KEY POINTS:
File this under "note to self": there may be a biologically planned obsolescence to marriage.
Depending on yours, that is either ecstatically good news and you're already dusting off your little black book and trimming nose hairs - or just plain sobering. If marriage is the hallelujah chorus for propagating the species, why wouldn't divorce also have an important use in the evolutionary scheme of things?
Just about the time you feel the need to biff out your "better half" for an even better one, our culture preaches that the Big "D" amounts to a Big "F" for failure.
We see marriage and children as a species necessity, but with all due respect to a good half-dozen religions that preach otherwise, why doesn't divorce get any biological respect? Research shows that all societies find a way to dissolve mating partners.
Divorce has been on the up and up for generations. What gives?
Leading evolutionary anthropologist Helen Fisher has an idea. When she tried to find a biological purpose for the supposed "seven-year itch" from United Nations data, she found surprising results.
In country after country, among millions from vastly different cultures, divorces regularly peaked at the fourth year of marriage - making divorce more like a four-year scratch and run than a seven-year itch.
Worldwide, not only did couples tend to divorce most often at year four, but divorces peaked among those in their late 20s, often with no children or just one child. The more children a couple had, the less likely they were to divorce.
Dr Fisher saw the evolutionary link. She explains that our hunting and gathering ancestors traditionally spaced their children about four years apart. Women in these societies breastfed around the clock, ate a low-fat diet and got lots of exercise - habits that tend to inhibit ovulation.
"Perhaps human parental bonds originally evolved to last only long enough to raise a single child through infancy, about four years, unless a second infant was conceived. By age 5, a youngster could be reared by a mother and a host of relatives. Equally important, both parents could choose a new partner and bear more varied young," Dr Fisher told The Edge website.
We're not just talking about Kiwis or Canadians. In Yanomano villages in Venezuela nearly all children to age 4 live with their mother or both parents, but cohabitation declined sharply after their children reached 5, according to studies by anthropologist Napoleon Chagnon.
In what is no surprise to any of us, the less economically dependent couples are on each other, the more likely we are to seek new partners.
In societies where women have financial resources, like the Yoruba in West Africa, who control a complex marketing system, as many as 46 per cent of marriages end in divorce, said Dr Fisher in Natural History magazine.
Our myopic Western perspective on marriage is just one measly take on the entire human mating game. A whopping four-fifths of human cultures permit men to have several wives simultaneously, though only about 10 per cent actually do, says Dr Fisher.
So when your best mate is crying into his or her foam about their windscreen-shattered heart, here's your cue.
Divorce is as much a natural part of human evolution as bearing children.
If yours is one of the one-third of marriages in New Zealand that will end in divorce, you will actually be doing society a favour. Over 90 per cent of you will remarry. More importantly, many will bear children with a new partner, thus diversifying our gene pool.
"Like pair-bonding in many other creatures, humans have probably inherited a tendency to love and love again - to create more genetic variety in our young," said Dr Fisher.
Whenever I hear that an acquaintance is divorcing, my first twisted instinct is to offer congratulations.
I figure a couple have already done the painful hard yards by the time they're ready to make their split public. We're probably not ready to convince therapists that it's all about primate biology - and get away with it. But once in a while, cap the moral judgments and see divorce for what it is - a primal fact of life.
Dr Fisher reminds us, "Deep in the human spirit is a restlessness in long relationships, born of a time long gone, as poet John Dryden put it, 'when wild in wood the noble savage ran'."
I can hear the thud of spouses elbowing their partner in the ribs across this fine land. Just watch it, Noble Savages; no one ever said natural selection wasn't painful. But whether we like it or not, our species depends on it.
www.traceybarnett.co.nz