So seeing all the fuss about Nauvoo polygamy, I thought to myself, history schmistory, let’s talk biology. Biologists know plenty of titillating facts about reproductive strategies—including polygamy and polyandry! However, watch out, biologists tend to be ribald and earthy in these descriptions so if you tend towards reserved euphemisms in your discussions about what the ‘stork brings’ and the ‘nether parts’ of the body stop reading now. You are duly warned that I will splash some rather unsettling biology across the page. Also, I assume sexual strategy is an evolved response and what I’ll be presenting represents what biologists call an ‘evolutionary stable strategy’ meaning that there are demonstrable benefits for organisms to evolve these ways of getting at creating a new generation. Polygamy, monogamy, and polyandry are all ways of dealing with having healthy offspring that can compete with other organisms in the game of survival. (If you are surprised at my strident use of evolution, I assure you I am as strident defender of my Faith. I write about this on my other blog. Especially look at the early posts where I introduce my defense of evolution and the church) One or another strategy will work in various situations. So let’s briefly sketch a sidewalk caulk outline of when each works best and why. Note: this post is merely a cartoon of complicated research and I’m hand-waving through loads of missing detail. I’ll give you some references at the end. Also, please do not think that this biological information tells you how to live. As Hume said long ago, you cannot derive an ‘ought’ from an ‘is’.
First some things you need to know to set the stage.
A) In most organisms, females bear the brunt of direct reproductive costs. They carry the baby, provisioning it from conception on—indeed until it can make its own way in the world completely. They bear the costs of lactation or feeding their young offspring. They bear the risks that pregnancy and delivery carries (birthing is one of the most dangerous things animals do). They bear the risks of guarding the young from predators and all the other uncertainties play out in bringing young to adulthood. This means huge costs in risk and energy expenditure for females.
B) Females have only a few reproductive opportunities in their life because of the time required to raise each child.
C) Males in general have few direct risks in reproduction, bear little cost, and have as many opportunities for reproduction as they can get. Technically they could father a child a day (or more) their whole lives. Sperm is fairly cheap and readily available, eggs are costly and are available less often.
These things set up a situation where males and females have very different interests in reproduction. Because of the costs they bear in reproduction, females in most species are very choosy. You’re only going to get a few offspring off during your life so you better select the best male you can—the male animal equivalent of Twilight‘s Edward, who oozes virile perfection, would be best. Trying to impress these fussy girls is why it’s common for males to be colored or have secondary sexual characteristics like nice tail feathers or a stunning set of manly antlers. Ofttimes a male may have to fight other males to properly dazzle the female of the species, or do a dance, for example, if you’re a prairie chicken, perhaps sing like an angel, or other things that let females compare him to the sorry losers standing about posturing. Females really don’t want to waste their chances on a ner-do-well. Males have to strut their stuff. So in reality although they could father a child daily, the reality is much different. For a male, reproduction is actually limited by his success in impressing that special lady (or ladies if he’s good!) enough that she is willing to accept him as a mate. This takes effort. So males do bare costs in other ways: bloody battles, way too big of tail feathers, movie tickets, expensive dinners, nice cars, stunning wit, being a vampire, etc.
Polygamy tends to show up when a male can impress a number of females, guard them from other males, has exclusive access to scarce resources, can beat up or drive off the other males, out-dazzle the females in the presence of the other males also trying to dazzle them. (And Speaking as a male I can vouch that it’s a tough gig).
Strict polyandry (one female many males) is very rare the animal kingdom. Actually, what people are writing about happening in Nauvoo was not what biologists or anthropologists mean by polyandry (I’m disagreeing with Wikapedia on this). The technical term for what is being written about in Nauvoo is extra-pair matings or couplings. Polyandry implies a stricter reproductive strategy where the one-female-and-lots-of-males schtick is a little more formalized, and it does occur in humans. I just don’t think Nauvoo is an example of it’s implementation. But historians misapplied the term and I guess we are stuck with using it. Of course, as Wittgenstein pointed out, language is usage, so I might be wrong on this soon enough as historians keep using it this way.
So why would a male ever be monogamous? It turns out that if a male can be assured that he is the father of the children it’s a great idea! Why not help pay the reproductive costs by helping get the little tikes to adulthood, rather than the constant effort of impressing those fickle girls? Beats having those ungainly tail feathers, or spending you time chasing off amorous males who are constantly trying to sneak in and grab a little from your females. Two, parents working together are more likely to get the little rascals to the point they can have their own little rapscallions (see the Proclamation on the Family). But here’s the rub, if this is going to work as an evolutionary stable strategy: the male has to be pretty darn sure those are his brats before he starts paying those costs. Females, have a clearer sense that a particular young’n is her’s, I mean, really, she gave birth to it. Males? Not so much. Male helping (if that’s not an oxymoron) is usually associated with tight monogamous pair-bonding.
However, even in monogamous species, females tend to, shall we say, keep an eye out for those most-excellent genes. For example, in lots of birds monogamy is the rule and the pairs form tight bonds. But when scientists began to look at actual paternity it turns out, well, some things began to show up in the genes that seemed to cast a suspicious eye on our conception of tight ‘monogamous’ pair-bonds. For example, in barn swallows, it turns out that the big tailed males were mating with some of the females on the side while the poor average-tailed father was out bringing home the gnats. If you can have a male help (because he’s convinced he’s the father) and still grab some of those dreamy long-tailed stud’s genes, well why not the best of both worlds? If you are an Office fan you see this played out in Angela’s relationship with Andy and Dwight. She wants to marry Andy, because he’s stable, reliable, will make a great dad, and will take care of her. But she wants to mate with Dwight because he’s wild and virile and would bring some great things to the genetic table for future offspring (not that she specifically is thinking this, but in evolutionary time, that drive to have sex with Dwight could underpin such considerations and explains why such common depictions in literature ring true). These extra pair-matings are not uncommon in humans and and can run as high as 5% in some cultures, in terms of the number of fathers unknowingly raising someones else’s kids. Extra pair-matings (known as adultery in humans) run as high as 20-25% in males and 10-15% in females in humans and varies significantly by culture. But, again, this isn’t polyandry, it’s just messing with monogamy in creative ways. As might be said in bad translation, “Monogamy as she is practiced.” So I disagree with the term polyandry being applied in Nauvoo. So I think we have demonstrable polygamy, but not polyandry, in Nauvoo. But it’s monogamy that really interests me and why it works especially well in Mormonism.
And in general humans are actually fairly good at monogamy. Better than most birds.
So we will take a closer look at Humans in Part II.