No wonder Darwin was ridiculed when we proposed our descent from primates. The extreme reaction was merely hiding the fear that evolution is clearly true and that we are hairless chimps.
And don't forget, this was before DNA confirmation (greater than 98% identity) of our profound biologic similarity.
Therefore studying chimpanzee behavior is enlightening as well as frightening.
In his NYTImes article http://www.nytimes.com/2010/06/22/science/22chimp.html?hp Nicholas Wade explores the study of chimp behavior as it entails the equivalent of war parties which engage so-called enemy tribes. The analogy with human behavior during war is truly astounding.
The waring party stealthily approaches the target in what may be some altered state of consciousness. They will attack and confront smaller groups or individuals, disperse when met by larger more threatening groups.
Eventually they even take over the territory of defeated foes.
What is equally fascinating is the comparison between standard chimpanzees and their cousins the bonobos who are not bellicose but instead resolve their interpersonal relationships through having sex.
Hmmm. Too bad we can't choose our ancestors.