Kate Clancy, PhD

Thursday, November 4th 2010

Around the web: altruism and parenting

The “Around the Web” series highlights informative websites, and also targeted blog posts and news articles, relevant to the courses I teach. This semester I teach Anth 143: Biology of Human Behavior, an introductory-level course that covers the basics of evolution, behavioral biology, and the interaction of biology and culture. My hope is that these posts are useful not only for my current students, but other people hoping to gain background or insight into these topics.

Last week (because I’m a week behind on these!) we looked at altruism and cooperation, behaviors that appear to operate against the selfish behavior we often assume is necessary for reproductive success. From there we also explored parenting, where individuals often go to great lengths to care for their offspring, but also sometimes consider trade-offs between current and future reproductive opportunities.

Prisoner’s Dilemma

In lecture, the TAs modeled the Prisoner’s Dilemma (click the link if you’re unfamiliar with it) with candy prizes rather than jail time, and then I held a student tournament. Normally the Prisoner’s Dilemma is set up something like this:

It was loads of fun, but interestingly, the way I set up the game seemed to lead to cheating being the best strategy. I just couldn’t get any of them to brave cooperating, save one pair who were close friends. This is likely because the punishment for cheating wasn’t strong enough, and/or the reward for cooperating wasn’t great enough. I set it up like this:

If “both defect” was set up so that students would LOSE candy from their stash, perhaps it would have turned out differently. I also think this game is very different when it feels like the stakes are about winning (candy) rather than losing (jail time). Either way, it was a great way to learn about and understand the conditions under which reciprocal altruism could evolve.

If you’d like to play around with the game yourself, there are a few online Prisoner’s Dilemma games: here is one of them.

Altruism and cooperation

Two cool PLoS papers just happened to come out on cooperation in the last few weeks. Cooperation under indirect reciprocity and imitative trust by Saavedra et al looks at human behavior. They examine conditions under which reciproal altruism can evolve even when interactions aren’t iterated — that is, when people don’t encounter each other that often, but still act altruistically towards each other.

Chadefaux and Helbing look at different variables that may promote cooperation, in How wealth accumulation can promote cooperation. They use the Prisoner’s Dilemma model, but add a twist: players can accumulate wealth, and are able to invest their wealth in later interactions. Under these conditions, cooperative strategies dominated (unlike in my class exercise, where the temptation to defect was too strong!).

We discussed kin selection as one of the factors that promotes altruistic and cooperative behaviors among individuals. Recently some heavy hitters from within evolutionary biology have dusted off the ole’ group selection vs. kin selection argument, and you can read more here: Kin Selection Dead?

A wonderful bridge between these two topics (which is the reason I taught them together) can be found in this post at the old Neuroanthropology digs: Evolution of altruism: kin selection or affect hunger?

Parenting

The above link should give you a sense of why I covered parenting in the same lecture we did the Prisoner’s Dilemma. Parenting is incredibly costly, and while there is a reproductive benefit, the mental and physiological strain is substantial. Some days the cons seem to outweigh the pros. Yet many, if not most, people eventually become parents. Are we driven by an innate desire to pass on our genes? Are we mindless drones of culture, which sometimes seems to value parenting, and even implies it is inevitable and necessary?

One thing seems pretty certain: in the human lineage, if we didn’t invest in our children and parent them heavily, they would not survive. Kids are dependent on the help of others through adulthood. This isn’t just because of the transition in industrial cultures to have to go to school for long periods of time before getting a job: many individuals don’t master the skills necessary for survival in foraging societies until they are in their thirties or forties.

Parenting isn’t purely altruistic, because of the fact that we are usually related to our children. And there are significant rewards to having children. But some psychological studies suggest parents aren’t actually all that happy. Psychologist Dan Gilbert also offers his perspective.

Perhaps it is true that we outweigh moments of extreme, overpowering love, like the day this summer that my daughter Joan, for no reason at all, stopped what she was doing and felt compelled to hug me and whisper in my ear, over and over “I love you Mommy, I love you Mommy,” compared to my Tuesday evening this week when, after we voted, she decided to have an all-out temper tantrum at the voting site, and for the whole walk home. It seems like we need to think about how we measure happiness, then, before we simply decide that parents are not happy (or that non-parents are not happy).

A few last good links on parenting. Greg Laden’s great series of Falsehoods contains this one: A baby is not the biological offspring of its adoptive mother. Puts the kin selection concept of parenting into perspective. I also want to recommend a few websites: the blog parenthropology, and the site Parenting Science (which my students will recognize, as they had a reading from it for this week).

Then there is also the website for Aware Parenting, a type of parenting that I like and use with my child — check out the articles. Parent Effectiveness Training and Playful Parenting are other resources that I have found useful, particularly in my darker moments when I feel stuck. Last, some perspectives on the Mommy Wars to help you think about how and why parents (particularly from industrialized populations) can be so judgmental of each other.

