About evolution and gender roles (in nature)

This is not a debate that has anything to do with religion or sexism, this is me asking fellow Giant Bomb users for their input and ideas concerning some things about nature that I fail to understand within the context of science and culture. I'm sure many of you know more about this (or have thought more about it) than I do/have, so gimme your two cents!

I know it seems hard to believe on the internet, but I have no actual opinion on this, hence my seeking your input.

I'm onto the sixth episode of BBC Planet Earth and these two questions kept popping in my head repeatedly:

Evolution - the detailed and complex features of certain animals

Does evolution tell us that all these strange and very specific defense/survival mechanisms that strange animals have, were just developed naturally on their own to ensure the survival of these species in their dangerous environments?

I mean, regardless of whether God exists, the theory of God tells you that he created all these little details, and the idea of someone designing these very specific details deliberatelyis more plausible to me than nature just somehow designing all these things out of... nature being nature. How does evolution explain the pouch that male Emperor Penguins have, where they hide their females' eggs? How does it explain the microscopic claws that rare cave invertebrates have that allow them to hold onto rocks and not drift in the current? How does it explain snakes having heat vision in order to snatch bats in the dark? It just developed on its own? Doesn't that sound strange? It gives biology a conscious persona, like it knows what tools and adjustments are needed. I don't get that.

These features and body parts are extremely specific and detailed, with the purpose of allowing the animals to fit their respective environments, but IMO they are too specific to believe that nature just "did" the job.

Gender roles - males always wooing females

Yes we are cultured and intelligent beings, we should be different from animals and their basic functions, but at the end of the day we are biological animals that evolved from cells in the sea, so how do you explain the fact that almost EVERY species has the males doing all the wooing and the courting showmanship? I believe in equality in rights between the two (human) genders, but I do not deny gender roles because they are a part of nature and biology, which is evident in all other living beings. The fact that the male does the penetration and fertilization during intercourse, for humans and animals alike, really symbolizes this IMO.

So far I have seen male penguins "serenade" to attract females, some form of male mountain bucks fight for hours in order to win a "harem" entourage of females which they proceed to fornicate (the narrator actually called them harem...), and many male birds do crazy shows.

How do people who deny gender roles explain the fact that in nature, it's always the male who does the wooing, followed by the f*cking? That it's always the male going after the female and trying to get her in bed? I'm NOT saying they're wrong, I'm trying to understand their point of view, because as of now I don't.

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This here is a somewhat ignorant man (about this topic) who is asking for the input and perspective of people better educated on this matter, nothing more and nothing less :)

I'm sure science has explanations out there, so I'm seeking them!

All I got to say is I like this song.

Yes.

No.

Then it's just a matter of people explaining it to you poorly. Let me try to clear this up with the cave claw thing. (For the sake of argument, I'm changing them to monkeys, because my memory is terrible.) At some point in time, a monkey, for whatever reason*, developed claws. These claws allowed it to survive more easily in its environment. This gave that monkey an advantage over other monkeys, allowing it to breed more easily. This means monkey claws get passed down to the next generation. Essentially, those claws stay until they stop helping the monkey survive to breeding AND something better comes along. If one of those doesn't happen, the claws generally stay.

That might be more confusing.

*Genetics feels the most plausible, since that would let things get passed on. However, I'm not expert on this.

Also, you're lucky I can't find the Marc Maron clip I want.

When it comes to your question about evolution it is simply a common misconception about the theory of evolution. The theory of evolution doesn't say that nature is able to determine what is best for the species, there is decision making process. Instead evolution says that completely random mutations that occur individually in the species will sometimes give that individual an advantage in surviving and breeding. In your example it would be that a random male Emperor Penguin had a genetic mutation occur as it was created, resulting in having a pouch (or pouch like flap of skin or whatever). This pouch would allow said Penguin to keep the eggs warm and help ensure the survival of the eggs. These eggs would then also have a very high chance of having the pouch as well because they share DNA with the father Penguin who had the original mutation. These children would go on to have pouches and use them to ensure the survival of their children as well. Eventually the amount of Penguins with pouches outnumber those without due to their higher rate of survival, and in time those with pouches end up being the only penguins around.

