Knowledge of medicinal plants runs the risk of disappearing as human languages become extinct, a new study warns.
Indigenous languages contain a wealth of knowledge about the ecosystem services provided by the natural world around them. However, more than 30% of the 7,400 languages on the planet are expected to disappear by the end of the century, according to the UN.
The impact of language extinction on the loss of ecological knowledge is often overlooked, said the study’s lead researcher, Dr. Rodrigo Cámara-Leret, a biologist at the University of Zurich. “Much of the focus is on the extinction of biodiversity, but there is a completely different picture which is the loss of cultural diversity,” he said.
His team examined 12,000 medicinal plant services associated with 230 indigenous languages in three regions with high levels of biological and linguistic diversity: North America, northwestern Amazonia and New Guinea. They found that 73% of medical knowledge in North America was in only one language; 91% in the northwest of the Amazon; and 84% in New Guinea. If languages died out, the medical expertise associated with them likely would too. The researchers hope that their findings from these regions will be similar in other parts of the world.
“The loss of language will have a more critical impact on the extinction of traditional knowledge about medicinal plants than the loss of the plants themselves,” said Cámara-Leret.
The areas with languages most at risk were in northwestern Amazonia, where 100% of this unique knowledge was supported by threatened languages, and in North America, where the figure was 86%. In New Guinea, 31% of languages were at risk. The anticipated loss of linguistic diversity “would substantially compromise humanity’s capacity for drug discovery,” according to the article, published in PNAS.
This knowledge includes the use of plant latex to treat fungal infections, the use of the bark to treat digestive problems, fruits for respiratory diseases, as well as natural stimulants and hallucinogens. “The list goes on and on, it’s pretty impressive,” said Cámara-Leret. “Even the best plant taxonomists are amazed by the breadth of knowledge of indigenous cultures, not only about plants but also about animals and their interrelationships.”
It is impossible to know what has already been lost. Over 1,900 of the languages spoken now less than 10,000 speakers and the UN has declared that 2022-32 will be the International Decade of Indigenous Languages in recognition of this problem.
Jordi Bascompte, an ecologist at the University of Zurich and second author of the paper, said that European medical knowledge may represent the “tip of the iceberg”. Although many drugs are based on synthetic compounds, there may be many more chemicals provided by plants that could unlock the potential for new treatments. “Any information, no matter where it comes from, can end up being useful,” he said.
The paper did not examine the extent to which medicinal services are considered effective in the Western sense, although the researchers say that in many cases the plants have been shown to be effective.
Much of the world’s linguistic diversity is being safeguarded by indigenous peoples whose culture and livelihoods are threatened as barriers between groups are broken down. Unlike societies where information has been transcribed into books and computers, most indigenous languages transmit knowledge orally.
Government programs to stimulate language transmission, bilingual schooling and interest in cultural heritage would help communities preserve linguistic diversity, Cámara-Leret said. But the medicinal aspect was just one of many reasons to promote the conservation and diversity of languages in the world, he added.
Dr Jonathan Loh, an anthropologist and conservationist at the University of Kent, who was not involved in the research, said he was surprised by the degree of linguistic uniqueness in the knowledge of medicinal plants. He had previously spoken about the parallels between linguistic and biological diversity, commenting that these had evolved in remarkably similar ways and both faced an extinction crisis.
However, he said it was important not to focus on utilitarian arguments for the conservation of languages, cultural diversity and biodiversity.
“There may be valuable knowledge of medicines unknown to Western science contained in these languages, and certainly that is true to some extent, but it is not the most important reason to preserve them,” he said. “Each indigenous language and culture is a unique evolutionary lineage that once lost is lost forever.”