Why do some humans and animals engage in sodomy if it allows easy transfer of STDs?

[mistermack]

One important fact is that because of sexual reproduction, nearly every individual is genetically unique. This is a huge benefit to the species, as it can adapt to various changes and niches. 

So there is variation inherent in the species, and that extends to sexual characteristics, just like everything else. Male and Female are not fixed characteristics, males have a range of "maleness" and likewise females a range of femininity. It's an advantage. If every male had the same amount of aggression, for example, it could lead to them getting worn out in conflicts, eventually leading to a lack of healthy males. If every male had the same identical urge to mate as the others, something similar could happen. Being less aggressively male might give you more chance with some of the females, who might be scared of the more aggressive males.

So if you have a range of males, it covers more situations. Some might survive and mate by being LESS male. 

If you have that variation, it's likely that some will vary all the way into the homosexual range of behaviour. It's a "price" of having variation, but it's well worth it.

[delboy]

3 hours ago, Area54 said:

Evolution is about populations, not individuals.

 

2 hours ago, swansont said:

I've already given a scenario showing that this is not necessarily the case. As Area54 notes, this is about populations.

OK, if they're closely related it could work.

While on the subject of populations with alpha males, there always seems to be plenty of non-alpha/smaller males around, so I'm sure there's plenty of sneaky matings going on. EDIT - as mistermack has already said.

Females will be happy to choose sneaky males if it leads to reproductive success in her male offspring. Some cuttlefish males imitate females to fool a male and sneak in with his female. 

Edited September 15, 2017 by delboy

[Moontanman]

My point about definition is a lot like my definition of porn, I know it when I see it. Are we going by a human definition of sodomy? Sodomy in Fruit bats is actually necessary for them to reproduce. Is sodomy anything other than man on top get it over with quick? Does sodomy include oral sex? Mutual masterbation? Anal sex only? Who decides? 

[J.C.MacSwell]

1 hour ago, Moontanman said:

My point about definition is a lot like my definition of porn, I know it when I see it. Are we going by a human definition of sodomy? Sodomy in Fruit bats is actually necessary for them to reproduce. Is sodomy anything other than man on top get it over with quick? Does sodomy include oral sex? Mutual masterbation? Anal sex only? Who decides? 

I always thought it was both oral and anal sex, and did not equate it with homosexuality. (not that there's anything wrong with that...)

I would think it would be advantageous for pair bonding and also for "playing around" which could lead to coitus and potentially fertilization by intent, experiment or accident. It is not like we are born with instincts to know exactly how to reproduce.

(uneducated opinion only...not my field of expertise...more of a hobby LOL)  

[Uncommon Ancestor]

On 15/9/2017 at 1:06 PM, mistermack said:

One important fact is that because of sexual reproduction, nearly every individual is genetically unique. This is a huge benefit to the species, as it can adapt to various changes and niches. 

So there is variation inherent in the species, and that extends to sexual characteristics, just like everything else. Male and Female are not fixed characteristics, males have a range of "maleness" and likewise females a range of femininity.

Well, it's actually an exception, as sexual traits are primarly given by a set of genes located in the heterochromosomes in many species, incluiding all mammals. And, when frooming the heterochromatic sex (males, in our case), those chromosomes can't actually recombinate except for tinny, non-sexual related, zones on the top and the bottom of those chromosomes. That means there is small variation in the main, sexual-defining Y (or whatever single-sex chromosome we're talking about) chromosome between individuals, far less, and the sole motor of that variation is mutation. Of course, there are a few exceptions caused by chromosomal translocations, by rare hormone exposure etc., but they are rare exceptions, not the norm.

Also, even if there is some variation, maleness-femaleness distribution is fairly discrete for most traits. For instance, I'm a rather short male for my country and age (anyway, within the normal range of variation, not a pathological or rare case) so most males of my age and country I know are taller than me, but I'm are, at the same time, taller than the great majority of females I know from my country and age. Of course, there are some females above my heigth, but they are rare (and I'm talking about young people in wich there is far more probability that males will grow in heigth than there is chance for our female counterparts), so ranges of distribution in this sexual dimorphism barely overlap. That same thing probably happens with strength, muscular mass, hormone levels and aggressiveness between males. That just shows how much of sexual dimorphism depends on the presence of just one, wee, not-so-variable chromosome (wich basicaly contains the SRY locus), as females and males share any other chromosome in similar frequencies (except for its pair the X heterochomosome, logically). Inter-sex variation is due to other causes much of the time (note that Y chromosome can be expected to be identical or with minor variation within the males of a small population, thus not correlating with male traits variance, which is far greater).

