Talk:Evolution of sexual reproduction

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Former good article Evolution of sexual reproduction was one of the Natural sciences good articles, but it has been removed from the list. There are suggestions below for improving the article to meet the good article criteria. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.

older entries[edit]

Great article! I immediately nominate it as a featured article. --Lexor|Talk 06:21, 18 May 2004 (UTC)

Uh... Somebody just did s/sex/apples/g on this thing. -- BillGarrett 18:03, 18 May 2004 (UTC)

Is there some kind of consensus as to which of the various explanations is most likely? At the moment, the article seems to imply that none of them are very plausible. Markalexander100 03:48, 20 May 2004 (UTC)

Well, in all honesty I don't think there is any concensus. Probably the most widely accepted is the parasite hypothesis, however, the explanations are not mutually exclusive, and I would suspect that the majority of evolutionary biologists are pretty open-minded on this. Having said that, the research that went into this article is about eight years old now... so there may well have been further experimental studies since then. - MykReeve 01:16, 1 Jul 2004 (UTC)

Red Queen hypothesis note[edit]

"Critics of the Red Queen hypothesis question whether the constantly-changing environment of hosts and parasites is sufficiently common to explain the evolution of sex." It should be noted parasitic life outnumbers 'free-living' life, 4 to 1, and additionally 'parasitic' is an ambigous term. All life is parasitic in some manner. This is why(partially) the RQ theory can hold its water. --Mike Spenard 06:50, 4 July 2006 (UTC)

It would be nice to have a reference for these critics - anonymous —Preceding unsigned comment added by 173.3.113.232 (talk) 12:22, 5 November 2009 (UTC)
Outnumber by what measure: individuals, species, biomass? And who said that? Paradoctor (talk) 14:48, 5 November 2009 (UTC)

Heterogonic species[edit]

One sentence of the article was changed to the following earlier today:

These species time their asexual reproduction with periods of environmental uncertainty, and reproduce sexually when conditions are more favourable.

I believe this is incorrect, and have reverted it to:

These species time their sexual reproduction with periods of environmental uncertainty, and reproduce asexually when conditions are more favourable.

This is consistent with the text of Mark Ridley, in his Evolution textbook. Not that this affects the basic point - which is that the species do choose to reproduce sexually, when they do not need to. - MykReeve 21:19, 29 Oct 2004 (UTC)

I've never edited a page before so I thought I would rather post my comment here than risk offending anyone by ignoring convention: Kondrshov's hypothesis is strongly supported by Mark Ridley's Mendel's Demon: Evolution and the Complexity of Life (2004), which I think is published under a different name in the US. It deals with precisely this subject and I think presents a compelling synthesis of modern thinking on the subject (which is what Ridley is good at). Also in connection with Kondrashov's theory, as I understand it, it does not require a high mutation rate but rather explains the fact of mutation rates as high as 20 point mutations per generation in some eukaryotes (including humans). Thus sex (more specifically, recombination linked with reproduction) magnifies selections' ability to remove deleterious mutations (as a result of the Kondrashov effect). This is, I think, the most convincing theory of sex not based on group/species selection (and if you are like me, you will not enjoy group-selectionist explanations). Also what is sorely missing from this encyclopedia is an article on the organelle theory of the origin of gender (also, see Ridley 2004). The distinction between the origin of sex and the origin of gender is important as they are entirely separate things that are circumstantially linked (according to this hypothesis, by the peculiar origin of eukaryotes - SEM theory). But I am only a student so I will leave it to someone more qualified to write ;-) Ramon Nogueira (the_great_ostrich_paradox@yahoo.co.uk)

I encourage you to be bold and go ahead and make changes. Many times new changes in the article will encourage other editors to work on the sections, in ways that suggestions on the talk page generally do not. Also, if you sign your comments with four tildes (~ ~ ~ ~ only without any spaces), it will automatically record your name and the date of your comment, and link to your Wikipedia user page. Lyrl 12:21, 4 July 2006 (UTC)
Even better, first read Kondrashov's paper on zebrafish mutation rates. - Samsara (talkcontribs) 13:00, 4 July 2006 (UTC)

made a few changes[edit]

I've made some changes in the intro of the article Evolution of sex as well bumping up the section sex creates variation among siblings to the beginning of the page. I was hoping to make the text a little clearer. Hope I didn't offend anyone. seb951 (seb951@yahoo.com)[1]

Crippled is not a friendly word. That was my non-pc comment. Other than that, let me point out why I object to much of your edit - your original edit had the following passage.
One of the most widely accepted explanations for the advantage of sex lies in the creation of genetic variation on which natural selection can act.
The last five words restrict the range of hypotheses that the sentence can embrace, because, although genetic variation may be the key, it may not be for the benefit of natural selection in this direct way, e.g. trophic diversification among siblings may be nothing to do with supplying material for natural selection to select from, but rather with avoiding sib competition.
Then you exclude even more hypotheses by talking only about purging deleterious mutations and fixing beneficial ones. For instance, you're thereby excluding the Red Queen hypothesis, which has nothing to do with fixed effects of mutations (i.e. in your exposition, an allele is either good or bad; in the Red Queen, that is not so: it is the combination of alleles that matters). - Samsara contrib talk 21:17, 23 January 2006 (UTC)

Nomination[edit]

I nominate the article as a feature article. Article tackles a difficult and complex subject in a complete and clear manner. Much work has been done since the last submission as featured article (2004). Notably, it now has a good, clear intro; links to related wikipedia articles; presents all sides of the subject; terms and concepts are wikified. I think it is of similar quality compared to what you find in highly respectable scientific journals. Seb951 15 Feb 2006

References on biological reproduction[edit]

These are two references I salvaged from biological reproduction. They should probably be replaced with something more general:

  • S. P. Otto and D. B. Goldstein. (1992) Recombination and the Evolution of Diploidy. Genetics 131 (1992): 745-751.
  • Tobler, M. & Schlupp, I. (2005) Parasites in sexual and asexual mollies (Poecilia, Poeciliidae, Teleostei): a case for the Red Queen? Biol. Lett. 1 (2): 166-168.

- Samsara contrib talk 13:13, 18 February 2006 (UTC)

Ghettoizes[edit]

Can someone explain to me what the statement "In essence, sex ghettoizes the deleterious mutations." means? I am not an expert in the subject matter but I have never seen the word ghettoizes in any schoolarly work or non-schoolarly work for that matter. - Unsigned by 67.172.180.75 at 21:47, 26 February 2006

Changed to "compartmentalises". Regards, Samsara contrib talk 15:59, 27 February 2006 (UTC)
I'm not sure I agree with the word "compartmentalises" - this implies that a separate 'compartment' of some sort is created, whereas ghettoise implies that sex acts merely to move deleterious mutations together - without creating any separate discrete region. The word "ghettoize" is true to Mark Ridley's popular science description of Kondrashov's theories in the book 'Mendel's Daemon'. - MykReeve T·C 17:05, 27 February 2006 (UTC)
"Compartmentalisation" is used in statistics to describe assigning effects to causes. Hence, phenotypic variance can be compartmentalised into genetic, maternal and environmental effects (and genetic effects can be split into additive and dominant). Compartmentalisation is a term that has been often used in the evolutionary literature to refer to the increase in fitness variance effected by recombination, which is what the passage we are discussing here also refers to. I'm not sure why you think we have to follow Mark Ridley. - Samsara contrib talk 20:10, 27 February 2006 (UTC)
Largely because Ridley was responsible for promoting the concept in popular science, and used the word to neatly illustrate how recombination acts to collect deleterious mutations together, so that they can be more efficiently expunged.
I certainly didn't intend, when I wrote that passage, that it should discuss the compartmentalisation of the phenotypic variance changes between generations - simply that it should illustrate the method by which this mechanism is theorised to remove deleterious mutations, in lay language. If you feel that the word "ghettoises" is unclear as an explanation for the mechanism by which this operates, then fine... but I'm not entirely comfortable with the use of "compartmentalisation" here. - MykReeve T·C 13:00, 28 February 2006 (UTC)

I think we're getting off of the original question, what does "ghettoise" mean in this context. My understanding of it is that sexual selection will tend to mate the best with the best, and the worst with the worst (in that case "ghetoiseing" the genes that made them the worst). Is that about it?

