It is likely that humans have used plants as medicine for as long as we have existed. Archeological excavations dated thousands of years ago have found remains of medicinal plants, such as opium poppies, ephedra, and cannabis.

So this tells us since the beginning, humans have experimented with plants to learn how they can help us heal. In essence, humans have been involved for thousands of years in a vast  with medicinal plants. The wisdom that resulted from this global experiment is a large part of our history of healing and healthcare from all over the world.