Bruce Bawer at The Dish recounts the multifarious forms of “marriage” cataloged in the Bible:
“Lamech [Noah’s father] married two women, one named Adah, the other Zillah.” (Genesis 4)
“Sarai brought her slave-girl, Hagar the Egyptian, to her husband and gave her to Abram as a a wife.” (Genesis 16)
“When [Rachel] gave [her husband Jacob] her slave-girl Bilhah as a wife, Jacob lay with her, and she conceived and bore him a son.” (Genesis 30)
“Esau took Canaanite women in marriage: Adah daughter of Elon the Hittite and Oholibamah daughter of Anah son of Zibeon the Horite, and Basemath, Ishmael’s daughter, sister of Nebaioth.” (Genesis 26)
“When a man has two wives, one loved and the other unloved, if they both bear him sons, and the son of the unloved wife is the elder, then, when the day comes for him to divide his property among his sons, he must not treat the sons of the loved wife as his firstborn in preference to his true firstborn, the son of the unloved wife.” (Deuteronomy 21) [READ THE REST]
Though I haven’t read it yet, I assume this is the same trajectory in the Unprotected Texts: The Bible’s Surprising Contradictions About Sex and Desire.