Other Benifts- Cover Up bad genes[edit]

Has any scientist explored the idea that the benefit of sex is just to cover up bad, potentially deadly, mutations. I think I remember reading that every generation will introduce 1-10 potentially deadly mutations. But, with such a long genome, the odds of inheriting 2 bad genes at the same loci is small. This does nothing to remove the bad genes in the long run, but so what? Evolution can be short sighted. I seems to me that the moment the our primitive ancestors grow in complexity such that there genome got so long that the probability of a deadly mutation became greater that %50, sex would then become a positive strategy.

The sad fact that the bad gene is not removed, and will at sometime, in the distance future, meet up with another bad gene (or itself) in the same loci, wouldn't make it a bad strategy at the time it was "invented". Maybe, as time when on, sex had other benefits that sustained it as a winning strategy.

Steve

Well, first the probability of a deleterious mutations (let alone « deadly ») is much smaller than 50%. Remember that cells possess many different mechanisms to repair mutations in their genome. In fact, there is debate as to what the mutation rate in an organism is. Some have agreed to say about 1 deleterious mutation per genome/per generation, others say it’s less, few say it is a little above 1, in any case not a 50% lethality!
One of the ways by which mutations can be repaired at a particular locus is via recombinational repair. This process uses a sister chromatid as template and uses enzymes nearly identical to the machinery responsible for chromosomal crossover during meiosis. Thus DNA repair is in someways at least sometimes, linked to sexual reproduction.
This could explain how sexual reproduction originated (see section Origin of sexual reproduction). However, it does not explain why the whole sexual cycle (which implies much most than a few rec. enzymes) is maintained. If recombinational repair was the only advantage of sexual reproduction, then organisms would have lost the rest of the sexual cycle long time ago. Seb951 21:08, 23 March 2006 (UTC)seb951

Well, there was time in evolutionary history BEFORE all this really good proof reading came into being, true? I didn't say that there is a 50% lethality NOW, but that there could have been IN THE PAST (hence the words "our primitive ancestors"), that could have given rise to sex. It might have been before eukaryotic, or even before cells. That was my question anyway, if such a thing could be true. And all I was talking about was the origins of sex, not the maintenance (re-read my last sentence).

Also, you start out by saying that "..the probability of a deleterious mutations (let alone « deadly ») is much smaller than 50%.." Then you say that "Some have agreed to say about 1 deleterious mutation per genome/per generation, others say it’s less..". Although we were talking about 2 different things, (me, primative life, and you human life (?)), 1 is still bigger than %50, not "much smaller"!!

I DO appreciate the info, thu!

SAK


Steve, what you're talking about is the evolution of diploidy, not of sex. See papers by Sally Otto. - Samsara (talkcontribs) 23:42, 23 March 2006 (UTC)

Samara,

I really was talking about sex, but I get your point, diploidy alone would provide the a good copy of the odd bad gene. It seems to me, thu, that if both halves of the diploid come from the same body, are exposed to the same environment, they might be more likely to be corropted in the same way, have a mutation at that same loci. If I were baking cookies, and had recipe that I didn't trust, I'd want to compare it to a recipe that came from a complitly different source. Still, bdelloids do exist.

Thanks for the feedback and the ref's. I'll do some reading. SAK

I would estimate that there are in the region of 1,000 scholarly articles written on this subject, in addition to the half dozen or so books, some of which are referenced in the article. I think someone counted 50 different hypotheses for the maintenance of sex alone (it may have been in Kondrashov's review paper), so just on probability, it is unlikely that you will come up with anything new. I know because I've tried (on those dark damp nights when I wear my academic cloak). - Samsara (talkcontribs) 11:12, 4 July 2006 (UTC)

Article?[edit]

I thought that the article would be about the evolution of sex from the SEX point of view (Porno)--67.49.215.31 02:24, 25 May 2006 (UTC)

Grin, would have been a possibility, but I guess that the title was already taken by this topic. Maybe try at porn? -- Kim van der Linde at venus 02:47, 25 May 2006 (UTC)

Little problem[edit]

The fact that evolution is a theory itself is not recognized. It would be a nice article if evolution were a fact. These are theories that try to paint over a major problem, to support it's parent theory, the theory of evolution. The fact that these are merely conjecture to the parent theory is not acknowledged. It is implied that these theories are base on facts. However, these facts, the observable things, are made to fit these theories. And the facts that are problem are convieniently missing, so the focus is diverted else where. It is assumed that the theory of evolution, is fact and these theories and the article rely heavily on that assuption. I don't mean to be picky, however, this article need work, lots of work. I mean it looks pretty on the surface and if one is ignorant of scope of the problem posed against the parent theory. Sure, it would market well. This article very subtlely and deceptively glosses over the facts.

Just for fun, let's examine the problem, so that this article may evenually become objective. And this will help explain why these theories exist, and why they are so illusive, and will reveal the massive hole in the theory of evolution. The problem is such: According to evolutionary theories, living things became increasingly more complex as they continued to reproduce. At some remarkable stage, the female of a many species emerged that had to develop reproductive cells requiring fertilization by a male also emerging at the same time with perfectly complementary reproductive cells. For the proper number of chromosomes to be suppied to the offspring, each parent's reproductive cells undergo a complex and remarkable process called meiosis, where the cells of each parent are left with half the usual number of chromosomes. This process prevents too many chromosomes apearing in the offspring.

The same process would be required for the other species that appeared at the same time. This ofcourse, is where the fossil record comes in. The questions are then, how did the "first mother" of each species gain the capacity of reproducing with a fully developed "first father"? How could both genders have suddenly been able to halve the number of chromosomes in their reproductive cells in the exact manner needed to produce offspring with some characteristics of both parents? If these essential reproductive features developed gradually, how is it possible for the male and female of each species to have survived while such vital features were still only partially formed?

Even in one species, the probabilities against this reproductive interdependence arising from chance are beyond measuring. Therefore, the event taking place in one species after another defies the odds repeatedly on a large scale and without reasonable explanation. Do the theoretical process of evolution explain these complexities? How is it that these random, accidental, purposeless events resulted in such complex and intricately inter-related systems?

This is the problem that so many are trying to hide. This article does not explain that these theories exist to explain this major problem facing the theory of evolution. This article presents conjecture as if it were fact. And this is the furthest thing from the truth. For this article to be truthful it must present the facts, and the theories of the evolution of sex as the established opinions or theories. Another thing establish the relative relationship of the theories of the evolution of sex to the theory of evolution. 24.150.46.62 23:36, 12 September 2006 (UTC)

Response to little Problem[edit]

Well, I do enjoy this. First, I never said all living things. I said living things. You were reading what you what to read, or maybe you need glasses, I don't know. So you were arguing a non-existant point. A bit over zealous I guess.

