Next time you try to avoid a sick friend or refuse to hug a sick family member, don't feel bad—you're just doing it to protect yourself. And humans aren't the only ones who exhibit such behavior: House finches, which are normally very social creatures, go out of their way to avoid sick birds.
Similar behavior has been observed in lobsters and bullfrog tadpoles, but this is the first time researchers have seen birds acting in such a manner.
"In addition, we found variation in the immune response of house finches, which means that they vary in their ability to fight off infections," says Maxine Zylberberg of the California Academy of Sciences. And just like us, those with the weakest immune systems are the ones who are most cautious when it comes to avoiding their sick friends.
So the next time you dive into your supervisor's office just to avoid the sick guy two cubicles over, remember: you're only doing what comes naturally.