A number of studies have been conducted exploring the potential for orangutans, chimpanzees, gorillas, and bonobos to understand and utilize human language and symbols. The results have been impressive.

Studies have shown that orangutans are naturally inclined to at least some level of gestural communication. Cartmill and Byrne were able to identify 64 gestures through extensive observation of 28 individual orangutans in three zoos. Of those 64 gestures, their analysis established “tight meanings” for 29. That is, those 29 gestures were used more or less consistently to convey a particular meaning. These meanings were very broad in nature (Affiliate/Play, Stop action, Share food/object, etc.), and do not appear to approach the specificity humans are familiar with in their own communication, (Cartmill and Byrne, 2010). That being said, this is already strong evidence that the orangutan capacity for language goes far beyond their vocal limitations.

Shapiro has been one of the pioneering researchers in the area of orangutan sign learning ability. His research in this area began in 1973 at the Fresno city zoo, where his eighteen-month study of symbolic capability with an orangutan named Aazk became the basis of his master’s thesis. Through her relationship with Shapiro, Aazk was able to learn to arrange symbols meaningfully on a board in order to build sentences (Thompson, 2010). A few years later, Shapiro traveled to Borneo to conduct more extensive studies teaching sign language to orangutans in their native environment.