Second, My statement of the problem, starts off, According to evolutionary theories, putting me in a neutral position on this arguement. Where as you advocate the theory of evolution.

Next, I avoided the Bacterial conjugation discussion altogether.

Further, I will discuss this, "I believe that if I have an apple in my hand, and then let go of it, it will fall to the ground. I suppose I therefore have blind faith in the existence of gravity. Maybe I'm not understanding your point?" I am sure you are refering to the theories pertaining to the causes of gravity. Many make the mistake that these theories exist to prove the reality of gravity. Actually, the observable phenomenon of gravity is fact. And a fact many laws were derived from this fact and the laws were validated by math and experiments. And were thus proven fact themselves. The facts of both gravity and these laws are not disputed. However, the question was then asked, what causes gravity? Based on the facts of gravity and the laws of gravity, and on the data from the experiments, theories were formulated to explain the cause of gravity. However, being unable to gather conclusive results these theories remain theories today. These theories of gravity do not affect, the fact of gravity or the laws and math derived from experiments with gravity. From your misunderstanding of the fact of gravity and the theories of the causes of gravity you are trying to discredit my statement of your blind faith in the theory of evolution. I on the other hand do not have blind faith in the existence of gravity because it is observable fact. There is no need for faith at all because it is observable fact. And as for the theories of the causes of gravity, they have merit, because they do not conflict with the math and are founded on observable fact and the proven laws derived from this observable fact and are thus proven facts themselves. These theories of the causes of gravity thus require faith, however it is not blind-faith. Further, the theories of the causes of gravity went through the proper scientific procedures to become theories, and if one piece of evidence appears that goes against anyone of these theories, they are rendered false and abandoned. Then the evidence is taken into account and a new theory is formulated.

This is not the case with the theory of evolution. It continue to exist even in the face of much proven evidence against it. These facts are simply ignored, the theory is not reformulated, it is not rendered false. The evolutionary biologist simply state we don't have the scienfic capabilites to test the theory, never even taking into account the many facts against the theory. The theories of the causes of gravity some have not been tested and there were found evidence agaist them and they were rendered false the evidence was taken into account and reformulated. There is a vast difference between these two theories and between how these theories are formulated. Therefore, your crude understanding of real science as is revealed in your ignorance of what is fact and what is theory reveal only one conclusion, absolute blind-faith in the theory of evolution.

Your next statement, goes further reveal your ignorance of valid fact. simply because I stated fact and you ignored it completely. The fossil record is up-to-date and valid fact. You ignorance in this area is quite apparent. According to the fossil record organisms emerged suddenly in large numbers and variety. At many stages throughout the record this sudden emergence of even more complex organisms in large numbers and variety occurs. This record works against the theory of evolution. I used the fossil record along with a simple question, to which your response was to fall back on an unproven theory. Then, your reverted back to conjecture from your theory.

This statement, very interesting, "I'm at odds with math? If you are referring to the odds of sexual reproduction evolving - what are they? One out of one thousand? One out of one trillion? One out of one googolplex? Well, how many organisms have existed in the history of life? About that many, I would expect. That evens the odds out some." My suggestion to you is to learn math, the higher the better. Learn the rules of math applied to science. There is a point were something goes so far against the odds it is considered impossible. For example, the odds of me winning the lottery is possible, the odds of me winning the lottery twice in a row is improbable, the odds of me winning the lottery three in a row is impossible. The odds are too much against me. And if you ignore this as just technicalities, I ask you how many times could I keep winning the lottery in consecutive order until it is considered impossible? Four times, five, ten, fifty, one hundred, one thousand, etc. My point is, there exists a stage where the numbers say impossible. So go learn math until you understand this.

Moving on to the next one, yes, you misread again and imagined this arguement as you wanted, then replied implusively, I gathered as much.

Next, I'll be simple this time, "VITAL FEATURE." That's what vertebrates have to do with this discussion. Even with the ability to generate eggs and sperm, without, the vital features, no copulation, means no offspring. And because they are vertebrates, no asexual reproducing.

Well onward, I suppose comparative reasoning will work here. "If evolution were random, you would expect to see orders of magnitude more simple species than complex ones, right?" Is this a question or a statement? You tried to make a retorical question. However, you made one of two mistakes. You either put a question mark at the end of a statement. Or you inverted "you would, with "would you." So, since you tried to make a retorical question I read it as, "If evolution were random, would you expect to see orders of magnitude more simple species than complex ones, right?" You are contradicting your self. I suppose I sould have read it this way,"If evolution were random, you would expect to see orders of magnitude more simple species than complex ones. Right?" This, is a statement and a retorical question, but this is not what you wrote. Your statement here to explain that it was not a question, but a statement,My point was that the ratio of simple species to complex species supports the view of evolution as a random process. I apologize for the misunderstanding. Please, next time remember, question marks for questions, periods for statements. My question was "How is it that these random, accidental, purposeless events resulted in such complex and intricately inter-related systems?" We were talking about the sexual reproducive system and the development of reproductive features. Since, this whole discussion is about reproduction, these are two valid subjects of discussion. However, both, your so-called retorical question, and your point, have nothing to do with what this discussion is about. It was a detour of your imagination. I apologize again, for making one of the three correction as I read the statement, or question, or both, in order to understand what you were talking about.

Lastly, Darwin, he was a scientist, he gathered data, then theorized. Yes he did. I rather like Darwin because he was scientific. His was theory was wrong, but he was scienfic. Did Darwin ever claim that his theory was "Fact?" He did not have the knowledge we have today. In fact, Darwins theory has long been disgarded by evolutionary biologists because of that knowledge. Except instead, of rendering the theory false, the evolutionary biologist fractured into different groups holding to their version to his theory because of that knowledge. Darwin never base his theory on a theory. He based it on observation. His conclusions were wrong. Evolutionary biologist around the planet, cannot prove these theories. Because they cannot proven these theories, they create new theories based on the theory they want to prove. These new theories are purely conjecture, and yet these evolutionary biologist set out to prove their conjecture, and they use observations through the view of their conjecture to support their conjecture. This allows them to present both their conjecture and the falsified evidence as facts to their theory of evolution. In doing this they ignore facts, and do not allow the evidence they present to speak on its own. This theory does not belong in science, it belongs in fiction or the garbage. This theory goes against many proven laws and principles in true science. For the sake of true science I am against the clear fecel matter as this evolutionary theory most definitely is. It is nothing more than another religion of ignorance. 24.150.46.62 03:41, 15 September 2006 (UTC)

Response to a response to a response to "a little problem"[edit]

