In many small-scale societies, there’s an institution that looks like marriage, where people “pair bond,” but there’s philandering on the side by both men and women. They’ll often just cycle to another pair bond. It’s not uncommon for hunter gatherers to have three, four or five pair bonds in the course of their life, while getting children from each one.
So far as I know, our species of human has been around for about 260,000 years. According to several scientists, it’s a reasonable guess that, for most of that time, we lived as hunter/gatherers and had marriages that resembled those Henrich describes as common in small-scaled societies today.
It also seems a reasonable guess that people in our ancestral societies most often married for romantic love. Hunter/gatherers tend to have very few possessions, so marrying someone for their goods is a relatively bad idea. People might have married to create alliances between families and groups, but hunting/gathering marriages tend to be comparatively short lived — so marrying to create alliances between groups might not always be an especially attractive idea. And humans seem emotionally tailored by evolution for romantic love. For those and other reasons, I think it’s safe to say our ancestors most often married for love.
I suspect that was not only the traditional pattern of marriage in our own species of human, but also the traditional pattern of marriage in our precursor species. In other words, when we think of traditional marriages — the kind of marriages we would have if left to nature — we should think of folks most often marrying for love, now and then screwing around on each other, and eventually traveling on to a new wife or husband. All within the context of having kids who would — to a large degree — be raised with help from the entire band.
In my opinion, marriages were very unlikely to differ from that model until about 10,000 years ago, with the beginnings of agriculture. Once you start growing crops, owning the cropland is not far behind. And once you have landowners — and inheritances — then you have all sorts of pressure to marry for possessions, or for alliances, and not necessarily for love. You also have extraordinary pressure to stay married at almost all cost. And you now have agricultural surpluses that can support extra wives. The extended family becomes more important than the band, but the nuclear family — a byproduct of the Industrial Revolution — is still more than 9,000 years in the future.
Anyway, just some Sunday morning thoughts on traditional marriages.