Problems with both Creationism and Evolution

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Microscopic organisms do not reproduce like humans or most other plants and animals. How do you explain the differences in the two means of reproduction?

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There are microscopic organisms that have sexual reproduction, just alike larger organisms (for instance Chlamydomonas ).
What is exactly your question, Why and how sexual reproduction started?, Why asexual reproduction is still functioning?

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[This message has been edited by Andor, 06-24-2002]

-The obvious advantage of sexual reproduction is a much faster production of genetic variation. It's then a great improvement when the species confront a rapidly variable environment.
On the other hand when the environment is stable, without changes, asexual reproduction may be advantageous.
There are species (mainly plants), that alternate between both ways of reproduction according to the environment.-A theory relates sexual reproduction with a better defense against parasites.

I don't know if this topic has been previously discussed in other threads. ?Probably the origin of recombination was not related with reproduction but as a DNA (or RNA) repair process. This model was proposed by Bernstein and col. (though I'm following Maynard Smith here): In the early Earth, with an atmosphere devoid of oxygen and ozone, haploid organisms would be very vulnerable to damage by UV radiation. It should be a great advantage to have copies of the genes in the cell. The high cost of this would be resolved by a periodically fusion with another cell, originating a dipoloid transitory, which would allow mutual repair.
With the progressive growth of genetic material, also increased the probability of lethal mutations, and the advantages of a duplicated genome, caused that, in time, the diploid state became the dominant one.
This process wasn't instantaneous. Have in mind that recombination probably evolved about 3 billion years ago as a mechanism of DNA repair, while sex evolved about 1-2 billion years ago in the early eukaryotes.

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[This message has been edited by Andor, 06-27-2002]