Rise of the Planet of the Apes and Project Nim and the science of chimpanzees.

The state of the universe.
Aug. 26 2011 7:02 AM

Risibility of the Planet of the Apes

On the great divide between humans and chimpanzees.

Caesar in Rise of the Planet of the Apes. Click image to expand.
Caesar in Rise of the Planet of the Apes

In the gorgeous and stupidly fun Rise of the Planet of the Apes, Caesar, a chimpanzee, has an oh-so-poignant identity crisis during a walk in the Muir Woods near San Francisco. Thanks to an experimental gene therapy for Alzheimer's that a biotech firm tested on Caesar's mother, the CGI-created chimp has inherited a brain with extraordinary wiring. He lives with the drug's developer, Will Rodman (James Franco), who occasionally takes Caesar on strolls through the giant redwoods and unleashes him, letting him express his inner ape. This day, they startle a woman walking a German shepherd on a leash. Caesar looks at his own collar and, in American Sign Language, plaintively asks Rodman, "Am I a pet?"

Leaving aside the spectacularly implausible scientific scenario that made Caesar a few marbles short of a human, Rise of the Planet of the Apes flirts with an idea that has beguiled researchers for more than a century. What if we could speak with one of our ape cousins? What would they tell us about their views of the world, their disappointments and dreams, their spirituality and existential angst? A second, recently released movie that includes a flesh-and-blood talking chimp, the documentary Project Nim, offers a most sober answer: not much. The subject of the sad documentary (based on the Elizabeth Hess book, Nim Chimpsky: The Chimp Who Would Be Human) mastered only 125 signs after years of training. "Give orange me give eat orange me eat orange give me eat orange give me you," he said in his most elaborate string of words ever recorded.

Rise of the Planet of the Apes and Project Nim have a mess of overlap, from the clothes that Caesar and Nim wear to their longing stares out the windows of their nicely appointed homes, the close-ups of their soulful eyes, the horrors of well-meaning scientific research, and the outright cruelty of some human caretakers. Yet there's one less obvious parallel: Both feature humans who have wildly exaggerated what we have in common with chimpanzees and blurred the line between our differences. The humans in each film are gobsmacked that the cute, innocent creatures they've adopted, so strikingly similar to our own kootchy-kootchy-coo babies, grow violent and dangerous by about age 5, ripping off faces and fingers of college-educated Homo sapiens who apparently forgot that Pan troglodytes is a distinct species. In answer to Caesar's humanlike question, Rodman says, no, you're not a pet—I'm your father. Ahem.

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Much as we may want to believe that a brain gene or two separates the chimp from the human mind, that with proper upbringing and training a chimpanzee could snuggle into our necks and share its innermost thoughts, the reality is that a great, inviolate divide separates the species. Two revolutionary and rightfully celebrated scientists, Charles Darwin and Jane Goodall, along with the masses that promoted their agendas, have lulled us into thinking otherwise.

The exaggeration of our similarities is a pendulum swing from the 1700s, when the Swedish taxonomist Carl Linnaeus feared a theological backlash if he followed his convictions and placed man and other "simians" on the same branch of the tree of life. By the time of Darwin, a century later, the religious still saw chimpanzees as "inventions of the devil." An infamous cartoon mocked Darwin by depicting the head of the longbearded scientist atop a chimp torso.

Darwin supporters soon turned the chimpanzee to their advantage, using the physical similarities between us and them as a cornerstone to prove evolutionary theory—they even tried to introduce one, resplendent in suit and bow tie, at the Scopes trial. Behavioral research with captive chimpanzees that began in the early 1900s demonstrated their remarkable, humanlike cognitive skills. Then in the 1960s, Jane Goodall emphasized chimp-human similarities in her pioneering studies of wild chimpanzees, overturning the canard that only humans used tools and, with her many disciples, going on to document a wide range of "human" attributes, from empathy to transmission of behaviors ("culture"), that existed in chimpanzees, too. In the 1970s, biologists cemented the evolutionary argument when they revealed that chimpanzee proteins differed from those in humans by a mere 1.2 percent. By this measure, we were 98.8 percent identical.