[mistermack]

I'm sure that's all right. It wouldn't do to have too much variation, it would be wasteful, as in the end, males and females have one sexual job to do.

It's not just genetics though. Hormones play a big part, although of course, they are the result of genetics. Young males have a different mix of hormones up to a certain age, and it keeps them on more on the feminine side. So they don't appear threatening to bigger, older males, until they are big and strong enough to either outrun the dominant males and escape, or to defend themselves against them.

When that happens, the male hormones kick in, and they start showing more maleness physically, and in behaviour. And there is variation in how and when this comes about. Maybe some homosexual animals never produce much testosterone. I have no idea if that's the case, but if so, it could be due to an accident of development, rather than pre-determining genetics.

Edit: of course, no amount of hormones would change a person's sexual orientation. That's been tried in the past, in vain attempts to "cure" gays. What happens in the brain to cause sexual orientation is much more complicated, and seems to be irreversible by any known means.

 

Edited September 17, 2017 by mistermack

[Uncommon Ancestor]

That was more or less my point, that recombination isn't likely to play an important part (yes, hormone regulation is also likely to be regulated by recombinable genes, to an extent, I didn't realise that, my bad). However, I fear I have to disagree about the hormone-lack hypotesis (only to an extent):

1. Correct me if I'm wrong, but I thought those same hormones triggered sexual drive, so low hormone levels would rather kill sexual drive than change it's target, I guess. Of course, a change in wich hormone raises levels at some stage of life would actually be a different thing. That remains to test.
2. Focusing on human-like mechanisms, my first reaction is to reject any implication of hormones themselves in homosexuality, as bot gay man and women usually display the rest of the sexual-specific traits normally, which doesn't go well with a lack of correct sex-specific hormones. Of course I might be wrong. Of course, there are exceptions. And of course that may be very different for other species. But I feel it fails to work as a general explanation for the phenomenon, assuming humans aren't the weirdo case here.

Yet, hormones regulate sex drive, so yeah, probably they are still rellevant here, just not (or not necessarily) in that way.

Thank you for answering.

[Thorham]

On 9/9/2017 at 6:12 PM, mad_scientist said:

What evolutionary advantage does sodomy give to animals which choose to engage in this activity?

Is it relevant? They probably just do it because they're horny, evolutionary advantage or not.

[Anthony Morris]

On ‎9‎/‎9‎/‎2017 at 0:12 PM, mad_scientist said:

What evolutionary advantage does sodomy give to animals which choose to engage in this activity?

If you are asking about it in relation to STDs I have to ask "why aren't you concerned about heterosexual animals getting STDs through their sexual activities?" They get them too. 

 

While "straight" animals need to reproduce they have to run the risk of STDs while "gay" animals might not need to run the risk of STDs? These animals don't know about STDs for one and since homosexual activity doesn't produce offspring then any STDs the "gay" animals get would not affect selection in future generations. There is little to no selective advantage to not engaging in "sodomy" because of STDs. "Straight" animals get them too and have not selected against sexual reproduction yet (at least not usually).

Edited October 12, 2017 by Anthony Morris

[Uncommon Ancestor]

On 12/10/2017 at 4:27 AM, Anthony Morris said:

If you are asking about it in relation to STDs I have to ask "why aren't you concerned about heterosexual animals getting STDs through their sexual activities?" They get them too. 

 

While "straight" animals need to reproduce they have to run the risk of STDs while "gay" animals might not need to run the risk of STDs? These animals don't know about STDs for one and since homosexual activity doesn't produce offspring then any STDs the "gay" animals get would not affect selection in future generations. There is little to no selective advantage to not engaging in "sodomy" because of STDs. "Straight" animals get them too and have not selected against sexual reproduction yet (at least not usually).

First of all, we must be clear about whether we are talking about anal intercourse happening in any kind of animals, any kind of homosexual intercourse or just anal intercourse happening between animals from the same sex. If its the third one, there's clearly no point on it as long as exclusively homosexual animals (fitness=0, in principle) are concerned, but any other possible option involves either parental capital being supposedly "wasted" in non-reproducing descendence or reproducing animals engaging in a risky activity. Sex will always mean taking risks, but there are clear advantages for vaginal intercourse which justify those risks. However, anal intercourse carries a lot of risks but none possibility of that advantage (=reproduction), so it's difficult to explain unless one argues that those animals are "too horny" to make a difference between similar holes, that is, that useful instincts for reproducing carry at the same time the possibility of getting into the wrong hole sometimes.

