Evolution of sexual reproduction?

[CrochityOldMan]

I have wondered about how sex evolved for quite some time, if anyone could shed some light on this issue it would be appreciated, because it seems to be a legitament problem.
According to the current theory of evolution the first organisms reproduced asexually, so at some point organisms must have developed the ability to reproduce sexually. I know there are some explanations at a unicellular level of cells connecting and exchanging DNA, but on a multicellular scale there seems to be a large problem. In order for sexual reproducation to be possible it takes a male and female, so a male and female would have to evolve seperately(while reproducing asexually) to the point where two of these different organisms get together and decide to reproduce. It seems very improbable that two such organism would evolve seperately and in such a compatible way. A completely worthless penis would have too be grown and mainted for generations without haveing a purpose, and then be lucky enough to run into a female that had developed an equally useless organ set over an extended period of time. How is this possible?
I know that many plants are both male and females and this seems to get around the problem, im not sure if there are any such examples in the animal world that have the ability to reproduce with themselves and with others, but even if there are, why would you ever lose the ability to reproduce with yourself? as it is obviously an advatage to have both options avalilable.

[underbear1]

worms have both sexual organs but they line themselves up against another worm so one's male part is next to the other's female part.

[CrochityOldMan]

That is an interesting example, but even if all sexual species evolved from something like this it doesnt show why some species lost 1/2 of there parts. Can these worms reproduce with themselves? because if they cant then the problem remains. Even though it becomes slightly more feasable because only one set of organs must be developed, they would still be completely useless until full evolved.

[gallo]

Quote by: CrochityOldMan I have wondered about how sex evolved for quite some time, if anyone could shed some light on this issue it would be appreciated, because it seems to be a legitament problem.

And it is a very good question. But your thinking is quite limited. You first try to limit it to mammals and then you talk about plants that don't reproduce in any similar way. By the way, not all plants have both sexes.

However, it is true that it is a perplexing question and the answer is still being sought. In asexual an asexual species, every individual produces offspring, even among the few species of asexual animals. However, in sexually reproducing species, only half bear offspring. It can easily be seen that the asexually reproducing species seems to have a distinct advantage. When other factors are taken into account, it is apparent the sexual reproduction is very expensive. And yet, only a small percentage of vertebrates reproduce asexually. There must be some advantage in sex.

Relatively recently biologists have been finding evidence for a surprising hypothesis: sex fights helps organisms shed parasites. The hypothesis is known as the Red Queen Hypothesis. You can find information about this hypothesis at the following sites:

Evolution: Library: The Red Queen

Red Queen Hypothesis

A second hypothesis (and slightly older one) is also known as the Red Queen Hypothesis. It involves the evolutionary arms race between predator and prey. You can get more information on this hypothesis at the second url above and at the following:

Red Queen - Wikipedia, the free encyclopedia

There are lots of sites that have information that will be helpful in informing you. Just Google "red queen hypothesis" and check out a few for information on both hypotheses.

You might also read Ridley, Matt. The Red Queen. 1995. Penguin Books, New York. 405 pages. ISBN 0140245480

That's the U.S. paperback. The book was first published in Great Britain in 1993, and in the U.S. by Macmillan Publishing in 1994.

Happy learning.

[JohnMK]

Quote by: CrochityOldMan It seems very improbable that two such organism would evolve seperately and in such a compatible way. . . . I know that many plants are both male and females and this seems to get around the problem, im not sure if there are any such examples in the animal world that have the ability to reproduce with themselves and with others, but even if there are, why would you ever lose the ability to reproduce with yourself? as it is obviously an advatage to have both options avalilable.

Do you mean to say that you think nature might have got it wrong and that you might have a more efficient way? I would advise reversing that premise as you proceed with your research, and definitely share with us more information as you turn it up if time permits. :)

I tried to google up some literature but didn't find anything within 30 seconds that was especially germain.

