Koko has been called the "world's most intelligent gorilla."
The beloved 44-year-old western lowland gorilla uses over 1,000 signs from American Sign Language to communicate, and has gained a sophisticated understanding of spoken English through the help of a team of psychologists and researchers who have spent decades training her.
Now, a new study is suggesting that the brainy ape may be closer to verbal communication than we've thought. Published last month in the journal Animal Cognition, the research finds that gorillas may be capable of complex vocal behavior that defies previous beliefs about their communicative abilities.
"Traditionally, many scientists thought that apes had extremely limited vocal abilities," wrote cognitive scientist Marcus Perlman, a postdoctoral researcher at University of Wisconsin-Madison and the study's lead author, in an email to The Huffington Post. "It was thought that they were not able to voluntarily control their vocalizations, and also that they were not able to to learn new vocalizations outside of their species-typical repertoire."
The analysis of Koko's vocal behaviors suggests that humans are not the only animals to have developed an ability for spoken language.
Perlman and his colleagues began observing Koko to study gorilla hand gestures, but their research took a different turn after they became fascinated by the array of vocal behaviors she displayed.
The researchers analyzed 71 hours of video showing Koko interacting with the scientists who have trained her, discovering that she used nine different learned behaviors that required some degree of control over her vocal activity and breathing.
These behaviors included blowing a raspberry (which Koko did when she wanted a treat), playing wind instruments, mimicking a conversation by jabbering into a fake telephone, coughing on demand and blowing her nose. In the video below, you can watch Koko play a recorder.
Koko's behavior was voluntary, and appears to be the result of living with humans throughout her life.
This was surprising, since scientists had generally believed apes were incapable of controlling their vocalizations or their breathing. Documented gorilla vocalizations were limited to a set of calls related to relaying information about the environment (such as the presence of food or predators) or the apes' emotional states.
While Koko's behavior clearly transcends these simple calls, that doesn't mean that other gorillas aren't also capable of what she's achieved.
"Presumably, she is no more gifted than other gorillas," Perlman said in a statement. "The difference is just her environmental circumstances. You obviously don't see things like this in wild populations."
The Beginning Of Language
The findings have some fascinating implications for our understanding of the evolution of language.
Most theories of language evolution have held that spoken language is unique to humans, developing as the human line evolved after splitting off from chimpanzees roughly 7 million years ago. But the whole picture may be more complicated than that, and it's distinctly possible that the seeds of spoken language go much further back than we've thought.