I read somewhere that because the Y chromosome is gradually becoming more and more "defective" eventually the male species is going to die off and by that point genetic engineering will be advanced enough that women will be able to reproduce by taking the nucleus from one womans cell and inserting it in another woman's egg. women have two x chromosomes so when there is a defect on one it is highly unlikely that the other one will have the same defect so it will cancel it out. Men dont have this advantage so they continuously pass on the defects in their y chromosome.
i'm sure someone can explain this better but you get my point... i hope