The predicted disappearance of certain indigenous languages could also lead to the disappearance of the knowledge of many medicinal plants. In three-quarters of the cases identified by researchers in Zurich this knowledge is transmitted only orally in one of these languages. Linguists estimate that about a third of the 7,400 languages currently spoken in the world will have disappeared by the end of the century. Yet the only way some indigenous cultures transmit their knowledge is by word of mouth. To investigate the extent to which the medical knowledge surrounding plants is under threat, Rodrigo Cámara-Leret and Jordi Bascompte from the University of Zurich collected data on 3,597 medicinal plants. They looked at 12,495 ways of using these plants, the knowledge of which is transmitted in 236 indigenous languages spoken in North America, the northwestern Amazon and New Guinea. Their study is published in the journal PNAS. ‘Tragedy’ The result is that 75% of the knowledge of...