According to science journalist Sonia Shah, author of the 2017 book «Pandemic,» the expansion of humans onto more and more of the planet’s land has increased the likelihood of disease outbreaks in two ways. First, as humans move into what were once animal habitats, we end up living closer to animals that might contain dangerous pathogens; and second, as we destroy or alter animal habitats, we’re driving away or killing off animals that once served as a “firewall” between those pathogens and us.

And the human land development driving this trend shows no signs of stopping. Correction: At 4:28​ and 4:49​ we mistakenly depict the European robin. The species actually responsible for the spread of West Nile virus in North America is the American robin.