Communication studies bridge the gap between humans and apes.

If there's one remarkable animal that I'll always be in awe of, it would be the kitten-loving, American Sign Language-knowing gorilla named Koko. Prior to her death last June at the ripe age of 46 (just one year past average gorilla life expectancy), Koko had mastered over 1,000 ASL signs and could understand 2,000 spoken English words which showed the world that apes are more sentient than once believed.

Koko's handler, Francine "Penny" Patterson, began teaching Koko modified ASL when Koko was a year old. As time went on, Koko's language skills evolved and their relationship became the longest interspecies communication study to date. 

As Koko's skills developed, she became an international celebrity who not only could carry a conversation but could express her feelings of joy and sadness. Koko could recognize sad moments in films, such as Tea With Mussolini, and would turn away from the TV and express her feelings to those around her.

For the study of primate cognition, Koko's grasp of ASL and spoken English showed that apes could attain a grasp of human language when presented with the means to do so.

Another communication study involving Kanzi, a bonobo monkey, showed that language could be learned by the use of a lexigram keyboard. Two other studies discovered that Kanzi was able to correctly respond to over 70 percent of 660 spoken requests and could make primitive tools when showed how.

If there's anything that apes like Koko and Kanzi have taught us, it's that animal behavior and cognitive studies show significant strides in breaking down communication barriers. If progress is made in teaching apes ASL and using other language-teaching methods, it could open the door to understanding how we as humans can better teach language to those with communication difficulties as well as improve the welfare of apes as a whole.