The larger majority of human intimate relationships have involved two people, historically a man and a woman (though not always): this man and woman live together, have children together, have sex with each other, and don't turn to other people to fulfill any of those needs. However, it is possible to put together intimate relationships that involve more than two people. These situations are what this article is about.
PolygamyThe practice of having more than one spouse is called polygamy; the conditions of having more than one husband or wife actually have their own names (polyandry and polygyny respectively).
- Polyandry: One wife, and two or more husbands
- The advantages: In a sexist world where men work and women stay at home, is that her children receive more care and nutrition; the presence of more than one breadwinner increases the likelihood that the little tots will live to adulthood—an important consideration if, as it was throughout history, child mortality rates are in the 50% area.
- Another major factor is that in mountainous regions where land is scarce, if brothers marry the same women, their joint household can inherit the family land together. Otherwise, the land would either (a) be split into pieces that are too small to support any of the brothers, or (b) it would all be left to the eldest brothers, with the others getting nothing.
- Alternatively, at varying times in varying societies, traditional men's work—such as farm labor was vital for the family. In other words, multiple husbands meant less work for each of the men and greater family productivity over all.
- Polygyny: One husband, and two or more wives
- The advantages: (in the same sexist world where men are the breadwinners) It allows women to get very high quality husbands. Well, think of it this way: if you could contrive it that your child would be fathered by Brad Pitt, or Albert Einstein, or Johann Sebastian Bach, but to do it you had to become that man's second wife, would you? You might: the benefits to your child outweigh the inconvenience to you. Besides, these are rich, successful men who can probably provide for you more healthily than their currently-single competitors. This is the impetus behind animal herds involving one alpha male and a bunch of women: he who is best and most fit (as chosen by natural selection) is the one I want my kids to be fathered by, for the sake of their futures.
- In a society where men are warriors or soldiers, they get killed at a higher rate then women, leaving a gender imbalance. Doubling up on husbands then becomes the only way for there to be enough to go around. Also, if the widows of the dead warriors are now single mothers, and—in the same sexist world where men are the breadwinners—that's a very hard position for her and her children. If their society allows her to remarry, it's better for her kids.
- Alternatively, at varying times in varying societies, traditional women's work was the most labor intensive or provided the most economic advantage for the family—for instance, some native American tribes went from monogamy to polygyny as American colonization became more prominent, because it became financially advantageous for the families to be able to produce more textiles and other goods that the women typically made, for trade and the like. In other words, multiple wives meant less work for each of the women and greater family productivity over all.
- Group marriage: And finally there's the group marriage, which is a marriage between three or more people of any combination of sexes and genders. These can get complicated, but in theory bring all the advantages listed above under one (very big) roof.
If you're looking at these ideas and thinking that they're all about straight practicality, well, you're right. The idea of marrying for love—a marriage in which your personal happiness is of prime importance over questions of procreation, economics, etc—is much Newer Than They Think; it's only been standard practice since about the 1600s. Before then, marriages had more to do with child-rearing and political alliances than anything else. And even today, would you seriously marry someone who you thought would make a bad parent? Or, for that matter, who couldn't provide for you if push comes to shove? You probably wouldn't.
Incidentally, polygyny was legal in several ancient cultures, including the ancient Israelites of The Bible; Solomon was said to have 700 wives. It's still legally recognised in much of the world, especially in countries where Islam is the predominant faith. (Eritrea, India, Sri Lanka, and the Philippines recognise polygynous marriages among their sizeable Muslim communities, but not among other people.) Polyandry... not so much, and has mostly been practiced in the Himalayas.
PolyamoryThe next idea down the list (from most commitment to least) is the idea of polyamory, which is when you are in more than one committed relationship at a time, with the consent of everyone involved. This is a modern variant, focusing on love and dating.
Most people will tell you that, even if you can love more than one person at a time, it's hard to be committed to more than one person at a time, due to the selfish aspects of human nature. Polyamorists disagree. They don't reject commitment, but they do reject exclusivity, jealousy, possessiveness and the negative or limiting emotions that seem to come with it so very often. The main difference between this and polygamy is that marriage is not considered a necessary part of a polyamorous relationship—and nor, for that matter, is sex. Polyamory simply means that you want to form significant emotional bonds—of any manner—with more than one person. In that sense you could argue that we are all polyamorists: even people who get married and have a spouse (or two) still have emotional bonds with their friends, their siblings, their parents. Not the same kinds of bonds they have with their spouse, or so we hope, but bonds nonetheless.
SwingingYou also have swinging, which is the belief that you can be in a committed emotional relationship while still having sex with other people—with, of course, the consent of everyone involved.
The root of swinging is the understanding that sex and love are not faces of the same coin, and that one does not have to proceed directly from the other. This is of course patently Truth in Television; regardless of what the "Sex Equals Love" trope would have you believe, it's possible to have sex with someone you don't love (see: casual sex, Rape Tropes), and possible to love someone romantically without having sex with them (see: Courtly Love, Chastity Couple). People who swing simply maintain this idea into their committed relationships: as long as they have permission from their spouse/significant other/etc and are taking all appropriate precautions, they don't see anything wrong with having some casual sex on the side. Obviously, the spouse gets the same rights and privileges as you do.
MonogamyAnd then finally down at the bottom is the idea of the two-person committed monogamous relationship, which is what Western culture (currently) considers the ideal. In this relationship it's against the rules to do anything sexual or romantic with someone besides your spouse/significant other/etc. If you break the rules, you're cheating. If you change the rules, then you're not in a monogamous relationship anymore; you belong to one of the poly* categories discussed already.
Consent of partnersYou'll notice that none of these relationships give you the right to just go out and do whatever (or whomever) you want, without the permission or consent of your partners. Generally, that's reserved for being single. All these relationships involve being committed to somebody—sometimes more than one somebody—and if you get together with someone when your partner(s) has told you not to, then you are cheating and that's that. This is where multi-partner relationships get tricky. Say you're in a relationship with Alice and Bob, and you then want to sleep with Charlie on the side. Alice is amenable... But Bob says no, and won't budge. (Maybe Charlie was mean to them in high school.) It's hard enough to get permission to do anything from one spouse; imagine having to clear your actions with two! This is one of the arguments people bring up when declaring that multi-partner relationships don't work... and, to be fair, they've got a point. But just because something is difficult doesn't mean it's impossible.
Open vs closed relationshipThis brings us to one last distinction: an open relationship versus a closed one. A closed relationship is just that: whoever you're with, that person/those people are it for you.
It's possible to have a closed polygamous marriage—for instance: say you have three wives, and all three of them have you. If the marriage is closed, then that's it as far as sex, intimacy, etc is concerned: you're not allowed to get any more wives (or sleep with anyone else on the side), and your three wives are likewise limited to you (and maybe each other).
In an open relationship, partners are allowed or even encouraged to venture outside their current roster of (sexual and/or romantic) partners. If you're a swinger, that line starts to blur a little: sex can be a lot more casual, although it may still involve deep romantic feelings, or great friendships with various sex partners; and all of it can change for individuals over time, of course. But it's still possible to swing with only a specific set of people ("Okay, hon, we're going to sleep with each other and also with the Joneses, but with nobody else.") or for limits to be placed on some other element ("If you find anyone you'd enjoy spending the night with, hun, have fun! Just make sure they know it's not going to go beyond sex.")
Long story short, a "closed" relationship is one that is exclusivenote . The only question remaining is who you're being exclusive with.