Questions about genders ... male/female

[JuliaL]

We are currently in the biology unit ... and I've pondered this question from an atheistic evolutionary viewpoint for a bit ... and I can't seem to find an answer.

So, I thought I would post here to see if you all could offer some insight.

Why do we only have two genders, male and female? [excluding asexual animal reproduction] ... just humans and almost all animals? Why only two? Why not ... say ... seven, or seven-thousand? If we have evolved over time from a single celled organism ... why did we only evolve into two genders and not more? Why did it stop at two? Thanks for your time.

The atheistic evolutionary view on the development of sexual reproduction differs little from a specifically deist theistic view.
Deists (god exists, but is not immanent)
use the same data as atheism (insufficient evidence to believe that god is immanent whether it exists or not)
and find the same conclusions.
The other bajillions of kinds of theists each have their own wacky origin myths which obviously differ from the above. Their individual differences are too many and varied to mention here, involving as they do such things as flecks of mucus from the Great Green Arklseizure.

Why two? As others have laid out, because, on balance, it works well enough to have led to us. We are not an optimized system, rather we are a system which is constantly being optimized to its local environment by natural selection acting on our current varied states. Why not more? Because the zillions of individual events on the evolutionary path to us did not, on balance, lead to more. Two was good enough.

http://en.wikipedia.org/wiki/Evolution_o...production

I think the real question is how could evolution come up with both sexes before the organism winked out of existence

You should really try to educate yourself, if only in order to know your enemy.
Sex evolved at a time when multi-cellular organisms were just getting going.

All sexually reproducing eukaryotic organisms derive from a common ancestor which was a single celled species.

-Wikipedia op cit.

The species that invented sex essentially didn't have male and female, it just exchanged genetic material with another individual externally indistinguishable from itself. Male and female only became identifiable when individuals of a (much later) species gradually differentiated into two classes, one of which specialized in making larger, more robust, but more costly reproductive cells and one which did the opposite; making smaller, less costly, but more vulnerable reproductive cells.