Tuesday, April 12th 2011
Biological anthropologists are a cool lot. We study bones, death, fossils, phylogenetics (how things are related to each other), hominin evolution, behavior, reproduction, physiology, primates, communication, cognition, genetics, migration and more. We study how these things vary, what produces their variation, and why that variation is meaningful. So the AAPAs tend to be a fun conference full of lively conversation, strong sessions, and engaged attendees.
Plus, you see a lot of people wearing sandals with socks.
This year, that particular population might be slightly underrepresented, because we are having the meetings in Minneapolis, where snow is predicted on Friday and Saturday. While that has impacted the wardrobe that will be crammed into my carry-on luggage tomorrow, I still expect a great meeting, because there are several wonderful symposia planned, a lunch event for women in biological anthropology, and a BANDIT Happy Hour on Saturday at 5pm. Julienne Rutherford has curated a great list that can be found by reading the posts under her AAPA label.
Me? I’m going to self-promote, but I’ll encourage you to do the same in the comments.
On Thursday morning you can find me in Session 3, the invited podium symposium chaired by Grazyna Jasienska and Diana Sherry entitled “Evolution and Health over the Life Course” in Salon C. The session starts at 8am with what looks to be a great talk by Beverly Strassmann, “Evolution and health from infancy to adolescence in the Dogon of Mali.”
My talk is at 9:30am, is co-authored with my former students Theresa Emmerling and Ashley Higgins, and is entitled “Variation in adolescent menstrual cycles, doctor-patient relationships, and why we shouldn’t prescribe hormonal contraceptives to twelve year olds.” I’ll be talking about what we know of adolescent menstrual cycle variation, what we know of the impact of hormonal contraception on different reproductively-aged women, and some pilot data from our focus groups on doctor-patient relationships. I hope the last bit will provide a bit of framework for understanding how and why US women use hormonal contraception in such comparatively high proportions for off-label use.
On Friday afternoon, you can find me in Session 31, the invited podium symposium chaired by Julienne Rutherford and me entitled “Eating for Two: Maternal Ecology and Nutrition in Human and Non-Human Primates” in Marquette V/VI. The session starts at 2pm with a talk by Betsey Abrams and Julienne Rutherford entitled “Risky business: an evolutionary perspective on placental nutrient transport and postpartum hemorrage.” I am VERY excited to hear this paper!
My talk is next, at 2:15pm, and is called “Pro- and anti-inflammatory food proteins and their impact on maternal ecology.” This talk is co-authored by two of my students, Laura Klein and Katherine Tribble. I’ll be doing a bit of a review of the literature to place this topic in context, and discussing some pilot data.
I may be biased, but the rest of this symposium is pretty kick-ass.
- 2:30 Yildirim et al speak on vaginal microbial communities and maternal ecology (University of Illinois research!)
- 2:45 Milich et al discuss habitat quality and reproduction in female red colobus monkeys (University of Illinois research!)
- 3:00 Julienne Rutherford has prepared a version of her talk to be shown at 3pm on energetics and life history plasticity in callitrichine primates as she is on maternal hiatus
- 3:15 Valeggia shares insights into the metaboliv regulation of postpartum fecundity
- 3:30 Nyberg discusses HPA activity in pregnant and lactating Tsimane’ women
- 3:45 Miller shares recent work on breastmilk immunity in Ariaal women
- 4:00 Pablo Nepomnaschy will be the discussant for the first half of our symposium.
- 4:15 In our second half, Hinde et al discuss commensal gut bacteria and breastmilk
- 4:30 Quinn and Kuzawa developmental trajectories in infants and later milk composition
- 4:45 Fairbanks shares her work on nutrition, energetics and vervet maternal investment
- 5:00 Piperata and Guatelli-Steinberg discuss how social support may impact the costs of reproduction
- 5:15 Dunsworth et al look at some very interesting data on energetics versus pelvic constraint in determining human gestational length
- 5:30 Finally, Leslie Aiello wraps it up as the discussant of the second half of our symposium.
Science bloggers and writers, like any of the topics above? Consider interviewing some of these symposium participants! You won’t be disappointed.
Wednesday, April 6th 2011
When I was younger, periods were not a fun time, and I was plagued with dysmenorrhea, which is a fancy term for really bad cramps. In high school, I would often take 1000 mg of ibuprofen every four hours to alleviate symptoms to get through all my classes, band, sports practice, and homework (what, it took you this long to realize I was, and am, a dork?).
After having my daughter in 2008, and the thirteen months of lactational amenorrhea that followed it (lactational amenorrhea means absence of periods due to lactation), my periods resumed. Pain during my periods has almost totally ceased, but I have noticed more cycle-related variation in emotion. In particular, my patience and tolerance for rude behavior, and my tendency to cry sentimentally at even the lamest greeting card, skyrocket in my premenstrual phase. I already have low tolerance for rudeness, and I already cry easily. But something about progesterone decline — which is a normal process towards the end of ovulatory cycles — seems to make it harder for me to repress these behaviors in order to fit in culturally with those around me.
