And now my response from your other thread. This will look a little out of place since it was an answer to why there were two genders.

Ah, the fallacy that for evolution to be true, one day something would have had to have been born fully developed into the form you see it today. This is going to be fairly long, but I will keep it as short as possible, since I know most of you aren't really interested in getting an answer anyway, you just want to try and shoot holes in evolution that don't exist.

Early on, all organisms were completely lacking in sex. They reproduced through mitochondrial division, which usually produced nearly identical copies of themselves. Over time, as organisms became more complex (multi-celled) they became what one would commonly think of as asexual. In these cases, they needed genetic material from other organisms to produce an offspring, but either organism could create the offspring. They both possessed the ability to do so. This method of reproduction allowed them to create stronger offsprings that shared the trait of paired reproduction, and was able to take advantage of the genetic traits of both parents. Organisms that possessed traits that gave themselves a competitive advantage survived to reproduce further. Asexual organisms that reproduce in this manner still exist, as do the aforementioned organisms that reproduce without the need to interact with others.

As organisms continued to develop into more complex organisms, members with certain chromosome combinations began developing primary sexual characteristics, while their reproductive characteristics for the other half of the reproductive function became less developed. Certain members of the species were better able to function in reproductive roles than others of that species, and thus began the divergence into two sexes. The specialized sexual characteristics allowed these organisms to breed stronger offspring as their reproductive characteristics were better suited for breeding strong offspring and their body could devote a greater part of its make-up to the single sexual characteristic instead of having to split evenly between both, so, as is always the case of survival of the fittest, the weaker members without these specialized characteristics began dying off. Note, these were gradual changes. Slowly the primary sexual characteristics became stronger while their opposite sexual characteristics waned. This was not as you probably want to characterize it, suddenly one insect was born a male and another a female.

Through this progression, we gradually ended up with two well-defined sexes that were only capable of breeding with a member of the opposite sex, but could create far stronger offspring due to their highly developed sexual characteristics. You can find organisms all over the world today that are at the various stages of sexual development and definition throughout the spectrum I have briefly explained.


Now, I eagerly await the straw men and fallacies you religitards use to shoot this down. I don't have any illusions that explaining this to you will change your mind or enlighten you, as I am sure that by this point, you are beyond hope. I only answered because you asked the question and no one else showed you the courtesy to explain how it works under evolutionary theory. I'll also note that I tried to keep this brief, so I am obviously leaving out a lot and don't have room to cite and explain everything in depth. You wanted an answer, I gave it. Now you know how it is explained. You are free to believe whatever you like though.