A new study indicates that, like humans, great apes go through a nadir of happiness in middle age. Image via Wikimedia Commons/Zyance

Stereotypically, people experiencing a mid-life crisis desperately seek to justify their lives through superficial means, perhaps by buying an expensive sports car or getting into a relationship with a younger romantic partner. Although their behavior looks rather different, a new study says that chimpanzees and orangutans go through a mid-life nadir in overall well-being and happiness that roughly resembles our own.

A team led by psychologist Alexander Weiss of the University of Edinburgh asked zookeepers and researchers around the world to keep track of the well-being of resident chimpanzees and orangutans—508 animals in total. The results of all that record-keeping, published today in the Proceedings of the National Academy of Sciences, show that, like humans, these great apes generally experience a U-shaped pattern of happiness and well-being, starting off with high ratings for happiness as adolescents, declining gradually during middle age (bottoming out in their late 20s or early 30s), and then rising back up again in their elder years.

Although popular conceptions of human mid-life crises focus on material acquisitions, psychologists believe they’re driven by an underlying decline in satisfaction and happiness as we go through middle age, and reflected by increased antidepressant use and suicide risk. In this sense, the primates studied went through a similar pattern:

The chimps and orangutans studied went through a human-like U-shaped pattern for happiness over the course of their lives. Image via PNAS/Weiss et. al.

Of course, unlike with humans, no one can directly ask chimps and orangutans how they are feeling. Instead, the researchers relied upon surveys, filled out by zookeepers and caretakers, that rated the animals’ mood and how much pleasure they took from certain situations. They acknowledge the ratings are necessarily subjective, but they feel that the size of the dataset and consistency in the trends as reported from the different zoos with different animals suggests that the pattern is legitimate.

Weiss’ group originally embarked on the ape study to answer the question of why mid-life dissatisfaction is so common in humans. “We hoped to understand a famous scientific puzzle: why does human happiness follow an approximate U-shape through life?” Weiss said in a statement.

Although many are apt to blame external cultural factors such as disappointing careers or mounting bills as the cause, Weiss felt it was something more fundamental. By showing that a similar pattern exists in other primates, he argues that his team has dispelled the notion that these types of external factors are solely responsible. “We ended up showing that it cannot be because of mortgages, marital breakup, mobile phones or any of the other paraphernalia of modern life,” he said. “Apes also have a pronounced midlife low, and they have none of those.”

Instead of these cultural factors, Weiss suggests that this pattern is rooted in biological or evolutionary factors. It might have been the case, for example, that the human ancestors who had an innate tendency for happiness and satisfaction at the stages of life when they were most vulnerable (youth and old adulthood) might have been less likely to venture into risky and potentially harmful situations in the pursuit of more resources.

Kanzi the bonobo is quite the musician. Image courtesy of the Great Ape Trust

In the new movie Rise of the Planet of the Apes, the leader of the ape revolution can talk. In the real world, apes can’t speak; they have thinner tongues and a higher larynx, or vocal box, than people, making it hard for them to pronounce vowel sounds. But that doesn’t necessarily mean they don’t have the capacity for language—sign language, after all, doesn’t require any vocalization.

Over the years, researchers have succeeded—and failed—in teaching apes to use language. Here’s a look at some of the more famous “talking” apes.

Viki: Viki, a chimpanzee, came closest to being a real talking ape. In the late 1940s and early 1950s, Keith and Catherine Hayes of the Yerkes Laboratories of Primate Biology, then located in Orange Park, Florida, adopted Viki and raised her at home as if she were a human baby. With the Hayeses moving her lips for her, Viki learned to utter “mama.” Eventually, with much difficulty, she managed to say three other words—papa, cup and up—on her own. Viki’s tenure as a talking ape didn’t last long; she died at the age of seven of viral meningitis.

Washoe: In the 1960s, psychologists Allen and Beatrix Gardner of the University of Nevada, Reno recognized that chimpanzees naturally gesture a lot and thought chimps would be well suited for sign language. In 1966, they started working with Washoe. Later, psychologists Roger and Deborah Fouts, now retired from Central Washington University, continued the work. By the end of Washoe’s life in 2007, she knew about 250 signs and could put different signs together to make simple combinations like “Gimmie Sweet” and “You Me Go Out Hurry.” Washoe’s adopted son Loulis also learned to sign—by watching his mother. He was the first ape to learn signs from other apes, not humans. For more on Washoe’s life, read Roger Fouts’ Next of Kin.

