Nicholas Wade, "Deciphering the Chatter of Monkeys", NYT, 1/11/209, starts out with a Dr. Dolittle trope that may raise a red flag or two among those who are tired of facile anthropomorphizing in stories about animal communication:
Walking through the Tai forest of Ivory Coast, Klaus Zuberbühler could hear the calls of the Diana monkeys, but the babble held no meaning for him.
That was in 1990. Today, after nearly 20 years of studying animal communication, he can translate the forest’s sounds. This call means a Diana monkey has seen a leopard. That one means it has sighted another predator, the crowned eagle. “In our experience time and again, it’s a humbling experience to realize there is so much more information being passed in ways which hadn’t been noticed before,” said Dr. Zuberbühler, a psychologist at the University of St. Andrews in Scotland.
Do apes and monkeys have a secret language that has not yet been decrypted? And if so, will it resolve the mystery of how the human faculty for language evolved?
But there really are referentially specific alarm calls of that kind, of course, even if they don't amount to a Dolittle-style "secret language". So having lured its readers in, the article settles down to a sensible sort of survey:
Biologists have approached the issue in two ways, by trying to teach human language to chimpanzees and other species, and by listening to animals in the wild. [...]
But with a few exceptions, teaching animals human language has proved to be a dead end. They should speak, perhaps, but they do not. They can communicate very expressively — think how definitely dogs can make their desires known — but they do not link symbolic sounds together in sentences or have anything close to language.
Better insights have come from listening to the sounds made by animals in the wild. Vervet monkeys were found in 1980 to have specific alarm calls for their most serious predators. [...]
Wade quickly surveys Cheney & Seyfarth's vervet work, their baboon work, and Zuberbühler's work with Campbell's monkeys and putty-nosed monkey. His conclusion, though, is that
Monkeys and apes possess many of the faculties that underlie language. They hear and interpret sequences of sounds much like people do. They have good control over their vocal tract and could produce much the same range of sounds as humans. But they cannot bring it all together.
It's possible to question this way of putting it. It's not so clear that monkeys and apes have "good [conscious] control over their vocal tract" or that they "could produce much the same range of sounds as humans" — for example, it's effectively impossible to teach chimps to sing, as far as I know. There's nothing crucially human or linguistic about this, obviously. Many birds are excellent vocal mimics, and dogs can be taught to produce specific pitch contours on cue. Gibbons are excellent singers, but as far as I know, their song patterns are instinctual rather than learned. Still, if you or I were given a chimp's vocal tract and a chimp's degree of cortical control over it, I bet that we could probably learn to do something approximately like talking.
And Wade makes the point that I've always thought is the most important thing about the evolution of language:
This is particularly surprising because language is so useful to a social species. Once the infrastructure of language is in place, as is almost the case with monkeys and apes, the faculty might be expected to develop very quickly by evolutionary standards. Yet monkeys have been around for 30 million years without saying a single sentence. Chimps, too, have nothing resembling language, though they shared a common ancestor with humans just five million years ago. What is it that has kept all other primates locked in the prison of their own thoughts?
He cites Seyfarth and Cheney's idea that the crucial missing ingredient is
… a “theory of mind”; the recognition that others have thoughts. Since a baboon does not know or worry about what another baboon knows, it has no urge to share its knowledge.
Again, this way of putting it may not be quite right. Cheney and Seyfarth use Premack and Woodruff's 1978 definition of theory of mind, which goes beyond "know[ing] or worry[ing] about what another … knows". In addition to attributing mental states such as beliefs, knowledge and emotions to self and others, and recognizing that the mental states of others may differ from one's own, a "theory of mind" in this sense also crucially involves the ability to use these attributed states to explain and predict behavior, and to predict how such mental states would be affected by hypothetical actions. Still, Wade's formula is short and clear and close enough for the purpose.
Wade ends with another theory, from Marc Hauser:
“For whatever reason, maybe accident, our brains are promiscuous in a way that animal brains are not, and once this emerges it’s explosive,” he said.
In animal brains, by contrast, each neural system seems to be locked in place and cannot interact freely with others. “Chimps have tons to say but can’t say it,” Dr. Hauser said. Chimpanzees can read each other’s goals and intentions, and do lots of political strategizing, for which language would be very useful. But the neural systems that compute these complex social interactions have not been married to language.
Alas, at the end of his sensible survey, Wade can't resist a final dose of Dolittlery:
“I’m becoming pessimistic,” [Hauser] said of the efforts to explore whether animals have a form of language. “I conclude that the methods we have are just impoverished and won’t get us to where we want to be as far as demonstrating anything like semantics or syntax.”
Yet, as is evident from Dr. Zuberbühler’s research, there are many seemingly meaningless sounds in the forest that convey information in ways perhaps akin to language.
It would be uncharitable to say that I sometimes feel the same way as I wander through the newspapers, so instead I'll say that this is a remarkably good article, in comparison to many that I've seen on similar topics.