>> some bat species actually migrate thousands of miles, and hence the viruses that they carry traffic along those migratory routes. >> and though some of the pathogens bats play host to can make them sick, like rabies, they also have the unique ability to host and withstand some viruses without getting sick. >> understanding how bats co-exist with diseases is very critical. bats have a very unique relationship with pathogens generally. they have a unique biology and it allows them to co-exist with pathogens in different ways. >> there are various theories about why that is. it might have to do with how long bats have been around. >> bats are an ancient species. they have been on planet earth a long time and that means they've had a long history of being exposed and adapting to viruses in nature. >> another theory involves their body temperatures. >> a lot of people have come up