For many years, researchers have been exploring the question of why humans are the only primates that can talk. While our primate cousins have shown time and again that they are more intelligent and capable than we previously thought in terms of cognitive functions and tool usage, their lack of vocal ability has remained puzzling, writes the BBC.
A new study comparing different primate species’ brains has given insight into how our brains are “wired” for speech ability. The results of the study showed that species with wider vocal ability, or those that can produce a greater variety of speech sounds, have a larger region of their brain dedicated to the physical voice apparatus.
Instead of the previous conclusion that humans are capable of language simply because we are more intelligent than other primates, scientists are discovering that our speech capabilities have evolved because our brains have rewired themselves to be better able to control our voice apparatus.
This conclusion makes sense when comparing the actual voice anatomy of humans and other primate species. The physical machinery in our throat, including our vocal chords and tongue, that allow us to turn air into sound is very similar to that of other species. This fact has begged the question as to why only humans can speak.
Dr. Jacob Dunn from Anglia Ruskin University in Cambridge proposed an answer to this question, reports the BBC.
“That’s likely due to differences in the brain but there haven’t been comparative studies across species.”
Dr. Dunn and his colleagues set out to test the idea that brain differences account for our vocal abilities. They started out by ranking 34 species based on the number of different distinct calls they make in the wild. For example, the proboscis monkey ranked low with just four distinct calls while the ape family ranked towards the top. In fact, bonobos led the ranking, with 38 distinct calls.
The scientists found that the apes had more cortical association areas in their brains, or areas designed to receive sensory information and decide what to do with it. Additionally, apes had larger regions of their brain designated to control tongue movement, which suggests that while our cousins may be able to develop and understand complex language, they are unable to reproduce it simply because they don’t have as much voluntary control over their vocal apparatus.
The findings of the study put us one step closer to understanding one of the crucial features of humanity — our ability to use and understand complex language.
Dr. Dunn spoke once again on the matter.
“Understanding how the brain is wired in these different primate species and how that relates to vocal ability could go some way to helping us understand how the complex voluntary control over vocal production may have evolved in humans.”
Professor Zanna Clay from Durham University cautioned against jumping too quickly to conclusions about the findings of the study and provided some insight into the direction researchers can move in from here, writes the BBC.
“We do not even really understand how the primates themselves classify their own vocal repertoires – this needs to come first before correlations are made. We [also] know that many primates and other animals can escape the constraints of a relatively fixed vocal system by combining calls together in different ways to create different meanings. The extent to which call combinations might map on to [brain anatomy] would be a promising avenue to explore.”