quote:
Originally posted by sonnikke:
First, please answer my original question and explain in detail how evolution could have produced male and female.
Regards,
S
In bacteria, sex (sharing of DNA) and reproduction are not linked. In eukaryotes, they are, nuclear DNA being spliced and recombined at the same time as it is passed on to the next generation. Prokaryotes have no gender. Many eukaryotes do.
All eukaryotic cells have DNA in their mitochondria as well as their nucleus. Mitochondria bud like bacteria in a cycle not necessarily in step with the cell’s own life cycle. Any mitochondria DNA in a gamete should have a 100% chance of continued propagation.
In a few species, such as sea lettuce, both sperm and eggs have mitochondria. After they fuse, there is a fight to the death, always won decisively by the mitochondria of one parent. All of the rest of the cellular machinery remains duplicated, including nuclei. This fight is very energetically expensive for the cell, but the mitochondria - genetically unrelated to the nuclear DNA - are playing their own game, competing for a fixed resource, the stakes being life or death.
Almost all the mitochondria in the sperm of all other species are ejected deliberately before fertilisation. Those that make it into the zygote are promptly destroyed.
[just so story] Some early eukaryotes mutated to destroy non-self mitochondria effectively. This gene spread as long as it was rare. It did not enjoy meeting copies of itself.
Other early eukaryotes mutated to eject their mitochondria. This gene avoided conflict and waste in fusions with ordinary cells, and so spread as long as it was rare. Meeting copies of itself led to fiasco, but if it met the first mutant, they got on perfectly. Soon they would work only with one another.
The first mutation led to females, the second to males. Thus the fact that sex and reproduction are linked in eukaryotes, and that eukaryotes have two unrelated DNA lineages led naturally to gender.[ /just so story]
This is taken from
'Mendel's Demon' by Mark Ridley (Published by Phoenix in 2001). Other theories about gender are based on ideas about resistance to parasitism.
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Then he said unto them, O fools, and slow of heart, to believe all that the prophets have spoken. Luke 24 v 25
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