Mapping Earth’s Medicine Cabinet: The Ancient Roots of Medicinal Plants

Humanity’s relationship with healing plants stretches back tens of thousands of years, long before pharmacies and synthetic drugs. A new study published in Current Biology builds on this long history, revealing that some of today’s richest reservoirs of medicinal plant diversity coincide with regions where humans have lived, and experimented with nature, the longest.

 “Human ingenuity takes time — and I think that that’s what we’re seeing. As humans were exploring the flora, they were identifying which plants might actually be useful for medicinal purposes, said co-author Professor Charles Davis.

The study tallied more than 32,000 medicinal plants among more than 357,000 vascular plant species across 369 regions worldwide. About 9 percent of all vascular plants — the dominant group of land plants — have some documented therapeutic use, from medicines and lotions to intoxicants and fragrances.

Medicinal plant diversity mirrors broad biodiversity patterns, increasing toward the equator and diminishing at higher latitudes. Yet the researchers uncovered notable outliers. Several hot spots, including India, Nepal, Myanmar, and China, contained far more medicinal plants than expected based on their overall floral diversity. These areas also have long-standing healing traditions such as Ayurveda and traditional Chinese medicine, suggesting that cultural knowledge has helped drive and preserve medicinal plant use.

“It seems that centuries to millennia of cultural knowledge and human interaction with plants have helped build and maintain this rich diversity,” said lead author Nawal Shrestha, former research associate in OEB and currently assistant professor at Kathmandu University in Nepal.

By contrast, some of the world’s botanical treasure troves — including the Andes, Madagascar, Western Australia, New Guinea, and South Africa’s Cape Provinces — showed lower-than-expected medicinal plant diversity. Shrestha noted that these “cold spots” may reflect historical disruptions or gaps in record-keeping rather than a true scarcity of useful plants. “Many of these areas have rich local knowledge that has not yet been systematically recorded or incorporated into global databases,” he said. “It really highlights the need to work with local communities and revive traditional knowledge to better capture these resources.”

The strongest predictor of medicinal plant richness, beyond diversity, was the length of human occupation. Regions with the longest history of human occupation — particularly in sub-Saharan Africa — showed greater numbers of plants used for healing, while areas settled more recently, such as parts of South America, had fewer. As Davis put it, “Human ingenuity takes time — and I think that that’s what we’re seeing. As humans were exploring the flora, they were identifying which plants might actually be useful for medicinal purposes.”

The findings reveal how deeply medicinal plants are woven into human history and the vulnerability of that heritage. At least a quarter of modern prescription drugs trace their ingredients to plants. Archaeological and historical records show that both humans and other primates have long turned to plants for healing — from yarrow in hominin dental plaque to 5,000-year-old Sumerian tablets listing botanical remedies. But the world’s medicinal species, along with the cultural systems that safeguard knowledge of them, face growing threats. Davis emphasized the urgency of protecting both. “Our findings reveal areas where not just biodiversity, but priceless traditional and local medical knowledge are at risk,” he said. “They must be prioritized for conservation and revitalization — and for future public health benefits to humanity.”