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 Hibernian1960
Joined: 9/13/2008
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Why sex?Page 1 of 2    (1, 2)
More properly, "Why sexes?"

It is generally the rule that in a given species of animal life, two sexes are prevalent while true hermaphrodites are rare. This is counterintuitive since hermaphroditism would double the number of potential mates and thus help ensure both propagation and greater genetic diversity.

All comments are awaited with interest and thanks in advance.
 IgorFrankensteen
Joined: 6/29/2009
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Why sex?
Posted: 6/11/2011 6:03:16 AM
I think a likely reason is, CHANCE.

It's very easy to accidentally assume that what IS, in the universe, IS, as it is, for GOOD, AND NECESSARY, REASONS.
Actually, as so often in one's personal life, there are a number of possible ways things might have gone, and still ended up as they have.
Evolution happens as a result of action and reaction, to things that happen as a matter of the chance interaction of many forces. One can enjoy the belief that there is an intelligence behind it all, but that leads to closed-loop reasoning. Closed-loop reasoning isn't informative or interesting, since it essentially declares that what is, is so, because it is intended to be that way. In other words, it is, because it is. If it wasn't as it is, that would be because it wasn't supposed to be that way.

As to the direct question, I THINK we have examples in nature which MIGHT be illustrative. Some creatures here on earth do change gender in response to environment, thus being functionally 'hermaphroditic', so to speak. Has it made their species propagate more? Maybe, within the limits of the CAUSE of the sex-change. Maybe not a good example, then.
I don't believe that the examples of Human hermaphrodites would be useful to investigate, because they are clearly functionally mutations, rather than being a common result of standard mating (no offense or judgment intended ). It is likely that they are not all physiologically capable of performing successfully as both sexes, thus they are not complete hermaphrodites.

Maybe it's as simple as, that SPECIALIZATION of sexual function works better than trying to have both functions performed by one "mechanism." It's certainly true of all the MECHANICAL TOOLS of the world: a COMBINATION tool, always does each function less well than a specialized tool for each function. Perhaps it IS therefore actually 'counterintuitive' that hermaphrodites, combination people, would be better for propagation of the species than would SPECIALIZED sexes.
 stargazer1000
Joined: 1/16/2008
Msg: 3
Why sex?
Posted: 6/11/2011 10:01:45 AM
As in all questions re: why? Well, why not?
 Hibernian1960
Joined: 9/13/2008
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Posted: 6/11/2011 5:47:46 PM
Specialization? The ultimate example of specialization in reproduction would be the social insects such as ants and bees and termites, yet these, too seem to be in the minority, albeit a hugely successful one.

Thank you all for your thought provoking replies.
 nipoleon
Joined: 12/27/2005
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Posted: 6/14/2011 2:21:56 AM
The driving force behind evolution is genetic mutation. The more mutations the more diversity and the more evolution occurs in a changing ecosystem.

It seems that with hermaphroditism, where every individual can exchange genes with every other individual, there would be more genetic mutations and thereby more evolution. But, if you think about it mathematically, that really isn't the case.

The key is diversity. When all the individuals mate with each other and produce each others offspring , the gene pool becomes more stagnant. All the individuals become more and more alike genetically and there is less evolution instead of more.

Sexual reproduction " stirs the pot " better.
 nipoleon
Joined: 12/27/2005
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Posted: 6/14/2011 3:58:17 AM
There's nothing wrong with asexual reproduction as long as the environment doesn't change very much or very quickly.

A single cell of bacteria in a fertile petri dish will very quickly become a whole colony of bacteria, each cell genetically identical to all the others. The petri dish is a stagnant ecosystem and wont change.

However, once penicillin is introduced to the dish all the bacteria will die.
Except.... for that one cell which happens to have a purely accidental genetic resistance to penicillin. That one will survive and continue to reproduce until something else comes along which it can't handle.

