ARUN RATH, HOST:
You're not special. Sorry, not to be rude. I don't mean just you in particular. I mean the whole human species. We used to think using tools and complex problem-solving set us apart, but crows proved us wrong. Songbirds got us on culture. Now a new study adds to the list what seem to be fashion trends. Katherine Cronin of the Max Planck Institute for Psycholinguistics co-authored the study. And she joins me now from the Netherlands. Welcome to the program, Katherine.
KATHERINE CRONIN: Thank you. Thank you for having me.
RATH: Can you tell us what your research team observed in Africa?
CRONIN: So in 2010 we went to visit a chimpanzee sanctuary in Zambia. And we noticed that this one adult female, Julie, had this peculiar behavior of putting grass in her ear. But it didn't really pique our interest until we came back the next year in 2011, and it had started to spread throughout the group. So we started the daily video collection program with our Zambian colleagues who were there year-round and could see the chimps every day. And it was when we were able to go back through this video and document the spread of the behavior that we got interested.
RATH: Why is that?
CRONIN: Well, because we know that chimpanzees can copy behaviors from others. But usually what we find is that they're copying behaviors that clearly have some kind of important function. But here, this silly behavior doesn't bring them any of the things that are so important to animals, like more food or potential mates. And so when we see them copying this odd behavior that doesn't seem to have any function, we learn that they have some kind of intrinsic motivation or some kind of desire to perform the behaviors that others in the group are performing.
RATH: There was one that seemed to actually not really enjoy sticking the grass in his ear, but he did it anyways. I'm thinking of me being a kid having to wear a tie to go to a nice restaurant. Is that silly?
CRONIN: Yeah, yeah. The first time I saw Val was his name. He was an adult male in the group. And he took this piece of grass that was actually quite a bit shorter than the size that Julie usually uses, and he stuck it in his ear, and he was shivering every time he did it. And he would put it back in and he would get the shakes, basically, and pull it out. And then try it again. And so I think that anthropologists and psychologists have known for a long time that humans tend to copy behaviors of others in their social groups, so things like you're saying, what we wear, what we say, what we eat. But here we see that chimps are also copying this sort of arbitrary behavior, which shows us that it's not only our species that tends to behave in ways that lead to some kind of cultural similarity, but actually that this tendency could have some deep biological roots.
RATH: Dr. Katherine Cronin of the Max Planck Institute for Psycholinguistics in the Netherlands. Their research was published in the journal, Animal Cognition. Katherine, thank you again.
CRONIN: Yes, thank you very much.
RATH: This is NPR News. Transcript provided by NPR, Copyright NPR.