The death of the famous gorilla, Koko, at the age of 46, after years of learning to speak through her hands, may make us pause a bit to consider just what it means to be human.

In a world that seems to insist upon a concerned or even angry contemplation at what seems to be an unending stream of dreadful iniquities, wars, civil commotions, natural calamities, and long-term global environmental catastrophes, sometimes it is also important to pause over a much smaller event that helps bring some wonder to the human heart and soul.

On 19 June, Koko passed away in San Francisco, after a very long life (at least for a gorilla) dedicated to scientific research into communication and behavioural theory. She also had a well-pronounced tendency of showing kindness towards other smaller creatures of the feline variety. There were no immediate family survivors and an announcement of memorial arrangements has not yet been forthcoming.

Koko was born 46 years ago to gorilla parents who had been serving out their days in placid captivity. Koko was originally named Hanabi-ko, Japanese for “child of fireworks”, by virtue of her birth on 4 July, but her name was quickly and mellifluously shortened to Koko, and it was by that name that the whole world came to know her.

Koko, it turned out, had an unexpected, and seemingly unreasonable, even impossible – according to some zoologists – talent for communication. Not just the usual run of gorilla grunts and other vocalisations that had increasingly been documented by naturalists, but she became capable of communication through a modified version of Amslan – American Sign Language.

Following an illness, as a youngster, Koko was sent to a primate research facility attached to Stanford University where she was introduced to Francine Patterson, a young scientist there, who cared for Koko. (Koko and Patterson eventually moved on to the Gorilla Foundation in Woodside, California after Patterson’s Ph D was finished.) Until that felicitous partnership began its run, it was generally understood, for the most part, that “speech’ was almost certainly a uniquely human talent, not unlike the usual pronouncements by scientists of a couple of generations earlier who had argued that tool making (and even the conceptualising of such a thing) was similarly a uniquely human attribute.

The latter issue has been significantly resolved in favour of the animals, however, by discoveries that some rather bright bird species such as crows make use of stones to break up food located inside shells, and that chimpanzees similarly have a variety of techniques for using rocks to crack nuts, as well as sticks to extract those presumably tasty ants and termites from their respective nests. Meanwhile, orangutans are now also known to use crumpled leaves to slurp up water.

But creating or fostering real communication still seemed to be a barrier between humans and other animals, even if we accepted the idea that animals could communicate. (We will leave aside for this discussion the views of all those people who are absolutely convinced that their dog, their cat, their ferret, or even their koi goldfish really can read their thoughts, let alone what, precisely, those whale whistles and subsonic sounds from elephants may mean.)

But perhaps the old but still potent shadow of controversy over the horse, Clever Hans, still has constrained researchers from making exaggerated claims about brain power or capabilities on behalf of animal interlocutors. This was two centuries after that supposedly mathematically inclined horse (and his owner) were unmasked as frauds, but only after having been lauded across Europe as an example of some superior equine intelligence. The horse in question had presumably provided answers to arithmetic problems via hoof taps, after the questions were posed to him. But, actually, unmasked, it turned out the answers had been provided on the basis of some subtle, near-invisible cues given by Hans’ owner, thereby being an early, and very public, example of operant conditioning and how it might mimic something else.

But then along came the revolution in the study of primates (other than humans) in their natural environments, as a possible avenue into gaining insights about early hominid society and capabilities that could possibly amplify the new fossil discoveries. Paleontologist Louis Leakey, working with his wife, Mary, and others of his famous hominid fossil hunting team in Kenya and Tanzania, conceived the idea of recruiting several volunteers – women, because of a presumed greater level of patience and empathy – to spend long days, weeks, months, and ultimately years to study gorillas, chimpanzees, and orangutans. The research would be carried out to gain insights into those primate societies and, hopefully, glimpse their secrets. Leakey eventually selected Dian Fossey for gorillas and Jane Goodall for the chimps in Africa, and Biruté Galdikas for the Indonesian island of Kalimantan/Borneo to work with orangs.

The ongoing discoveries about the range of these astonishing creatures – their uncanny resemblance to human beings  in some ways, as well as the very real differences that have been documented – helped encourage other kinds of research, including the question of speech and range of cognition among the pongids ( the great apes). The physical architecture of the apes’ would-be vocal equipment – tongues, lips, larynx, throat – seemed to preclude human-style speech, even if their minds were in the game. But what about another way of communication?