Our environment tends to change a lot and pretty quickly and sexual reproduction is simply a more efficient way of stimulating and encouraging genetic mutations which keep us evolving and surviving.
 IgorFrankensteen
Joined: 6/29/2009
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Posted: 6/14/2011 4:31:49 AM
Perhaps another way to look at this is, starting from after a two-gender system came into being AND SUCCEEDED.
It's quite possible that the world MIGHT have chanced to evolve into a completely hermaphroditic one, and that when uni-sexual children were born, they would have been seen as handicapped mutations. Maybe, what happened was simply that, entirely by chance, a two-sex world came into being, and succeeded rapidly. Once it was ESTABLISHED, the natural tendency would be for everything about the species to adapt to support that.

Thus to this day, MOST of us are only attracted to one sexual format. It increases a species survive-ability for it's members to be excited about procreating, so our chemistry evolved that make us "horny" for others that we can make more of ourselves with. If we had chanced to develop as a species that was entirely hermaphroditic, I imagine we'd get 'turned on' by every one, as some bisexuals say they are. But once we existed as we do, natural selection isn't likely to change, because our chemical processes tend to make us turn away from others who appear NOT to be able to make babies with us. Since subconscious minds don't generally behave rationally as we might think, as soon as we see something about the other person that means "same sex, no babies" to us, we lose interest. That's why so many males respond negatively to hairy faces on women, to lack of recognizable mammary glands, to poor health, and so forth. Having a penis certainly makes ME immediately think "male," and therefore "no babies." That there MIGHT also be a vagina doesn't make it past my basic visual analysis systems.
 stargazer1000
Joined: 1/16/2008
Msg: 8
Why sex?
Posted: 6/14/2011 8:02:57 AM

It is generally the rule that in a given species of animal life, two sexes are prevalent while true hermaphrodites are rare.


Well, first of all, understand that the basic purpose of sex is gene transfer. However, bacteria trade genes all the time. So you're never going to fully be able to trace back the origin of "gender" entirely. Was there a point where once multi-cellular creature became "male" and another "female?" What was the ineffable quality that set the two apart? Again, a mystery that may never be solved. However, we can make various deductions about what having that split means to evolution of species based on the evidence at hand.


I think a likely reason is, CHANCE.


Yes...and no. There is undoubtedly an element of chance that goes into genetic mutation that leads to advantage. However, natural selection is the mechanism by which those mutations are weeded out. Let's face it, if a creature isn't well suited to a sudden change in salinity of a body of water, for instance, he's going to be pretty handily selected out of the evolutionary race in favour of critters that can handle that salinity. Again, it's not the whole answer. Remember, we're talking a very, VERY complex process.

It should also be noted here that sexual selection is also highly important for multi-cellular, sexually-reproducing creatures. But external selection pressures will mute sexual signals of brightness of size i.e. guppies and elephants.


Specialization? The ultimate example of specialization in reproduction would be the social insects such as ants and bees and termites, yet these, too seem to be in the minority, albeit a hugely successful one.


Actually, by population, these represent some of the most numerous species on the planet but I'm not sure where you're going with this. Ants, bees and termites still reproduce sexually. It's just that only one female is in charge of the reproduction.


It is one of those irreducibility things where most evolutionists will just mumble their own private theories.


Since irreducible complexity is pretty much a dead horse, I wouldn't worry about it. "Evolutionists" is a key word for creationists. You'll note, no one ever talks about "gravitationlists" or "germists." Evolution is a robust theory. I've yet to see any creationist come up with anything better than "godidit."


Obviously from a religious perspective the answer is… God did it.


And that would be a cop-out.


However, to go from a more efficient reproductive method to a less effective one with no known mechanism is hard to explain.


And this is the problem...the assumption of "either/or." Especially when we can see examples of both sexual and asexual reproduction taking place presently. Evolution isn't an agenda-driven business. It just happens.


So not only have we a Why? But a How? To explain.

Good luck on that one


Pending the invention of a time machine, sure. Some people have a problem with the idea that we can't have absolute knowledge of things. That's how we get creationists.
 stargazer1000
Joined: 1/16/2008
Msg: 9
Why sex?
Posted: 6/14/2011 8:47:56 PM
Okay, so here's hoping I don't have to retype this a third time!


so why move to something that is less efficient.


