or standing. Rising by groomee stimulates groomer to resume grooming. 2. See video. arm ladder See extend arm as ladder. arm round See embrace half. arm stretch See extend hand, palm downward. arm swing See brachiate. arm threat See raise arm quickly, shake arm and hit toward. arrive Goodall: Chimp arrives and joins the group. Often accompanied by greeting. See video. Assirik Study area of Pan troglodytes verus in Niokolo-Koba National Park, Senegal. Research done by W.C. McGrew and C.E.G. Tutin from 197 to 1979. attack Goodall Attack: Aggressive physical contact between two, or more, individuals. Includes charge, push, hit, grab, scratch, pinch, slap, drag, kick, stamp, and bite. Cf. battle. Also in bonobos. See video. attack concertedly 33 attack concertedly Nishida et al. Gang attack. Two or