Can psychotherapy help apes as well as people? Steve Farrar reports on the case of a bonobo that breaks new research ground

Harry Prosen will never forget the first time he met Brian. It was not as though he had never come across a difficult patient before. As a psychiatrist and departmental chair at the Medical College of Wisconsin, he was used to dealing with disturbed individuals. But this was the first time a client had covered him with excrement, spit and vomit. Then again, Brian was the first bonobo Prosen had worked with.

Prosen says: "My first visit found Brian screaming, pacing in circles, clapping his hands together, inducing himself to vomit, inflicting open injuries and abrasions on himself and seeming not to sleep. I have had some difficult interview situations but, at first glance, establishing communication looked very difficult indeed."

Brian came to Milwaukee County Zoo in 1997, at the age of eight. Staff at his previous home - a research laboratory - said he had been severely intimidated by his father and had taken to self-mutilation. Their efforts to help him met with failure and, after keeping him in isolation for eight months, they contacted Milwaukee, a zoo with a reputation for handling difficult bonobos.

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Zoo keeper Barbara Bell, who has perhaps built the closest relationship with Brian, was particularly surprised by his reaction to other bonobos. "Brian would curl up in a foetal position and scream non-stop when faced with even a slightly stressful situation," she says. He was aggressive, terrified of males and could not relate to females.

This was odd as bonobos are perhaps the most sociable and empathic primate - indeed, Prosen says he now wonders whether these close relatives of chimpanzees are not more empathic than humans. There are certainly similarities between human and bonobo behaviour. Bonobos frequently walk upright, use tools to make everyday tasks easier and are boundlessly social, not to mention sexual. They are the party animals of the primate world. But not Brian.

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The zookeepers tried techniques to reward and encourage positive behaviour. Bell had built trust with many troubled bonobos in this way. But after six weeks, the ape showed few signs of improvement. Euthanasia was not an option - there are fewer than 5,000 bonobos left in their native forests in the Democratic Republic of Congo and less than 150 in captivity.

Bell and Jan Rafert, the zoo's primate curator, had an idea - maybe a human psychiatrist could provide fresh insight. They turned to the Medical College of Wisconsin for expert advice. On October 30 1997, Michael Bolger, president of the college, called Prosen, who specialises in human developmental deficit.

Prosen's curiosity was aroused. Was it possible that bonobos could suffer the same psychological problems that blight the lives of humans? Even more tantalising was the prospect that, if this was the case, the same therapies that help people might work, albeit in modified form, on a different species.

Prosen was no expert in primate behaviour, so he had no option but to treat the case like any other. After meeting Brian, he started to piece together a case history. He gathered all the available documentation, including detailed medical records from the laboratory where Brian was born, to build a picture of the bonobo's earliest years.

In case conferences with Bell and the other zookeepers and vets he discussed how events in the past might have been responsible for Brian's behaviour.

It soon became clear that his life had not followed the usual pattern of bonobo infancy during which there is constant contact with the mother for 14 or 15 years. In his early formative years, he had been caged with his father. There was evidence that his father had abused him, certainly physically if not sexually. Prosen saw Brian's behaviour as a response to his extreme anxiety.

"I believe that he had what in humans would be called a social phobia of mass proportions and a complete inability to understand his environment or to accurately interpret attempts to relate to him as helpful and not dangerous," Prosen says.

Among his human patients, Prosen has seen similar cases - people who missed out on normal childhood development and whose problems later in life were tackled by "filling in" those gaps through talking about the situation. While Prosen could hardly sit down for a chat with Brian, he used his human experience to provide a framework for the ensuing therapy.

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He suggested that the vets start by giving Brian small doses of the antidepressant Paroxetine. Brian also needed a stable environment. Everything was to be made safe and predictable. His meals arrived at the same time every day. Staff ensured they used the same tone of voice in front of him. Anything new was introduced very slowly to enable him to adjust to its presence. Brian was gradually introduced into bonobo society: his first year as part of a group of three, his second in a group of five and now as one of a group of seven.

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His mixed-up behaviour deeply upset his fellow bonobos. One minute he tried to act like a stud, the next he tried to nurse. The females often responded by attacking Brian, who would need rescuing by the keepers or by more compassionate apes.

One of these was Kitty, a 49-year-old female bonobo, who played a vital role in Brian's rehabilitation by tolerating his irrational fits of pique and always being ready to comfort him when he needed reassurance. A -year-old male called Lody provided him with protection.

There were times when Prosen and his colleagues doubted whether Brian would recover, but little by little he began to show signs of progress.

"He surprised everybody by showing decreasing anxiety, increasing playfulness and a steadily expanding maturity," says Prosen. He has recently been put on exhibit, something Prosen and zoo staff did not originally think possible.

"In his controlled environment, he has begun to view the world more calmly, and for the past year there has been no mental, verbal or physical abuse to or by Brian. A couple of the females are even starting to let him hold their babies. He grins and glows," says Prosen.

Prosen has little doubt that Brian suffered the effects of severe developmental deficit from the loss of his mother. He also believes that this is unlikely to be a rare phenomenon among primates in captivity. Yet there is reason to be optimistic. "I would be very foolish to make a comparison of one species with another, but I would say that it is apparent to me that bonobos are empathic continuously," he says.

Empathy is the key, Prosen insists. It was the empathy of Brian's companions, Kitty and Lody, that enabled them to play a central role in saving him. Cross-species, it enabled a group of humans to get to the heart of an ape's personal problems and devise an effective treatment. If anything, Prosen believes the bonobo's heightened empathy makes developmental deficits more repairable than in humans.

Today, Brian is a very different animal from the screaming, self-mutilating individual Milwaukee took charge of three years ago. He has some way to go before he could be called a well-adjusted ape, but he is now clearly one of the gang.

The zoo's reputation for helping highly disturbed animals continues to grow. Prosen has carved himself out a role as consulting psychiatrist and has helped other animals, such as Dick, a depressed orang-utan.

A couple of months ago, the keepers took delivery of a two-year-old bonobo, called Zuri, from another zoo. Maternal neglect had led to him being brought up by people. As a result he was unable to relate to his own kind. He would curl into a foetal position and cling to his blanket. After a few weeks, Brian was introduced to the infant. He walked over, stared hard at Zuri's terrified face and scooped him up into his arms. The keepers held their breath, but they need not have worried.

Brian clasped Zuri to his breast and calmed his cries. It was as if, Prosen remarks, he deeply empathised with the mental state of his new playmate and sought to fill that missing gap himself.

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