As reported in National Geographic, geneticists agree that chimpanzees are humans’ closest living relative, sharing 98% of their DNA with humans. This close relationship is apparent when observing chimp behavior, especially during aggressive confrontation. Chimpanzees generally attempt to avoid aggression by behavioral manipulation but will certainly defend themselves if necessary.
Chimpanzees are highly social animals with a rigid social structure. Males always dominate females, and each community contains one male who dominates the group. Communities contain 15 to 150 individuals who all share a social bond and tend to get along, but aggression frequently comes into play when a male challenges the dominant male or when confronted by outsiders who may try to encroach upon the community’s territory. When faced with a hostile encounter, a chimpanzee’s self-defense depends upon his social standing compared to his rival.
When the chimp initiating the confrontation is of a superior social standing within the community, the non-dominant chimp will display overt signs of submission to appease the aggressor and defuse the situation, thereby avoiding an all-out attack. The victim will attempt to make himself look as small and non-threatening as possible by hunching over, bowing his head and crouching. The victim might move toward the aggressor with a so-called fear grin on his face and often make submissive-type noises such as grunting or whistling. If the victim is highly stressed, he may squeak or scream, and turn his back on the aggressor as a display of trust.
Frequently, an inferior male will challenge the dominant male to attempt to take control of the community. When the alpha-male is charged by an inferior, he will attempt to make himself look as large and powerful as possible, a spectacle known as a dominance display. He will stand upright or run very fast toward the challenging male, slapping his hands and feet on the ground to simulate the footfalls of a much larger creature. He will often hoot and scream and will often throw rocks and branches in a show of power.
When an outside group challenges a community for control of its land, most members of the community will join in the display, usually with the exception of mothers with very small young. The adult males will patrol the borders of the territory, confronting any members of rival groups that wander onto their land. The patrol group will stand erect and hoot or bark, making as much noise as possible to make it seem like there are more of them than there are. The intruders will generally return to their own territory, but if they do not, aggression usually results.
When a chimpanzee’s multiple methods of intimidation and avoidance are ineffective, they will resort to aggression. All-out non-hunting attacks that result in the death of one or more combatants are very rare in the animal kingdom and are almost wholly the domain of chimpanzees and humans. Chimpanzees have been known to raid rival territories, killing other chimps and stealing food.
When a chimpanzee is dead-set upon fighting, he will run straight at his opponent and latch on with his arms. They tumble and wrestle, hit each other with their hands and feet, and even bite. The victim usually does not die at the time of the fight but concedes defeat and runs away. His wounds will fester, and death usually results from infection days or weeks later.