ABSTRACT
In the 1970s, pnmatologlstS' - reported on the mter-commumty relatIonships of the Gombe (Tanzania) population of chimpanzees, especially episodes of what Goodall literally called 'primitive warfare'. Goodall describes several such lethal male raiding episodes in some (gruesome) detail. 'It seems,' she states, 'that we have been observing a phenomenon rarely recorded in field studies - the gradual extermination of one group of animals hy another, stronger, group.' \Vhy, she wondered, would the aggressors attempt to kill, maim or injure their victims instead of merely chasing them away? Both Goodall and colleagues and Bygott emphasize that the males actively seek out agonistic interactions with the adjacent community during-their patrolling. Soon afterwards, Nishida, as well as Itani,:n observed similar !"rroup antagonism in chimpanzees, which was described by Itani as a 'skirmish in a war'. On the patrolling behaviour of some 'warrior groups' Itani also reports that 'they looked as if they were aiming lor the l)t>st chance of encountering another group', or as if they were looking for an opportunity to 'hunt down' conspecifics and inflict fatal injuries.:1 ) Furthermore, the attacks were all characterized by 'unusual hrutality and persistence',:!'> and the observers could not escape feeling that the aggressors were 'intentionally' trying to kill their victims. As Itani phrased it: 'antagonistic interactions of a group versus an individual, or a group versus another group, l.f.lith the intenl to kill, is peculiar to chimpanzee society'. :11;
Interestingly, these inter-community encounters involve mostly males. Females (usually while in oestrus) sometimes accompany males OIl patrol, hut they do not typically initiate 'hostilities,.:17 Another intriguing observation is that the intense excitement shown by the aggressors during and after the
202 , I ('ffilll'. HI/Illicit}' and :lItruislIl
attacks rather easily "spills owr' into huntil1~ and killing other primates (red colobus or young baboons), which mi~ht suggest that at least in some instances similar moti\'ational mechanisms may be im'olwd in both intraspecific \'ioicnce and interspecific prcdation.:m Both Ghiglieri and Alexander:;!1 speculate that the raiding strategy may be a patterII common to the h uman-chimpanzn"-bonobo (H U C H IBO) dade.
