The life of a chimpanzee raised like a human makes for a rich documentary, which is assembled with considerable skill and intelligence.
In November 1973, a professor at Columbia University began an experiment to raise a chimpanzee like a human being in order to explore how this would affect the his communication skills with humans.
If Man on Wire played like an unlikely heist movie, this film is more like Frankenstein or a genre film where scientific breakthroughs have unintended consequences.
But as it progresses, the film is more than just about a curious scientific exercise as it peels away the different layers of the story to become something profound and unsettling about the relationship between humans and animals.
The opening section explores the behavioural psychologist who supervised the experiment, Professor Herbert Terrace, and his various assistants during the 1970s who treated Nim like a human child – a period which saw him introduced to human breast milk, alcohol and marijuana.
This makes for some eye-opening comedy in places, which is brilliantly augmented with interviews, period photographs and various other media from the time.
Part of the virtues of choosing a scientific project as the subject of a documentary is that the original observational materials can be incorporated into the film, as well as contemporary TV reports and magazine covers.
But the film really hits another plateau when we follow what happened to Nim when he left the supervision of Professor Terrace and his various surrogate mothers.
The story then becomes a darker tale which gradually holds up a mirror to the humans involved with Nim’s life.
Without going in to too much detail, it says a lot that the person who emerges with the most credit is Bob Ingersoll, a pot-smoking Grateful Dead fan who seemed to have Nim’s best interests at heart.
The second half of the film has some genuinely surprising twists and if you aren’t familiar with the real-life events I would recommend going in cold.
Part of what makes the film so effective, is the overall journey of Nim’s extraordinary life, which is presented with a meticulous care that is rare, even for a documentary.
Whilst the scientists depicted in Project Nim held up a mirror to a chimpanzee, the film also holds up a similar mirror to the audience about their relationship with animals and themselves.
On one level the film powerfully depicts the growing pains of a chimpanzee, but as this journey grows messy and painful, it is hard not to see the human parallels – we share 98.7% of our DNA but also a range of emotions and experiences as we age.
Marsh develops this material in such a way that it never feels simplistic or sentimental and along with his editor Jinx Godfrey have managed to whittle the story down to something that is both specific and universal.
Whilst the story of Nim is about an experiment from another era, the film of Nim is a vivid document of the humans who conducted it.
In a week which sees the UK release of an expensive reboot of the Planet of the Apes franchise, it is ironic that the chimpanzee film made for a fraction of the budget should have more drama and surprise.
But then this year has been a very strong one for documentaries with films like Senna, The Interrupters and now Project Nim prove that real stories told well can provide the drama that expensively produced fiction simply cannot match.
Project Nim is out at selected UK cinemas from Friday 12th August