Again, evolution is not agenda driven. It's a process. Clearly, the process works because, well, it exists and is being used by a plethora of species to reproduce. Sure, if you go by numbers, asexual reproduction through mitosis is the MOST successful process. But that doesn't necessarily mean other processes aren't going to evolve. Evolution doesn't have an agenda. It's blind and its intention-less.


Asexual reproduction is equally successful method so why would natural selection select a less efficient method? What would be the natural mechanism that would drive bacteria to do this? What would make a self-reproducing organism suddenly start impregnating another with half its DNA which is less efficient as a means of reproduction?


Again, evolution by natural selection is a process, not an intention. Sexual reproduction exists because it works. How it got started, as I have stated, is something we may never know for sure. But does that mean biologists should stop investigating?

Also, the process by which bacteria share DNA I don't know if you can call it sexual since the transfer, at least as far as I know, doesn't lead to the mitosis of the cell. It's just an exchange.


Think you will find that is a matter of opinion, unless you can explain how inanimate material became animate or as in this thread asexual became sexual. The concept of irreducibility is where there is no predecessor.


Um...no. First of all, the concept of "irreducible complexity" is a term coined by Michael Behe to argue that there are structures in nature such as the eye or the bacterial flagellum that, once a single part is lost, would render the entire structure useless. The public and very thorough trouncing of this is a matter of public record but, for your edification, please feel free to look up Kitzmiller v. Dover board of education.

Secondly, and I've seen this pointed out time and time again to creationists, abiogenesis - the process by which chemicals become self-replicating molecules - is not evolution. Evolution is what happens after the molecules begin replicating. As for how asexual becomes sexual, as I have stated, we may not understand the specifics. But that hardly is a reason to stop looking, don'tcha think?

Unless, of course, you want to argue in favour of external agency. In which case, it's going to be up to you to provide evidence of said outside agency. Good luck with that.


One of the favourite terms used by people who do not understand…


Not understand what? I think I'm keeping up pretty good. Please feel free to specify.


You seem to have trouble with your suffixes, -ist just means someone involved in the activity or field of. But I’m glad you agree that people who study things that were created from nothing are creationists…sorry evolutionists

That’s comical, that’s going to keep me amused for days… Ever heard of a scientist… you know someone involved with science…Instead of a germist, you may get a chemist…or cosmologist, physicist… lol


Ummm...okay. However, the term "evolutionist" has been used numerous times by the religious as a pejorative. While there are cosmologists and biologists, evolution is a scientific theory. Therefore, as I said, you are not going to get people who consider themselves "evolutionists" the same way you're not going to get "gravitationalists." Unless, of course, someone is advocating intelligent falling.

However, creationism - the belief in external agency influencing or "creating" life either from initial starting points (theistic evolution) or special creation (everything in place, as is), is a matter of doctrine. It's advocates could, therefore, be said to be creationists. Ah, command of the English language is a good thing, eh?

Oh, you'll note the bolded part above. Yeah...seen that "logic" from quite a few unabashed creationists. Just sayin'.


Missed the point again… It isn’t about either/or, it is about how you go from 1 to the other when the latter is less efficient than the former and when nature is supposed to select the more efficient.


Again, there is no direction, goal or direction to evolution. It just happens.


We aren’t looking for absolutes, just explanations, plausible ones would be useful. That is what science does


That is what science does. And it does the best with what it has. However, just because we don't have all the answers yet, doesn't mean the entirety of evolutionary theory needs to be rewritten or thrown out. On the whole, evolution is well supported. But any evolutionary biologist worth his/her salt will tell you that the theory could be overturned tomorrow if the right evidence was found. However, if you've got an alternative that work better, let's hear it.


Not sure how you associate absolute knowledge with creationists unless you are scared by them. Ever thought your fear could come actually being one, maybe you should just come out of the closet?




Okay, I read that and nearly spit my tea halfway across the room! Especially given that I'm currently reading Richard Dawkins' The Ancestor's Tale and am thoroughly enjoying the read.

