This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
In high school, my mother occasionally found babysitting jobs for me. Parents, desperate for a trustworthy kid to watch their own, would entrust their offspring to Katie the honors student while they went to a meeting, or to work, or perhaps on a date.
If any of those parents are reading, I have a confession for you: I didn’t like watching your kids.
It’s not because any of these kids were bad – they weren’t. It’s because I was totally uninterested in children. I had no desire to bear them, raise them, make room in my life for them. I dreaded my babysitting jobs, and as a result have a keen eye for that same mixed look of revulsion and desire to make a little money in the eyes of potential babysitters for my own daughter.
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Then, in college, I spent a weekend with an eleven month old cousin, a boy who was so amazingly sweet and loving that I hardly gave him back to his mother. One day in class I watched in awe as the 8-month pregnant belly of my mentor moved after we all laughed and shared a joke. Over time, I softened to the idea of having children. I got engaged, and then married. I got a job. And then one day, I wanted a baby, two babies, a million babies, and I wanted them now and if you stand in my way I will cut you down.
Many of you know the restofthestory.
My maternal tendencies were age, partner and wealth-dependent. There is surely a biological component as well. But these life experiences and my own status as someone with a stable partner and income helped produce the biocultural milieu that led to me waking up one morning and realizing that I needed to smell a baby’s hair as I cradled her in my arms.
* * *
I have always appreciated the thoughtfulness and rigor of the work that is affiliated with Perrett. You may even be familiar with some of their findings related to mate preferences and face shape (Perrett et al 1994):
I teach this material to my students; the studies are always thoughtful, the papers well-organized, the results interesting. So it was with some excitement that I read the latest paper in Perrett’s group published in Hormones and Behavior, “Maternal tendencies in women are associated with estrogen levels and facial femininity” (Law Smith et al. 2011). Scicurious was the one who passed it on to me, and recommended that we do a tag-team on the paper, as we have done in the past on PMDD. Sci covers some important sociological aspects to the paper.
It’s ok. I’ll wait while you read her post.
Anyway, Law Smith and colleagues performed two studies: one where they correlated subjects’ estradiol concentrations to their self-reported desire to have children, and another where they correlated ratings of subjects’ faces as more feminine with those subjects’ self-reported desire to have children. This group has previously found a relationship between estradiol concentrations and facial femininity (Law Smith et al. 2006).
So, is this the end of the story? Women who are more feminine have higher maternal tendencies?
Sci and I probably wouldn’t be blogging about it if it weren’t.
Here’s the thing. Just like all those other papers I have loved, this one is on the whole carefully constructed. And the correlations are correlations, nothing fishy going on there. But I worry about two things: how the media will frame the article, and how the study authors defined two of their most important variables.
First, the study authors themselves don’t help the situation: in the introduction, they point out only the biological underpinnings of maternal tendencies in a way that is essentialized, reduced to an individual’s hormones prenatally and in adulthood. But many studies have examined maternal ambivalence in contexts where there is high infant mortality (Scheper Hughes 1985), or as it relates to age, as in teen pregnancy (Kramer 2008). These also have biological origins, in part, as they involve the kinds of trade-offs individuals may consider when investing, or not, in offspring. So maternal tendencies are rooted only partially in whatever essential mix of hormones contributes to our being gendered feminine.
Then there are the usual issues with study population: subjects were white, nulliparous (no pregnancies) college students, average age of nineteen for the first study and twenty for the second. In addition to the usual issues of studying a WEIRD population (Western, Educated, Industrialized, Rich, and Democratic), studying the hormones of a population that young may yield different results than in older populations. Girls can have irregular cycles for as many as twelve years after their period (Vihko and Apter 1984), and they have lower hormone concentrations than adult women (Lipson and Ellison 1992). How might that interact with the questions the study authors are asking? How important is it that a teenage girl’s hormone concentrations correlate with maternal tendencies?
Then, there is the way that they define maternal tendencies. The study authors asked subjects at what age they wanted to have children, and how many they wanted, in order to arrive at that subject’s maternal tendencies. Again, I wonder how the study’s results might change if they asked an older population, or a population from another country or ethnicity.
Law Smith et al themselves admit in the discussion that their study sample of white college students may have impacted their results; they found no correlation between estrogen concentrations and ideal age at first child, only with the desired number of children. The mean age at desired first child was higher, and range of variation smaller, than that found in other studies with broader subject pools.
Rather than frame this as the subject population confounding their results, I would submit that this confirms that one’s “trait estrogen,” as the authors put it, is only one aspect of the biocultural milieu in which women find themselves when making reproductive decisions. Overall women have been having children at older ages and, when they have control over their reproductive lives, generally choose to have fewer of them. But if anything, estrogen would be increasing in these populations, as they are often also well-fed and therefore never needing to divert resource away from reproductive hormone production.
While this study provides some interesting evidence, it does not tell us that women with low or high maternal tendencies necessarily have higher or lower estrogen, or are more or less feminine. Not wanting a baby today, or any day, does not make you less feminine. And when the media onslaught begins over these findings, we would do well to remember it.
References
Kramer KL. 2008. Early sexual maturity among Pume foragers of Venezuela: Fitness implications of teen motherhood. American Journal of Physical Anthropology 136(3):338-350.
Law Smith M, Deady D, Moore F, Jones B, Cornwell R, Stirrat M, Lawson J, Feinberg D, and Perrett D. 2011. Maternal tendencies in women are associated with estrogen levels and facial femininity. Hormones and Behavior.
Law Smith M, Perrett D, Jones B, Cornwell R, Moore F, Feinberg D, Boothroyd L, Durrani S, Stirrat M, and Whiten S. 2006. Facial appearance is a cue to oestrogen levels in women. Proceedings of the Royal Society B: Biological Sciences 273(1583):135.
Lipson SF, and Ellison PT. 1992. Normative Study of Age Variation in Salivary Progesterone Profiles. J Biosoc Sci 24(2):233-244.
Perrett DI, May K, and Yoshikawa S. 1994. Facial shape and judgements of female attractiveness. Nature 368(6468):239-242.
Scheper Hughes N. 1985. Culture, scarcity, and maternal thinking: maternal detachment and infant survival in a Brazilian shantytown. Ethos 13(4):291-317.
Vihko R, and Apter D. 1984. Endocrine characteristics of adolescent menstrual cycles: impact of early menarche. J Steroid Biochem 20(1):231-236.