A new BBC1 documentary reveals the difficulties of living with a chatty gorilla for 44 years. American animal psychologist Dr Penny Patterson has spent more than four decades teaching a gorilla called Koko to communicate via human sign language.

What started as a short-term research experiment in 1972 has taken over Penny’s life – Koko has twice featured on the front cover of National Geographic magazine and was the subject of an acclaimed 1978 documentary – with every waking hour dedicated to caring for the superstar gorilla.

Bridget Appleby, producer of the new BBC1 film, Koko, tells TV Times that while the subject matter was enticing, the practicalities were hugely testing….

When did you first hear about Koko?
“About eight years ago and it has literally taken that long to get the film off the ground. It was difficult to convince Penny because she’s very worried about anyone new coming in and stressing out Koko.

“It took years of phone calls to gain her trust, but the idea that a gorilla could speak 1000 words of sign language really caught my imagination and people in this country don’t know anything about it. That made me really driven to tell the story.”

And of course it wasn’t just Penny who had to green light your film, was it…?
“Anybody making the film had to be vetted by Koko, so really she made the final decision on whether the documentary went ahead. Thankfully she invited me into her enclosure and was signing ‘good’. She was incredibly excited by our cameraman, Johnny, which was a delight. It also made it hard to film her because her priority was playing chase with him!”

Your team had only six weeks to shoot the documentary, what were some of the challenges you faced?
“Most people drop everything for a documentary crew, but obviously Koko and her activities have to come first. One time we were set up to film and were told we couldn’t come because there were kittens coming to meet her, so we sat there twiddling our thumbs in disbelief!”


What did make of Penny and Koko’s relationship?
“They have an incredibly intense bond. There are some people who accuse Penny of not acting in Koko’s best interests, but for a 70-year-old to be up till 4am every morning cooking meals for her adopted daughter, it’s not an easy life. Her entire waking existence is dedicated to her, she can never take a holiday.

“I think it’s been incredibly enriching for Penny, but it’s also a burden. She knows that she was the one who took Koko away from any gorilla relationships that she would have, and that responsibility weighs heavy.”

There is much debate about how meaningful Koko’s sign language really is, what’s your take on that?
“Koko is certainly using simple signs to express her needs, without doubt she was communicating with us. In terms of talking about feelings, dreams or memories, it’s hard to know at what point she means those signs, and when it’s our interpretation. We realised early on that we weren’t going to solve a problem that hadn’t been solved by numerous scientists over four decades.”

So how human do you think Koko has become?
“Koko looks you in the eye the way a human does, and it’s very hard not to believe you are in the presence of another person. I hope the film makes people really think what’s going on inside the mind of an ape, then it’s done its job.”

Koko: The Gorilla who Talks to People screens on Wednesday, June 15 at 8.30 on BBC1.