[CrochityOldMan]

In response to John:
Evolution is still a theory, Until it becomes a law, and until it is confirmed one should approach every problem we find with evolution assuming that it may not have occured. To say there is no probelm because evolution did occur is false because the premise of this statement is "evoluation did occur" which has not yet been proven. Hence it is known as "the theory of evolution"

In response to the other writer:
Perhaps my thinking is limited, but how does it make a difference in any group of creatures so long as they reproduce sexually? At some point a asexual creature evolved into a sexual creature, if its a snake a bird or a mouse, how does it make a difference?
Another thing is that while evolution does encourage any trait that has an advantage it does not neccisarilly create every trait that has an advantage. Even if there is a definite advatage to sexual reproduction this does not explain how it came to exsist. With some traits an explanation as to how the trait is advantageous may be enough (i.e. the classic example of black and white moths in london during the industrial revolution) but for this explanation to be sufficient the trait must occur within the normal variation of a species(or at least a simple one step mutation). obviously there is no species that produces offspring that are both sexual and asexual. Nor is it feasable that a one step mutation could cause the rise of a fully functional male and female.

[another day]

Well obviously sexual reproduction allows for the mixing of different genes and traits. As well as creating more "desire" to reproduce and also making it more difficult to reproduce which can be beneficial.

I see this all the time. Creationists trying to debunk evolution by using simplistic reasoning. Evolution is an extremely complicated concept, you can't just look at it like that. You need to study it extensively if you want to understand it. Trust me, the answers are there if you want to study them, but you're not going to get satisfactory explanations just through simplistic reasoning like that.

[CrochityOldMan]

Too simply point out that my reasoning is simple and therefore wrong does not exactly explain how two sexes evolved. I understand sexual reproduction has its advantages but that does not mean it would evolved(as i explained earlier) There are many characteristics i could imagine that would be advantageous that do not exist.
If you would like to attack my argument please explain what is wrong with it and not simply state that it is "simple reasoning" i do not deny that there may be a solution but obviously you do not know it, yet you seem to have a great deal of faith that an awnser exists.
I have researched this question, and am still doing so. One of the reasons i made this post was to get awnsers. I have asked several biology professors(one of which has there ph D's in evolutionary biology) at my college about this question and no one has had an awnser too it. So if you see a solution or know how to find one, please do so. And if you admit that many solutions have not yet been foud then please also admit that evolution is at best an incomplete theory.
Evolution is one of the most complex theories man has come up with and i do not claim to fully understand it. For this reason i am still reaserching it too discover if it is valid. If i can find solutions to many of its problems then i will accept it as a scientific truth, until then i veiw it as nothing more than an overly accepted beleif, and i suggest you do the same.

[underbear1]

Seperate sexes pre-dates mammals, and seperate sexes just is an inherited trait that has followed the rest of the species along the way, like the brian stem.

[CrochityOldMan]

underbear regaurdless of when this change occured, an asexual creature had to evolve into a sexual creature. How did this occur, not when, is my question.

[underbear1]

It occured shortly after worms, reptiles have seperate sexes.Seems as soon as a creature developed legs, one of them was throwing their's in the air...LOL

[Jack]

In response to John: Evolution is still a theory, Until it becomes a law, and until it is confirmed one should approach every problem we find with evolution assuming that it may not have occured. To say there is no probelm because evolution did occur is false because the premise of this statement is "evoluation did occur" which has not yet been proven. Hence it is known as "the theory of evolution"

Please Google "scientific theory" and learn what the terms mean. Evolutionary theory is a fact, just like gravitational theory. If you think gravity isn't a reality, how do you get around town?

but how does it make a difference in any group of creatures so long as they reproduce sexually?

Asexual reproduction produces exact replicas, since the source material is all from one individual. Differentiation requires a mixture of genetic material. In asexual reproduction, the death of the parent ends that genetic line. With two individuals contributing genetic material, the death of one parent does not mean the other can't still reproduce. Genetic diversity is nature's way of assuring the survival of a species.

[CrochityOldMan]

Quote by: Isherwood Please Google "scientific theory" and learn what the terms mean. Evolutionary theory is a fact, just like gravitational theory. If you think gravity isn't a reality, how do you get around town? Asexual reproduction produces exact replicas, since the source material is all from one individual. Differentiation requires a mixture of genetic material. In asexual reproduction, the death of the parent ends that genetic line. With two individuals contributing genetic material, the death of one parent does not mean the other can't still reproduce. Genetic diversity is nature's way of assuring the survival of a species.