Nim: After the success with Washoe, psychologist Herbert Terrace of Columbia University decided to replicate the project. At first, Nim—full name Nim Chimpsky, named after linguist Noam Chomsky who thought language was unique to humans—was raised in a human household. (Washoe had been treated like a person too but had her own trailer.) Later, Nim was removed from the family and his language lessons moved to a lab on Columbia’s campus. In the end, Terrace concluded Nim never really learned language; he had merely been trained to imitate his teachers to get rewards. The sad story of Nim’s life after the project ended is told in the new documentary Project Nim.

Chantek: Chimpanzees are not the only talking apes. In 1978, anthropologist Lyn Miles of the University of Tennessee at Chattanooga began studying an orangutan named Chantek. During eight years of study, Chantek learned 150 signs. He also showed signs of being self-aware: he could recognize himself in a mirror. Today, you can visit Chantek at Zoo Atlanta, his home since 1997.

Koko: Koko the gorilla is probably best known for her love of kittens and Mr. Rogers (and maybe less well-known for her encounter with Captain James T. Kirk). Koko’s sign-language training began in 1972 with then-graduate student Francine (Penny) Patterson of Stanford University. According to the Gorilla Foundation, Koko knows 1,000 signs and understands spoken English. It also claims the gorilla has an IQ somewhere between 70 and 95 (the average human IQ is 100). (Critics, however, remain skeptical about some of Koko’s supposed abilities due to the lack of recent scientific publications supporting the claims. (PDF))

Kanzi: Kanzi, a bonobo, doesn’t use sign language; he uses different combinations of lexigrams, or symbols, to communicate. In the early 1980s, psychologist Sue Savage-Rumbaugh, then of Georgia State University, was trying to teach Kanzi’s mom, Matata, to use the lexigrams; instead, Kanzi was the one who mastered the symbols. Kanzi understands spoken English and knows close to 400 symbols. When he “speaks,” his lexigram usage follows rules of grammar and syntax, according to researchers at the Great Ape Trust in Iowa, where Kanzi now resides. Kanzi is also an accomplished stone-tool maker.

Still from Rise of the Planet of the Apes, photo courtesy of WETA Digital

It’s the summer of the chimpanzee, at least at the movies. The documentary Project Nim and the sci-fi flick Rise of the Planet of the Apes offer audiences very different forms of simian entertainment, but moviegoers will walk away from both wondering, “Is it ethical to use chimps in research?”

Project Nim chronicles the life of Nim Chimpsky, the chimpanzee who was the focus of one of the most (in)famous ape language studies. In 1973, just days old, Nim was taken from his mom at an ape lab in Oklahoma and brought to New York City. Herbert Terrace, a psychologist at Columbia University, wanted to see if he could communicate with a chimpanzee through language (Nim was named after linguist Noam Chomsky). Because apes do not have the proper physiology to speak, Terrace decided to teach Nim sign language.

The best way to do this, Terrace thought, was to raise Nim among humans. Terrace gave Nim to one of his former graduate students, a mother in a Brady Bunch-style household. Life there was chaotic, with few rules, and no one in Nim’s human family really knew sign language.

Lacking results, Terrace once again took Nim away from his mother. This time he brought him to an old mansion in the New York suburbs owned by Columbia. Nim lived there with a few college students who were his teachers. Nim also made trips to the university’s campus for language training sessions, which he apparently disliked. One former teacher claims Nim used the sign “dirty,” meaning he needed to use the bathroom (he knew how to use a toilet), to get out of the classroom.

As Nim got older, he became stronger, unpredictable—and violent (his teachers have the scars to prove it; he bit one woman’s face so hard that she had a gaping hole in her cheek for months.) This is normal for a chimpanzee. “Nobody keeps a chimp for more than five years,” Terrace says. Soon Terrace ended the project.

Nim is then returned to the Oklahoma lab. This scene is why you should bring tissues to the theater. Nim gets locked up, forced to live alone in a small cage next to the cages of strange creatures he’d never seen before: other chimps. The lab looks like a primate prison. The workers shock the animals with cattle prods to keep them in line. One former worker describes Nim as a “spoiled child.”

Nim’s life gets worse. He is sold to a medical lab for vaccine testing. Later he moves to a sanctuary—for horses. He lives there in almost total isolation, as the owners don’t know how to care for an ape. Nim appears lonely, depressed. It’s heartbreaking.

Nim eventually gets some chimp companionship. But there’s no real happy ending for him. He died in 2000 at the age of 26, quite young for an animal that can live up to 45 years in the wild and 60 in captivity.

