Animal speech was previously believed to be very random. However, a recent study found that many creatures may have more complicated "speech" patterns than once thought. Scientists have found that the calls of many animals, from whales to wolves, may contain more language-like structure than previously thought.
For the study, researchers analyzed the vocal sequences of seven different species of birds and mammals and found that the vocal sequences produced by the animals appear to be generated by complex statistical processes, more akin to human language. The researchers also noted that some species, like the mockingbird, can mimic over 100 distinct song types of different species. However, though this study confirms language-like characteristics in the vocalization on animals and birds, the study was not able to define and identify the complexity.
In fact, scientists have long assumed that the sequence of animal calls is generated by a simple, random process, called a "Markov process." This means that the vocal elements are dependent only on a finite number of preceding vocal elements, making the process fairly random and far different from human language. The Markov process is the most common model used the examine animal vocal sequences, which assumes that a future occurrence of a vocal element is entirely dependent by a finite number of past vocal occurrence. However, the new study no evidence for a Markovian process after using mathematical models to analyze the vocal sequences of chickadees, finches, bats, orangutans, killer whales, pilot whales and hydraxes. In fact, most of the vocal sequences were more consistent with models that are more complex than Markov processes.
"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," said lead author Arik Kershenbaum, a postdoctoral fellow at the National Institute for Mathematical and Biological Synthesis, in a press statement.
The findings suggests there may be an intermediate step on the evolutionary path between the regular grammar of animal communication and the context-free grammar of human language that has not yet been identified and explored.
The study was published online in the journal Proceedings of the Royal Society B.
