not in Primary anymore

what if polygamy was for birth control? part 1

Guest post by xenawarriorscientist

Researchers who do such things have long known that if you put boy fruit flies in a jar with an equal number of girl fruit flies, you’ll wind up with a lot of baby fruit flies.  (Suckers for the obvious, these guys.) But if you take the same number of lady fruit flies and only give them a few males to go around, the females all have fewer babies each. You thus wind up with fewer babies total. For fruit flies it sounds like a simple case of fewer sperm to go around. They dubbed this decrease in fertility the “Bateman gradient,” presumably after the poor sucker graduate student whose job it was to count baby flies.

At this point you’re thinking “Ermagerd, what do maggots have to do with polygamy?” but fear not it will soon become clear.

Moorad et al. of Indiana University (2001) wondered whether this could be true for humans as well. They turned to one of human geneticists’ favorite resources: the Mormons!  We Mormons have a rare one-two punch of having a kajillion kids each and still being literate, so there are lots of large, well-documented families to work with. Moorad et al. got double-lucky since Mormons also changed from polygamy to monogamy within historical times. We have good documentation for both during and after polygamy, allowing the scientists to compare both Mormons with their non-Mormon neighbors in the same area, and with later generations of non-polygamous Mormons.

(I have to say it’s pretty hilarious to see your Big Fat Mormon Family History expressed in science-ese: e.g., “Polygamy benefitted males by increasing reproductive rates and by lengthening reproductive tenure.” Yes. That is one way to put it.)

Here’s what the scientists found: yes indeed, polygamous men had many more children than their monogamous counterparts. Again, it’s funny to see this in science journal format, since it’s something so frequently encountered in Sunday School– “Raise up a righteous seed,” etc etc.

But something pretty basic gets forgotten in that Sunday School explanation. Men ain’t everybody. Polygamous women actually had fewer children than monogamous women—and that means that the pioneers as a whole had fewer children than if they’d stuck with monogamy. They took a ride right down that ol’ Bateman gradient.  In fact, Moorad’s research group found that for each additional wife in a marriage, all wives’ “reproductive success” decreased by one child or more. (To a point, of course; the average number of children for women in the early Utah days was somewhere around 8 or 9, and I don’t imagine that Angus M. Cannon’s 86 wives all had -77 children each. Also, rating human “reproductive success” simply by number of births is problematic. More on that later.)

So, to review: it is a fact, recorded right there in our family histories, that polygamy appears to have caused women to have fewer children. The “raising up a righteous seed” logic seems to need a second look.


I’m going to throw a really crazy idea out there: that polygamy caused women to have fewer children, and maybe that was the point.

As evidenced by Brigham Young’s call for women to return east for obstetrical training, the maternal and infant mortality situation in early Utah was pretty grim.  Each pregnancy and birth was a ripe new opportunity to die. Needless to say, a dead mom is not great news for herself, her baby, nor for any children that woman has already had.

Further, the settling of early Utah meant adjusting to a difficult new environment.  The colonists were dependent on agriculture. However, the vast majority of them were from exceptionally wet and rainy areas like the British Isles, Scandinavia, the eastern half of the US, and even Hawaii. Farming in the desert ain’t nothin’ like farming in Lancashire, and mistakes are deadly. There was also a huge amount of infrastructure—dams, irrigation canals, roads, etc—that had to be built before the desert could “blossom as a rose,” and dams don’t build themselves. Perhaps this was why Brigham Young insisted that “no man ought to do any job a woman could do.” Men’s labor was recruited for building projects. Of course, this also indicates how important women’s agricultural and artisanal labor were to keeping the settler economy afloat. Pioneer women may have been based at home, but they were not “stay-at-home moms” in any sense we would recognize today.

Remember how I took issue with the authors of this paper framing women’s “reproductive success” by number of births? Let’s think about that high infant mortality rate that the pioneers experienced. You and I both know that the number of babies born has little or nothing to do with how many children a family actually raised to adulthood.

There are many more factors that play into how many children survive to adulthood.  To wit: sufficient food. Sufficient clothing and shelter to avoid frostbite and disease. Adequate hygiene, which eats up man-hours like you wouldn’t believe when there’s no running water. Sufficient adults on hand to keep kids out of, or nurse them back from, life-threatening accidents. Those are the things that, frankly, are better accomplished with a relatively high ratio of adults to young children. A super-high birth rate in many circumstances does not actually lead to more “reproductive success.”  For that, you want to count number of children that actually live to adulthood.


I’m also going to throw this out there: that pioneer women may well have been aware of all this.

