by Roger Bourke White Jr., copyright March 2012
Marriage and kinship systems are important in all human cultures, but they are also somewhat arbitrary -- they vary from culture to culture without apparent rhyme or reason. How can something like this be both important and arbitrary? That is the topic of this essay.
Who is a relative and what their relation is varies from culture to culture. Anthropologists have categorized the numerous systems into various groups such as: Hawaiian, Iroquois, Sudanese, Crow, Eskimo and Omaha. An example of a difference of definition within contemporary US culture came up with the YFZ Ranch Raid of 2008. The Texas CPS removed over 400 children from an FLDS settlement there, but in the aftermath it had a difficult time determining the biological relations of the children they moved out. Part of the problem was hostile suspicion, but part was that the kids were not used to thinking in terms of nuclear families -- they grew up in a different kinship system.
Likewise what it means to be married varies not only from group to group but from time to time within a group -- much as language drifts steadily with time, so does the definition of marriage. What it means to be married has been a conversational topic in my culture throughout my lifetime, and it is now a red hot item of controversy.
Having marriage and kinship systems is a human instinct. This means having them has been beneficial to humanity for hundreds of generations -- so long that human thinking has evolved to support the concepts.
What is the benefit?
The benefit is helping to distinguish who to trust.
Think of this in terms of the Prisoners Dilemma. All living organisms can benefit quickly and easily from successful betrayal. Betrayal can be as quick and simple as an ambush attack on unsuspecting prey, or as elaborate and patiently planned as Benedict Arnold's attempt to hand over West Point to the British during the American Revolutionary War. It can also be powerful even as fiction such as the Secret Protocols of the Elders of Zion -- betrayal is simple, effective and scary.
Cooperation is also powerfully beneficial, even more so than betrayal. But the benefits of cooperation take longer to establish, require more specialized circumstances than betrayal, and are deeply damaged by betrayal. Finally, the benefits of cooperation increase dramatically when protections against betrayal can be minimized.
So knowing who can be trusted has long been important to human survivability.
Kinship and marriage systems help humans decide who can be trusted. This is their enduring benefit to society. This is why they can also be somewhat arbitrary and still work well. As long as all the people of the community, and surrounding communities, can understand the system, it will serve its purpose of identifying who can be trusted implicitly and who can be trusted only after protections are put in place.
Marriage fits into this picture because it is a way of changing kinship relations.
The important-but-arbitrary nature of kinship relations signals that their importance is not tightly tied to either genes or procreation, but to the benefit they are bringing to the community. The benefit is defining who is trustworthy so low-protection cooperator relationships can be developed. These are highly beneficial to the community, but they take special circumstances to thrive in. Kinship relations define those circumstances, and marriage is a tool for defining kinship relations.