Altruism is behavior that benefits another individual at some cost to the "altruist"
or helper. The cost, at times, may be high - an altruist may even lose his or her life. Altruism in chimpanzee communities
can be directed toward close kin, who share many of the altruist's genes, toward individuals who are not closely
related, or not related at all. Both male and female adults are likely to go to the aid of their mothers if they
happen to be nearby. It is also not unusual for a male to support an ally who is being threatened or attacked by a
third, more dominant individual.
Jane's observation:
This incident took place one summer when Melissa was in estrus. For the first
part of the morning she had foraged peacefully with two of her offspring, five-year-old Gimble and his
adult sister, Gremlin. At 10:13 Satan approached the small family party. Hair bristling, he began to
court Melissa, staring up at her as she fed and shaking branches. At once she climbed down to him and,
with pant-grunts, crouched for mating. As he began to copulate and she to squeal, her daughter suddenly
jumped to the ground and with her year-old infant clinging to her belly, leaped toward the pair, and hit
at Satan. The vegetation was thick, and the observer thought that Gremlin had perhaps mistaken the sexual
act for one of aggression. Be that as it may, Satan at once stopped mating Melissa and turned to attack
her daughter. Gremlin, screaming, crouched protectively over her infant as Satan stamped on her, pounded
her with his fists, then dragged her through the undergrowth. At this point Gimble ran at Satan with
waa-barks and hit him repeatedly on the head and shoulders. Satan, ignoring this puny assault, continued
to attack Gremlin. Then Melissa, who had rushed up a tree, returned to the fray and, along with Gimble,
hurled herself at the big male. Satan instantly turned on Melissa. Seizing hold of her by one arm and
the hair on her back, he actually picked her up off the ground and threw her some three meters. Melissa
once more seized the opportunity to escape. As she ran, screaming loudly, Satan charged after her and
little Gimble followed behind, still uttering waa-barks, as did Gremlin from the safety of a tree. Melissa
also took refuge in the branches. Satan did not follow but stopped below her tree, glaring up, hair still
bristling. Presently he began to shake branches again, summoning her to him. For one and a half minutes
Melissa refused to obey; then she climbed down and, still screaming, crouched before him. Satan carefully
inspected her genital area, then wandered away. Soon afterward Melissa, Gimble and Gremlin settled down to a twenty-minute grooming session.
Source: Patterns of Behavior, p. 377. 15 August 1983. Observer: Y. Alamasi