"I on the other hand do not have blind faith in the existence of gravity because it is observable fact. There is no need for faith at all because it is observable fact. And as for the theories of the causes of gravity, they have merit, because they do not conflict with the math and are founded on observable fact and the proven laws derived from this observable fact and are thus proven facts themselves. These theories of the causes of gravity thus require faith, however it is not blind-faith. Further, the theories of the causes of gravity went through the proper scientific procedures to become theories, and if one piece of evidence appears that goes against anyone of these theories, they are rendered false and abandoned. Then the evidence is taken into account and a new theory is formulated."
Could you please carefully define your phrase "observable fact"?
"This is not the case with the theory of evolution. It continue to exist even in the face of much proven evidence against it. These facts are simply ignored, the theory is not reformulated, it is not rendered false."
Such as? Please carefully cite your sources.
"Therefore, your crude understanding of real science as is revealed in your ignorance of what is fact and what is theory reveal only one conclusion, absolute blind-faith in the theory of evolution."
Again, would you care to define and carefully contrast "fact" with "theory"? I suspect that you are using the lay definition of theory to mean approximately "unfounded conjecture", which evolution is not.
"Your next statement, goes further reveal your ignorance of valid fact. simply because I stated fact and you ignored it completely. The fossil record is up-to-date and valid fact. You ignorance in this area is quite apparent. According to the fossil record organisms emerged suddenly in large numbers and variety. At many stages throughout the record this sudden emergence of even more complex organisms in large numbers and variety occurs. This record works against the theory of evolution."
How precisely does this work against the theory of evolution?
"There is a point were something goes so far against the odds it is considered impossible."
What is that point, precisely, since you are apparently so educated in higher mathematics, and while you're at it could you please quantify the odds of sexual reproduction evolving?
"Next, I'll be simple this time, "VITAL FEATURE." That's what vertebrates have to do with this discussion. Even with the ability to generate eggs and sperm, without, the vital features, no copulation, means no offspring. And because they are vertebrates, no asexual reproducing."
There are plenty of vertebrates that can reproduce asexually via parthenogenesis. That aside, there are also numerous species of vertebrates (c.f. most fish and amphibians) that can reproduce without physical copulation. I don't see how it's especially relevant to the discussion either way, however.
"Well onward, I suppose comparative reasoning will work here.... However, both, your so-called retorical question, and your point, have nothing to do with what this discussion is about. It was a detour of your imagination. I apologize again, for making one of the three correction as I read the statement, or question, or both, in order to understand what you were talking about."
I think your critique of his sentence structure is mistaken and also more than a little bit ironic in light of the errors peppered throughout your diatribes (here's a hint, "you are" != "your"). Your irrelevant sophistry is impressive, though, I must admit.
"In fact, Darwins theory has long been disgarded by evolutionary biologists because of that knowledge."
Like whom? Please identify these individuals. Note carefully however that Henry Morris, Duane Gish, Kent Hovind, and William Dembski are not evolutionary biologists.
"This allows them to present both their conjecture and the falsified evidence as facts to their theory of evolution. In doing this they ignore facts, and do not allow the evidence they present to speak on its own."
What falsified evidence? Are you accusing evolutionary biologists of falsifying evidence? All of it?
"This theory goes against many proven laws and principles in true science."
Such as? Name one or two and let's see if we can't sort your objections out.

Extra comments culled from earlier discussion:

"Curious question indeed, "If evolution were random, you would expect to see orders of magnitude more simple species than complex ones, right?" You mean to say, that evolution is controlled. Interesting by this question, you admit intelligent design beyond human comprehension and reason. So, if evolution is not random, ahhh, who's controlling it?"
You are either equivocating here or (more likely) just ignorant the difference between "random" i.e. non-teleological (the evolutionary sense) and "random" i.e. a process which has an output that is not a function of its inputs.
"The questions were, I'll quote: "How did the "first mother" of each species gain the capacity of reproducing with a fully developed "first father"? How could both genders have suddenly been able to halve the number of chromosomes in their reproductive cells in the exact manner needed to produce offspring with some characteristics of both parents? If these essential reproductive features developed gradually, how is it possible for the male and female of each species to have survived while such vital features were still only partially formed? Do the theoretical process of evolution explain these complexities? How is it that these random, accidental, purposeless events resulted in such complex and intricately inter-related systems?"
These questions are all grounded upon the fallacious assumption that sex arose as a fully functional, obligate mode of reproduction with dichotomous genders that reproduced via haploid gamete meiosis. Genetic recombination is certainly possible and certainly occurs in organisms without any of those traits. Mnc4t 07:24, 8 October 2006 (UTC)

The opening paragraphs[edit]

Just a few questions, The opening paragraph starts off, "The evolution of sex is a major puzzle facing evolutionary biology." Why is sexual reproduction a major puzzle to this field exactly? What exactly is the "puzzle?" The first statement just says it is a "puzzle." Then, forgets it happened. Why is evolution of sex a major "puzzle?" Please explain.

The second sentence points out that may organisms reproduce sexually. However, Why is this a puzzle? What is so puzzling about sexual reproduction? What exacty is puzzling about organisms reproducting sexually? Please explain.

This third sentence, "The evolution of sex contains two related, yet distinct, themes: its origin and its maintenance." It is misleading, it very carefully suggests that evolution is a "fact." It further relies on this suggestion to establish that really the themes of this particular part of the theory are the major puzzle. Please rephrase this sentence, as these themes are not the puzzle. Might I suggest this: "According to the theory of evolution, there two related, yet distinct, fields of theory to the emergence of sexual reproduction: its origin and its maintenance." It is just a suggestion, the sentence still needs rephrasing.

This Next one, "However, since the hypotheses for the origins of sex are difficult to test experimentally, most current work has been focused on the maintenance of sexual reproduction." Perhaps, if the reader where made aware why this "hypotheses" are so difficult to test experimentally. And perhaps, if the reader understood that the hypotheses were not formulated from observable facts (solid data), but from the theory of evolution itself, they might be able to comprehend why the most focus is on "the maintenance of sexual reproduction." Although, that would pose a great deal of difficulty for the theories, because people reading this article would conclude that these theories are merely conjecture, and the evidences the present are distorted facts. Well, again, here this article presents that the "puzzle" is the hypotheses and the difficulty of properly testing them. Then, it points out that most of these theories avoid the real "puzzle" by focusing on the maintenance of sexual reproduction. Why hid this fact? However, this article makes it sound valid because they are actually related themes. If the reader was aware of the actual "puzzle," they would see that these maintenance theories distort the facts as well. The maintenance of sexual reproduction is a good field of study apart from the theory of evolution. The problem with these maintenance theories is that they make the facts fit the theory. This is bad science. I suppose, beside the point. The article here is the objsct of critisism because it does not present these facts or even establish them. This article right from the beginning advocates these theories. This ofcourse is a highly bias position. Meaning, the writers are protecting and projecting there personal beliefs as general facts.

On to the next sentence, "Several explanations have been suggested by biologists including W. D. Hamilton, Alexey Kondrashov, and George C. Williams to explain how sexual reproduction is maintained in a vast array of different living organisms." There is really nothing wrong with this sentence, except it's postion in the first paragraph. The first paragraph shifts the focus away from the "puzzle" of the first sentence, then away from the origin theories, to the maintenance theories. Then states, this last sentnce. Just one question, How does the maintenance of sexual reproduction in a vast array of different living organisms explain or relate to the origin theories of sexual reproduction? How does it explain the "puzzle?" The article title is "Evolution of sex" however, very subtlety and rapidly the focus is shifted to these experts, and their explainations of the maintenance of sexual reproduction. Doing so by avoiding the "fact" that they are applying the theory of evolution, and assuming that their origin theories of sex are already "Fact." Ofcouse, if nobody knows, what harm is there? I'll answer that because they are doing that they are "making the facts fit there theory." And if everybody knows how unscientific this is, nobody will listen to them. So I ask: Does this article carry the facts or does it present conjecture as fact.

The entire second paragraph is praise to the theory of evolution. It sets the tone. It holds in this article that the theory of evolution is "fact." What an assumption to make. It makes a so-called summary of the theories that will soon follow, however, in a format of "a matter of FACT." So this one needs to be revised to reflect a neutral view, instead of on the "authority" of the "theory of evolution."

