My hypothesis is that during human evolution, the species spread out in different regions of africa and underwent slightly different evolutionary paths. Some sub groups developed erogenous zones such as the g-spot, some sub groups developed erogenous zones in the anterior or posterior fornix and some sub groups became mostly sensitive in the clitoris. Then, at some point, the human brain or human culture became more developed and the species became so successful that the regions that divided the sub groups became populated and the sub groups started to mix together. The end result being a species that has alot of vaginal variation. Does that sound like a plausible theory to you? Does anyone have any other ideas?