This idea was revolutionary. It suggested that aggression was not a social construct or a learned behavior, but an inherited biological imperative—a "territorial imperative" that drove evolution.

Specifically, researchers looking for are often writing papers on:

African Genesis (1961) by Robert Ardrey is a seminal, controversial work that popularized the "killer ape theory," proposing that human evolution was driven by an inherent predatory instinct. While influential on popular culture, the book's claims regarding innate human violence and territoriality have been largely superseded by modern anthropological research. Access a digital copy of the work via The Internet Archive .

If you are searching for , it is highly probable you are looking for the section where he introduces the concept of amity (in-group bonding) versus enmity (out-group hostility). Page 23 of multiple early editions begins the discussion of the A. africanus skull found at Taung, and the fatal wounds it displayed.