The last pharagraph of the three in the presentation area. By now, no one notices the extreme bias, and sudden focus shift. So the first sentence in this perspective is fine. However, it should be noted the article now clearly show no intention of talking about the "puzzle" first vaguely presented, or any of the undefiled facts about this subject. So because of this fact I'll leave the first one alone.

So now the second sentence I am going to consider. "It is important to realise that any number of these hypotheses may be true in any given species (they are not mutually exclusive), and that different hypotheses may apply in different species." Here the article says one of the so-called hypotheses is true but which one. It makes the assumption that one of them is fact, yet none yield proof. It clearly states here evolution is "fact" to which it is not. It is "THEORY." Not only that it also clearly states all the finding are inconclusive. Quite a condradiction. Evolution is fact but there is no proof, no conclusive evidence, no observable facts to support it. Do I need to even break this one down. Well, why not? "It is important to realise that any number of these hypotheses may be true in any given species (they are not mutually exclusive), and that different hypotheses may apply in different species." The bolded words not in the brackets claim no conclusive, if any evidence. The bolded words in the brackets claim one of them is true and fact. This is clear evidence of the writers unproven personal beliefs in evolution are again being projected as scientifically proven fact. Is this not critical bias?

Moving onto the last sentence. "However, a research framework has yet to be found that allows one to determine whether the reason for sex is universal for all sexual species, and, if not, which mechanism is acting in each species." The first part admits, the reseach framework is seriously flawed, inhibiting one ability to determine, if it is just one reason or many behind sexual reproduction. The reasons being stated in the second paragraph. Then goes on to state after finding these which reason or reasons we will know which evolutionary mechanisms are acting on what species. Okay, first evolution is not "fact." Second, nothing in this enire presentaion that have been examined is "fact." It avoids the real "puzzle", actually it completely bypasses the "puzzle" altogether. Therefore, After careful analyses of this article's presentation, the conclution is: This whole section is pure bias conjecture presenting pure conjecture based on a theory as "fact." 24.150.46.62 03:42, 15 September 2006 (UTC)

This article has failed the good article criteria in the first three pharagraphs, In respects to the following:

3. It is broad in its coverage. In this respect :

(a) it addresses all major aspects of the topic (this requirement is slightly weaker than the "comprehensiveness" required by WP:FAC, and allows shorter articles and broad overviews of large topics to be listed); (b) it stays focused on the main topic without going into unnecessary details (no non-notable trivia).

4. It follows the neutral point of view policy. In this respect:

(a) viewpoints are represented fairly and without bias; (b) all significant points of view are fairly presented, but not asserted, particularly where there are or have been conflicting views on the topic. 24.150.46.62 14:07, 16 September 2006 (UTC)

I totally agree, thanks. Could you write a more neutral text? I'm not a native English speaker so I dare not make that change. 80.101.41.186 (talk) 00:35, 15 December 2008 (UTC)

Tangled bank hypothesis[edit]

I closed an AfD on this article as a redirect to here, but if someone can add to the article it's ok to reverse the redirect and restore it. ~ trialsanderrors 05:33, 18 November 2006 (UTC)

Big Question (?): Hermaphrodites[edit]

There is a major question of why sexual organisms aren't all hermaphrodites, when the system of separate, unchangable males and females obviously cuts the number of potential mates for an individual in half. We should try to address this in this article. Unfortunately, I don't know of any research that has been done on this, other than in my own head, which is certainly not a valid source...


As said in this article, the effect of sexual reproduction is to create variation on which natural selection can act. Hermaphrodites mate with themselves, which greatly reduces the potential to create variation (as you are creating new genetic varation with very limited material, i.e yourself). This is not very advantageous and is very comparable to an asexual, clonal system; potentially with even more negative effects as you still require the mechanistic side of reproduction, but do not get the genetic variation advantages. seb951 --Seb951 21:37, 1 December 2006 (UTC)

But isn't it possible for two hermaphrodites to do it, where the top impregnates the bottom? Why did sex evolve with two different sexes, rather than just two participants? --Damian Yerrick (talk | stalk) 20:11, 14 July 2007 (UTC)

This question was answered 40 years ago by V. Geodakian in its "Evolutionary theory of sex". He also developed two other theories that explain the Evolutionary Role of Sex Chromosomes and Lateralization of the brain hands and body. The article and related materials were removed from Wikipedia, so now this article has more questions than answers and discusses theories that can not explain and predict much.Sashag (talk) 16:01, 28 April 2008 (UTC)

As I understand this page, it boils down into specialization for gathering resources vs. for converting food into babies. Has any other reliable source commented on this hypothesis? --Damian Yerrick (talk | stalk) 14:48, 30 September 2008 (UTC)

There are several Theories on this. Many of them focus on the fact that for it to be a valid strategy to be an hermaphrodite the "return on investment" of one sex must be diminishing. If for example the density of a population is low, it might not pay to invest more resources in the male side (mostly producing sperm) because there are no additional partners to inseminate. If the sex functions aren't diminishing it pays to invest in just one sex, because it's better to be a good male or a good female instead of being a crappy hermaphrodite. Think of deer for example: If you want to be a successful male you must be big and invest all your resources otherwise you won't have any luck with the ladies. Most of this is explained in:

Charnov, E.L. 1982. The theory of sex allocation. 

I'm currently doing research on this, so I could write a passage on this if others think this would be interesting. Reafdaw (talk) 14:16, 8 July 2014 (UTC)

Criticisms of Evolution of Sex from Creationist perspective Needed[edit]

I think it would be helpful if this article had some criticisms of the Origin of Gender and Sexual reproduction from a evolutionary perspective. I think if the article had the information from these articles incorporated it would make for a better article: The Origin of Gender and Sexual Reproduction by Bert Thompson, Ph.D. and Brad Harrub, Ph.D. and Argument: Evolution of sex by Jonathan Sarfati

Lex Rex 12-1-06 22:27, 1 December 2006 —Preceding unsigned comment added by 65.116.143.83 (talkcontribs)

I started reading through the first article, read through quite a bit of fluff, then got to its first claim: How is it that, at one point in time, “nature” was able to evolve a female member of a species that produces eggs and is internally equipped to nourish a growing embryo, while at the same time evolving a male member that produces motile sperm cells?
at one point in time is inaccurate. All the leading theories of evolution of sex have it occuring gradually (Bacterial non-reproductive "sex" (conjugation) is known to be caused by an infectious organism known as the F plasmid. One of the theories about eukaryotic (reproductive) sex is that it was also originally an infectious genetic element. Another theory is that primitive sex was a form of cannibalism - one organism ate another one and then incorporated its DNA. And there are more.) The produces eggs... sentence is also inaccurate. The first sexually reproducing species was almost certainly isogamous - meaning the two different sex cells were the same size, and not referred to as 'egg' or 'sperm'.
An apologetics article has limited credibility with me to begin with. When their very first "Look at how inaccurate evolution is!" claim has gaping holes in its facts - I lose my ability to suspend disbelief. I strongly oppose including such arguments in this article. These types of arguments - and their refutations - would be better placed in Creation-evolution controversy. Lyrl Talk Contribs 23:27, 1 December 2006 (UTC)
Agreed - someone who denies that evolution occured isn't the type of person who can add to a discussion about how a particular current function in nature happened to come about. John Broughton | Talk 18:54, 2 December 2006 (UTC)


So balance is out. Wikipedia is Talk Origins. Whats the point of a pedia?

Did you know Einstein recklessly courted falsification? Why not Evolution?

