How Human are Gorillas?

Researchers are often struck by gorillas’ apparent humanity. Taking into account our genetic similarities of 95% or above, there has been a long debate about how close humans and gorillas really are.

George Schaller — one of the world’s most preeminent field biologists —travelled to the Virunga Volcanoes in the 1960s, at age 26, to study and live with mountain gorillas. He, together with Dian Fossey who followed his footsteps, was a predecessor in changing the perception about gorillas as violent monsters. He wrote the following in his book

“The mind of the gorilla has its own mysterious paths that even the most persistent observer may find difficult to trace … Yet the apes are not under the total grip of their instincts. Learning and tradition play an important role in their lives, a role that is difficult to assess in the wild, because each youngster gradually and unobtrusively learns the things that help it fit into its group and environment. Knowledge of food plants, route of travel, the proper way to respond to vocalisations and gestures—these, and many other aspects, are undoubtedly part of the gorilla’s tradition, handed down as a result of individual experience from generation to generation and constituting a rudimentary form of culture.”

Nevertheless, he believed that the ape’s brain had evolved to, or just over the threshold of insightful behaviour. He argued that there was no selective pressure for them to evolve more sophisticated brain power and concluded that it was an evolutionary dead-end.

In more recent times there is less certainty and there are major question marks over the validity of the above opinion. It is now questioned whether there is always a relationship between selective pressure and evolution, i.e. is intelligence an evolutionary progression or a freak aberration?

Scientific opinions of the 1960s have been constantly revised to reflect the changing dynamics of gorilla troop formation over time. There is no set troop composition; each develops its own hierarchy and pattern of relationships that develop over time. There is greater variety and subtlety in gorilla behaviour and cognitive processes than was first thought.

According to some researchers, gorillas, like other great apes, have individuality, can laugh, grieve, have ‘rich emotional lives’, develop strong family bonds, and can make and use tools. They can have individual colour preferences. In general, gorillas are believed to have ‘cultures’ in different areas revolving around different methods of food gathering. They can think about the past and future; they use past experiences as a guide for decision-making, which often have a future element. 

No one who looks into a gorilla’s eyes – intelligent, gentle, vulnerable – can remain unchanged, for the gap between ape and human vanishes; we know that the gorilla still lives within us. Do gorillas also recognise this ancient connection? 

George Schaller

From Gorilla Gestures to Gorilla Music

Their rich emotional lives are also exemplified by their vocalisations, physical gestures and movements that they use to communicate with each other. Gorillas are always aware of group activities and take their information and signals primarily from this source. Sound, especially contact grunts, is very important for group cohesion and coordination in an environment where members of a group often can’t see each other for long periods.

While gorillas can be noisy, these sounds are not necessarily symbolic but purely express emotion, i.e. when content, anxious or angry. Some vocalisations are warnings, which cause the troop to congregate around the leader for further instructions, imparted physically.

They have at least 25 vocalisations including roars, grunts and growls. There are also variations in pitch, intensity and pattern, which also provide context. A few lowland individuals in captivity have been taught a subset of sign language, like chimpanzees.

Walter Baumgartel records one evening with guests:

I encouraged Reuben to show off a little and entertain our guests with his star act, ‘Old Silverback’, a clever imitation. He started shyly and quietly but soon forgot himself, hooting and clicking full blast. Instantly from up the hill came the response, “hu, hu, hu, hu,” in high falsetto, followed by the wooden “click, click, click, click”. A cordial to and fro went on for a while between original and imitator, then an infant, apparently disturbed in its sleep, began to whimper like a puppy that had not yet learned properly how to bark. Eventually the mother’s voice, trying to calm the child joined in.

Even more interestingly, Bill Weber and Amy Vedder Weber found that around abundant quality food:

One individual would start a low rumbling sound, breathing loudly in and out in a modulated tone. This might remain a solo performance and last no more than a minute. Often, however, others would join in, adding gender- and age-specific basses, baritones, tenors and sopranos to the mix. The result was a chorus of intertwined melodies, rising and falling in natural rhythm that might continue for several minutes: a gorilla Gregorian chant in the Virunga cathedral.

Pictures by Molly Feltner