Because one can't evolve without the other.
So the evolution of my reproductive system depends on the evolution of my wifes reproductive system??? Absurd.
These is no evolutionary advantage to growing a set of gonads that is useless to the opposite sex of the species.
But in order to "grow a set of gonads" that are useful is presupposing the need to grow anything useful. As it goes through the selection process of deciding what is useful and what isn't useful, how was any reproduction taking place? Remember, natural selection selects, so before it found the right selection, how was there any reproduction?
In fact, it's a hinderance. If there were any mutations that led away from compatibility, natural selection would have killed them off.
Ok, so during this "killing off" process, how was there any reproduction? And whatever stage of reproduction that this process went through, there had to be compatibility on all stages, the first through the last.
So the compatibility issue is dealt with.
It has? Where, because I didnt see it. All you did was presuppose compatibility without explaining how things became compatible. That cant be the best you have.
It's a bit of an oversimplification, of course. The changes are gradual. It's not like one day you wake up and your penis is suddenly a massive Great Bombard of a sperm cannon.
And thats my point. On your view, it takes time. If it will take a million years before one gender develops the right system to reproduce with the other, how was there any reproducing of any kind during that million year stretch??? A male and a female have two different systems that are compatible. This compatibility had to be "fine tuned" as an initial conditon of the species. This is not something that could have happened over millions of years with wishful thinking.
Change in the structure and function of the gonads is possible only if there is a corresponding change in the female genitals. Anything else would not be selected for as it would be more difficult to produce viable offspring.
You already said that it takes time. And my question is, in that time, how was there any reproduction at all?? If I am building a car and I have built the whole car and all i need is the motor, and my friend takes a million years to build the motor, how will I ever get my car to run if I have to wait a million years for him to build the motor?? Obviously, I wont be driving the car for a long time. This is the same thing with the gender problem.
Complexity is simply the natural result of more genetic mutation that is regulated by natural selection.
You are begging the question. I am asking how can a unguided and blind process produce this much specified complexity and your answer is genetic mutation regulated by natural selection, which doesnt answer the question because before you can have genetic material you have to have cells and dna, and these are the two things that are IN QUESTION AS TO HOW AND WHY ARE THEY COMPLEX.