TED視聴：オウムはなぜヒトを真似て話せるのか。そしてなぜ真似るのか。

Humans vocalize with their throats using bodywork. Birds, on the other hand, have vocal cords called syrinxes, and use the vibrations of flowing air to produce sound.

This is the way parrots vocalize. Since parrots do not have lips, they have an esophagus and use the force of the air between it and the trachea to produce sound.

Why parrots can talk like humans

This is what a macaque monkey would sound like if it suddenly proposed.  Will you marry me? Yeah, I hate it too. Let us play it again: Now, of course, that is not a real monkey, it is a computer simulation that was part of a study on monkey vocal tracts. And what it shows is that monkeys have a strikingly similar vocal structure to humans. But despite all these similarities, they can not speak So here is a question. Compared to monkeys, birds are nothing like us. 

Yet this bird is talking to me right now. How?  Birds do not have lips. They do not have teeth, their “nose” is totally different from ours, but they do have something we do not. They actually have a different kind of voice box than we do. It is called a syrinx. This is Mya Thompson – She studies birds at Cornell University. They actually have two independent voice boxes. In birds, and in humans, the lower respiratory system is shaped sort of like an upside-down slingshot(パチンコ). The top part is the trachea or windpipe(気管), the bottom part is the lungs(肺), and these two pieces move air in and out. 

In humans, the voice box is called the larynx(喉頭), and it is located above the trachea. It contains vocal “folds” that vibrate when air flows through to produce sound. And humans primarily shape that sound with their mouths. But in birds, the voice box is called the “syrinx”. And it is at the bottom of the trachea. Instead of just sending air through vocal folds like we do, birds actually control the muscles on the walls of the syrinx to shape and produce sound.  Take a look at this is cardinal as it sings. You can actually see that the noise comes directly from the chest. The bird extends and shortens its neck and opens or closes its beak to refine the noise, but most of the control is actually happening in the syrinx. It is a powerful sound for such a small animal, but that is not even the most impressive part: Cardinals tend to make these “whoop” notes and they go by very very quickly. They are able to produce more pitches than a piano in less than a tenth of a second. They are actually switching from one side of the syrinx to another seamlessly to make this very very incredible span of pitches. 

The syrinx also lets some birds replicate sounds with astonishing accuracy. For example, BBC Wildlife caught a lyrebird perfectly imitating a camera in the wild.  And of course, some of them imitate us. Parrots are born communicators. From the start, their brains are wired for speech. So when they are first hatched they are learning right away and they are learning from everything around them. But speaking human is no easy feat. We have got our vowels A-E-I-O-U. Our plosives “Pocket”. And a variety of consonants – that we even sometimes struggle to enunciate clearly Rural? So to pull off such clarity in human speech, parrots really show off their ability to manipulate their vocal tract. Plosives, for example, require using our lips. To make up for the lack of lips, parrots use something called esophageal speech – it is almost like burping that comes from within the trachea. The force of air replicates the plosive. 

As for vowels, where we use our lips, tongue, and jaw, researchers have found that parrots move their tongues forward and backward and adjust their break opening to alter the sound. It seems like they are the only birds that are actually using their tongue like humans do to shape the sound that is coming out. Parrots have a natural desire to communicate. In the wild, they form strong bonds with their flocks but in captivity, the parrot forms a social bond with you and they want to communicate with you and they have the vocal anatomy(発声解剖学) to start mimicking(真似) you. When parrots live with us, we are their flock and they are determined to sing our song. So in this video, I showed you some of the physiology that lets birds produce sounds. But I wanted a quick and easy way to show you some of the interesting background research on neurology(神経学) that allows some of them to speak. So I created a website with Wix, where I have compiled a bunch of extras, including research and related content that gets you animals. It is a super-easy way to make a website, so click on your own. Wix does not directly impact editorial but their support does make videos like this one possible, so go check them out.