Credit Stanford University researcher Francine Patterson for picking up and expanding on bits of earlier research that had tried teaching sign language or symbols drawn on boards to chimps. She began working with Koko, using a modified version of that signing language. (But maybe we need to give some credit to Koko for being one really smart gorilla as well.) As the years passed, Patterson reported that Koko had gained a mastery of some 2,000 words (for comparison, note that the Voice of America’s Special English vocabulary for broadcasts to people still learning English is only 3,500 words). Moreover, Koko seemed to have the capability to express thoughts and ideas, beyond simply the capability of signing the equivalent of a point-and-name level of things. She apparently had gained some abstract thought and some grammatical structure in her signing too.

Still, some researchers remained unconvinced of Koko’s real control of actual language, rather than just our old friend, a sophisticated version of operant conditioning. After all, it was noted by some that the psychologist BF Skinner had perfected such training with pigeons to get them to do all kinds of behaviours alien to pigeondom. Then he had drawn on those lessons and techniques to train bombardiers for the US military, drawing on the realisation that if you could train pigeons to do unbelievable things, surely you could train air crews with cleverly calibrated and administered rewards and punishments. And if that were true, perhaps Patterson had been doing this with Koko, perhaps without even knowing she was doing it. A kind of unconscious, innocent echo of the pedagogy directed towards Clever Hans, but this time with a big cuddly teenage gorilla.

But although she was learning her lessons, her handlers and teachers felt Koko was lonely and so they introduced her to a Manx kitten at their research facility – and Koko bonded with the little creature almost instantly (and vice versa). Cognitive ability? Koko named the feline: “All Ball” via signs for the cat’s tendency to curl up in a, well, a tight little ball. But tragedy struck. All Ball took to exploring the outdoors beyond the enclosure and was killed by a passing motorist. When Koko was informed of the tragedy, she had signed, “Sad, bad sad.” Then, according to the Guardian, “when the [first] feline was hit and killed by a car in 1984, Patterson was filmed asking Koko what had happened. Koko signed in response: ‘Cat, cry, have-sorry, Koko-love.’”

Cognition? Logic? Awareness of others and an ability to abstract that information into a new thought? Seemed so.

Over time, Koko gained the companionship and trust of two new kittens which she named Smokey and Lipstick. Then, years later, she paired up with two additional cats, Miss Gray and Miss Black, each named respectively by Koko for what they looked like, of course.

Moreover, Koko had the ability, apparently, to demonstrate a sufficient level of self-awareness that she could recognise herself in a mirror and then, more recently, to take a selfie with one of her cat companions. Beyond being a cat fancier, as she stayed at the gorilla preserve, Koko met and befriended a variety of celebrities, including Robin Williams, Fred Rogers, Betty White, William Shatner, Flea, Leonardo DiCaprio, Peter Gabriel, and Sting.

Following the death of her first pet, the Guardian noted:

“Further anguish was to come for Koko following the death in 2014 of the actor and comedian Robin Williams. Koko and Williams had struck up a firm friendship in 2001, with the two filmed laughing and cuddling together. The Gorilla Foundation said Patterson told them Koko was ‘quiet and very thoughtful’ when told of Williams’s passing,” when we learned of his death, as were most of us, right?

Along the way, Koko was the subject of several cover stories in National Geographic, as well as with dozens of other print media stories, coverage on television, and even a best-selling children’s book, Koko’s Kitten. Like so many others who discovered Koko’s story, my own family was fatally captured by the tale of the gentle gorilla and her tiny feline buddy, and we literally wore out our copy of Koko’s Kitten, reading it so often. Still, some critics of Koko’s larger story pointed to the relative paucity of scholarly publications on Koko’s breakthrough communications triumph, and far too much popular coverage of the clever gorilla, all as kind of evidence that all was not as it was hyped up to be. Clever Hans lives on?

But such reactions seem somewhat churlish. If we have learned anything from all the other primate research, it is that primates are a lot more capable of surprises than had been expected. Individually they have different skills and personalities – and some were just plain smarter than others were. They had real qualities in the emotional intelligence realm as well. And Koko had managed to gain the love of other living human and feline creatures, as well as the affection of millions who only knew her via television and print. Along the way, her educational attainments have helped push out the boundaries of what we understand about the capabilities and talents of other primates, besides humans, of course. And this understanding may also be pushing outward on the limits of what we believe may also have been true of our own hominin ancestors, even if we are unable to experiment with them and Amslan. All of that, in turn, is influencing the scientific conversation and inquiry about the origins of speech.

“Sad, bad sad” indeed, Koko’s passing. In contemplating this news, I also began to think about the movie that will inevitably come from this poignant story. One wonders if some clever producer is not already in conversation with Andy Serkis to be in a filmic version of Koko’s life. After all, that actor has already become what is probably the world’s best known cinematic pongid – Caesar of that Planet of the Apes franchise, besides the nearly indestructible character of King Kong from several cinematic portrayals. And who else but Meryl Streep as Serkis’ co-star? This could be a great flick. DM