I think the women with more spine curvature allows them to do doggy style easier. Some men have wives who can't do that position without feeling discomfort, and the spine curvature probably has something to do with it. Unfortunate, I had a girlfriend like that, and another girlfriend who couldn't be in that position too long. They both been in bad car accidents before. But I think that was the excuse for only one of them. The one that had the most trouble, could do it easier when she had only one knee down.
I'm surprised at the article. I thought White men didn't care for a big a**. But I always knew they did. However most of their women look like number 2, and lucky to have a number 4.
Btw, I went with number 6. I had a chick with an a** like that. But her face was kinda... I saw her on facebook a few years ago. I don't know what happened to that body, and it's hard to believe I ever kissed her.