Survival of the fittest is one of the key concepts of evolution. Characteristics are randomly created due to mutations and some of these mutations will give a creature a competitive edge.

The new series of Cosmos has an episode about evolution that explains this pretty well.

Well for humans, I'm pretty sure you'd agree that women do much more of the "wooing" than the men in today's world, in terms of dancing and trying to look good. There are probably plenty of other animals that make an exception out there, but I'm not a biologist.

If you haven't seen Cosmos yet (the new one... but either is good I guess), you should. It's a good primer. Basically: most animals have lots of kids. The kids who don't make the cut die. This happens over thousands of years to create fairly small changes. It takes a long time. Humans themselves were a step away from extinction, with only a couple thousand remaining, if not hundreds. Here's a book on it: http://www.scientificamerican.com/article/when-the-sea-saved-humanity/

Other than that, try these links:

A good thread on the topic: http://www.reddit.com/r/askscience/comments/p6csa/evolution_why_i_dont_understand_it/

Questions you might have: http://www.reddit.com/r/askscience/search?q=evolution&restrict_sr=on

Don't forget it is estimated that over 99.9% of all species to have ever existed are now extinct.

@zella: @video_game_king: Thanks for the replies, but neither of you told me what causes these mutations and, more importantly, how it's plausible to you that these extremely specific mutations that serve a specific purpose to allow the animal to survive in its specific environment, are merely mutations of nature and not the work of a conscious observer who is deliberately designing the necessary mutations into these animals.

Who is behind this and how did it come to be?

I always found evolution easy to accept as a concept of iteration of something based on success and failure of certain features within a climate. When people jump to a conclusion of a creator because "things seem to perfectly fitted for a specific purpose" they're looking at it as if it happened yesterday and not over the course of several hundred thousand years with all sorts of variations in between. We live maybe 100 years, we don't see the big effects of evolution on the grand scheme. Nature didn't "do the job" as some form of engineering, it just became the dominant and most successful trait over time.

In nature (though not all species have the males do both of those things, actually) there is a need for wooing as a way to make sure your genes go forward. A basic need for reproduction. I am not really comfortable calling it "gender roles" because that's a much broader concept with much broader implications than really seen in nature. Besides, if you look at a lot of what the different genders do in certain species, you would probably find a lot of things that doesn't work translating it into traditional human gender roles (whatever those might be).

But even taking that off the table, there are so many things we humans do that nature does not do. For example; rationalize things and make our own decisions on how we feel we want to live our lives. And that's the key, really. It's pretty irrelevant what nature does, if I can will my way another way. So even if nature had specific gender roles that could be applied to humans, why should we adhere to those rules if we didn't necessarily care for them?

It's difficult for humans to comprehend massive swathes of time and changes that take place at a glacial pace can seem utterly profound when viewed from our current perspective, but that's all it is, a problem of perspective. These things you mention about specific animals, they didn't just pop into existence overnight, rather generations upon generations of very slight mutations led to certain traits becoming dominant. Just to give you some perspective, if we put the entire history of the Earth into a 24 hour day, humans only came onto the scene in the last 20 seconds of that 24 hour day.

The mutations are random. Your mistake is thinking that there is anything specific going on. What you're missing out on are the non beneficial mutations. It's not that an animal evolves to survive in a specific environment, it is more that a mutation occurs that gives the animal a better chance of survival. It's not that snakes evolved the ability to sense heat because they lived in a place with lots of bats, it's that the snakes that did evolve that ability added another food source to their diet and therefore had a better chance of survival.

