If evolution gives us the best adapted organisms for survival of the fittest, why does so many of Earth's organisms require two sexes for reproduction? Shouldn't this have been bred out of our populations millennia ago?

  • $\begingroup$ BTW - I (naively) suggest the tags evolution, gender & sex, but don't have the rep. to suggest tag edits. $\endgroup$ Sep 29 '15 at 17:21
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    $\begingroup$ Welcome to Biology.SE. I agree the question is a duplicate and I closed to vote. Note also that your first sentence If evolution gives us the best adapted organisms for survival of the fittest is both wrong and misleading. You might want to have a look at an introductory class to evolutionry biology such as Understanding Evolution. $\endgroup$
    – Remi.b
    Sep 29 '15 at 17:46
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    $\begingroup$ I don't think this is a duplicate. As I understand it, this Q is asking about why we have sexes and why all organisms dont reproduce asexually (so the costs and benefits of sex), while the other Q is asking why we only have two sexes and not more. This Q has a very weak background though. $\endgroup$ Sep 29 '15 at 21:12
  • $\begingroup$ If it is not a duplicate then it is unclear for 3 reasons: 1) because we don't if it ha to do with sexual reproduction or the number of genders. 2) because it is unclear why it is especially talking about the earth. 3) Because it is unclear why the OP would expect the two sexes to be bred out of our populations millennia ago. It is also primarily-opinion based because the first sentence is wrong. Finally, the answer (to whatever question the OP is asking) may well ask for writing A LOT given the current OP's knowledge (that we can guess from the post) in evolutionary biology. $\endgroup$
    – Remi.b
    Sep 29 '15 at 21:25
  • $\begingroup$ I agree with @fileunderwater, it's an entirely different question. And even when we have lots of similar questions, they usually put together so many different interesting answers (because of the scoring logic), that some SHORT AND GOOD answers end up arising. And since SHORT AND GOOD answers are quite rare, I think we should go in the direction of having more repeated questions, instead of less. $\endgroup$
    – Rodrigo
    Sep 29 '15 at 22:42

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