Why should people protect biodiversity? Researchers from a number of disciplines have proposed ethical, aesthetic, and utilitarian reasons to do so. But recently some researchers have argued that ecosystems that support high diversity pose a danger to human health. They argue that because areas with high biodiversity are likely to support a high diversity of potential human pathogens, these areas should be hotspots for the emergence of infectious diseases.
In this paper, Felicia Keesing and Rick Ostfeld evaluate the evidence for three necessary links that are required by this argument. They found no support for one critical link—that high total diversity of pathogens correlates with high diversity of actual or potential pathogens of humans. This suggests that high biodiversity should not be expected to lead to more infectious diseases of humans. In contrast, there is now substantial evidence that high diversity protects humans against the transmission of many existing diseases.