These two plants grow in close proximity in the amazonian region. Where there is an ayahuasca vine, you will find a chacruna plant near by. But, there are a massive amount of plants which also grow in this same region near ayahuasca vines that do not combine to bring about a hallucinatory experience. Every plant in the region has a use and the tribes people grow up learning the medicinal properties of plants before they ever learn to read and write. This is an essential part of their survival and often implemented into the language they speak. Because of this we can deduct that the knowledge was passed down verbally in songs, like icaros. Anthropologists have estimated they began taking ayahuasca some 5,000 years ago. It is possible, but not likely, an accident of the brewer. So then how did these, so called, primitive people know?
Let us imagine they were not primitive people, they held a knowledge vastly different from our own. They could feel plant energy. For those of us who have closer relationships with plants and entheogens, this is easier to understand. If you lived in not just a jungle, but the amazon jungle, reading plant energy is part of your survival toolkit. There are plants in the amazon that can easily kill a human, there are plants that can save your life. If other animals can sense what plants are beneficial to them, why not humans? The tribes believe the plants have spirits and that you can hear the plants, they are living things just like anything else. By listening to the plants on a profound level, it is believed they were able to speak with the spirits. The spirits came to them and told them how to use the plants to heal.
Then there is the theory where humans are not insightful to their surroundings and the idea to mix chacruna leaf and ayahuasca together came from an outside source. Depending on who you speak to this could mean gods or aliens told the people to mix the plants. Who it was depends on the perspective of the storyteller. It is fun to speculate how such an important life saver in amazonian medicine came to be.
It is an important teaching in letting things be as they are. We may never know how exactly ayahuasca tea came to fruition, but we do know we are grateful for it, that is most important. This medicine saves lives and brings forth great positive personal change. It is fair to say there is no other entheogen like it.