According to feminist historian Sarah McDougall, the Christian European insistence on monogamy and its enforcement arose as a consequence of 16th Century Islamic incursions into Central Europe and the advent of European colonialism within the Americas, Africa and Asia, which exposed European Christians to cultures that practised polygamy.
The monogamy hypothesis, formulated by Jacobus Boomsma, is currently the leading hypothesis concerning the evolution of eusociality and uses Hamilton's kin selection approach in a way that applies to both haploid and diploid organisms.
Orioles are monogamous, breeding in territorial pairs (although the Australasian Figbird, and possibly also the other figbirds, breed in loose colonies).
The Scarlet Robin is a territorial and monogamous species, and defends its nesting territories both from others of the same species and pairs of the related Flame Robin.
The Myth of Monogamy: Fidelity and Infidelity in Animals and People is a 2001 book by psychologist David P. Barash and psychiatrist Judith Eve Lipton.