By the way, while I have you: The human female reproductive mechanism operates by scent. We know the mechanism emits a scent that only attracts the sperm cells that it was designed to attract. How could this mechanism evolve step-by-step? We also know that no human female has ever been successfully impregnated by a non-human. How did it happen in the Stone Age?

Lex Rex 12-2-06

There are other articles within wikipedia that discuss whether evolution as a theory is true or not. This isn't one of them. This article is to discuss one part of the evolutionary theory, a part that happened millions of years before human beings existed.
Also, in the future, it would be appreciated if you'd follow Wikipedia:Sign your posts on talk pages. Thanks. John Broughton | Talk 22:50, 2 December 2006 (UTC)

horizontal gene transfer[edit]

I know this would be a blatant case of original research, but I want to mention my theory. It is that sexual reproduction evolved from the horizontal gene transfer that we see in virii today and which appears to have been prevalent in the very earliest life. Does anybody know if something like this has been worked on before and have links to such a theory? At first horizontal gene transfer would have happened simply by accident due to genetic material being left about by accident and possibly crashing into other cells which are in the process of dividing perhaps. Such a process would eventually be deliberately used in preference to relying on one's own mutations, as your neighbour's DNA would likely be better (as the worst mutations won't get a chance to be transferred horizontally). There is nothing new so far; but, if neighbouring cells are going to accept your DNA, then perhaps it'd make more sense to eject genetic material into the environment as well as, and eventually instead of, making viable daughter cells. This would be like ejecting sperm into eggs. Aaron McDaid (talk - contribs) 19:15, 16 December 2006 (UTC)

Natural selection is not a cognitive process[edit]

This sentence, These mutations have to be purged from the genome by natural selection, in order for individuals to maintain a high overall fitness and stay competitive. implies that it is.

Those mutations do not have to be purged at all. If they are successful that strain will survive. If they are not then it will not. Natural selection is a process of things happening that are either successful (when they will continue) or unsuccessful (they die out).

If I had a decent expertise in this topic I would edit the article to reflect this, but I do not, so I have not. Fiddle Faddle 17:26, 11 January 2007 (UTC)

In the sentence you mention, these mutations, refer solely to deleterious mutations (read the previous phrase) which, as the name implies, have a negative fitness effect on the organism. The previous section dealt with mutations of positive effect. --Seb951 02:46, 13 January 2007 (UTC)seb951
The words I am objecting to are "have to be purged". But they do not have to be purged. The idea that something has to be done implies that a cognitive process is at work. Survival or lack of survival of a mutated strain is not a cognitive process, but is, instead, a matter of viability, and later of fertility. Thus "These mutations" are the strain which will either succeed because it is viable (and later fertile), or fail because it is not. So "have to be" is incorrect because nothing has to happen at all, and "purged" is incorrect because purging is wholly incorrect as a verb here. They are not purged, they vanish. "have to be" plus "purged" implies a process of eugenics performed by something in a conscious manner. Fiddle Faddle 09:50, 13 January 2007 (UTC)
The rest of the sentence also fails. It also looks like a part of a doctrine for eugenics. Individuals of any strain are either viable or not and competitive or not and fit or not. It is the overall strain that is successful or fails. Fiddle Faddle 09:54, 13 January 2007 (UTC)
I agree that the phrasing "have to be purged" might be inappropriate. I've changed it to address your concerns.
However, I feel you are getting into a semantic argumentation and I am not sure what you are trying to show. There is no denying that in a natural, competitive environment, less fit individuals will be selected against. This is the foundation of natural selection. Also, deleterious mutations (or less fit individuals) do not vanish, they are selected against, such that they can still be present in the population for many generations depending on the fitness effect of the mutation.
Remember also that selection acts on individuals and not strains, such that it is not a strain that is successful or not, but the individuals that compose it. --Seb951 22:44, 13 January 2007 (UTC)seb951
Not an argument :) A discussion which we seem to agree on, thus the article becomes stronger. Perhaps the word "vanish" was wrong. They simply do not prosper. Selected against? Not so sure. Lack of viability is not really selection against, it is simply lack of viability, and death. Natural selection is about success or lack thereof for the environment that obtains for the time that entity exists.
It is about semantics, yes. Such things are vital in an article such as this where precision is extremely important. Regrettably TV documentaries have oft implied that natural selection is a matter of choice by the language they have used. "The bee evolved longer appendages in order to harvest the nectar from the flower." But it did not. Bees with longer appendages were successful in harvesting the nectar and thus prospered. They passed their genetic material on and bees with longer appendages, because they were more successful, became plentiful compared with the others. Yet the quoted sentence implies that the bee chose.
Does that help you understand where I am coming from? Fiddle Faddle 23:10, 13 January 2007 (UTC)

I notice this is a good article[edit]

What might be useful is to have it peer reviewed in order to take it to the next level. I have run the semi-automatic tool over it in order to assist:

The following suggestions were generated by a semi-automatic javascript program, and might not be applicable for the article in question.

  • The lead of this article may be too long, or may contain too many paragraphs. Please follow guidelines at WP:LEAD; be aware that the lead should adequately summarize the article.[?]
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  • There may be an applicable infobox for this article. For example, see Template:Infobox Biography, Template:Infobox School, or Template:Infobox City.[?] (Note that there might not be an applicable infobox; remember that these suggestions are not generated manually)
  • Per Wikipedia:Manual of Style (headings), headings generally do not start with articles ('the', 'a(n)'). For example, if there was a section called ==The Biography==, it should be changed to ==Biography==.[?]
  • Please reorder/rename the last few sections to follow guidelines at Wikipedia:Guide to layout.[?]
  • There are a few occurrences of weasel words in this article- please observe WP:AWT. Certain phrases should specify exactly who supports, considers, believes, etc., such a view.
    • are considered
    • might be weasel words, and should be provided with proper citations (if they already do, or are not weasel terms, please strike this comment).[?]
  • Watch for redundancies that make the article too wordy instead of being crisp and concise. (You may wish to try Tony1's redundancy exercises.)
    • Vague terms of size often are unnecessary and redundant - “some”, “a variety/number/majority of”, “several”, “a few”, “many”, “any”, and “all”. For example, “All pigs are pink, so we thought of a number of ways to turn them green.”

Avoid misplaced formality: “in order to/for” (-> to/for), “thereupon”, “notwithstanding”, etc.

  • As done in WP:FOOTNOTE, footnotes usually are located right after a punctuation mark (as recommended by the CMS, but not mandatory), such that there is no space in between. For example, the sun is larger than the moon [2]. is usually written as the sun is larger than the moon.[2][?]
  • Please provide citations for all of the {{fact}}s.
  • Please ensure that the article has gone through a thorough copyediting so that it exemplifies some of Wikipedia's best work. See also User:Tony1/How to satisfy Criterion 1a.[?]

You may wish to browse through User:AndyZ/Suggestions for further ideas. Thanks, Fiddle Faddle 13:24, 13 January 2007 (UTC)

New theory of role of sex and selfish chromosomes[edit]

I have quite a few objections against the new theory paragraph you added. First, you need to mention a valid reference. There has been so much work on the evolution of sex that you must mention an important paper or book on the subject. I don’t know exactly what kind of publication Calodema is (peer reviewed?) but I don’t even see it in the web of science. There is loads of work on selfish chromosomes (such as B chromosomes), intragenomic conflict and the role of selfish genetic elements and their relation to sex. Also, sex usually favours selfish genetic elements. Look those papers up to have a more objective view of the theory. Second, explanation is not clear. Third, I don’t really see how this relates with Kondrashov’s theory. Fourth, I’ve glanced a the paper you mentioned, your calculations are very basic, and need a much more detailed explanation.--Seb951 21:43, 16 January 2007 (UTC)

03:45, 17 January 2007 (UTC)

Information on "Calodema" is available on the Internet. Since there is no consensus on these matters, I think it is valid to propose that sex might have evolved to deal with selfish chromosomes. The calculations in the paper are basic but it is a simple idea, and the calculations should be easy to check given the assumptions. (You can do it with a pen and paper by simple enumeration).