[Moontanman]

4 hours ago, Uncommon Ancestor said:

First of all, we must be clear about whether we are talking about anal intercourse happening in any kind of animals, any kind of homosexual intercourse or just anal intercourse happening between animals from the same sex. If its the third one, there's clearly no point on it as long as exclusively homosexual animals (fitness=0, in principle) are concerned, but any other possible option involves either parental capital being supposedly "wasted" in non-reproducing descendence or reproducing animals engaging in a risky activity. Sex will always mean taking risks, but there are clear advantages for vaginal intercourse which justify those risks. However, anal intercourse carries a lot of risks but none possibility of that advantage (=reproduction), so it's difficult to explain unless one argues that those animals are "too horny" to make a difference between similar holes, that is, that useful instincts for reproducing carry at the same time the possibility of getting into the wrong hole sometimes.

Male elephants have anal intercourse, in fact it has been asserted that many male elephants never have sex with females at all... Sheep, many other animals pair bond in same sex relationships. See the link below... 

 

https://en.wikipedia.org/wiki/Homosexual_behavior_in_animals

 

Quote

Elephants

Further information: Elephant § Mating

African and Asian males will engage in same-sex bonding and mounting. Such encounters are often associated with affectionate interactions, such as kissing, trunk intertwining, and placing trunks in each other's mouths. Male elephants, who often live apart from the general herd, often form "companionships", consisting of an older individual and one or sometimes two younger males with sexual behavior being an important part of the social dynamic. Unlike heterosexual relations, which are always of a fleeting nature, the relationships between males may last for years. The encounters are analogous to heterosexual bouts, one male often extending his trunk along the other's back and pushing forward with his tusks to signify his intention to mount. Same-sex relations are common and frequent in both sexes, with Asiatic elephants in captivity devoting roughly 45% of sexual encounters to same-sex activity.

 

[StrontiDog]

On ‎9‎/‎23‎/‎2017 at 0:10 PM, Thorham said:

Is it relevant? They probably just do it because they're horny, evolutionary advantage or not.

If anybody can't see the evolutionary advantage of a species with an overwhelmingly-strong sex drive, then they would seem oblivious to some of the basic evolutionary tenants.

Only humans even 'know' that mating is what produces offspring.  Any other population mates due to their biological imperative to do so. 

[Anthony Morris]

7 hours ago, StrontiDog said:

If anybody can't see the evolutionary advantage of a species with an overwhelmingly-strong sex drive, then they would seem oblivious to some of the basic evolutionary tenants.

Only humans even 'know' that mating is what produces offspring.  Any other population mates due to their biological imperative to do so. 

And they are less likely to even make the connection to STDs. If a sex-drive is required by the heterosexual component of the population then the homosexual component will likely have the same drive. And the homosexual members are going to have less effect on the future generations than the heterosexual members will. 

[Thorham]

On 10/24/2017 at 3:46 PM, StrontiDog said:

If anybody can't see the evolutionary advantage of a species with an overwhelmingly-strong sex drive, then they would seem oblivious to some of the basic evolutionary tenants.

I'm just saying that perhaps not all behavior in non-human animal species is evolution driven.

Furthermore, is an overwhelmingly strong sex drive a requirement for adequate reproduction? Because if it's not, then why would a very strong sex drive be selected for? Then after that you have to ask yourself if all successful species have very strong sex drives.

All in all, what I wrote doesn't seem as unreasonable as you make it out to be.

Edited October 27, 2017 by Thorham

[ATP]

On 9/9/2017 at 11:12 AM, mad_scientist said:

What evolutionary advantage does sodomy give to animals which choose to engage in this activity?

There's two questions here.

1). Why do some humans and animals engage in sodomy if it allows easy transfer of STDs?

For animals, I think it's because they don't know on a conscious level that they are contracting STDs. From an evolutionary perspective, the adaptation against sodomy must not be as necessary as the things it would sacrifice for this adaptation.

For humans it's a similar tale. To go against sodomy, our bodies would have to develop an adaptation against it. STDs don't prime us to lose sodomy but rather for our bodies to develope grater defenses against the diseases.

2). What evolutionary advantage does sodomy give to animals which choose to engage in this activity?

In social animals, it could be the hierarchical component. It doesn't need to be an advantage but rather a result of other factors.