The debate comes about because there are two different types of yam. The "true yam" or "tropical yam" is a tuber that originated in Africa. This type of "yam" isn't grown in the United States, but is usually imported from countries around the Caribbean.

What Americans usually refer to as a "yam" is a particular variety of sweet potato, native to tropical North America. These "yams" are sweet potatoes that have a dark orange flesh and are denser than other varieties of the sweet potato.

To further complicate matters, the sweet potato isn't even a potato. It belongs to the same family as the morning glory.

And what does all this have to do with oral contraceptives? We're glad you asked. Manufacturers are able to create progesterone from the Wild Mexican variety of "true yam." This hormone is the basis of the common birth control pill. So now you know.

As Popeye often said, "I yam what I yam, and that's all what I yam."