There are no causes. There's nobody behind it. It just happens.

also "both genders"

pbbbbbbbbbbbt

Well the mutations are usually caused by the process of creating a creature being really complicated and in the process where the creature's genetic makeup is developed something will go wrong ( I am not a geneticist so can't be too specific) which will result in a mutation. We only notice the mutations that end up serving a purpose, there are countless other mutations that either do nothing or are detrimental to the survival of the species. These mutations don't come about to serve a purpose, it is totally random whether or not a creature with a mutation will have a competitive edge. We only see the mutations that are useful because they allowed that line of creature to strive and eventually take over the species.

The creatures that exist in any specific environment are there not because they were groomed to be there but because every other creature that was there died because it couldn't compete. That is what one can draw from the theory of evolution at least. Take for example the Polar Bear, evolution would say that a mutation long ago caused a random individual bear to have white fur, the mutation could have messed up the pigmentation process in the bear's fur. A bear with brown or black fur could survive in the Arctic was well but the white fur of this specific bear made it much easier to hunt in the snow and survive. This longer live enabled the bear to have more offspring which also had white fur and also had an easier time surviving. Eventually the white bears would grow so numerous that they would either push out or absorb the brown and black bears.

Also for the other part "gender roles" (it's not accurate to really call it that) differ by species. I don't know enough about bird mating rituals to be sure but in prey species of birds the males take a more active role in the wooing for the simple reason that they are usually more colorful/noticeable. The females tend to be plainer because it makes them harder to spot and let's them have a better chance of survival while laying eggs and taking care of their young.

Genetic mutations are simply an accident. When our cells divide via meiosis in order to create the egg and the sperm, DNA is copied via a very complex process. Things go wrong, they get miscopied. Other contributing factors can increase the likelihood of mutations (e.g. radiation exposure) but they happen all the time. Similar mutations in the process of mitosis (non-sexual cell division which your body uses to repair itself and replace old cells) can lead to cancer. And lots of people get cancer - that should help explain how common genetic mutations are. And the vast majority of genetic mutations don't lead to cancer. They happen all the time.

Anyway, back to the topic of mutations occurring during reproduction - Often, these mutations don't lead to any meaningful change in the species. Other times they lead to genetic diseases and disorders, which may cause the offspring to die, and even if they survive, they will be weaker and be an easy target for predators. They'll also be seen as a less viable mate to other members of the species. These therefore do not pass on their genes, so do not spread this disadvantageous mutation. But sometimes these genetic mutations just happen to give them an advantage. Like the tiny claws for the cave monkeys. Like the flap of skin on the emperor penguin. These mutations give the offspring a higher chance of survival, and therefore a higher chance of passing on their genes (and therefore the mutation) to their offspring.

Evolution doesn't have a will. There is no consciousness. Mutations happen at random. Some just happen to give the animal an advantage, and they can then pass that onto their offspring.

Also, I think you'd be surprised at the number of species in which the females play a dominant role in the mating process. Whilst it's probably more common for the male to be the dominant mate, there are countless examples of species where the female is the dominant one.

@artelinarose: Thanks for spamming my thread with two consecutive enormous posts with no actual discussion or useful words from you. Appreciate it, and so does my mouse wheel.

Ohhh I see what you're saying. In that case I blame the show's narrator for making it sound like these useful mutations were the only ones that happened and that they somehow magically appeared to serve their purposes! It still sounds too good to be true for me, I mean these mutations are seriously complex and surprisingly fitting for the conditions of the environments they're in, but you're making me believe now, good point dudes.

Interesting questions .. I have nothing to add but to say that nature is wiser than us... and yes gender roles are clear cut as nature intended , only we human have came up with many more just because we can (so no I dont believe people are born with different gender roles than male or female , they just think they do ... but that is their perrogative anyway) Because reproduction is the name of the game from "nature´spoint of view" (not Im not giving it a personality or anything like that to nature)

Well it's only natural that is the way it appears, because we usually only get to see the outcome of mutations that ended up being successful, because success = offspring = more success = more offspring = we can study it to this day. We don't get to see the outcome of the countless other mutations because they didn't end up being useful to that particular animal in that particular environment, but that doesn't mean they didn't happen. Evolution is still happening every day and will continue to do so as long as there is life.

