Monogamy (Greek: μονός+γάμος; monos+gamos meaning one+marriage) is a form of marriage in which a person or animal has only one spouse at any one time.

The word monogamy comes from the Greek words "μονός", monos which means one or alone, and "γάμος", gamos which means marriage.^[1]

Monogamy is one of the beliefs of Judaism and Christianity. An exception is the fundamentalist branch of The Church of Jesus Christ of Latter-day Saints (Mormons) who strictly follow the teachings of founder Joseph Smith. Smith allowed polygamy, and had many wives. In Jewish and Christian doctrine, marriage is between one husband and one wife, which is monogamy.

In most countries, monogamy is the only legal form of marriage, either between a man and a woman in most of these countries, and between two persons of the same gender (gay marriage) in some of the Western world. In these countries polygamy is illegal, and a person who has more than one spouse can be prosecuted for bigamy.

Polygamy without equality was almost universal in ancient human tribes.^[2] By "without equality" is meant that of the wives only one would have full rights and recognition as the main wife.

The fact is that all societies of which we have good records lost men disproportionately, mainly because of warfare, but also accidents in hunting. This left widows who were not responsible for being widows: they were just unlucky.

It might be thought that this would be counter-balanced by loss of females during child-birth, but apparently not so. A full appreciation of this fact needs to take into account:

1. On the one hand, the absence of modern medical technology, and
2. The well-known fact that earlier societies had younger mothers.^[3]
3. The life expectancy in prehistoric times was low, 25–40 years,^[4] and with men living longer than women; archaeological evidence of women and babies found together suggests that many women would have died in childbirth.

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