Animal calls 'more like language'
Dr Dolittle's ability to talk to the animals may have at least some scientific basis, according to new research that challenges the uniqueness of human language.
An analysis of vocalisations made by animals ranging from finches to whales and orang utans has shown they share more in common with human speech than was previously thought.
The findings threaten to overturn accepted ideas about the apparent randomness of animal noises - one of the key differences believed to separate humans and other species.
They suggest there may be a "missing link" step on the evolutionary path from animal communication to human language that has not yet been identified.
US lead scientist Dr Arik Kershenbaum, from the National Institute for Mathematical and Biological Synthesis in Knoxville, Tennessee, said: "Language is the biggest difference that separates humans from animals evolutionarily, but multiple studies are finding more and more stepping stones that seem to bridge this gap.
"Uncovering the process underlying vocal sequence generation in animals may be critical to our understanding of the origin of language."
Many animals produce apparently complex sounds. The mockingbird, for instance, can mimic more than 100 other birds' songs, while the hyrax, or rock badger, produces a range of wails, chucks and snorts that define its male territory.
But traditionally animal calls were thought at a fundamental level to lack the intelligent intricacy of human speech.
Until now, they were all assumed to involve a simple structural system known as the "Markov" process.
"Markov" vocalisations are made up of sequences that can easily be predicted by listening to a finite number of preceding elements.
Animal calls are said to be restricted by rigid Markovian rules of "regular" grammar that operate a little like a washing machine's automation programme.
Human language, in contrast, employs what are called "context-free grammars" that apply the same set of rules in widely different ways, making it much less predictable. It is non-Markovian.
Scientists conducting the new study looked for evidence of Markovian dynamics in the vocalisations of seven species - chickadees, finches, bats, orang utans, killer whales, pilot whales, and hyraxes.
They found little evidence of Markovian processes in animal calls. Instead, the sounds made by animals were more consistent with statistical models relevant to human language.
The researchers wrote in the journal Proceedings of the Royal Society B: "Our data suggest that non-Markovian vocal sequences may be more common than Markov sequences, which must be taken into account when evaluating alternative hypotheses for the evolution of signalling complexity, and perhaps human language origins."