Although chimpanzees are not able to talk they do have a language and are able to communicate. A recent study suggests that chimps may have what it takes to be able to evolve language by linking sounds and levels of brightness, similar to what is called synaesthesia in humans. This association could offer an explanation as to how our early ancestors evolved from grunts to words.

In human synaesthetes there is a connection between different senses, for instance someone may associate numbers by certain colors, or have a specific taste when they hear a certain piece of music. It is not as unusual as you may think. “The synaesthetic experience is a continuum,” explains Roi Cohen Kadosh of University College London. “Most people have it at an implicit level, and some people have a stronger connection.”

Vera Ludwig and associates, from the Charite University of Medicine in Berlin, Germany, have been able to show for the first time that chimpanzees also make cross-sensory associations, suggesting they evolved early on.

In their study the team flashed either black or white squares repeatedly on screens in front of six chimpanzees and 33 humans for 200 milliseconds at a time. Each were to indicate whether the square was black or white by touching a button of the right color. In the background, a randomly played high or low-pitched sound was played.

Both the chimps and humans were better at identifying white squares when they heard a high-pitched sound, and more likely to correctly identify dark squares when played a low-pitched sound. Their performance was poor when the sounds were swapped – humans were slower to identify a white square paired with a low-pitched noise, or a black square with a high-pitched noise, while the chimps’ responses became increasingly inaccurate.

These results offers credence to the belief that cross-sensory associations are not learned behavior, but innate. V. S. Ramachandran and Edward Hubbard of the University of California at San Diego, asked adults in 2001 to refer to the words “kiki” and “bouba” to a spiky shape and a rounded shape. Nearly all labeled the spiky shape “kiki” and the rounded one “bouba,” regardless of culture or language. They found that children also find it easier to learn the names of rounded objects when they associate their names with rounded vowels.

Ludwig surmises that an inborn ability to link sounds and sights may have evolved because it was advantageous to our ancestors. “If two individuals both think a word that contains a high pitched vocal fits a lighter object, then it would be easier for them to develop a common vocabulary and to understand the words that others use,” she says.

Ramachandran agrees, that innate associations would have played a crucial role in language evolution. “These experiments suggest there were non-arbitrary similarities between sounds and sights which could have helped get it started,” he says.

If this was the evolution of language, then why aren’t chimpanzees able to speak? According to Morten Christiansen who studies language evolution at Cornell University in Ithaca, New York, “Crosstalk between the senses was likely just one part of the evolutionary toolkit.” Humans no not share all the same features of other primates, such as the ability to process information in sequence, which could explain why our ancestors were able to develop speech while other primates could not.



About the author:

Ron White is a two-time U.S.A. Memory Champion




New Scientist – Chimp brains may be hardwired to evolve language:

Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1112605108