Chimpanzee legal aggression study facts
Charlie Coffey/Iowa State Daily
Jill Pruetz, professor of anthropology, has studied chimpanzees since 1990.
September 30, 2014
ISU professor Jill Pruetz collaborated with 29 other primatologists on a study. They found that lethal aggression was not a result of human impact but rather an adaptive behavior.
| Variable | Human Impact | Adaptive Strategy |
| Chimps kill more than bonobos | None | Study found only 1 suspected bonobo event compared to 151 chimp event |
| Sex bias: attackers | None | Study found 92% attackers were male |
| Sex bias: victims | None | Found 73% were males |
| Number asymmetries | None | Attackers outnumbered victims 8:1 |
| Eastern vs. Western | None |
Found more lethal events in eastern Africa |
| Mean number of males | None | Communities were there were more males, there was more aggression |
| Mean population density | None | More dense communities also saw more lethal events |
In the variables they tested, they discovered evidence to support the idea that lethal aggression is an adaptive strategy.
