Why Was Sexual Reproduction Selected?

[Rduke55]

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Rduke55,

I am going to defer any evolution questions to you because

1. you really seem to know your stuff
2. you display more patience than I ever would when it comes to explain the obvious.


Have a great festive season dude! [img]/images/graemlins/smile.gif[/img]

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Thanks!
Any patience I have is because I remember people being patient with me when I first started learning this.
You have a great one as well.

[Borodog]

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I can't follow too closely this sub-thread, but, if this is seriously about reproduction of life and "two-sex prevalence", please consider this:

Our world on Earth has been from the beginning, still overwhelmingly is, and probably will continue to be until the sun goes out, a world of bacteria.

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In one sense. And in another sense, the world is a world of vegetation. In other senses, it's other worlds. And none of these is inherently a "better" view than the other.

So while most of the biomass might be locked up in bacteria, like most of the mass of the universe is locked up in dark matter, that doesn't mean the rest isn't "important" or at the very least, begging for explanation, which is what your original post in this thread implied.

[_Z_]

Dawkins mentions in The Selfish Gene one theory on how gender evolved. Once you have a setup where two partners reproduce by combining their DNA (how this arises, I don't know) by each supplying some material - half an egg, so to speak, it becomes beneficial to "cheat" a bit, supplying a little less than half an egg, so you don't have to waste as many resources creating your "half".

But if a large percentage of the population is cheating so much that they can't reproduce with each other, it'd be benefical to be one of the non-cheaters, since you would be one of the few who can reproduce with anybody. It's concievable that this mechanism could run-away and make some of the population sperm producers and some egg producers.

Incidently, many differences between males and females stem from the fact that females produce more of the reproductive material than males do. It would be bizarre, for instance, if the gender who produces less of the material was the one who tended to be in charge of a child before hatching/birth.

Z

[Rduke55]

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females produce more of the reproductive material than males do

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Great point. Things like parental investment is huge in determining a ton of stuff, including the operational sex ratio that underlies so much of sexual selection.

Not only differences in the gametes (which is smaller in most mammals compared to other critters) but mammalian females also get stuck gestating the offspring. Then you got lactation, etc.

[Borodog]

Not that that isn't all interesting stuff, but it all comes about after sex has already been established.

[Rduke55]

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Start with the premise that humans are a small part of mammals who are a small part of vertebrates who are a tiny, tiny part of the fauna extant on earth -- and that the "paradigm" of "two-sex, sperm/egg congress" is not really that frequent.

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Um, in fauna it is.

[/ QUOTE ]Um, I ommited several steps to make my point. Tried to save space.

Cellular organisms; Eukaryota; Fungi/Metazoa group; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; Sarcopterygii; Tetrapoda; Amniota; Mammalia; Theria; Eutheria; Euarchontoglires; Primates; Haplorrhini; Simiiformes; Catarrhini; Hominoidea; Hominidae; Homo Sapiens; Sklanskyata.

Mickey Brausch

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Huh?

[Mickey Brausch]

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While most of the biomass might be locked up in bacteria, like most of the mass of the universe is locked up in dark matter, that doesn't mean the rest isn't "important" or at the very least, begging for explanation, which is what your original post in this thread implied.

[/ QUOTE ](Oh brother.) I did not imply that "our" part of the story is not important or that sexual/two-sex reproduction isn't interesting.

It has been advocated here that "our" model is the most successful in nature -- but the numbers are not with us. It's asserted that Man is but a wiglet of a very large bush, and that the overwhelming majority of the bush couldn't care less about penises and vaginas.

Coupled with the assertion that evolution does not necesarily mean "progress" (i.e. a march towards more complexity of "perfection"), except topically, if at all, and we have something like a whim of history, as far as the sexual model of animals is concerned.

Mickey Brausch

[Borodog]

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While most of the biomass might be locked up in bacteria, like most of the mass of the universe is locked up in dark matter, that doesn't mean the rest isn't "important" or at the very least, begging for explanation, which is what your original post in this thread implied.

[/ QUOTE ](Oh brother.) I did not imply that "our" part of the story is not important or that sexual/two-sex reproduction isn't interesting.

