The result of this instability meant that the social functions of alpha male dominance were no longer working. Conflict and killing over females must have increased dramatically, putting group survival in jeopardy. The need for social order became paramount, and yet killing the alpha male did not lead to a stable or satisfactory solution, because he was replaced by another alpha who became equally vulnerable to attack.
Monogamy, the social recognition and organization of the male and female pair bond, exists in all human societies, and is prevalent in most, but, to a lesser degree, polygamy and promiscuity also exist in most societies. In terms of being monogamous, humans are outliers compared to most other apes and primates, who are mostly not monogamous, and far more promiscuous. The few apes, such as orang-utans and gibbons, who are monogamous are also solitary and do not live in large groups. Humans are the only primates that both live in large multi-family groups and live in monogamous families.