Absolute knowledge? Well, given that creationists argue that "science is always changing its story," well, that would be the giveaway there. Science is always making new discoveries. As a result, theories are revised, changed, even discarded. That's how it works. Are you denying this position by creationists? By what authority do you speak on behalf of creationists? Are you one yourself?

But yes, creationists do scare me. And well they should. Given their determination to dominate public discourse and education and their tendency to try to advocate as absolute "truth" what are essentially bronze age mythologies, they represent one of the greatest threats to forward progress in science, education, public policy, social justice...the list goes on.
 Hibernian1960
Joined: 9/13/2008
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Why sex?
Posted: 6/16/2011 6:48:15 PM
The penis of the barnacle is up to seven times the length of its body, reflecting a limited pool of potential mates. It is sort of like being unable to date anyone outside your apartment complex- scary thought in my case!
 nipoleon
Joined: 12/27/2005
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Posted: 6/16/2011 10:32:03 PM
There is a difference between asexual reproduction and hermaphroditism.

Asexual reproduction is simply one individual spitting into or giving birth to another without trading any genetic material from another. The offspring is essentially a clone of the original. There is no male and female . Almost all single cell organisms reproduce asexually and very few multi cellular organisms do this.

Hermaphroditism is still sexual reproduction except all the individuals are both male and female. Most snails are hermaphrodites and a few species of reptiles and fish can be hermaphrodites under the right conditions.

As I stated before, hermaphroditism as a form of sexual reproduction isn't very good at preserving genetic diversity. When all the individuals trade each others genes it tends to wash out all the diversity over the generations.

Genetic diversity is very important in a constantly changing environment. That's why no one disease can come along and completely wipe out everybody all at the same time.
 Hibernian1960
Joined: 9/13/2008
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Posted: 6/16/2011 11:22:13 PM
But is it merely a matter of biology? There seems to be a biological basis for homosexuality in other species as well as in humans, and it is indeed puzzling to speculate on what procreative value such a trait has.

The entire issue of monogamy is a related topic- certain species mate for life and display consistent fidelity, obviously humans are not any such example. Instead, we get a bewildering array of endogamous and exogamous groups, polygyny, polyandry, etc.

Humans seem better able to adapt their mating habits to changing circumstances, for example, so many Soviet males died in The Great Patriotic War that women shared the available men in order to bear children.
 60to70
Joined: 7/28/2008
Msg: 13
Why sex?
Posted: 6/17/2011 12:32:27 AM
Sex produces children at the right time of the month. Sex is why children are born. Sex is better and sweeter when a child is conceived. All of the rest of the suppositions and wondering is beside the point. smile.
Why sex? Why not? Let the sperm meet the egg...sometimes. Otherwise...it ain't that complicated. All of the extraneous details are just that...not central but easily brushed aside.
 UnixGrand
Joined: 5/9/2011
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Posted: 6/17/2011 11:16:37 AM

Why sex? Why not? Let the sperm meet the egg...sometimes. Otherwise...it ain't that complicated. All of the extraneous details are just that...not central but easily brushed aside.


Do people realize the breakdown in the DNA Ladder we are facing in this country? Most of people in America born in this country are having children with other people who are born Americans. This is causing a lot more instances of Diseases, Syndromes, and Genetic Anomalies in new born. We are becoming kissing cousins if you may. I think this is why the US government allows foreign people to flow into the States every decade. Then they put the stop on it.
 stargazer1000
Joined: 1/16/2008
Msg: 15
Why sex?
Posted: 6/17/2011 1:27:47 PM

Do people realize the breakdown in the DNA Ladder we are facing in this country? Most of people in America born in this country are having children with other people who are born Americans. This is causing a lot more instances of Diseases, Syndromes, and Genetic Anomalies in new born.


Wow!! Just...wow!! And do you have any sort of citation for this piece of sh...um..interesting hypothesis?


We are becoming kissing cousins if you may. I think this is why the US government allows foreign people to flow into the States every decade. Then they put the stop on it.


Okay, props for the support of immigration but...wow!
 UnixGrand
Joined: 5/9/2011
Msg: 16
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Posted: 6/17/2011 1:43:08 PM

Wow!! Just...wow!! And do you have any sort of citation for this piece of sh...um..interesting hypothesis?