@development: Interesting links, I will look at them, thanks.

I see what you're saying - the bad mutations disappear with the death of the offspring that had them, the good mutations are perpetuated by their survival, and those become the convenient mutations seen in this documentary. Nature is amazing. I might be sounding stupid though but I'm still not 100% on the origin of these mutations. The fact that these animals mutate at all, let alone having some mutations that are so convenient for their environment, is a bit hard to grasp. Somebody's pulling those strings I just know it :P

That is good to know! But so far after 5.5 hours with Planet Earth it's been males doing the work in various species. The fact that the narrator called a group of female mountain bucks (of a certain area) a "harem" that the male must win by fighting other males was kind of weird. Doesn't that offend somebody somewhere?

I can actually speak, at least I think, to the boundary between the biological and the social as someone who has confronted that very thing with grad students in the context of criminology. Although before anything I'd like to remark that it may seem to be a reasonable hypothesis that almost every male in the species does the wooing so speak, with the way we classify species it is overwhelmingly not the case taking in all the staggering varieties of insects, bacteria, protozoa, and simple multi-celled creatures. Beyond that even we see a great number of fish and reptiles who frankly could give a damn about courtship and just throw their eggs and sperm together into pits, ponds, or shallow river beds and let the rest happen.

So in fact the reason there exists such elaborate courtship rituals among certain mammals has to do with ecology and the metabolic differential between those who gestate eggs, i.e. females, and those who fertilize them, i.e. males. Generally speaking the act of growing and birthing a young among a vast amount of animals takes a lot of energy. If you take note of any nature documentary, it's common to see female animals at specific stages foraging like mad for food and shelter and/or eating a ton. Regardless, males don't have this energy demand but do have the inclination to fertlize eggs at a certain stage in their life course. With nothing better to do so to speak, evolution seems to have afforded certain advantage to males who in addition to seeking out females have behaviors which draw them out in particular as they benefit from selective mates given their requirements once fertilized. Once the wooing begins and females in their way respond, then that arms race begins and so on.

Now I technically already mentioned something, the inclination to fertilize eggs by males, which requires one of the two concepts I'm about to mention and that first one is biological behaviorism. In effect, evolution determines incidental favoring to genetic mutations based upon environmental stimuli but clearly animal behavior as routinized or innovative are rather transparently tied to that evolutionary process it seems. The conclusion from biologists is that a species' DNA not only determines their physical makeup and life course development but impacts their behaviors, whether directly through arrangements in hormones and brain chemistry and indirectly through biological limits and environmental adaptation. It is theorized that the drive to procreate and all the minutiae therein is derived from biological behaviorism.

But what about animals who are smarter? Namely a lot smarter, like us? That's where the biosocial perspective comes in. In sociological and psychology it is the perspective that accounts for the boundary between biological characters of people and socio-cultural characters of people. We know rather resolutely from social science that practically everything of our understanding and experience is socially determined, that they are learned through a process of socialization over the life course and that those self-same concepts we learn are themselves already influenced by historical and macro-social factors before we're even born. So first and foremost it is crucial to note that gender is our ad hoc interpretation and societal conception of observable biological differences. Secondly it is also important to note that gender and to a lesser extent sex are both binary largely because we have cast our social weight and consensus at it due to an ongoing moral or social understanding of it. In technical reality gender and sex are complicated and operate under spectra which better account for the varieties of gender and sex we see today.

