Karen Joy Fowler monkeys around with the family

The ‘70s were a tough time to be a chimpanzee in America. Sure, some costarred with Clint Eastwood in movies and on TV in the inexplicable “BJ and the Bear,” but the relationship between humans and primates was not a kind one in the scientific world, as shown in Deborah Blum’s “Monkey Wars” and Elizabeth Hess’ “Nim Chimpsky: The Chimp Who Would Be Human,” which became the affecting 2011 documentary “Project Nim.”

“Project Nim” told the story of a Columbia University study that attempted to teach language to a chimp raised as if it were part of a human family; the tale turned tragic after the study ended and Nim was lost between two species. That’s the conflict explored by Karen Joy Fowler in her latest novel, “We Are All Completely Beside Ourselves,” which imagines the impact such research also would have on the host family after research has concluded — particularly if that family had children of its own.

At the center of Fowler’s story is Rosemary Cooke, who narrates with a bit of a barbed edge while looking at her past, first as a precocious toddler and most prominently as a troubled, introverted twentysomething at UC Davis in 1996. Telling her story from the safe distance of her early forties in 2012, Rosemary is the daughter of two scientists who grew up in what seems a typical if emotionally repressed Midwestern family (at least from a modern literary standpoint). Her father drinks too much, her estranged older brother, Lowell, is an animal rights activist who ran away as a teenager, and her twin sister, Fern, was lost when Rosie was only 5.

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The loss of both children has left the Cooke family shattered, particularly with regard to Fern — who happens to be a chimpanzee. Fowler takes her time revealing that rather key detail in a way even Rosemary describes as “irritatingly coy,” but the choice points toward her hazy feelings about her family that slowly come to a boil as the novel continues.

Fowler makes reference to multiple studies in cross-fostering chimps with human families, including psychology researcher Maurice Temerlin’s experience raising a chimp as a human infant in the 1970s. But her novel hinges upon Rosemary’s sharp voice, which at its best includes funny, self-aware asides such as an early reference to a character at a holiday dinner where she flippantly advises the reader, “Don’t get attached to him; he’s not really part of this story.”

When she was 5, Rosemary was told Fern went to live on a farm, which is no more true than the stories most parents tell children about a lost pet. While this deception eats away at Rosemary, she’s also haunted by a sense of culpability for her role in Fern’s dismissal from the family. Did Fern’s behavior grow more unmanageable as she went from a sign language-capable chimp in diapers to a maturing adult? Or was a vengeful Rosemary to blame for splitting the family by spinning a story that revealed Fern’s wild nature as a threat to the family’s safety?

The truth begins to seep out in a reunion with her brother, Lowell. Running from the FBI as part of the Animal Liberation Front, Lowell tells Rosemary the reality of her father’s research and Fern’s sad later life. The feverish details of Rosemary confronting both her past and Fern’s present feel particularly vivid, especially as she reveals the many ways the two “sisters” communicated in a manner that blurred the differences between the species.

But Rosemary has her failings as a narrator: Lowell’s voice hardly distinguishes itself from hers — a fact later explained when Rosemary admits she retold her brother’s story so he sounded more lucid. The admission sheds light on her own damaged character even as it robs us from truly knowing his.

Although Fowler is perhaps most known for the bestselling “Jane Austen Book Club,” she has often flirted with fantasy, most recently in parts of the story collection “What I Didn’t See.” Here, however, her efforts remain grounded, even somewhat matter-of-fact as the book goes on with anecdotes taken from the research that surrounded Rosemary’s upbringing.

Still, it’s perhaps fitting that Fowler leans on the reader to infer so much from her characters in a book whose deepest impact is in forcing the reader to reconsider the divide between humans and animals. Rosemary undercuts the emotional impact of an eventual reunion with Fern, admitting, “I can’t tell you what I felt; no words are sufficient. You’d need to have been in my body to understand all that.” But the line just as easily could come from Fern as the lesson remains that some divides are just too painful to bridge.

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We Are All Completely Beside OurselvesKaren Joy Fowler
Marian Wood/Putnam: 320 pp., $26.95