The theory relates to Kondrashov's theory because it considers a conceptually similar way of getting rid of deleterious genetic material.

The paper in Calodema cites three relevant works, including a major recent work on intragenomic conflict.

Remove the paragraph if you wish, but since there is no consensus on why sex evolved I think the suggestion deserves to be considered.

03:45, 17 January 2007 (UTC)

Selfish chromosomes are still a rarity (either in sex or asex species) and as so, it would be doubtful that sex evolved to get rid of the rare occurence of selfish chromosomes.
You are implying that selfish chromosomes are homologous to normal chromosomes and will recombine freely with them. This is not the case, as selfish chromosomes are not homologous to normal chromosomes. (You must define what you mean by a selfish chromosome).
I really don’t follow your calculations. I am not sure if you talk about segregation of homologous chromosomes into daughter cells or actual crosssing over between homologous and selfish chromosomes. If you are talking about the second option (which, as previously said is not the case), it would only be true that sex is advantageous provided a synergistic epistatic fitness effect caused by the selfish material.
In any case, I think your theory still needs work. Sorry, but if Wikipedia is too stay objective, we can't just write all possible views and theories. Otherwise, this article could easily be 500 pages long.

--Seb951 22:17, 18 January 2007 (UTC)

Paragraph in section 5.2 needs fixup[edit]

This paragraph in section 5.2 needs to be fixed up, because it doesn't make sense at the moment.

There has been much criticism of Kondrashov's theory. First, it requires a very high mutation rate – one mutation per generation, which there is some empirical evidence for it (for example in Drosophila[14] and E. coli[15]). Second, it also requires deleterious mutations to act in a synergistic way. While there is some evidence for this kind of mutation – fitness relation – there is also the same amount of evidence that mutations do not act synergistically. Instead, there may be no epistatis (one mutation does not influence another) or antagonistic interaction (each additional mutation has a disproportionally small effect).

The second sentence doesn't make sense. I'm not going to touch it because I don't know what it's trying to say, but someone more versed in the matter might be able to fix it up. Maelin (Talk | Contribs) 04:40, 5 February 2007 (UTC)

I've modified the paragraph a little. Might make more sense now. Although might still not be perfect. suggestions are welcomed if it is still unclear. --Seb951 21:05, 15 February 2007 (UTC)

Need editing assistance[edit]

at Evolutionary theory of sex--Filll 23:09, 26 July 2007 (UTC)

distinguishing sex as a special case of recombination[edit]

This is a worthy article. However, it confuses the evolution of sex and the evolution of recombination. I would be happy to help edit the article, but wanted to get some agreement on how to proceed. This article is mostly about the advantages of recombination and the disdvantages of sex, both of interest, but somewhat conflated. More careful parsing of the effects of recombination (two parents) and sex (males and females) is in order. Worth noting, a proper accounting of the dis/advantages makes explaining sex more difficult.

Shall I have a go at it or is more coordination required?

By all means have a go. As a note, this article needs more high-quality citations, so your help there would also be appreciated. This tool lets you paste in a PMID and gives you a formatted reference. You might find it useful. All the best Tim Vickers 23:17, 4 August 2007 (UTC)
Recombination does not imply two parents - frequently a hermaphrodite is capable of reproducing sexually with itself, bacteria conjugate (recombine their DNA) without reproducing.
Perhaps this article needs to be moved to Evolution of sexual reproduction, since it is about sexual reproduction, not about the definition presented at sex (although that alternative definition is included in the "sexual reproduction" definition). LyrlTalk C 13:52, 5 August 2007 (UTC)

Crucial importance of sexual selection dynamics forgotten here.[edit]

Here it is again. A discussion of “why sex?” that covers every base except what is probably the most important: sexual selection. Just about every lay introduction to natural selection will utilize as prime examples traits such as opposable thumbs and beak shapes. I would argue that sexual selection is of crucial importance to evolution and over the last 100 thousand years has been of far greater importance than traits developed through interaction with purely physical forces such as heat, cold, and resistance to bacteriological elements. In sexual selection, the woman will typically prefer men with a good balance of strength and gentleness, being cognisant that she expects him to help rear their children. As a result, women characteristically are attracted to strength, but not to sadism, to affluence, but not to meanness, to a sense of humour, because a man with a sense of humour will be more likely to be charmed by the activities of their children, and so on. In an oral society, a well-spoken man will receive preferential treatment when compared to one who is tongue-tied. A man who has “people-skills” and can handle and lead people will attain personal power that others will not. Traditionally, people who attain privileged positions have greater choices available to them, in terms of who they marry, in terms of provision for their children. In this way, such behavioural and personality traits can become fixed in a community through the simple functioning of selection pressure via sexual and cultural selection. Yet these mechanisms are given short shrift in the literature of evolution. Sexual attraction between the genders is the next best thing to direct phenome to genome transfer. In effect, a strong, intelligent man is given his procreational advantages on credit, as it were, just as a fertile, intelligent woman is given hers. I often wonder why these HUGE affects are forgotten by writers, in favour of such piddling ones as resistance to parasites. Is it because evolutionary pressure from within society sounds less “scientific”? Myles325a 05:49, 16 August 2007 (UTC)

This article is about the evolution of sexual reproduction. Multitudes of very simple organisms (e.g. ants, who do not express mate preference) or solitary organisms (e.g. lizards) reproduce sexually, and the fact that they continue to reproduce sexual rather than developing asexual reproductive mechanisms is what this article is focused on. Sexual selection is a completely separate article. LyrlTalk C 21:06, 16 August 2007 (UTC)

New Scientist article: Has the mystery of sex been explained at last?[edit]

Has the mystery of sex been explained at last? http://www.newscientist.com/article/mg20227121.600-has-the-mystery-of-sex-been-explained-at-last.html?full=true Stikko (talk) 12:30, 15 June 2009 (UTC)

Cost of sex[edit]

There are fallacies in the picture as well as in the description:

"If each individual were to contribute to the same number of offspring (two), (a) the sexual population remains the same size each generation, where the (b) asexual population doubles in size each generation."

Well, doh. If each individual were to contribute to double the number, the sexual population also doubles in size. They can do that because they are twice as many individuals, sharing the cost.

"This implies that an asexual population has an intrinsic capacity to grow more rapidly each generation."

No, it doesn't.

