Not to mention the fact that through much of the history of the tribe of Israel they, like most other tribes in the area, practiced polygamy. Jacob had two wives *and* two concubines...none of whom were free to refuse him. Solomon had a harem.

The Hantu, possibly the oldest culture on the planet, do not have marriage and most couples stay together for 5 to 7 years, which is to say enough time to conceive and wean one child. Then you switch partners. Life bonds are known and accepted, but unusual. Most Native American tribes only had informal marriage, not seen as permanent.

Marriage almost certainly started out as consortship mating, which is practiced by chimpanzees, and became longer because it was advantageous to the female to keep the male around until the child was weaned. FORMAL marriage, as we see it today, appears to have started after we became farmers and having multiple kids around became an economic benefit. This resulted in long term consortship.

But think about how many marriages you know fail at, oh, the 5 to 7 year mark... Marriage is not naturally permanent, although no doubt past selection pressures have favored people who do want, and can handle, a life bond.

IOW, we've taken marriage rather too far. And these people believe that their view of marriage is the original one when history, prehistory, and evolution (in which they probably don't believe) say otherwise.