This conversation is closed.

Why, or more importantly, how, did sexual reproduction of life forms evolve?

It seems that this reproductive mechanism would be rather cubersome: two essentially different organisms of the same species come together to exchange genetic material and hope to see offsring into the next generation... single cell organisms seem to be a whole lot more efficient at reproduction by just cloning ... so how and why did nature "decide" to also include sexual reproduction mechanisms in the "fight for survival?" Dawkins ascribes this whole reproductive thing as DNAs way of maikng more DNA. ... So to be ultra-reductionist we are mere DNA making machines??...

Closing Statement from Lincoln Solomon

Closed out. And no conclusion. Some evolutionists postulate random selection of mutant genes and transfer of such between single celled organisms as the architypes of sexual reproduction as we observe it today. Creationists / ID folks believe in the design of a Creator. I have not been convinced, from this conversation, about the evolutionary mechanisms which gave rise to sexes and sexual reproduction methods.
Thanks for the input every-one. I Think I'll ask Google ...

  • Feb 18 2013: If i may sum up so far:

    Essentially there are theories (let's assume evolutionary) about two aspects of sexual; reproduction: One to do with why it should be advantageous (introducing recombination, which is assumed to be a good thing ...), the other as to its origin, which is murkier water altogether. KPs timeline " gene transfer -> multicellular reproduction with gene transfer -> separate sexes" looks logical, but those arrows '->" need some mechanistic explaination. This is what I want to know about, from an evolutionary point of view. Talk to me.
  • Feb 17 2013: May I add my three cents? Basically evolution is a process, not a start from nothing.

    We are here for a reason and a purpose and evolution does not change that.

    The reason or cause of why there is male and female

    Then there is the relationship between sex and marriage. This was written in 1951 but not much has changed since then, in what makes a female, female and a male, male. And I'm not just talking plumbing :)
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    Feb 15 2013: To Edward Long.
    Sir, all I am saying is that evolution works in such a huge span of time and since it s ongoing we can not conclusively say the last word about it.
  • Feb 15 2013: @ KP

    So you are saying sexual reproductive mechanisms predated multicellular organisms? SO unicellulars were doing it before the multies came along? Or did the multies derive from sexual reproduction?
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      Feb 15 2013: not precisely. "horizontal" gene transfer predates. sexual reproduction is a variant of that.

      gene transfer -> multicellular reproduction with gene transfer -> separate sexes
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    Feb 14 2013: Why questions can have infinite regression.
    I think there are three hypotheses on the origin of sexual reproduction.
    1. Sexual reproduction aids in spreading of advantageous traits and speed up evolution.
    2. Sexual reproduction aids in removal of deleterious genes and speed up evolution.
    3. Sexual reproduction aid is improving upon new gene combinations for more fit organisms and speed up evolution.
    At the heart of all three is the mechanism of DNA repair and the reasons 1 to 3 are not mutually exclusive.
    Obviously the three mechanisms as stated above are among many ways of transferring genetic material and information but the three turned out to be very effective for multicelluar organisms through vast number of blind trial and error in nature.
    • Feb 15 2013: OK so we have some reasons why sexual reproduction is advantageous from an evolutionary viewpoint: viz. getting DNA into the next generation of organisms, but HOW did nature "decide" on this method of reproduction. What were the (postulated) mechanics? Which organisms stumbled onto this in the first place, and what were the possible push factors for this to happen?
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        Feb 15 2013: Nature never decided anything. What we see is what came to be out of trial and error. Evolution works over a huge span of time and through huge number of reiterations with slight modifications. It's like the game of Life.
        There are number of push factors like speeding up of evolution and survival. Sex produces genetic variations, which is good for increasing chances of survival under different conditions by trial and error. Rolf Hoekstra's book The Evolution of Sex and its Consequences is a good read if you want to know in detail.
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          Feb 15 2013: RE: "I agree in principle. . . "
          So you are saying that the less-efficient reproductive process has been naturally selected over eons of time from beneficial mutations of a common ancestor because it increases chances of survival? Less efficiency= Greater survivability? Sounds wrong.
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    Feb 14 2013: Matthew 19:4 (NIV)
    “Haven’t you read,” he replied, “that at the beginning the Creator ‘made them male and female,’

    Genesis 3:16 (NIV)
    To the woman he said, “I will make your pains in childbearing very severe; with painful labor you will give birth to children....”

    • Feb 15 2013: Peter

      I am well versed with this viewpoint. I need an evolutionary answer ...
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        Feb 15 2013: Two computers were discussing their origins. They were unaware of anything outside themselves, so the answer to their origin was to remain a mystery. They contented themselves with making up just-so stories.