I tell this to you to say, I don’t doubt that hormones, and hormonal variation through the cycle, plays some role in variation in female behavior and emotion. And I find this kind of work inherently interesting. I hate to repeat myself, but you will find echoes of my structural and methodological concerns with evolutionary psychology in this post as well.
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Durante et al (2011) observe that women spend more money on their appearance than men, and claim that this sex difference is cross-culturally consistent (I wonder, is this consistent across cultures without money?). In order to understand this sex difference, they wish to see whether spending or shopping behavior is dependent on cycle phase. Therefore the authors hypothesize that women choose sexier clothing during ovulation — “even if the women themselves are not consciously aware of this biological fact” (Durante et al 2011: 922), a problematic turn of phase if I ever saw one, but I’ll get to that later. They also consider the effects of priming a shopping woman with images of attractive women and hypothesize there is a greater effect of this priming on high-fertility women.
Methods
The participants were female undergraduates and were compensated with course credit or money. The authors claim the participants had no idea the study had anything to do with the menstrual cycle, but the participants had to use LH strips at midcycle to see when she was ovulating (this is a urine test to check for a luteinizing hormone peak, which comes before ovulation).
Here’s the important part, for me:
“The first urine test was scheduled 2 days before the expected day of ovulation. If an LH surge was not detected, women came back each day until an LH surge was detected or six tests had been completed, whichever came first” (Durante et al 2011: 924).
Here are my questions: what is 2 days before the expected day of ovulation? The follicular phase — that’s from menstruation to ovulation — is the most variable phase of the menstrual cycle (Fehring et al. 2006; Lenton et al. 1984). I wonder how many ovulations they missed because of this. Perhaps even worse, how many participants had six LH tests and didn’t have a detectable LH surge? It sounds like they were included in the project. But, they either ovulated before the authors started testing, or they had an anovulatory cycle. That means the authors were including participants in their study that weren’t ovulating… in a study of behavior during ovulation.
Participants viewed a made-up shopping website on a high-fertility (near the LH surge) and low-fertility (about eight days later) day, where they had to select ten items they would like to buy that day. They were randomized into two groups: one shown a site featuring casual clothes, the other featuring clothes and accessories. The clothing on these made-up sites were “pretested to be sexy” (Durante et al 2011: 925). While that is a phrase I never expected to write on this blog, the separate validation they did to determine sexy versus nonsexy clothing seems fine.
Results
Hypothesis 1: Near ovulation, women should be more likely to choose sexier and revealing clothing and other fashion items rather than items that are less revealing and sexy (Durante et al 2011: 923).
Women chose a greater percentage of sexy clothing and accessory items near ovulation: 59.8% ± 21.6 during ovulation, 51.3% ± 22.4 during low fertility. This was a statistically significant difference, but they did a repeated measures ANOVA, and I don’t understand why they didn’t do a paired t-test. Further, statistically significant or not, I question how meaningful it is when the averages are so close and the standard deviations almost completely overlap.
H2: Ovulation should lead women to be especially likely to choose sexier products when women are primed to compare themselves to attractive female rivals (Durante et al 2011: 924).
H3: There should be no differences in product choice between ovulating and nonovulating women when women are primed with unattractive women or men (Durante et al 2011: 924).
Follow-up studies primed sub-sets of participants (so a different cohort, same recruitment methods as above) to think about 1) attractive local women, 2) unattractive local women, 3) attractive local men, 4) unattractive local men. They did this by showing photographs of people who they claimed to be local and asking participants to rate their attractiveness.
When primed with attractive women, the percentages of sexy items chosen were 62.7% for ovulating women and 38.2% for low fertility women (I could not find standard deviations for these values so have no idea how much the two groups overlap). Priming with unattractive women, attractive men, or unattractive men produced no significant difference between low and high fertility women.
H4: Ovulation should lead women to choose sexier products when primed to think about local attractive women who constitute potential direct rivals. However, ovulation should not influence product choice when women are primed to think about women from distant locations because such women do not constitute direct rivals (Durante et al 2011: 924).
The authors used a different method for assessing fertility this time; they asked women their normal menstrual cycle length and counted back from menses to estimate when ovulation would be. So AGAIN, we don’t know how many women actually ovulated in this study, and we don’t know whether a significant portion of women were then grouped in the high-fertility group who shouldn’t have been.
This study is like the previous one in terms of photo priming, but this time the photos were said to be local or distant, and were of women only (so the four groups were local attractive, local unattractive, distant attractive, distant unattractive).
The authors claimed that the relationship between fertility, photo attractiveness and location was “marginally significant,” but the p-value was 0.09. That is, in fact, not significant, as significance is generally only considered under 0.05 unless you cheat and say your study is special and should consider a different limit (they don’t say this in their study).
That said, the only significant effect found of photo priming on high versus low fertility women was in the local attractive women group: high fertility women chose 65.8% sexy items versus low fertility’s 39.1% (I could not find standard deviations for these values so have no idea how much the two groups overlap). These results are almost identical to those found when priming women with attractive women without saying if they are local or not.
