只有母亲会为患病吸血蝙蝠梳毛

This is Scientific American's 60-second Science. I'm Jason Goldman. Epidemiologists have long known

that socially connected individuals like friends, family and co-workers are more likely to transmit pathogens to each other. But when an individual becomes obviously ill, their social connections become temporarily reduced:

When we feel sick, we tend to stay away from others. And when we appear sick, others tend to stay away from us.

That distancing usually helps to slow down the spread of a pathogen. But not all social relationships work the same way.

Parents of sick children will continue to care for those children at the risk of their own health. And that devotion is true beyond humans.

Consider vampire bats. They usually groom their own offspring as well as other bats. And they share food.

But illness changes some of those activities. To track illness and behavior in a vampire bat community,

researchers injected some bats with a substance that triggered their immune systems- the bats felt less well than usual without actually suffering from a disease.

In this situation, unrelated bats stopped grooming each other. But mothers continued to care for their offspring, even if one of them seemed to be infected.

"In these changes in grooming, there was a difference between unrelated bats and maternal relationships. So what it looked like was that sick moms kept grooming their offspring,