In the mountains of Japan, there exists a small and remote village called Yuzurihara. It's a village where 70, 80, and even 90 year olds are still able to comfortably squat, twist and bend for up to 8 hours a day to farm their rice crops. They plow their fields without the help of modern machinery, and they continue to harvest their fruit and vegetables by hand. In fact, so-called "wear and tear" barely seems to exist in the joints of these Japanese seniors. The secret lies in the village's fertile soil where a unique type of purple sweet potato grows. It's called the satsumaimo, and it's rich in a joint-supporting molecule called hyaluronan.