The therapeutic benefits of ayahuasca are well-known and celebrated worldwide. However, when conducted by the wrong individuals, ayahuasca ceremonies can also lead to harmful outcomes. In this episode, host Mark Plotkin talks with author and explorer Robert Tindall about some of the potential risks and downsides of ayahuasca use.

Many people associate cacao (and chocolate) with its origins in Mexico, but few are aware that the plant itself is native to the rainforests of the northwest Amazon. Previous episodes of this season of "Plants of the Gods" traced the journey of cacao from the Amazon to Central America and then to Europe. In this episode, ethnobotanist Mark Plotkin continues to explore the captivating history of this remarkable treat, spanning from the American Revolution through the Industrial Revolution and into the 21st century.

The concept of uncontacted or isolated indigenous rainforest groups enthralls many people, even those who have no particular interest in rainforest conservation or tribal cultures. Yet there certainly exist dozens of these groups in Amazonia, if not more. How can we estimate what and how much they know about the healing plants of the rainforest if we do not contact them first? This episode attempts to answer this seemingly oxymoronic question.