By the time Project Nim ended, I was ready to cheer on the ape rebellion in Rise of the Planet of the Apes. Watching it, I was struck by how much the protagonist’s story paralleled Nim’s.

The movie begins in Africa with the capture of a female chimpanzee. In the next scene, she’s solving a puzzle in a lab. (Today, chimps used in research are bred in captivity. It is illegal to bring them in from the wild.) This chimp is part of a medical trial for a gene therapy to treat Alzheimer’s. The treatment goes beyond the expectations of medical researcher Will Rodman (played by James Franco); it enhances the cognition of the chimp, making her super-smart. (Ed. note — Mild spoilers ahead, though its nothing you haven’t already seen in the trailers, so consider yourself warned. You can read on after the note below)

The ape passes down her superior intellect to her son, Caesar (played by Andy Serkis with the help of amazing CGI effects). After an unfortunate incident, Caesar’s mom is killed, and the lab manager halts the project and orders all the chimps to be put down. Rodman saves newborn Caesar and takes him home.

This is where Caesar’s life begins to resemble Nim’s. Rodman treats Caesar like a human and teaches him sign language. Several years later, a bigger, stronger Caesar attacks a neighbor while trying to protect Rodman’s father, and is sent away to a primate “sanctuary” that bears a striking resemblance to the Oklahoma lab where Nim lived, right down to the cattle prods. And Caesar must learn how to interact with other apes.

Eventually, Caesar breaks out, steals some of the medicine that made him smart and returns to give it to his ape comrades. The apes revolt and descend on San Francisco. During an incredible battle on the Golden Gate Bridge, it’s clear that the California Highway Patrol—and perhaps all of humankind—is no match for this army of super-simians. By the end (stick around for the credits), it’s clear how the apes will conquer the rest of the world.

What happened to Nim and Caesar made me incredibly sad and made me think about the ethics of captive ape research. I’m not alone.

(Spoiler-concerned readers: You’re safe to read on from here)

Although the premise of Rise of the Planet of the Apes seems absurd, some scientists worry that genetic engineering is advanced enough to create primates with human-like behavior and self-awareness. The U.K. Academy of Medical Sciences released a report last month suggesting such experiments should be off-limits. The United Kingdom along with many other countries already ban the use of great apes in research. The subject is now being debated in the United States.

In the case of Nim, Terrace concluded years after the project ended that the chimp never really understood sign language; he just learned to mimic his teachers to get rewards. As the movie implies, the lack of results could be blamed on the lack of a proper experimental design in the first place. Other apes—most notably Washoe the chimpanzee, Koko the gorilla and Kanzi the bonobo—have been taught to use sign language. The researchers studying them believe they are truly communicating with these animals via language, but there are still some skeptics, including Terrace, who think otherwise.

I have mixed feelings on chimp studies. The sad irony is that the very reason it seems wrong to study chimps is the same reason why they are attractive study subjects: they are our closest living relatives, and the animals that come closest to being like us.

A young gorilla in the Hirwa group in Rwanda, 2009 (courtesy of flickr user petercolesdc)

On the one hand, it’s pretty amazing that I can find images of a specific mountain gorilla family in Rwanda through a simple Flickr search. But the availability of those photos comes from the numerous visits of humans to the national parks in Congo, Rwanda and Uganda where the world’s remaining 786 mountain gorillas live, and those visits may have a deadly downside for the gorillas: respiratory infections from human viruses.

Mountain gorillas (Gorilla berengei berengei) live only in the mountainous region where Congo, Rwanda and Uganda meet, and their small numbers make them vulnerable to extinction. To make matters worse, they are sandwiched between some of the most populous areas of Africa, and threatened by habitat destruction and poaching. A lesser known problem is infectious disease, which is the second biggest cause of death for the gorillas, after trauma, and accounts for one fifth of all sudden deaths.

And now a study in the journal Emerging Infectious Diseases documents two gorilla deaths from the human metapneumovirus (HMPV) in 2009. During that summer, the Hirwa family of gorillas in Rwanda experienced an outbreak of respiratory disease; 11 of the 12 animals experienced symptoms including coughing, nasal discharge and lethargy. Veterinarians from the Mountain Gorilla Veterinary Project treated five of the gorillas with antimicrobial drugs, but an untreated adult female and a 3-day-old male died. Analyses of the remains revealed that both individuals had been infected with HMPV, though the adult female died of a secondary bacterial pneumonia infection. The HMPV infection likely predisposed her to pneumonia, the researchers say.

