Biodiversity is one of the key parameters in the sustainability of the ecosystems, of which humanity is a part. Its current collapse, along with global warming, is undermining the earth's habitability for humans and many other living beings, with a cascade of consequences for health and food. This conference will explain the concept of One Health, the importance of biodiversity and the issues researchers are working on. It will present a number of results obtained by a Franco-Chinese team on the transmission of certain diseases and the ecology of the Black and White snubbed-nosed monkey, a species of primate endemic to southwest China.