When humans will learn to speak animal languages
Researchers have tried to decode the language to animals so that humans - the most intelligent species on earth, could someday learn it rather than teaching human communication to animals.
Many scientists are trying to do this and hope to someday learn dolphin, elephant, gorilla, dog and all the other animal tongues.
One scientist has already decoded a great deal of prairie dog.
However, researchers are off to a slow and late start down this road, because they are having to overcome a major obstacle of their own making - the idea that animals don't actually have languages.
"It's a hotly debated area, because there are still people who want to separate humans from other animals," Marc Bekoff, professor from the University of Colorado, Boulder, said.
"So if you're doing fieldwork and you see something in the animal's communication system that looks like syntax, they're going to say it isn't," he said.
Constantine Slobodchikoff from Northern Arizona University may have ventured further beyond this barrier than anyone. He has spent decades decoding the communication system of Gunnison's prairie dogs, a species native to the Four Corners region of the U.S. Southwest.
Prairie dogs are rodents. They aren't particularly renowned for their smarts. And yet, in dozens of books and articles over the past three decades, Slobodchikoff and his colleagues have laid out extensive evidence that prairie dogs have a complex language. And he can understand a lot of it.
When they see a predator, prairie dogs warn one another using high-pitched chirps. To the untrained ear, these chirps may all sound the same, but they aren't. Slobodchikoff calls the alarm calls a "Rosetta stone" in decoding prairie-dog language, because they occur in a context people can understand, enabling interpretation.
Spectrograms of prairie dog alarm calls in response to potential predators.
In his research, Slobodchikoff records the alarm calls and subsequent escape behaviours of prairie dogs in response to approaching predators.
Then, when no predator is present, he plays back these recorded alarm calls and films the prairie dogs' escape responses. If the escape responses to the playback match those when the predator was present, this suggests meaningful information is encoded in the calls.
Indeed there seem to be - Slobodchikoff has discovered the rodents have distinct calls pertaining to different potential predator species, such as coyotes, humans or domestic dogs.
Their calls even specify the colour, size and shape of the predator; for example, they'll differentiate between an overweight, tall human wearing a blue T-shirt and a thin, short human wearing green.
Remarkably, the prairie dogs even create new alarm calls in response to foreign objects introduced by the researchers, such as a picture of a large black oval.
Although the prairie dogs never would have had cause to discuss such an object previously, they all generate an identical alarm call in response to it, suggesting they are describing the oval's size, shape and colour in a standard way.
Just like different groups of humans, different species of prairie dogs have distinct dialects. The Gunnison's prairie dogs that Slobodchikoff studies are unlikely to understand the calls of Mexican prairie dogs, Slobodchikoff said.
Their communication goes beyond alarm calls.
"Prairie dogs also have what I call social chatters, where one prairie dog will produce a string of vocalizations, and another prairie dog across the colony will respond with a different string of vocalizations," Slobodchikoff said.
"I can show that there seems to be some syntax in these strings, but since nothing about the behaviour of the prairie dogs changes, I can't say anything about the context, and so I have no way of decoding the possible information contained in these [social] chatters," he added.
Slobodchikoff has laid out his efforts in his new book 'Chasing Doctor Dolittle: Learning the Language of Animals', which is scheduled for release on Nov. 27.