​Data from Simon Skjodt International Orangutan Center reveals distinctive case of great ape vocal learning

Groundbreaking data from the Indianapolis Zoo’s Simon Skjodt International Orangutan Center gives clues to the evolution of human speech. 11-year-old Rocky revealed a previously unknown level of vocal learning for orangutans.

Collaborating with International Researchers

The research, conducted at the Zoo in 2012 by scientist Dr. Adriano Lameira, was published today in Scientific Reports, and provides key insight to understanding how speech in humans evolved from the time of ancestral great apes.

The results showed that Rocky not only learned new sounds, but controlled the action of his voice in a “conversational” context as he took turns exchanging utterances with a social partner. In an imitation “do-as-I-do” game, Rocky copied the pitch and tone of sounds made by researchers to make vowel-like calls. Prior to this research, many researchers still presumed that great apes’ sounds were driven only by reflex.

England’s Durham University’s Dr. Lameira, the lead author on the research, analyzed Rocky’s ability to exert fine and precise vocal control, giving the orangutan a unique capacity to learn new vocalizations — a historic first. Dr. Rob Shumaker, the Indianapolis Zoo’s Director, is a co-author on the publication.

What does this Study Mean?

“This important work fundamentally alters our understanding of the capabilities of orangutans. It also reveals the significant value of carefully conducted studies with apes living in highly enriched, behaviorally naturalistic zoos,” said Shumaker. “Research that expands our awareness of orangutan intelligence inevitably leads to a greater commitment for their conservation in the wild.”

Using the largest database of assembled orangutan calls, including a collection of more than 12,000 observation hours of 120 individuals from 15 wild and captive populations, the researchers concluded that Rocky’s vocalizations were incomparable.

“This opens up the potential for us to learn more about the vocal capacities of early hominids that lived before the split between the orangutan and human lineages to see how their vocal systems evolved towards full-blown speech in humans,” said Lameira.

At the Indianapolis Zoo

In addition to collaborating with international scientists, researchers at the Simon Skjodt International Orangutan Center offer the apes computer-based cognitive tasks on a daily basis. These opportunities for learning and problem solving are conducted in a demonstration format with visitors. By directly witnessing the intelligence of orangutans, the Zoo inspires and empowers people to advance the conservation of these critically endangered great apes.​