Anyway, back to the biosocial perspective. So keeping all of the above in mind the biosocial perspective views behavior, or many behaviors, as first being set in motion or dictated by biology to some degree over the course of humans' lives but that society and culture then pick up the baton and go from there. Often there are interactions between biological factors and social factors and will do so multiple times. One basic example is biological development itself wherein behaviors are contingent both upon the psychological development of the person at the time and what stage of puberty they are experiencing. Those states then can interact with social environments which afford opportunities to say commit crimes more often, to be socialized more readily around violence, to be associated with criminal peers etc. This is often one of the explanations we afford to the sharp increase in crime during the teenage years, peaking at around 18-21 and then steadily dropping from there. Some of that is socio-economic, since adults tend to be more socially integrated in jobs than teenagers and there are values which tend to be internalized in later years which discourage crime. And here there is a gender factor as well since in crime men for most crimes are overrepresented by margins of up to 80/20. The biosocial perspective has its conclusions on this and finds that at very young ages, where psychological development and social experience are nascent and biological influence larger, there already exist differences in self-control and aggressive behaviors between girls and boys. If girls tend not to be as aggressive, there is also the tendency to socialize them to that end and constrain them in other ways which can produce such gulfs in criminal activity.

So when we see that males penetrate females, that is biological history at work. If we see the tendency to want to procreate, that is biosocial history at work. And if we see cultural interpretations, understandings, and values associated with procreation and how we define gender roles, that is sociological history at work. Anything else is a function of humans' tendencies to take biological explanations as disproportionately powerful and essential which indeed drives a good amount of our historical views of the social world via gender, race, etc.

@singingmenstrual said: Somebody's pulling those strings I just know it :P

If someone were pulling them then why have so many failed and useless mutations that die out in a single generation? Wouldn't it make more sense to just make it perfect every time?

There is a lot of popular rhetoric about evolution being the idea of "survival of the fittest" - this is the first thing they beat out of your mind when you study evolutionary biology. Evolution is based on four key mechanisms that drive ultimate speciation; genetic drift, genetic flow, mutation, and selection.

Start by researching those, and you'll be on your way to answering most of your questions. And for every example of an organism that is so well adapted to an environment it gives the impression of some sort of "celestial guidance", there are a thousand others that show the exact opposite.

Also, the member of the species that gestates the progeny is the one that the one that has impetus to select for positive traits - this is why it often seems like males put all the effort into mating. If men could gestate their young, you'd see the opposite effect.

@singingmenstrual:

That is good to know! But so far after 5.5 hours with Planet Earth it's been males doing the work in various species. The fact that the narrator called a group of female mountain bucks (of a certain area) a "harem" that the male must win by fighting other males was kind of weird. Doesn't that offend somebody somewhere?

She's up a few posts (though I'd rather not perpetuate that argument).

But yes, we're talking about millions of years of seemingly random changes, a handful of which we happen to notice because they're useful. I used to believe in God, and looking back, a lot of the evidence put forth by Creationists for God seems to consist of "Don't you think it's a little weird that nature is this way? Doesn't that just scream organization by a higher power"? And, well, it doesn't. Not to me. We're talking about a vast amount of time that has produced some useful mutations. A handful of creatures survived, a lot of them didn't. Wouldn't you think that a supposedly-almighty creator being would have done it right the first time instead of millions of years worth of fuck-ups for no discernible reason?

@video_game_king: Evolution is a mystery

I'm confused, why are you basing these questions only on Planet Earth?

Also gender roles in animals vary crazily:

http://www.bbc.com/news/science-environment-27056809 Female insect has a penis that sucks the sperm out of the male

http://www.livescience.com/7426-sex-role-reversals-common-wild-kingdom.html The female antelopes compete for the males

http://news.nationalgeographic.com/news/2002/06/0614_seahorse_recov.html Male seahorses get pregnant

Even your own example of evolution of the male Penguin sitting on the egg is a gender role reversal.

This really isn't the place, brah. Our demographics are crazy skewed toward Young White Males.

I'd recommend reading up a bit more on evolution and sexual selection.

Or go ask these questions on a scientific community like AskScience on Reddit.

On the "males doing all the wooing", look up the phenomenon of choosy females and the Bateman's Principle.

Rationalizations are incredible things. People think that because they have one behaviors and beliefs are allowable. That somehow this excuse condones actions that can hurt others.

Nothing works that way. Rationalizations and excuses are irrelevant. If you have a belief or act a certain way just own it. But don't hope that a rationalization will make others care or think any other way about you.

