"Monogamy: Researchers Disagree on Why Mate Fidelity Evolved
Is it because of infant killing (infanticide) or where females live or ...?
While there has been a good deal of interest in the evolution of monogamy, we still know little about why mate fidelity has evolved in mammals. In the recent studies using similar methods of analysis in which social monogamy was defined as "males and females living in breeding pairs", "One group of researchers says monogamy evolved in primates to counter the threat of males killing babies to boost their siring success. The other team concludes that mammals, including primates, became monogamous when females live far away from one another."
And, as evolutionary anthropologist Eduardo Fernandez-Duque of the University of Pennsylvania notes, “It’s unlikely that one size will fit all.” We need to be very careful about grand theories because different factors may lead to the evolution of social behavior in different species."
PsychologyToday
A for in humans, I'm goanna go with "or"....
Therefore shall a man leave his father and his mother,
and shall cleave unto his wife:
and they shall be one flesh.
Genesis 2:24