Scientists have long suspected that better biodiversity keeps human diseases in check, but they've lacked solid evidence until now. In a new "landmark paper," as the head of the Wildlife Trust calls it, researchers from Portland State University studied the occurrence of hantavirus in deer mice living in five Portland-area parks with varying degrees of biodiversity. More mice were infected in parks that had less mammal diversity, and disease rates were highest in the least diverse park, suggesting a direct correlation. (Text from The Daily Briefing)