Just a thought, but is it possible that the way we think of animals is skewed by inherent gender bias/roles in human society at the time the animals were classified and studied?

IE: Researchers looked for patterns that mirrored the dominant gender ideals in our society and fit animals society into that structure?

No one. This very question is why you believe some form of a God is behind it. You assume someone must be behind it, while that isn't the case. There have been massive amounts of research to prove evolution. Species change to fit survival. I have to admit I do not remember specific studies, but for the sake of example: if you put mice in an area with relatively low oxygen, over time they will produce offspring with inherently more efficient circulation (just random non-existent example).

You specifically want answer to something you cannot have answered. 'Why'?

Nobody can answer this question. Ever. The mere fact that no one can't doesn't mean that 'someone is behind it'. You're searching for a way to explain something you do not understand, and this is where God comes in. There have been countless Gods over the years. Every situation man does not understand, has had a God.

Simple fact is: some things will probably never be explained. Like death. What happens after? You don't know. No one does. There are only theories and there will always only be theories.

That's a great explanation of it all. Random accidents in the complicated reproductive process that alters the coding of the offspring's existence.

I think the fundamental mistake you're making @singingmenstrual, is replacing God as a designer with nature as a designer. It's not a matter of conscious design. These are mutations that happened to be more beneficial to a species' survival, which in turn promotes the spread of that mutation across generations, as those organisms survive and mate. A big reason this might all seem implausible to you is because of the timeline being difficult to visualize. These changes occur in small steps over hundreds and hundreds of millions of years.

The apparent specificity of a species' features to their environment doesn't imply that the species was consciously mutated by nature to better fit that environment. Like @cale pointed out, what you're seeing is the result of mutations that just so happened to provide some better means of survival in that environment. The mutations occur irrespective of the landscape around the organism.

As for your thoughts on gender roles in nature, you're mixing up sex with gender and are also generalizing far too much. The role one sex has in the reproductive process of that particular species doesn't necessarily have anything to do with gender roles at large, or as they pertain to humans. Also, that you've seen examples of some species where the males typically pursue the females doesn't justify saying that "in nature, it's always the male who does the wooing".

There are species that are capable of changing their sex to match their circumstances in order to reproduce. Organisms that reproduce without a partner. Examples in nature where the female is more proactive in the wooing process. Examples where males are more involved in the raising of offspring. Examples where animals will have intercourse with others of the same sex.

Outright denial that gender roles exist is ridiculous, but that doesn't support the suggestion that all males must behave one way, or that all females must behave another. That it's natural for girls to like princesses or boys to like trucks. "Gender roles" tend to not be merely observational, but prescriptive, at least so far as humans are concerned. The rejection of gender roles in that context is simply the rejection of that prescription. Accepting that, for example, girls can like trucks or boys can like princesses. Accepting that a woman can work and the man take care of the household, and so on and so forth.

Then you are a horrid monster.

It makes me laugh that something being too ridiculous for someone to comprehend, with the narrow, shallow minded perspective of a human being who has seen a tiny percentage of the planet, is therefore automatically considered divine intervention.

Forget it.

All right, m8. Here we go.

Think of it this way. Let's say, hypothetically, you and your spouse have ten kids. Your environment consists of predators and prey with advanced camouflage capabilities. Nine of those kids have the same traits as you. One has eyes that can see heat. Freak of nature, right?

Well in nature, most of your kids would die, especially the one without arms. None of them pass their traits on. One of the survivors is the kid with super vision. Survivors get to breed. There's a chance your super-vision kid will pass down this mutation, and give birth to more super-vision children. These new children will survive while other normal humans die, and get to breed. And get to breed. And get to breed. And get to breed.

Evolution is a chance. A roll of the dice. Humanity's probably stagnating because we're capable of supporting the individuals who are more dependent on civilization than others.

This is why the Darwin Awards exist. Because an individual has taken his or her genetic code out of the gene pool, and thus can not pass down such stupidity.