“Because there are fewer than 800 living mountain gorillas, each individual is critically important to the survival of their species,” said Mike Cranfield, executive director of the Mountain Gorilla Veterinary Project. “But mountain gorillas are surrounded by people, and this discovery makes it clear that living in protected national parks is not a barrier to human diseases.”

The source of the HMPV is unknown, and the two animals that died had not been handled by any of the veterinarians or park staff during the course of their illness. But with the human population ever encroaching and tourists visiting them in their mountain homes, it seems better strategies are needed to protect the gorillas from human diseases.

Kigali, a western lowland gorilla at the National Zoo (Credit: Jessie Cohen, National Zoological Park)

About two western lowland gorillas are killed and sold in local markets as bushmeat each week in the region of Kouilou in Congo, according to an undercover investigation. It may not sound like much, but it represents about 4 percent of the local population each month, and half of the population each year. And there are likely only about 200 gorillas left in the area, the BBC reports.

[The conservation group Endangered Species International (ESI)] began its investigation by going undercover, talking to sellers and traders at food markets in Pointe Noire, the second largest city in [Congo].

Over the course of a year, investigators visited the markets twice a month, recording the amount of bushmeat for sale.

“Gorilla meat is sold pre-cut and smoked for about $6 per ‘hand-sized’ piece. Actual gorilla hands are also available,” says Mr Pierre Fidenci, president of [ESI].

“Over time we got the confidence of the sellers and traders. They gave us the origin of the gorilla meat and it all comes from a single region.”

ESI estimates that about 300 gorillas end up as bushmeat in Congo each year.

The Western lowland gorilla is the species of gorilla we’re probably all most familiar with, as they are the ones that are usually found in zoos. (Actually, they’re a subspecies of Gorilla gorilla, the other being the even rarer Cross River gorilla.) And though the 2007 discovery of a previously undiscovered population of the animals in northern Congo was promising, the species is still endangered, threatened by habitat destruction through logging and by outbreaks of the Ebola virus, in addition to commercial hunting.

Mr Fidenci hopes to go back to Kouilou to find out more about the remaining gorillas living there and to find a way to conserve them.

“We intend to stop the killing in the area by providing alternative income to locals and working with hunters not against them. We hope to conduct conservation awareness with educational programs with other NGOs and to create a gorilla nature reserve.”…

Currently, little is done in the country to prevent the poaching of bushmeat, Mr Fidenci says.

“Enforcement does not exist. Even though there are existing laws which protect endangered wildlife against such activities.”

Saving Kouilou’s gorillas may be a small goal for conservationists, but this species could use all the help it can get.

A Bornean orangutan. Courtesy of Flickr user Graham Racher

An orangutan will produce an alarm call known as a “kiss squeak” when it encounters a predator like a snake or a human. The kiss squeak is produced by drawing a sharp intake of air through pursed lips (see this video for an example). Sometimes, though, an orangutan will take a branch, strip the leaves from it, hold the leaves in front of its mouth and then make the sound. Why?

Researchers studying the wild Bornean organutan (Pongo pygmaeus wurmbii) recorded kiss squeaks made by the animals near a research station. (Their study appears in the Proceedings of the Royal Society B.) They found that the leaves lowered the maximum frequency of the sound (i.e., made it deeper). Also, smaller orangutans were more likely to use the leaves.

The orangutans appear to be using the leaves to make themselves sound like they are bigger than they really are. The scientists say that this is the first case of an animal using a tool to manipulate sound.

A silverback mountain gorilla (via Wikimedia Commons)

In July 2007, four members of the Rugendo gorilla family, which had been visited by our reporter, were killed. A total of ten gorillas were killed that year in the park. Then in January, we reported that the rangers who protected the park had been barred from accessing the gorillas because of the conflict between the Congolese army and rebel forces led by ex-general Laurent Nkunda. Of course, the rangers weren’t the only ones affected by the fighting; 800,000 people were forced from their homes, according to the United Nations.

Fighting flared again in Congo in recent weeks, displacing another 200,000 people. Virunga’s park rangers, who had been able to return to some of the park in recent months, were forced to flee into the forests when their headquarters were overtaken by rebel troops.

But now some promising news: 120 rangers returned to the park on Friday after the chief warden, Emmanuel de Merode, negotiated their safe return. As he told the Environmental News Service, “Rangers are neutral in this conflict, and it is right that they should be allowed to do their job.”

Though the rangers now plan to start a long-neglected survey of the park’s gorilla population, cleaning up will have to be a priority. Their facilities have been abandoned for the last 14 months and much of their supplies and equipment were stolen in the conflict. It may be a long while until we know how many of the gorillas survived.