Actuarial science. No good A++ Insurance company does business without a good Actuarial department.
 stargazer1000
Joined: 1/16/2008
Msg: 17
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Posted: 6/17/2011 1:46:27 PM
Not what "citation" means. You know...real links or sources for this little hypothesis of yours. That, somehow, a population of over 300 million people isn't diverse enough and is leading to some sort of inbreeding problem?

And you're serious with this one? Really?
 UnixGrand
Joined: 5/9/2011
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Posted: 6/17/2011 1:51:14 PM
And you're serious with this one? Really?


It's an unpublished source. Actuarial results would not be for the populations views. [The average person] It's for the Insurance company to maintain proper premiums vs. claims = profits. You would be amazed at what those 311,575,422 million that don't know.
 FrankNStein902
Joined: 12/26/2009
Msg: 19
Why sex?
Posted: 6/17/2011 1:54:25 PM

Actuarial science. No good A++ Insurance company does business without a good Actuarial department.

FYI: When making unfounded claims, it is best not to cite something that proves you wrong.
 nipoleon
Joined: 12/27/2005
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Posted: 6/17/2011 2:49:58 PM
There is a real problem with inbreeding among zoo animals in captivity. The populations of some of these animals have dwindled to the point that it's getting difficult to maintain enough genetic diversity.
Tigers are a good example. A few years ago white tigers and lions were being touted in the media as rare and special cases. Actually, there's nothing rare about them at all and they are becoming more common . They are the result of too much inbreeding and zoos don't want them. They usually have hearing and vision problems too.

With a population as big as North America and considering how mobile and diverse we are, I really doubt genetic inbreeding should be much of a concern for us overall.
But then, if the insurance companies feel that way, I really don't know.
 UnixGrand
Joined: 5/9/2011
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Posted: 6/18/2011 4:39:46 PM

It speeds up evolution, …obviously.


Now we are on to something.
 CallmeKen
Joined: 9/4/2009
Msg: 22
Why sex?
Posted: 6/21/2011 4:43:53 AM
two sexes are prevalent while true hermaphrodites are rare.

I would disagree with this. If hermaphrodism is rare, then why do so many women on POF tell me to go f ck myself?
 TinCanChalice
Joined: 6/18/2011
Msg: 23
Why sex?
Posted: 6/25/2011 7:33:49 AM
Two sexes increase the chances of a genetic drift. If there was asexual reproduction (like a cell or jelly fish) there would be a lesser chance of genetic mutation to make a species better.

Having to compete for a mate also drives evolution in that the weaker of the species would not be able to find a mate and pass on genes which would lessen the viability of the species.

Humanity is a bit different when you look at the equation. We are still driven by the biological need to procreate but at the same time there are social issues. Talent or intelligence alone would be a mark or a good gene to pass on but someone like Mick Jagger is as ugly as sin.... Money is the social issue which makes him have sex appeal.

To take the 'fluff factor' out of thing most of what people say is love is actually biological responses to pheromones and other more base reactions to our physiology. The taste of someone's kiss is a reaction to anti-bodies and comparability of immune systems.
 abelian
Joined: 1/12/2008
Msg: 24
Why sex?
Posted: 6/27/2011 6:06:52 PM
Can you think of a simpler way to ensure diversification of genetic material to facillitate long term survival of a species?

This is counterintuitive since hermaphroditism would double the number of potential mates and thus help ensure both propagation and greater genetic diversity.

It's also more complex. Male and female sex organs arise from the same primative structures. Your scheme for diversification would require a great deal more complexity with dubious benefit.

Many plants have devised more than one way of reproduction as a survival mechanism and as we look at them we may be observing nature in transition from one method to another

In nature, what works, works. What doesn't work doesn't last long.
 aremeself
Joined: 12/31/2008
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Posted: 6/30/2011 9:08:45 PM
abelien;

In nature, what works, works. What doesn't work doesn't last long.

so how many times did life start and die. no one knows.
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