And this is where things edge into Nazism.

@video_game_king: No, not really. What he is talking about is self correcting/self-determined. If your talking about Eugenics; thats about actively guiding the course of human reproduction.

@flindip:

To be fair, I did say it edges into Nazism, largely by suggesting that:

A.) Stupidity is genetic.

B.) It's a good thing that stupid people aren't allowed to breed.

Although I feel you already know that.

@video_game_king: Well stupidity isn't genetic. Even brilliant people can be guilty of stupid things. However, there has been a long standing debate to this day on the inheritable effects of intelligence. Its not a cut and dry answer.

As far as your other point, I can only speak for myself. If a society has any belief in personal liberty, there is zero point to oversight to one's reproductive choices. So its largely a moot point if its a good thing or a bad thing.

Plus, Eugenics precedes nazism. It didn't come from it. In fact, its one of the biggest dangers of unchecked socialist ideology(or any ideology for that matter) creeping into science.

Dave Lang.

There is no definite answer out there as to "who" made everything or even if there is a "who" that made everything. Its why we have religion and science, you choose what you want to believe.

@singingmenstrual: I don't mean to blow your mind, but... (NSFW if your boss doesn't like some hot, hot animal lovin')

The assertion that the animal kingdom exists exclusively of "males wooing females" just isn't even close to the reality. Sexual relationships in animals are extremely complicated to understand. One, because it's very hard to infer if any animal behavior is dictated by innate urges, or simply choice of a certain activity. And two, arguably more importantly, as @ravenlight touched on the study of animal behavior has historically been skewed by biologists and zoologists (even as dedicated to pure science as they were) who refused to accept non-reproductive sexual behavior as being natural. And even those who acknowledged the behavior, insisting on tying it back to reproductive sex, or it being a factor of something else socially driven, rather than just an activity that some members of those species innately engaged in.

You might also be interested in learning more about the Kinsey Scale and more recent analysis of human sexual orientation, which shows that sexual preference is far closer to a gradual gradient, rather than a this or that situation. And that, in some ways, labels like hetero-, homo-, and even bi-, are irrelevant distinctions.

Also, I applaud you for asking these questions rather than forming your own opinions based on assumptions, as so many unfortunately do. We can all only get better by learning more!

Didn't you hear? They just found the first species where the female has a penis and the male has a vagina. I forget what it was, but they found it. Colbert was joking about it this week. The female's penis reaches into the male's vagina and pulls out the sperm.

edit: also watch Cosmos. It did a good job explaining evolution.

@joshwent: Well, it manifests itself differently than humans. Even though homosexuality is common in the animal kingdom; its VERY uncommon for an animal to have long predisposition for same sex mating at the exclusion of the opposite sex. 99 percent chance if animals do mate in their lives they will mate with an opposite sex member at one point or another.

@video_game_king, Aww sheet, didn't think someone would quote that part of my stupid post of all things.

I was hoping that simply mentioning the Darwin Awards would make it clear I was joking. But hey, whatevs, my bad. To make my stance abundantly certain, I state that I'm not into eugenics. Or nazis. F those guys.

I think the previous responses have done a decent job of discussing natural selection and how differences in metabolic investment can give rise to sexual dimorphism, but if you'd like to go even deeper down this rabbit hole, I'd suggest reading The Spandrels of San Marco and the Panglossian Paradigm by Gould and Lewontin. It's a seminal paper in evolutionary biology which challenges a habit that many average Joe purveyors of evolution and even some biologists have: variation can always be explained away as adaptation, rather than a necessity born out of physical/environmental constraint or any number of other possibilities.

As for the reference to "harems," that's just a convenient, if unfortunate, analogy. Lots of anthropologists have observed and bemoaned the ways in which scientific discourse foists meaning on nature that really isn't there (e.g. pathogens/parasites are "bad," masculine, warlike language used in reference to sperm fusing with the egg, etc.)

Are you sure you want to post animal porn to the site?