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Meiosis is a type of cell division that reduces the chromosome number from 2n to n to make gametes viable for reproduction in humans. I know that during meiosis, there is independent assortment and crossing over that occurs, which help to make more genetically individual organisms.

My question is, why don't haploid gametes go through mitosis to reproduce instead of diploid germ cells going through meiosis to create more gametes, without considering crossing over and independent assortment? This is just my opinion, but meiosis seems like a much more energy intensive process. After the germ cells go through meiosis once to create the gametes, I do not see why the gametes don't then just multiply via mitosis (again, not considering crossing over/independent assortment.)

Is there any specific reason, other than to create more genetically diverse people, that gametes do not undergo mitosis to multiply rather than germ cells undergoing meiosis to make more gametes?

Sorry if my question is confusing, I'm just curious to what the reason is. It's probably something obvious I'm not seeing myself. :)

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    $\begingroup$ I think this is a great question, but it is based on two questionable assumptions: (1) that meiosis is more energy-intensive than mitosis; and (2) that energy efficiency is a key driver in evolution. $\endgroup$
    – Alan Boyd
    Commented Feb 21, 2014 at 19:27

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Couldn't fit in a comment...

To me, your question sounds like "what are the possible advantages of sexual reproduction over asexual reproduction?" but in the meantime you're saying that you're not interested neither in the advantage of recombination nor in the advantage of "independent assortment". I don't quite see what you mean by "independent assortment" in this context.

I just want to say some words about some "proximate" possible explanations of the evolution of sex. It's been suggested that meiosis have evolved in order to repair damage in double stranded DNA. Also, it's been suggested that meiosis is important for the problems of telomere length also.

You might be interested to have a look to the evolution of bi-phasic life cycles and, more globally speaking to the evolution of sex.

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  • $\begingroup$ I'm not interested in the advantage of recombination because I want to know if there's anything beyond that that makes meiosis more advantageous than mitosis. Also, I was always taught that "independent assortment" referred to how chromosomes line up independently of one another in Metaphase 1 before they split into separate cells. Is that term incorrect? Is it just a term used to help students learn the process? I guess I never really questioned the terminology before.. $\endgroup$
    – Nicole Rae
    Commented Feb 21, 2014 at 17:46
  • $\begingroup$ So, you're interested in what I called "proximate" explanations? Or we could call them physiological explanations. If yes, I'll let someone further develop these kind of explanations. $\endgroup$
    – Remi.b
    Commented Feb 21, 2014 at 17:48
  • $\begingroup$ Yes! Please. Sorry for not being clear initially. $\endgroup$
    – Nicole Rae
    Commented Feb 21, 2014 at 17:49
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I would suggest that the key here really is the variation produced from meiosis. Every gamete produced from meiosis is genetically unique. This gave rise to variation, which is the raw material for evolution. Meiosis would give a selective advantage in this way, therefore it could have allowed organisms to survive and pass on their genes.

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