How biological are we talking here?
The authors claim a biological cause for the differences found above. And maybe there is, to some extent. But there are two major issues with the authors’ conclusions.
First, there is the major methodological flaw of including women who probably aren’t ovulating in their high-fertility group. Heads up to people who don’t study female physiology: women, even healthy women with “normal” cycle lengths, don’t ovulate every cycle. So if understanding a behavior during ovulation is important to your hypotheses, you need daily hormones on top of that LH test. Then, you know, if you can’t document ovulation, you need to exclude those women from your sample. Oh, and while we’re discussing methods, the authors don’t mention whether the participants were in a relationship or not, or what their sexualities were, or their races or socioeconomic statuses. These are all important to understanding variation in female-female competition (Campbell 2004). And since ornamentation is likely related to honest signals of health, it would be good to know waist to hip ratios, or BMI, or facial symmetry (Streeter and McBurney 2003) (hello, I’m handing someone a dissertation here! Just remember to cite me correctly).
But the second issue relates to the theme I saw throughout this paper, that changes in mood or choice behavior due to ovulation or presence of attractive women is a “biological fact.” Female-female competition is certainly found within human behavior, and behavior changes through the menstrual cycle. But is it fair to call these behaviors strictly biological, or should we have a more nuanced understanding of the interaction between biology and culture?
There are alternative cultural theories out there. Objectification theory proposes that there are consequences to living in a culture that sexually objectifies women: when women are continually appraised based on their looks, it leads to a disconnect between their body and individual (Moffitt and Szymanski 2011). This disempowers women and leads to them feeling as though their bodies exist for the pleasure of others. And if this is what women learn they have to offer others, and they seek affirmation, praise or attention from those around them, it makes sense for women to compete around attractiveness, particularly sexiness.
I would posit that shopping, particularly when primed with the image of an attractive woman, is a kind of objectification. So really, what Durante et al (2011) are measuring are the results of objectifying their study participants. Under these circumstances, a woman is more likely to start treating herself as an object to be evaluated on the basis of her appearance, so it makes sense that she would choose sexier clothing, in an effort to produce a culturally-appropriate, attractive body.
As the study stands, there is no way to parse out the impact of biology or culture — and many cultures encourage objectification, female-female competition and female attractiveness towards men. As for how that interacts with high versus low fertility samples… that’s the interesting part of this paper. If we can trust how the women are parsed. Which we can’t, since some of the high-fertility sample might not have been ovulating.
These high heels are made of deer antlers
The authors also seemed enamored with the idea of comparing their female participants to male animals. Twice they mention the idea that they want to determine whether sexy clothing is analogous to a peacock’s tail, a deer’s antlers, or a lion’s mane (really). These three examples, according to the authors, reflect a courtship function, a same-sex competition function, or both functions respectively. The authors go on to say that their results suggest that sexy dressing in women is like deer’s antlers, or, a same-sex competition function.
First, since when are a deer’s antlers only a same-sex competition function? Second, doesn’t it say something that they couldn’t find any examples of this kind of display in a female animal? This begs the question of why female humans do so much more displaying and maintenance of their appearance compared to other female animals, and again, this suggests interactions between biology and culture (Smuts 1995).
We can spin all the stories we want to explain why many human females make efforts to be physically attractive. And I do think Durante et al (2011) are on to something here as, despite methodological concerns they did find differences in high- and low-fertility choices. But if we continue to do this research on undergraduates in western contexts without sufficient hormone analysis, I’m unsure that its meaning extends beyond the participant pool.
References
Campbell, A. (2004). Female competition: Causes, constraints, content, and contexts Journal of Sex Research, 41 (1), 16-26 DOI: 10.1080/00224490409552210
Durante, KM, Griskevicius, V, Hill, SE, Perilloux, C, & Li, NP (2011). Ovulation, female competition, and product choice: hormonal influences on consumer behavior Journal of Consumer Research, 37 (6), 921-934
Fehring, R., Schneider, M., & Raviele, K. (2006). Variability in the Phases of the Menstrual Cycle Journal of Obstetric, Gynecologic, Neonatal Nursing, 35 (3), 376-384 DOI: 10.1111/j.1552-6909.2006.00051.x
Lenton EA, Landgren BM, Sexton L, & Harper R (1984). Normal variation in the length of the follicular phase of the menstrual cycle: effect of chronological age. British journal of obstetrics and gynaecology, 91 (7), 681-4 PMID: 6743609
Moffitt, L., & Szymanski, D. (2010). Experiencing Sexually Objectifying Environments: A Qualitative Study The Counseling Psychologist, 39 (1), 67-106 DOI: 10.1177/0011000010364551
Smuts, B. (1995). The evolutionary origins of patriarchy Human Nature, 6 (1), 1-32 DOI: 10.1007/BF02734133
Streeter, S. (2003). Waist–hip ratio and attractiveness New evidence and a critique of “a critical test” Evolution and Human Behavior, 24 (2), 88-98 DOI: 10.1016/S1090-5138(02)00121-6
