You know how there's those horrible t-shirts for expectant dads expressing pride in having fast sperm and so on? It turns out that women's plumbing might actually make the final call in the mating game. Researchers are looking at female reproductive systems, and finding some things that they say explain female promiscuity in some species. The findings could also have implications in IVF and cloning and so on. They looked at the oviducts of pigs (we are kinda like pigs) and found that a series of changes occur when the presence of sperm is detected. Basically the oviductal environment changes to store sperm and get it to the egg safely. That's right: Females call the shots. Mmm hmm.

And how does this apply to tramping around? Well, there may be some selection of optimal sperm that goes on as well. If the presence of different sperm is detected, the top quality stuff might be chosen over the lower grade versions. Bottom line is that the female reproductive system has been relatively ignored in the competition side of procreation, and of course it probably plays a bigger role than was suspected before.

Oh, and IVF? Check this from the lead author: "The female reproductive tract is a very highly organized and regulated system," Fazeli explained. "With IVF, the embryo can develop into an adult, but the question remains: 'Are we doing the fine-tuning right'? We are not sure if what we are doing, based on differences between in-vitro and in-vivo fertilization, is creating health problems for these babies." I think the lesson is clear. It never pays to ignore the lady parts. Ever.