No great apes can speak as we do, and as they do in the film, because they lack the physical apparatus – the organs within the vocal tract, such as larynx muscles and vocal cords, cannot be moved as quickly or coordinated as well as in humans. However, that does not mean that they cannot understand us or learn to use sign language.
All four kinds of great apes have been taught to communicate this way in captivity. The current star students are Koko, a lowland gorilla, and Kanzi, a 34-year-old bonobo.
Koko was born at San Francisco Zoo in 1971and has been trained to a high level of proficiency in American Sign Language. She has a vocabulary of more than 1,000 signs and understands about 2,000 words of spoken English.
Kanzi was the first ape to acquire language by being exposed to it from a young age. He knows the meaning of up to 3,000 English spoken words and communicates using an electronic lexigram (geometric symbol) touchpad.
Watch Kanzi in action, displaying incredible understanding of spoken commands, and learn more about efforts to teach apes language: https://www.youtube.com/watch?v=QBlDGX95eys
Kanzi demonstrates the use of the lexigram for reporter Lisa Ling https://www.youtube.com/watch?v=jKauXrp9dl4
Scientists, including Dr Jane Goodall, have described apes displaying a wide range of complex emotions once thought to be uniquely human.
Chimps in particular have very expressive faces, with similar musculature to our own, revealing joy, grief, fear and anger, and Dr Goodall believes that they possess an “almost human-like enjoyment of physical contact”.
Orangutans are believed to have a keen sense of humour, while young bonobos in a sanctuary have been observed offering hugs and kisses to calm companions in distress.
Gorillas have tried to intervene to protect a scared young male from the troop’s silverback in a show of empathy, while Koko (see above) expressed sadness at the death of her pet cat – see https://www.youtube.com/watch?v=CQCOHUXmEZg
Ayumu the chimpanzee has made headlines around the world for his ability to beat humans on memory tests, in both speed and accuracy. Researchers at the Primate Research Institute in Kyoto, Japan, pit chimpanzees against human adults in tests of short-term memory, flashing up numbers in random places on a computer screen, then blanking them out. Ayumu can point out the correct order and location of the numbers in less than half a second. Impressive!
See Ayumu in action here http://www.bbc.co.uk/nature/16832379
Caesar and his buddies daubing their faces in war paint is not the first time apes have sported a spot of rouge.
The mirror test is used to determine if an animal can recognise themselves, which suggests a fairly sophisticated sense of self. The experiment involves marking an animal with a paint spot in a place that it can only see by looking at its reflection, such as on its face. If the animal tries to touch the mark while facing a mirror, it suggests that the animal recognises itself.
Human children gain the ability to pass the test around 18 months of age.
Interestingly, while chimps, bonobos and orangutans pass with flying colours, gorillas were thought to fail until Koko (see above) tried her luck. It is believed that she overcame her species’ natural avoidance of eye contact – which is interpreted as an expression of aggression – to look at herself in the mirror, suggesting that gorillas can recognise themselves if they can conquer their natural instincts.
5. Tool use
Tool-making was considered a uniquely human ability until the 1960s when Jane Goodall observed chimpanzees using a twig to "fish" for ants in Gombe, Tanzania – the first documented case of wild chimps making and using tools.
When their cousins in West Africa's Ivory Coast were observed using "hammers" to crack open nuts, it was apparent that chimps were capable of the higher intelligence required to adapt what nature provided to achieve a specific goal.
Since then, chimps in the Democratic Republic of Congo have been seen using a variety of tools to extract termites from their nests. These "tool kits" are among the most complex ever observed in wild chimp populations.
In 2007, scientists described chimps in Senegal fashioning sticks into spears to hunt other mammals – lesser bush babies, small nocturnal primates, hidden deep in tree holes.
Watch young chimps learn how to use tools to get their food https://www.youtube.com/watch?v=CnOu0_DATxY
Watch the first evidence that wild gorillas use tools to cope with their environment https://www.youtube.com/watch?v=GcqNzl49csA
Culture is another trait that’s no longer unique to humans. Researchers studying orangutans have demonstrated that great apes share our ability to learn socially and pass down certain behaviours through generations.
Studying six populations of orangutans in Borneo and Sumatra, Indonesia, researchers identified 24 behaviors that show evidence of being culturally transmitted. Many of the behaviors involve tool use – using sticks to dig seeds out of fruit, to poke into tree holes to obtain insects, or to scratch – or using leaves as napkins or as gloves to protect against spiny fruit.
Other traits that show evidence of cultural transmission include play and different forms of communication, such as blowing “raspberries" or making "kiss-squeaks" using leaves to amplify the sound.
Conclusion Great apes are smart, they’re sensitive and they’re self-aware. It seems that we humans aren’t so special afterall…