The human fingerprint of medicinal plant species diversity

Medicinal plants have long been crucial to human civilizations, supporting both traditional and modern healthcare systems. However, the processes influencing the global diversity and distribution of medicinal plants remain underexplored. Their diversity, like that of other species groups, is shaped by abiotic and biotic influences, which include, in unique ways, human ecological (including cultural) practices. Here, we investigate and compare these influences on the distribution and diversity of 32,460 medicinal plant species and on global vascular plant distributions. We identify significant regional variation in medicinal plant diversity, including "hotspots" (India, Nepal, Myanmar, and China) and "coldspots" (Andes, New Guinea, Madagascar, the Cape Provinces, and Western Australia) of unrealized diversity. Human migratory timelines have significant influence on medicinal plant diversity and distributions, underscoring the likely importance of accumulated ethnobotanical knowledge over time. Regions with long histories of human settlement typically boast more diverse medicinal floras than expected. In contrast, language diversity, an indicator of cultural diversity, appears to have a limited direct effect on medicinal plant diversity, but its indirect effects warrant further exploration. Our study emphasizes the need for integrated conservation strategies that incorporate both standard ecological factors and human ecological dimensions; the latter are critical for preserving medicinal plant resources and enhancing global healthcare solutions.