Orangutans, the most arboreal of the great apes, have more variety in their calls than their African cousins.
While being closely related to humans, African apes are not expected to have the same calls as us. The large and varied inventories of calls from tree dwelling apes like orangutans seem to have driven great apes to develop different vocal repertoires, rather than the ground dwelling apes. Our own evolutionary ancestors might have lived a more tree-dwelling lifestyle, according to the study.
Human spoken language is composed of vowels that take the form of voiced sounds, whereas voiceless sounds take the form of vowels.
The study of non-human primate's speech and language has been going on for decades. The calls of non-human primate are mostly made with vowels. "This raises questions about the origin of the vowels that make up the world's languages," said Dr. Adriano Lameira.
The connection between primate laryngeal anatomy and human use of vowels is the main focus of existing theories of speech evolution.
It's not clear how voice-less, consonant-like sounds became a fundamental component of every language spoken around the globe.
In order to understand the origins of human speech and the root cause of consonant sounds in the human lineage, Dr.
Similar to any spoken human language, great ape calls have both vowels and consonants. Great apes use different types of sounds in nature.
Chimpanzees and bonobo don't use a lot of calls.
Some gorilla populations have been found to use a particular call that is similar to a vowels. Chimpanzees produce one or two calls that are related to a single behavior, but these calls are rare in other populations.
Humans do with speech what wild orangutans do with calls. A rich display of smacking, clicks, kiss-sounds and splutters can be found in their vocal range.
Professor Lameira has observed orangutans in their natural habitat for the last 18 years and says their arboreal lifestyle and feeding habits could explain the complexity and sophistication of their calls.
Apes are accomplished foragers. It can be difficult to access protected or hidden foods like nuts or plant piths with either hands or tools. Orangutans are able to access their food up in the canopy because at least one of their limbs is used to provide stability among the trees.
orangutans can use their mouths as a fifth hand to hold food and maneuver tools because of this limitation. Orangutans are known for peeling an orange with just their lips so their fine oral neuro- motoric control is far superior to that of African apes, and it has evolved to be an important part of their biology.
According to the research, living in trees could have been a way for our ancestors to adapt to new sounds.
The paper was published in Trends in Cognitive Sciences.
There is more information about the origin of speech.
Journal information: Trends in Cognitive Sciences
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