Peter Dickinson, a worker at the zoo, has cited the sign language enrichment program to enable the chimps to communicate with visitors.
“I have watched our animals sign to visitors, asking them to carry out certain behaviors. What is more the visitors react and do exactly what they are told,” he said.
“If a visitor is reproached by a member of staff the excuse is always ‘But the chimp asked me to do it!'”
Washoe was the first chimpanzee to learn American sign language, picking up 350 words before her death in 2007, and teaching many to her adopted son Loulis. Other chimps, who are usually on a less rigorous regimen, learn about 150 signs and can combine them. Such expressions as these can translate the body language most animals exhibit into words human can speak back, and in this case, the chimpanzee touchingly wanted freedom.