Note that I don't comment on whether or not the basic premise is true, just that the explanations are fallacious. --91.55.208.202 (talk) 00:09, 27 January 2010 (UTC)


This should probably be reworded to something along the lines of "each individual/pair contributing to the next generation". Within sexual reproduction you obviously need two individuals. If this pair then to produce two offspring then they each produce a single "replacement", as it were. Within asexual reproduction, the individual merely divides creating two "offspring", in essence creating one "replacement" and a second offspring which adds to the next generation. So we have sexual reproduction as 1+1(2)>2, number of offspring=number of breeding individuals vs. assexual reproduction as 1>1+1(2), number of offspring=2*(number of breeding individuals). The initial statement could easily be misread and does need to be made clearer. - Wikim3 04:11, 24 February 2010 (UTC) —Preceding unsigned comment added by 89.241.186.67 (talk)

Well, what also struck me was the fact that hermaphrodites are mentioned briefly but then not talked about at all. The cost is not so much about sexual reproduction but about half of the individuals not being able to put energy into eggs/pregnancy and for some species not even into raising the young. Hermaphrodites do not exhibit this disadvantage and it is therefore not so much a puzzle to me why sexual reproduction developed but why it didn't generally develop into a hermaphroditic form. The actual number of offspring could then still be reduced for species that need more effort to be put into each of their young. --78.94.216.65 (talk) 07:34, 4 October 2010 (UTC)

Number of produced offspring is irrelevant[edit]

Fallacies I see in "Cost of sex": The long term replacement rate for every species on Earth is one. Because if not, you would get exponential growth and earth couldn’t support this. Beside this the number of offspring, who reach the phase of adulthood, is more dependent on the resources and perils of the environment. And not on the number of offspring produced by the parents.

The only disadvantage I see for sexual reproduction is, that a pair of individuals has to meet each other to reproduce. —Preceding unsigned comment added by 77.185.82.62 (talk) 20:21, 18 March 2010 (UTC)

Two-fold cost of sex vs. cost of males[edit]

This section does have several weaknesses, already noted. I think one basic issue is that the term "two-fold cost of sex" is misleading, albeit popular in the literature. I prefer the original term, which is the cost of males - it more precisely identifies the problem as the presence of a significant proportion of the adult population that is required for reproduction to occur, but does not itself reproduce; although Maynard Smith did show that this advantage is two-fold under the assumptions of his example, it can safely be assumed that this cost will vary depending upon a number of factors, such as mating system specifics, presence of hermaphroditism, prevalence of sex in the life cycle (i.e. if it is not obligate), etc.

And on that note, the combination of the reference to Maynard Smith being the first to mathematically describe the cost of males is juxtaposed with a nonsense graphic that, first of all, bears no resemblance at all to the schematic that accompanied his mathematical description, and second of all, erroneously gives the impression that a sexual population does not increase in size at all! "Two-fold" implies that the rate of increase is twice as great for the asexuals; the figure does not illustrate this. Maynard Smith's own diagram can be found in his book, which is in any decent science library.

Sexual selection is completely out of place in this section; the costs of sexual selection are completely irrelevant to the specifics of the two-fold cost of sex/cost of males. Sexual selection is worthy of attention, but it is a separate matter. Changing the section title to "Disadvantages/Costs of Sex" would make the inclusion more appropriate, along with the other disadvantages.

The paragraph claiming that evidence that the cost of sex can be overcome comes from George C. Williams makes no sense; the evidence that the sex can be overcome is that sex is utterly dominant as a reproductive mechanism in multicellular eukaryotes. One of Maynard Smith's major points in describing the cost of males was in contrasting the ubiquity and obvious success of sex, which evolutionary biologists had heretofore taken largely for granted, with the fact that it simply does not work according to standard population genetics. The paragraph describes a specific hypothetical advantage to sexual reproduction, which is often referred to as the "lottery ticket argument," since that was the analogy Williams used to make the point.

I apologize, because these points will seem "old-fogeyish," though I wish to return to make these edits, if someone does not beat me to it.

-colbyg 98.87.122.104 (talk) 04:02, 22 August 2011 (UTC)

why/how[edit]

This article needs restructuring. I came here looking for how sex evolved, but that part is hidden away at the end in sections 7-8. It's also very short. Most of the article talks about possible explanations why sex evolved (or what for) and historical perspectives on that. The introduction doesn't talk about the how at all. IMO an article entitled "Evolution of sexual reproduction" should first describe what we know about how it happened, and then go on to speculate about why sex is an evolutionary gain.--87.162.34.180 (talk) 17:20, 8 March 2010 (UTC)

The disadvantage of haploid versus diploid gametes[edit]

Good article. One of the main costs of sexual reproduction according to Matt Ridley in his book "The Red Queen", is that of sacrificing the passage of half of your genes into the next generation. I was expecting to find this fact noted in this piece but as I couldn't find it I added it. —Preceding unsigned comment added by RichardAndrewNevin (talkcontribs) 13:06, 13 March 2010 (UTC)

Fig 3 legend (epistasis) is wrong[edit]

I believe the legend to Fig 3 is seriously wrong: the red convex line is the synergistic epistasis case (required for Kondrashov's theory), since here 2 mutations have bigger effects than the sum of the effects of each individually. The concave blue line shows antagonistic epistasis. See Ridley's "Mendel's Demon" book.Paulhummerman (talk) 14:26, 18 October 2011 (UTC)

Yes, I have another Ridley book, Evolution, 3rd edition; it agrees (well, it would)... I take it he knows what he's talking about. Evercat (talk) 19:59, 29 November 2011 (UTC)

Also Charlesworth and Charlesworth, Elements of Evolutionary Genetics. I think it should really be log(fitness) on the y axis. Evercat (talk) 20:10, 29 November 2011 (UTC)

In fact yes, I very strongly believe it needs to be log(fitness) on the y axis... Evercat (talk) 22:58, 30 November 2011 (UTC)

The Introduction is mostly irrelevant to the subject[edit]

This article's subject is the evolution of sexual reproduction. 1. The introduction claims (correctly) that there is no consensus and then proceeds to ignore the evolution to speak about the maintenance of sexual reproduction. I should NOT have to delve into the rest of the article to learn about the theories/hypotheses, should I ?? 2. The introduction claims that all eukaryotes which reproduce sexually have a common ancestor. How is that reconciled with the species that reproduce both asexually and sexually? Are we sure that sex only evolved once? Given that most of the intro makes a strong case for its reproductive value, then either it must be linked to the cell wall (definition of Eukaryotes) or did not just evolve once. Have all asexually reproducing eukaryotes been shown to have sexual ancestors? {I am not well informed on this issue, please take my comments to indicate areas where the introduction fails to inform the average reader}. Is this well established (fact) or a working hypothesis/ assumption? What about the sexual prokaryotes? 3. The introduction should define what sexual reproduction is, to start out. It doesn't even mention the fact that it is between two (or more) individuals, that the sex of an individual may vary over its lifetime, and that its sex may be environmentally determined. It also doesn't mention the fact that the number of sexes ranges between 2 and ?? (I'm not sure, at least 3) 4. DNA is barely mentioned, and only in the context of repair. 5. If you threw out the "maintenance of sexual reproduction" part of the introduction, there would be almost nothing left. In my opinion, most people will come here NOT to learn about how sexual reproduction is evolving or contributing to the evolution of a species, but to learn about how it developed to begin with. Logically, origin should precede maintenance/continuing development processes. 6. I recommend a rewrite, focusing on the basics: What, who, when, why, and how. Overview (What is sex, who has it (which Domains & Kingdoms?) History when did it evolve? (NOT to be confused with the history of the study of it) Why and how did it evolve? If you really can't speak clearly to its causal origin, then you should speak in terms of it surviving originally because of utility. — Preceding unsigned comment added by 173.189.75.207 (talk) 21:40, 8 May 2013 (UTC)

May be of interest[edit]

"Copulation in antiarch placoderms and the origin of gnathostome internal fertilization" [2]. With a related simplified article [3]. 76.10.128.192 (talk) 23:29, 20 October 2014 (UTC)