Chinese goats, Spanish Conquistadors and Scottish longevity researchers aren't the only ones with an interest in vigorous love activities. The indigenous peoples of the wild Amazon have also been taking centuries of notes.
So here you are, buck-naked, smack in the middle of the rainforest - the largest natural pharmacy on the planet. You are an older person with no cable TV and not much else going on, and certain things just aren't working as often nor as they should. Viagra is a thousand years and a continent away. One day you eat this leaf, and then !boing! things work again and you feel so much better from head to toe. Well guess what? You take note of what leaf, flower or bark that was, and you eat some more tomorrow, and the next day - and the one after that too!
Thus, explorers entering various areas of the vast Amazon Basin, came back to civilization and compared notes. It seems that there were far distant tribes, with never any contact between them (nor with anyone else) who were using the exact same plants for the exact same things. Some of these herbs have now been used by people in the cities of South America and elsewhere for some two hundred years. They use them for the same health reasons, and with the same results, as that first naked pharmacist.
Of the long list of traditional Amazon herbs to choose from, we are most interested in a select few of these - the ones where their uses by indigenous people parallels their uses by modern people, and matches sophisticated scientific and clinical research. Of these, we then de-selected certain ones that were weak, and which overlapped, or did not meet some of our other criteria.