Nim Chimpsky. Click image to expand.
Nim Chimpsky

Darwin's theory of evolution and Goodall's conservation agenda today no longer need the help of chimpanzees. Modern genetics makes it abundantly clear that evolution is real. The conservation movement now rightly protects the welfare of all animals, putting special emphasis on threatened and endangered species, regardless of their human attributes: Many of us care deeply about saving black rhinos, beluga sturgeon, and northern right whales, none of which have looks or behaviors that make us purse our lips and feel a squishy bond.

The pendulum needs to swing back to find the actual divisions that separate us from them and better understand what it means to be human. We separated from a common ancestor with chimpanzees at least 5 million years ago, and random mutation coupled with the evolutionary forces of positive and negative selection have steadily driven the two species further and further apart. For starters, we have 46 chromosomes and they have 48. A recent comparison of chimp and human genomes that assesses all our DNA, including the vast majority that does not make up protein-coding genes but has a major influence on their function, finds about a 5 percent difference—more than a four-fold difference from what was previously thought. Many diseases that profoundly alter our lives—including Alzheimer's—have no impact on them. (Note to Rodman: lousy animal model.) Only humans primarily walk upright, cook, teach, swim, miscarry at high rates, run long distances, and depend heavily on grandmothers to raise children. Chimps have remarkable short-term memory that may outperform our own, and, as Rise of the Planet of the Apes repeatedly emphasizes, jump and climb with a power and grace that put Cirque du Soleil acrobats to shame. Side-by-side analyses of autopsied brains from chimpanzees and humans further reveal distinct architecture and gene networks in each species.

Language is one of our most pronounced differences. Chimpanzees and other nonhuman great apes communicate in sophisticated ways, and researchers working with the likes of Nim have shown that they can learn to use signs and symbols to speak with humans. But Project Nim, led by Columbia University psychologist Herbert Terrace, marked a watershed moment in ape language research—and effectively killed the high-profile field.

Documentary maker James Marsh ( Man on Wire) goes to some length to pillory Terrace for showboating and treating both humans and Nim callously, which oddly garbles the main import of his groundbreaking language research. In a devastating paper published in Science in 1979, Terrace and his co-workers asked, "Can an Ape Create A Sentence?" They analyzed more than 19,000 utterances of Nim and determined, convincingly, that their subject—along with other famous signing apes, Koko the gorilla and Washoe the chimp—had fooled researchers. Upon close inspection, Terrace's group decided that the apes were stringing words together in response to the recent signs of their teachers and, for the most part, were making simple demands. "Apes can learn many isolated symbols (as can dogs, horses, and other nonhuman species), but they show no unequivocal evidence of mastering the conversational, semantic, or syntactic organization of language," they concluded.

In the 32 years since, no one has proven Terrace wrong. Critics of the work with Nim rightly point out that Terrace and his slapdash crew of students had methodological problems with their experiment, and legitimate debates exist about the meaning of "language." But no compelling evidence has come forward that any apes, other than humans, can acquire massive vocabularies (we typically have 60,000 words by high-school age), use words with a set of rules, embed several ideas in a sentence, or converse with a humanish give-and-take of speaking, listening, and responding. Linguist Noam Chomsky, Nim's namesake, was right. Humans, and not chimps or gorillas or bonobos, seem hard-wired for language.

One of the most telling language differences between us and them comes from the researchers who claim to have made the most progress teaching apes to communicate. In an eyebrow-raising gambit, Sue Savage-Rumbaugh in 2007 co-authored a scientific paper with three bonobos. She spoke with her colleagues using symbols called lexigrams and vocalizations. The study, "Welfare of Apes in Captive Environments," recounts how Savage-Rumbaugh had a dialog with Panbanisha, Kanzi, and Nyota about what they need. She proposed various options and asked them yes/no questions. The 12 they deemed important—which include the ability to move and interact with others at their choosing, fresh food that they like, and freedom from fear of harm by humans—hardly surprise.

What if the design of the experiment actually asked the bonobos what they needed? These bonobos routinely go on walks in the woods near the sanctuary that houses them in Des Moines, Iowa. Their handlers restrain them with collars and leashes. Imagine if Panbanisha said, "To run free without a collar and leash, which demeans me and makes me feel like a pet." Now we're talking language, crossing the Rubicon, and being forced to reconsider where to place the line that separates Julius from Caesar, Noam from Nim. But of course none of them said anything of the sort.

Jon Cohen writes for Science magazine. Follow him on Twitter.