Monkeys are pretty quick on the uptake, but they are never going to be able to talk proper, concludes a St Andrews psychologist today.
Dr W Tecumseh Fitch, who is also trying to teach a seal to talk at the Scottish university, carried out research on tamarin monkeys with a colleague at Harvard to establish whether they could grasp the rules of grammar.
He and Professor Marc D Hauser found the monkeys could recognise simple patterns - like human babies - but didn't recognise the more complex patterns involved in human speech.
Their paper, Computational constraints on syntactic processing in a nonhuman primate, in the latest issue of the journal Science, provides the clearest example to date of a "cognitive bottleneck" which could help refine our understanding of how human language evolved.
Dr Fitch explained: "Grammar involves rules that allow a limited set of sounds to combine in an unlimited number of ways. These rules can be simple, controlling sequential order, or more complex, generating hierarchical structure. For example, 441334476161 might just be a list of numbers, but +44 1334 476161 is interpreted as a phone number with higher order structure (44 is the UK country code, 1334 is the exchange for St. Andrews, etc).
Since his arrival at St Andrews at the beginning of the academic year, Dr Fitch has recruited undergraduates to hang out with a seal pup to see if it will pick up some phrases. Seals are known to be able to imitate sounds and he was inspired by a talking seal called Hoover, which had been brought up by a Maine fisherman and later regaled visitors by saying "move over, Hoover" in a broad Maine accent.
In their monkey research, Dr Fitch and Prof Hauser showed that their monkeys were capable of understanding a simple grammar rule at the "finite state grammar" (FSG) level, which involves simple sequencing. However, the monkeys failed to grasp a crucial grammatical component of all human languages, the more complex hierarchical structures governed by phrase structure grammar (PSG). An example of such structure is the 'If...then' rule where the words 'if' and 'then' are linked and dependent upon each other, despite being separated by a large number of words.
At the Harvard primate cognitive neuroscience laboratory the two researchers played recorded examples of the two types of grammar to cotton-top tamarins, a new world primate species that has previously demonstrated successful discrimination of linguistic stimuli. Following this initial exposure, the tamarins heard a series of recordings, some of them violating the rules of Fitch and Hauser's grammars. When the animals perceived such inconsistencies, they tended to look at the speaker playing the sounds - something both animals and infants do when they detect something new. Based on whether the tamarins looked at the speaker, the researchers determined that the animals were able to perceive violations of the simpler FSG grammar, but did not take note of infractions of the more complex PSG grammar.
Dr Fitch explained: "Human language is a system which allows us to communicate about anything, with no obvious limits to subject matter, complexity or level of detail. In addition to the food, predators and sex that many other species communicate about, we can talk about quasars, the Roman empire, morality or mathematics."
He continued: "This technique can easily be applied to any other species, and we hope that it will quickly be tried with many others. Songbirds, and great apes like chimpanzees or gorillas, will be of particular interest. And of course it will be important to find out when this ability appears in human development. Do newborn babies already have the ability to perceive phrase structure, or is this something that doesn't mature till two years or later, when they start producing grammatically complex utterances?"
