With his frequent profound understanding, Konrad Lorenz explains why people often feel an instinctive revulsion for chimpanzees:
If people did not know the chimpanzee they would be more easily convinced of their own origin. An inexorable law of perception prevents us from seeing in the ape, and perticularly in the chimpanzee, an animal like other animals, and makes us see in its face the human physiognomy. From this point of view, measured by human standards, the chimpanzee of course appears as something horrible, a diabolical caricature of ourselves. In looking at the gorilla or the orang-utan, which are less closely related to us, our judgement is correspondingly less distorted. The heads of the old males may look to us like bizarre devils' masks, impressive and even aesthetically appealing. However, we cannot feel this about the chimpanzee. He is irresistably funny and yet as common, as vulgar, as no other animal but a debased human being can be....
Lorenz (1963)On Aggression p.190