yes....it would seem i am wrong about the definition of scientific theory. My mistake. However there still is a difference between a law and a theory. Also To say evolution is at the same level scientificly as gravity is absurd. Gravity can be tested in a laboratory over and over agian with the same result. Gravity can be observed directly evolution cannot be. We have not seen (macro)evolution occur. We have not been able to reproduce evolution in a laboratory. We can barely produce an organic molecule from non-organic ones. The only organic molecule we have been able to produce is methane. which is one carbons and four hydrogens. a far cry from an amino acid or from a many amino acids to produce DNA as well as a all of the molecules neccisary for the cell membrane and nucleosis. Im not saying evolution is clearly incorrect...simply that it is not at the same level as gravity. I understand that there may be a limitation to reproduceing evolution in a lab because of the lenght of time required for evolution to occur. I accept that there is evidence for evolution, but not that this evidence is at the same level as gravity. I think this is clear.
In response to your second statement you should read all the posts above and you would see that im not searching for how sex is an advantage, im searching for how sex evolved. Although everything that evolves is advantageous to that creatures survial, not everything that is advantageous will be evolved. If that were the case then every creature could reproduce bothy asexually and sexually since this would obviously be the best option. Please stop trying to awnser my question by saying that sex is advantagous. I get that....how did it evolve is the question.

[CrochityOldMan]

Also that qoute is completely out of context. The question is not simply what difference does sex make. The question is how does evolution of sexual reproduction become simpler based on which creature it evolved in. It was in response to someone saying that i limited my thinking to mammals. I was asking how this makes a difference as long as the creature in question evolved from asexual to sexual.

[underbear1]

There are more extinct animal species, than the number of species we have now. We may never find species that have become extinct which had all matter of different reproductions. Marsupials are a group which has live births and the infant continues to incubate in a pouch. There probably were a myriad of species who didn't survive due to inefficient reproduction, and those that did survive had seperate sexes.

[CrochityOldMan]

Quote by: underbear1 There are more extinct animal species, than the number of species we have now. We may never find species that have become extinct which had all matter of different reproductions. Marsupials are a group which has live births and the infant continues to incubate in a pouch. There probably were a myriad of species who didn't survive due to inefficient reproduction, and those that did survive had seperate sexes.

That would make sense if you assumed that the starting point was many different creatures with many different means of reproduction. However, we know that the first animal reproduced asexually, so how did sexual reproduction ultimately arise from asexual reproduction?
I understand sexually reproducing animals survived and have advantages over asexual creatures but look at it this way,

1) at the beggining creatures reproduced asexually

2)now many creatures reproduce sexually

how did this change from asexual to sexual occur? Just as evolutionist can explain the change from ape to man they should be able to show how asexual reproduction gave rise to sexual reproduction. There does not seem to be a feasible mechanism...im asking for someone to purpose at least one feasable way this could occur.

[CrochityOldMan]

Quote by: underbear1 worms have both sexual organs but they line themselves up against another worm so one's male part is next to the other's female part.

first of all from your description of worms above, it seems sexual reproduction predated worms since even though worms have both parts they still reproduce sexually.Secondly why would they ever give up one of the parts? there seems to be no advantage to loseing one part.

[underbear1]

You have good questions, I don't know if the answers are already discovered or not.

[Fonceai]

@COM

I took a two-semester course that detailed genetic evolution from single-celled organisms up to humans. It was awesome.

It detailed what would need to evolve in which order.

The development of current sexual reproduction (males and females with males doing fertilizing) is an issue of mobility.

Life and most forms of evolution are, ultimately, about mobility. At least in the "Survival of the Fittest" sense. You know, preferred characteristics. Guys liking nice curvy full breasts because they imply a woman who can feed her children well. Et cetera.

[gallo]

Quote by: CrochityOldMan In response to John: Evolution is still a theory, Until it becomes a law, and until it is confirmed one should approach every problem we find with evolution assuming that it may not have occured.

Theories do not grow up to become laws. You don't seem to understand much about science. Scientific laws are not theories that have been confirmed. A scientific theory is not a wild guess. Do you approach the germ theory of disease, atomic theory and the theory of gravity with the same disbelief?

Quote by: CrochityOldMan To say there is no probelm because evolution did occur is false because the premise of this statement is "evoluation did occur" which has not yet been proven. Hence it is known as "the theory of evolution"

But evolution has been observed. The theories of evolution explain the mechanisms by which evolution occurs.