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Uh, yes, you did:

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Here's something I don't understand about natural selection: why was the two-sex, sperm/egg congress paradigm selected? Many species have the ability to reproduce asexually, and I would think that that's more advantageous to survival as it's simpler. Can anyone shed some light on this?

[/ QUOTE ]Dear hmkpoker,

Start with the premise that humans are a small part of mammals who are a small part of vertebrates who are a tiny, tiny part of the fauna extant on earth -- and that the "paradigm" of "two-sex, sperm/egg congress" is not really that frequent.

Homo Sapiens is at the extreme right tail of the distribution of Life, as prominent an example of cosmic variance as any. Human "paradigms" are not typical of the ways of Life on Earth at all.

Regards,

Mickey Brausch

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It has been advocated here that "our" model is the most successful in nature -- but the numbers are not with us. It's asserted that Man is but a wiglet of a very large bush, and that the overwhelming majority of the bush couldn't care less about penises and vaginas.

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You're doing it again.

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Coupled with the assertion that evolution does not necesarily mean "progress" (i.e. a march towards more complexity of "perfection"), except topically, if at all, and we have something like a whim of history, as far as the sexual model of animals is concerned.

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a) I have no idea what sex has to do with the "progress" argument, and
b) It has been pointed out repeatedly that the sheer numbers of asexually reproducers do not make sexual reproduction a thing to be airily dismissed, so why do you keep trying to do it? In other words, why do you keep trying to kill my man's thread? [img]/images/graemlins/confused.gif[/img]

[Mickey Brausch]

I don't understand what you're accusing me of. I plead innocent and carry on.

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I have no idea what sex has to do with the "progress" argument.

[/ QUOTE ]The (more complex) model of sexual reproduction is "used" by the more complex organisms on Earth. However, Homo Sapiens --and his relatives-- did not appear as the result of some inexorable march towards more complexity, but, rather, through sheer happenstance. I claim that progress is not inherent in Nature (which is disturbing news not just for creationists!), so, sex was "selected" ---to use your man's lingo-- in the limited area of animal life as part of topical evolution, while asexual reproduction is here, it is prevalent and will almost certainly outlast the alternative model (ours).

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It has been pointed out repeatedly that the sheer numbers of asexually reproducers do not make sexual reproduction a thing to be airily dismissed, so why do you keep trying to do it?

[/ QUOTE ]I'm trying to do something very simple yet it seemingly goes over many heads: Our model of reproduction (the "sexual" model) is exceptionally important for our species' survival. For one thing, it keeps our gene pool changing quickly enough to confuse the parasitical micro-organisms that are out to get us.

But, our model has been "selected" for a small minority that's been onstage for a few "minutes" in the "year" of Earth's lifespan. We should admire a model that's topically very appropriate and successful, but we should also understand that it's inapplicable and not "selected" by the vast majority of organisms, ever since Life began.

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Why do you keep trying to kill my man's thread?

[/ QUOTE ] Hmkpoker asks "why was the two-sex, sperm/egg congress paradigm selected". The answer is that this paradigm was "selected" topically because it was best for the area it covers. Evolution is real; natural selection is real; and progress exists --albeit in spots and spurts. Sheer randomness rules.

Hmkpoker also says "Many species have the ability to reproduce asexually, and [one] would think that that's more advantageous to survival as it's simpler." The response is, Yes, it is more advantageous, which is why it is used by the vast majority of Life and for a much longer time than the alternative.

Mickey Brausch

[hmkpoker]

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Hmkpoker asks "why was the two-sex, sperm/egg congress paradigm selected". The answer is that this paradigm was "selected" topically because it was best for the area it covers. Evolution is real; natural selection is real; and progress exists --albeit in spots and spurts. Sheer randomness rules.

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This is simply incorrect. While individual mutations are random, natural selection is not. It's like looking at the individual hands of a poker game and concluding that one's BB/100 over three years is random.

Any phenotypic change that significantly changes reproductive success will have a strong tendency toward natural selection. There's nothing random about that. I have a very, very hard time believing that sexual reproduction didn't have a MASSIVE influence on reproductive success. The sex drive is about as important as eating and survival, and it's so radically different than asexual reproduction that I can't imagine it not having a significant impact. The overwhelming majority of the animal kingdom has genders, so there is almost certainly something advantageous to it (otherwise it would never have been selected). I just didn't understand what that something was.