With welcoming, albeit rather hairy, arms outstretched, their joy at seeing one another again is plain for all to see.
The photographs in yesterday’s Mail of two gorilla brothers hugging each other in delight at being reunited after three years apart are deeply moving. The affection is unmistakeable. They react just as human brothers might.
It’s heartwarming but not at all surprising to me. Many years spent working in the wild with these beautiful animals and their close cousins the chimpanzees have convinced me that the great apes have a range of powerful emotions identical to our own.
Gorilla brothers Kesho and Alf greet each other like old friends after three years apart
Siblings Kesho, 13, and Alf, 9, were separated when Kesho was sent to London zoo as part of a breeding programme
I have watched chimps displaying every kind of intense feeling — frustration, grief, anxiety, joy, playfulness — and all sorts of emotions in between.
For Kesho and Alf, who grew up together at Dublin Zoo and were reunited in Longleat Safari Park in Wiltshire (they were separated when Kesho was sent to London Zoo to breed), those feelings were patently much more than friendship — this was the bond of brotherhood.
I don’t know why anyone would imagine that humans are the only animals to experience these strong, noble emotions. Our feelings have evolved over thousands of generations, going back to the common ancestor we share with gorillas and chimps.
Kesho and Alf are said to be markedly different characters. Kesho is the dominant animal in his group of four, which is a sort of gentlemen’s club made up entirely of young males.
He’s a 13-year-old silverback lowland gorilla, weighing 220kg (35st) with a massive head and an impressive cape of grey hair across his back and shoulders that signifies senior status.
Alf, four years younger and half his brother’s weight, is more shy and cautious. He’s a ‘black back’ because he’s younger and hasn’t developed his big brother’s colouring. His keepers say he is a follower, not a leader.
The two gorillas are very different, just as human brothers often are, but they plainly appreciate each other’s qualities. It’s not just that they grew up as playmates — it’s an instinctive family bond that is crucial to survival. Knowing who your friends are could be the difference between life and death to gorillas in the wild.
They live in small, social groups of around a dozen, and sometimes have to defend their territory from invasion by other apes, especially aggressive males looking for food or a mate.
For five years I studied chimps’ communication, living close to a colony of about 30 in Tanzania, and I was able to observe and record sibling relationships as they matured.
Great apes have a wide range of communication but it obviously doesn’t include the kind of fine-tuned, introspective language needed to talk about their feelings.
The brothers recognised each other in an instant as they were reunited at Longleat safari park, Wiltshire
So we can’t say for certain that Kesho and Alf missed each other for three years with the same aching sense of loss that humans experience. But the real question is: why wouldn’t they? Indeed, how could relationships persist for 50 years if they didn’t?
I have seen chimps reunited with loved ones who not only embraced each other but kissed, almost as we do. I’ve even been lucky enough to be welcomed back after an absence by a chimpanzee who, it seemed to me, was pleased to see me again.
His name was Freud and I had been following him for a good many months. For a while I didn’t see him but one afternoon I observed him gathering fruit in a tree, high above me. And he observed me. He didn’t call out or show immediate recognition. He was much more relaxed.
When he’d picked enough fruit he came down the trunk, sat next to me and looked into my face. There was an expression that seemed to say: ‘Hey — there you are! How are you doing?’
Sceptics might reject such anecdotal evidence, but there is clear laboratory proof that primates can recognise human individuals and respond with unique behaviour.
One ape, called Nim Chimpsky, was in a language study at New York’s Columbia University and was separated from a favourite human trainer for more than a year.
When they met again, Nim used sign language to say the scientist’s name and ask to play a game they used to enjoy together.
No doubt about it: Nim recognised his friend.
The animal kingdom has evolved such a phenomenal variety of cues for species to recognise one another. Dogs use scent, for example — and so do their ancient ancestors. One of the most incredible moments of my career was to be greeted by a young timber wolf at Longleat who had been hand-reared and who rubbed herself over my legs to mark me with her scent — and signal I was part of her pack.
Dolphins identify themselves and their families with a variety of whistles. Seabirds such as kittiwakes can pick out individuals among a shrieking mass of thousands by their unique cries and remember their mates after many months apart.
Gorillas don’t appear to have significantly better hearing or smell than us. Instead they do what we do — look at faces.
Every gorilla face is different, especially the nose: researchers record each individual ‘noseprint’, as unique as a human fingerprint.
It’s highly significant that, like us, our close cousins don’t have full facial hair. This enables them to recognise individual features more clearly, and probably helps them to signal subtle emotions
Dr Charlotte Uhlenbroek, pictured in 2000 with mountain gorillas in Rwanda, says it’s obvious that gorillas share deep emotions with humans as well as 98 per cent DNA
Humans can display up to 7,000 feelings on their faces, with minute twitches and contractions of the muscles. These are much easier to spot when there is no hair to cover them up.
When I first arrived in Tanzania I thought I would never be able to tell apart 30 different chimps. But it was soon second nature, and once I learned the skill it was easy to apply to chimps from other groups.
There is a part of our right brain lobe that appears to be dedicated to facial recognition. It’s reasonable to theorise that gorillas would have this too.
We can recognise friends even when parts of their face change — a new hairstyle, different make-up or significant weight loss. Gorillas apparently share this ability. They spend a lot of time sitting and eating, and when they are together they look at each other, sizing one another up.
In Tanzania I was constantly moved and fascinated to see emotions that I knew well in myself.
One young chimp, hardly more than a baby, became very distressed one day — she sat with her hands over her bowed head, pulled up her knees to her chin and rocked back and forth. She was miserable because her mum was weaning her. She wanted the comfort and nourishment of her mother’s milk, and felt rejected.
Another young male punched the ground repeatedly when an adult brushed him aside during a courtship ritual. His emotions were palpable — he felt humiliated, outranked, belittled and frustrated.
Any human teenager would know exactly what that young ape was going through.
It’s that rush of empathy that makes the photos of Kesho and Alf so touching. We are looking at some of our closest relatives: gorillas share 98 per cent of our DNA, our genetic coding. And it’s obvious that they share much more than that.
Deep emotion is invisible, intangible . . . but whatever it is, our cousins have got it too.