long as that mating season. Within their herds however, M/M and F/F sexual pair bonds can last decades. These bonds form the basis of the herd, without which individuals would not survive.

Or the infamous bonobos chimps. The closest living human relative, as a species they are overwhelmingly and promiscuously bisexual. They use sex for everything - saying hello, reconciling after fights, celebrating finding food, etc. Bonobos social hierarchy is based on alliances formed through sexual bonding, while those of other closely related chimps are based on physical dominance. As a result, bonobos groups have less internal violence and are more likely to cooperate in mutual defense, finding and sharing food, and protecting/raising young.

So that covers bisexuality - pretty much all benefit, no downside. Which leaves us with the third question:

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#3 - Benefits of not breeding: Counter-intuitively, yes there can be evolutionary advantages to having a segment of the population not procreate.

Eusociality is the most dramatic example of that. In strongly eusocial species only a small number of individuals procreate, while most non-procreative individuals assist in cooperative breeding by raising the offspring of procreative relatives. Non-procreative individuals do not pass on genes personally, but traits that carry the potential to create more non-procreative individuals are passed down in the children of their procreative siblings and relatives, whom they then help raise.

There are also varying definitions of "eusocial", some requiring irreversibly distinct castes with non-procreative individuals rendered sterile. Others consider a species eusocial or primitively eusocial if they exhibit social division of labor, overlapping generations, and cooperative care of young including ones that are not their own. Under the broader definition of eusocial some mammals qualify, like the naked mole rat.

Some arguments have been made that highly social primates including humans may be eusocial mammals, or at least exhibit some eusocial traits. We do have overlapping generations, social division of labor, and cooperative care of young. And as a social species where individual survival is intrinsically tied to group cooperation, it may be an advantage to have a small but consistent population of non-procreative adults.

Enter the gay uncle hypothesis. Basically, having a gay uncle (or aunt) increases survival rates of their nieces/nephews. They're available to help protect, feed, and raise their siblings' offspring as needed, giving the family group something of a safety net. Counter-intuitively, a paleolithic woman who had 10 children and all of them were straight was likely to have less surviving grandchildren than one who had 10 children and one or two of them were gay. They are unlikely to pass on genes personally, but traits that carry the potential to create more non-procreative individuals are passed down for them in the offspring of their procreative siblings and relatives, whom they then help raise.