        What is 2+2 if the answer 4 is not allowed ?

        If evolution never occurred then the best you can expect is a just-so story.
        If evolution did occur the best you can expect is a guess.

        Sorry !

  • Feb 14 2013: @ KP:

    So HOW did mutlicellular organisms "decide" on sexual reproduction. This means that some organs had to develop the ability to produce half the genome needed to match half the genome of the female of the species (where did she come from?) and to develop a transfer mechanism (sometimes even using third parties like bees and butterflies) so that the gene transfer and matching is just right to combine and form a new organism of the same species ...

    Unicellular organisms do transfer genes, but it seems that E.coli now is still E.coli from 50 yrs ago, despite having acquired many genes that code for antibiotic resistance ...
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      Feb 14 2013: they did not. by the time multicell organisms came along, reproduction was already not as simple as you described. there never was a multicell organism that reproduced simply by cloning
      • Feb 15 2013: So if multicellular organisms did not decide on sexual reproduction, what did it for them? What laid down the rule that "if thou art an organism composed of two or more cells thou shalt not clone, but look for one such as yourself, but of opposite gender, and with him / her divide your genome in exactly half and combine it with his / her half and from that combination give rise to another like you ... "
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          Feb 15 2013: i said: they did not have to decide, because when they arrived, it was already invented. the task multicellulars faced was not this. they had to figure out how to reproduce at all! they could not just divide. if you divide a cow, you get a half cow and not a small cow. they had to come up with a way to regrow the entire thing from a dedicated reproducer cell, while maintaining the gene transfer mechanism of single cell ancestors. maybe the first multicell organisms didn't have dedicated sexes. they just manufactured cells with the ability of growing another organism. and occasionally, upon meeting with another organism, they exchanged genes between their repro cells. even today, many species do not need another organism to reproduce, but they do use if they can. why sexes then? it is beneficial, because you have to carry one set of "hardware" only.
  • Feb 14 2013: Hello Lincoln,
    I prefer to respond to you privately and would if you set up an email address in your TED profile.
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    Feb 14 2013: most likely from gene transfer. many single cell life forms do regular gene transfer. btw it is beneficial, contrary to what you said. sexual reproduction introduces combination, a very powerful tool for evolution. without combination, independent ideas have to compete. suppose you have a two bacteria clones. one undergoes a mutation that allows it to survive in some harsh environment, the other undergoes a mutation that allows it to eat something it could not eat before. as they multiply, you will have two different strains, both with one distinct advantage. one of these traits is more beneficial than the other, so those with it will outnumber the other variant with time. with gene transfer, it is possible that a bacteria acquires both mutations.

    multicell organisms need some more roundabout method to combine gene pools. that method turned out to be sexual reproduction.
  • Feb 14 2013: @ TED Lover

    You said:""Would you please furnish a reputable link? I've never heard of such a thing."
    What have you not heard of? The Evolution of sexual reproduction? Richard Dawkin's tome of Sociobiology called The Selfish Gene? What should I reference for you?
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    Gail .

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    Feb 14 2013: Would you please furnish a reputable link? I've never heard of such a thing.
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    Feb 14 2013: They didn't evolve. God created them that way.
    • Feb 14 2013: Hi Ed
      I know you are a creationist. I understand your views. I would like some-one with an evolutionary knowlege to respond, for this question bothers me ...
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        Feb 14 2013: As it should. In Biology asexual reproduction is almost twice as effective as sexual. Evolution offers no explanation as to how a profoundly less efficient system could gain sufficient advantage over a superior competitive system and be selected for survival. Nor is there an explanation for how physics and chemistry, both non-intelligent processes, plan for future coordination of complementary male/female organs.
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          Feb 15 2013: I agree in principle. The primary cost of sex is that a male has to find out a female (or vice verse) to reproduce. This is called anisogamism. I find the sexual reproduction a much less efficient process to pass on genetic code in it's entirety because sexual reproduction produces only haploids that is each organism can at best transfer 50% of its genetic code.
          But seen from variation point of view it has the advantages of producing recombinational variety in the new organism for adapting to environment in a slightly different way. This increases the chances of survival.
          Actually sex and reproduction are two separate events. Moreover we are never sure about how sexual reproduction will work out evolutionarily. The multicellular as well as more complex/higher life forms are by no means any favored ones when it comes to pure survival and I personally believe many simpler organisms, even plants, were there on earth before us and will be there when we are extinct.