Chimpanzee posture, gestures, and facial expressions communicate many messages and emotions between various individuals. When greeting a dominant individual following an absence or in response to an aggressive gesture, nervous subordinates may approach with submissive signals – crouching, presenting the hindquarters, holding a hand out – accompanied by pant-grunts or squeaks. In response, the dominant individual may make gestures of reassurance, such as touching, kissing, or embracing.
Friendly physical contact is crucial in maintaining good relationships among chimpanzees. For this reason, social grooming is one of the most important social behaviors, sustaining or improving friendships within the community and calming nervous or tense individuals.
The grin of fear seen in frightened chimpanzees is thought to be similar to the nervous smiles given by humans in tense or stressful situations. When angry, chimpanzees may stand upright, swagger, wave their arms, or throw branches or rocks, doing so with bristled hair and often accompanied by screaming and scowls.Male chimpanzees proclaim their dominance with spectacular charging displays. Chimpanzees will slap their hands, stamp their feet, drag branches as they run, and hurl rocks trying to make themselves look as big and dangerous as possible to intimidate a higher-ranking individual without having to fight.
Below are some chimpanzee facial expressions and their meanings.
|Grin with mouth closed or slightly open||Associated with submissive behavior and fear|
|Grin with open mouth||Non-aggressive physical contact with other chimpanzee or when threatened by a superior or other species a chimpanzee fears.|
|Open mouth threat-mouth open, teeth covered by lips glaring||Threatening a subordinate, distant subordinate, or another species that’s is not greatly feared.|
|Pout face||Situation of anxiety of frustration, detection of strange objects, begging, infant searching for mother, following threat or attack.|
|Play Face||During playful physical contact with other individuals|
|Lip smacking face||While grooming other chimpanzee|
Like humans, chimpanzees communicate using a variety of methods including body language (positions and gestures), facial expressions and vocalization. Calls can be intraparty (calls among chimps that are together) or distance calls (calls made between groups that are separated, sometimes over a great distance).
Each individual chimpanzee has his or her own distinctive pant-hoot making the caller easily identified. Food calls, a mixture of grunts, barks and pant hoots, alert other chimpanzees to the location of food sources. A high intensity of these calls usually indicates a successful kill following a hunt. A loud, long, savage-sounding “wraaaa” call is made when a chimpanzee comes across something unusual or dangerous. Soft grunts uttered by foraging or resting chimpanzees serve to maintain communication within the group. When young chimpanzees play, they emit breathy laughter.
Below are some of the calls used by chimpanzees and their meanings.
|Soft Bark, or Cough||Annoyance|
|Food-grunt or Food “aaa” Call||Food Enjoyment|
|Scream, Bark||Fear or Anger|
|Crying||Rage or Distress|
|Laugh, LipSmack, Pant||Enjoyment|