Orangutan speech is shaped by social mixing, just like humans, study finds
Orangutans have their own ‘languages’ that have been shaped by social mixing, just like humans, a new study reveals.
Researchers have studied the vocal calls of wild orangutans – one of four types of great apes – in Borneo and Sumatra, Southeast Asia.
Critically endangered creatures have distinct “vocal personalities” that depend on the social groups in which they live and communicate, experts have found.
In particular, high-density groups of orangutans exhibit more “original and acoustically unpredictable” vocal calls, while low-density groups are more conventional.
Previously, animals were thought to interact using a fixed repertoire of instinctive, automated calls – but the new research suggests that’s not the case.
Social mixing shapes and transforms the “vocabularies” of monkeys, just like in humans, according to the new research. Pictured, female orangutan in Sumatra, Asia
There are four living classifications of the great apes or “Hominidae” – the orangutan, the gorilla, the pan (composed of the chimpanzee and the bonobo) and the homo, of which only modern humans remain.
There are four genera of great apes:
– pongo (Orangutans of Borneo, Sumatra and Tapanuli)
– Gorilla (the eastern and western gorilla)
– Stove (the chimpanzee and the bonobo)
– Homo (of which only modern humans remain)
Compared to other monkeys, orangutans do not make much noise and generally travel alone in the forest.
However, they also maintain social relationships. Adult males sometimes utter loud “long calls” to attract females and repel rivals.
Orangutans were the first species to diverge from the great ape lineage, but are the only great ape that uses vowel and consonant as sounds in a complex way – giving a parallel to human speech.
The study was led by Dr Adriano R. Lameira, Assistant Professor in the Department of Psychology at the University of Warwick.
“Great apes, in the wild and in captivity, are finally helping us solve one of science’s oldest puzzles – the origin and evolution of language,” he said.
“We can now begin to design a gradual path that likely led to the rise of the talking monkey, us, instead of having to attribute our unique verbal skills and advanced cognition to divine intervention or a random genetic jackpot.”
There are three species of orangutans – the Bornean, the Sumatran and the recently confirmed new species, the Tapanuli. Pictured is a male Sumatran orangutan
Orangutans are critically endangered great apes found in the wild only on the islands of Borneo and Sumatra. Pictured is a female Borneo
FACTS ABOUT THE ORANGUTAN
Orangutans are great apes, as opposed to apes, and are closely related to humans, having 97% DNA in common.
Orangutans are extremely patient and intelligent mammals. They are very observant and curious, and there are many stories of orangutans escaping from zoos after seeing their keepers unlock and lock the doors.
Height: males – about 1.5 m; females – about 1.2 m
Weight: males – 93-130 kg; females – 48 to 55 kg
Lifetime: 60 years or more
Gestation: about 8.5 months
Number of pups at birth: usually 1, very rarely 2
For the study, Dr. Lameira and his research team recorded the calls of 76 individual orangutans in six populations in the swamps and lowland rainforests of Borneo and Sumatra in Southeast Asia.
The islands of Borneo and Sumatra are the only places in the world where orangutans exist.
The researchers found that orangutan populations naturally differed in terms of population density, from groups that socialized intensely to those that were more dispersed.
In high-density populations, orangutans communicated using a wide variety of original calls, trying out many new sound variants that were continually changed or deleted.
In contrast, orangutans in sparser, low-density populations preferred more established conventional calls.
While the more dispersed groups did not experiment with so many new sounds, when they introduced a new call variation, they kept it.
Conversely, orangutans in high-density populations have been heard to continually reject new call variants they have invented.
‘Low-density populations are not very varied in their signal choices, but they have a relatively rich set of choices,’ Dr Lameira told MailOnline.
“High-density populations are more cacophonous; there is wild variation in their call variants, but very original and rapidly lost and never produced again call variants, ultimately leaving individuals with a relatively depleted base set of calls that they use regularly.
Humans and orangutans share about 97% of their DNA, according to previous research.
If orangutan call communication is affected by social circumstances, it was likely also the case with our direct ancestors, such as Homo erectus.
Dr Lameira believes studying orangutans can reveal more secrets about human ancestors hundreds of thousands of years ago.
Social influence could have steadily increased, ultimately leading to the myriad ways in which human language is determined by the people around us, as seen today.
“Many more clues await us in the lives of our closest living relatives, as long as we manage to ensure their protection and preservation in the wild,” Dr Lameira said.
“Each population that disappears will take with it irrecoverable glimpses of the evolutionary history of our species.”
The study was published today in Nature ecology and evolution.
TIMELINE OF HUMAN EVOLUTION
The timeline of human evolution goes back millions of years. Experts believe that the family tree looks like this:
55 million years ago – The first primitive primates evolve
15 million years ago – Hominids (great apes) evolved from the ancestors of the gibbon
7 million years ago – The first gorillas evolve. Later lineages of chimpanzees and humans diverge
5.5 million years ago – Ardipithecus, the first “proto-human” shares traits with chimpanzees and gorillas
4 million years ago – Apes like the first humans, the Australopithecines appeared. They had a brain no bigger than that of a chimpanzee, but other more human characteristics
3.9 to 2.9 million years ago – Australoipithecus afarensis lived in Africa.
2.7 million years ago – Paranthropus, lived in the woods and had massive jaws for chewing
2.6 million years ago – Hand axes become the first major technological innovation
2.3 million years ago – Homo habilis would have appeared for the first time in Africa
1.85 million years ago – The first “modern” hand appears
1.8 million years ago – Homo ergaster begins to appear in the fossil record
800,000 years ago – The first humans controlled fire and created homes. Brain size increases rapidly
400,000 years agooh – Neanderthals begin to appear and spread across Europe and Asia
300,000 to 200,000 years ago – Homo sapiens – modern humans – appear in Africa
54,000 to 40,000 years ago – Modern man reaches Europe