VOA常速英语:Chimps Respond to Human Yawning

A new study says as chimpanzees grow, they increase their ability for empathy – the ability to recognize emotions in others. Researchers say they learned this by watching chimps yawn when they see people yawn.

Elaine Masden and her colleagues at Lund University in Sweden base their conclusions on studying the primates in a sanctuary. But you have to ask – why study contagious yawning?

Laughing, she said, “I don’t know.It’s a really peculiar effect. It’s such a small thing, but that nonetheless most of us experience. Most of us when we see or hear others yawn or just think about yawning or read about yawning then we ourselves begin to yawn. So it’s something that most people are familiar with.”
Dr. Madsen -- an evolutionary psychologist -- says not everyone reacts the same way. About half of people tested do not respond to contagious yawning.

“It begs the question, why? If it’s something that we find all over the world, why do only roughly half of us do it?

Not that she’s pointing fingers, but among those who generally do not respond to contagious yawning…

“Psychopaths, for example, don’t show contagious yawning. And we know that they are very low on – what’s called – effective empathy. There are two types of empathy that researchers usually operate with. One is cognitive empathy, which is a very high level of empathy where you sort of imagine how someone else must be feeling or thinking. And then there’s the more simple kind of empathy, which is more immediate and we see that in animals. The kind of empathy where, for example, if you see someone caught their hand you instantly feel in in your stomach. It hurts. Psychopaths, for example, don’t experience this effective empathy. They can be very clever, but they don’t experience this effective empathy,” she said.

So psychopaths don’t have as much effective empathy as a chimpanzee.

In humans, children begin to yawn when they see other people yawn starting at around four years old. It indicates they’re beginning to develop empathy. The yawning response – or yawn contagion – is strongest between people who know each other well.

There are a lot of theories as to why people and some animals yawn. Madsen thinks it could be something to synchronize group behavior.

Madsen and her colleagues studied 33 orphaned chimps, ranging from infants to eight years old. They had the chimps watch them as they yawned, opened and closed their mouths in fake yawns and wiped their noses. The chimps only responded to the yawns, but only if they were at least five years of age. Any chimp younger than that appeared immune to contagious yawning – just about the same as humans. So empathy develops over the first few years of life.

Madsen said, “Some people have looked at adult chimps and have shown them cartoons of other chimps yawning and that sets off their yawning as well. The stimulus, the yawn stimulus, can be very simple and still set off a yawn. We seem to have this very strong inclination to copy the yawn, whether it’s from a cartoon, whether it’s another human that the animal sees. I also catch their yawns. It also works the other way around. So very simple stimulus can make us yawn.”

Madsen said that the research poses more questions than it provides answers. So, a lot more study is needed as to what it all means.

This contagious yawning that’s seen between people and chimps is not common between people and other animals. In fact, cross species yawn contagion – that’s the scientific term – has previously only been demonstrated in dogs -- but not until the dogs are at least seven months old. Dogs can become so in-tune with their owners yawning that they not only copy the behavior, but get sleepy as well.