Moorad et al. don’t seem to be too familiar with the polygamous Mormon lifestyle, and that’s ok—they’re geneticists, Jim, not Mormon folklorists. The focus of their paper is also darling-ly androcentric. That is 100% in keeping (sadly) with the norm for human evolutionary studies. They discuss the pros and cons of polygamy for men at length without once touching on women’s reasons for choosing or not choosing polygamous marriages. Hello-o, women have agency too!  Since at least some polygamous women actually proposed to their already-married husbands—again, I’m thinking of Martha Hughes Cannon on this one— and the federal government found it necessary to take the vote away from women in order to outlaw polygamy, clearly women’s agency played some kind of role in perpetuating “the principle.” If we don’t look at women’s stake in the issue, we’re going to miss some central things.

The typical arrangement in polygamous Mormon families was for each wife to have her own household, often in different towns or different parts of the state from the others. (Pioneer women seemed blissfully unaware of the 20th century stereotype of sister-wives living under one roof in a giant live-in babysitting swap.) The husband travelled from household to household to spend time with each family, usually on some kind of regular rotation. For women in good health, it wouldn’t take genius-level intelligence for the women to work the visiting schedule so as to increase, or decrease, odds of conception as desired. And I’d have to go back and look (or ideally, have some graduate student write their dissertation on it), but I remember looking through old Women’s Exponents back in college and see them talking about polygamy in a way that made it sound as if they were perfectly aware of this.

This was a possibility entirely neglected by the authors. They explained the loss of female fertility entirely through “resource competition”—you know, they had to divide their husband’s stuff among more women, which miraculously (through starvation, one presumes) leads to fewer pregnancies.  This is actually an entirely different mechanism  of lowered birth rates— starvation— than that first described in the fruit flies (which was “too many uteri, not enough sperm”).  The scientists’ “resource competition” hypothesis is cute in and of itself because it just assumes that polygamous women got all their money and food and dresses and things from their husbands.

But knowing Utah history, I’d have to say that if anything, it was more like the wives’ work supported their husband—as documented by women owning businesses, working the farms, and sending money to their missionary husbands. In agrarian societies of the 1800s “the idea of a man supporting his wife was not commonly accepted, for ‘husband and wife were . . . mutually dependent and together supported the children.’” (Murphy 2005). That’s us in the 20th/21st century looking back and projecting our industrial-era lifestyle back onto them. It’s well known that polygamous men tend to be better-off than their monogamous neighbors. But let’s all remember that increased wealth just might have been the result of a man’s having multiple wives— not the cause.

You can read Part 2 here.


5 Responses to “what if polygamy was for birth control? part 1”

  1. Emily January

    I love this! Can’t wait to see part 2. My favorite part is when you mention us imposing our industrial-era views on the past, and dare I say, we continue to do that by embracing a cultural image of the family that has never really existed. Suburbia, among other things, created it, yet we cling to it.

  2. Frank Pellett

    Interesting stuff. Would be interesting to see if the lower birth rate amoung females corresponded with a higher survival rate amoung children. Could this mechanism allowing women to have fewer children also have allowed them to have time to seek more education and other opportunities, which in turn helped them have stronger families?

    It would be interesting to read the stories of women who entered into polygamy for the advantages they percieved in it.

  3. biobrit

    I think you’re on to something interesting here, but I have to point out a few things that I believe are incorrect. First, your description of the Bateman gradient is not right. Bateman showed that female fruit flies had the same amount of offspring regardless of the number of mates in the jar. On the other hand, the number of mates males had varied greatly on the numbers of males in the jar. This sort of set up it typical in animals with a few notable exceptions (e.g. pipefish). The gradient is not about losing fertility. It’s just a description of mating success to number of mates. It can be positive, negative, or remain the same.
    I’ve read the original paper that you are referencing in your article. It appears that humans tend to follow a similar Bateman gradient trend in that males greatly benefit by having more available mates, while in females it doesn’t seem to matter much. There was a weak disadvantage to females as you pointed out, but it was only a weak disadvantage.
    While I agree that measuring reproductive success through offspring is problematic, it is standard practice in population genetic studies.
    I look forward to your ideas behind why or why not women would have chosen to participate in polygamy.

  4. Al Pratt

    Love this article. I also highly recommend the new book by former plyg wife Joanne Hanks, “It’s Not About the Sex My A**.” Easy to find if you google her or the title. Casts light on the craziness of a contemporary plyg cult in Manti, Utah, and on how a woman who was basically raised to do what men told her to do had to find her own feet and stand on them.


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