There does appear to be strength in numbers, including among chimpanzees. New research has found that chimps in the wild tend to be more aggressive when they travel in large groups.
Chimps live in societies made up of groups of affiliated cliques. Periodically, some members of these groupings, mostly males, silently gather together and leave in an orderly, single-file line to patrol the boundary of their territory. These chimp patrols have long been known to attack, beat and sometimes even kill neighboring chimps they encounter. But the reasons for the attacks are unclear.
John C. Mitani of the University of Michigan and David P. Watts of Yale University collected data about a community of about 150 chimps in Ngogo, Kibale National Park, in Uganda between 1999 and 2003. On patrol days, researchers found that a larger number of males gathered together than on non-patrol days. The addition of each individual to the group increased the odds of a patrol by 17 percent, the researchers reported in an upcoming issue of the journal Animal Behavior.
"The take-home of all of this is that male numbers seem to matter, they find strength in numbers in doing this behavior, and they find strength in making these attacks," Mitani said.
Chimps are humans' closest living relatives, and it's rare for other mammals to attack their neighbors. But Mitani said he was hesitant to draw any analogies between human and chimp behavior:
"I think it is difficult to make any general conclusions about what this says about human behavior."