Random this week

Not too much to share this week. Neil deGrasse Tyson’s speech earlier this year on how Learning is Empowerment. And, two TED talks that are marginally related to this week’s concepts: The hidden influence of social networks and On the tribes we lead.

Speaking of altruism, have you checked out my DONORS CHOOSE GIVING PAGE? Imagine the massive effect a few minutes, and five dollars of your day, can have…

Tuesday, October 26th 2010

More on reproductive choice

Just a quick link I want to share today to Martin Robbins’s blog The Lay Scientist over at The Guardian. He has a guest post written by @naomimc that describes, more elegantly than I have, the importance of reproductive choice. Entitled “Where are the women in the ‘population control’ debate?” her post demonstrates how the conversation around population control, particularly in circles devoted to the ecological impact of human populations, seems to be devoid of women, or at least controlled by men.

One of my favorite passages is here:

The green movement is often, wrongfully, accused of misanthropy. “They care more about trees than people”, screech the professional oppositionists. But the obsession with population control by a minority of greens opens them up to very legitimate accusations of authoritarianism, ‘classism’ (i.e. it’s the poor we want to stop having babies) and gender-blindness. It is a paradigm dominated by elite men which spectacularly misses the point and ignores the evidence that actually protecting sexual and reproductive rights and empowering women to control their own fertility results in lower birth rates and importantly, lower death rates.

No one who works in maternal and reproductive health talks of ‘population control’. For historical and contemporary reasons it is associated with eugenics, China’s one-child policy, forced sterilisation and forced abortion. These morally abhorrent examples might be dismissed as extremes but they are simply the results of a way of thinking about reproduction which is coercive and rejects individual rights as fundamental to public policy. (my emphasis)

Go read the post.

Monday, October 25th 2010

How does an anthropological perspective contribute to our understanding of birth control? Part I

I polled my Twitter followers recently to find out what they wanted me to cover, and heard back a resounding “CONTRACEPTIVES!” So first I am going to re-post a series I wrote on my lab blog in July of 2009, with significant editing and updating. I think after these reposts I’ll have a better idea of where it would make sense for me to contribute more, if at all. This is post one of five.

I am not a medical professional. I am a PhD, not an MD, so this is not medical advice. And in fact, I am quite sure there are anthropologists out there who do not share my opinion, so this is not even anthropological advice. This is just one person’s perspective on a medication so pervasive few people even think of it as the serious prescription that it is.

Hormonal birth control has been around for many decades, and has seen many improvements, reductions in dosage, and different ways of accessing the medication, from a shot, to a patch, a ring or a pill. Hormonal birth control is used off-label for mood stabilization and acne, and increasingly these contraceptives are also approved for these non-contraceptive purposes. You’ve probably seen the ads of skinny-armed women punching at “irritability” and “bloating” in bubble letters before them with a girly rendition of “We’re not gonna take it” in the background. You’ve seen the slightly more “empowered” ads that have cropped up recently regarding the hormonal contraception that you can take continuously to avoid your period, where far stronger women are staring right into the camera and daring you to doubt their decisions.

I worry about health and safety issues related to hormonal contraceptives when I see these ads, because they are 1) focusing on the non-birth control aspects of the drug in order to increase the number of consumers and 2) trying to frame the debate about contraception with a watery version of “choice” feminism. However, how one feels about a commercial is not a good enough reason to dismiss a medication used by a huge fraction of reproductively aged women in the US. I was recently annoyed by a Tylenol ad, but I give my daughter acetaminophen when she has a very high temperature (not when she has a mild one — but that’s a whole other issue!). I am able to get off my high horse, folks, and I’d like to do that to discuss some recent evidence around hormonal contraception. This post will cover contraindications and side effects for hormonal contraceptives. The other posts will cover variation in menstrual cycling; population variation and environment; hormones, behavior and cognition; and non-hormonal contraceptive options.

Contraindications

If you read the packaging and/or you have a doctor worth his/her salt, you know if you have high blood pressure, a history of blood clots or liver dysfunction, you should not take hormonal contraception. End of story, and don’t try to get around it.

But do you know that if your BMI is over 25 you are at an increased risk of unintended pregnancies? The dosage for hormonal contraception was designed for average to low-average weight women from developed countries (the issue of developed versus developing countries will be important in later posts). Brunner Huber and Hogue (2005) found that contracepting overweight and obese women had twice the odds of an unintended pregnancy compared to normal weight women. The authors surveyed women after they had given birth and asked if the pregnancy was intended or unintended, and whether the individuals had used contraception or not. Among contracepting women, the number of overweight and obese women with unintended pregnancies was much higher than those with intended pregnancies. Further, they cite a convincing literature and provide a credible mechanism for why overweight women tend to have reduced efficacy on hormonal contraceptives. Burkman et al (2009) recently found similar results, but the relationship was not quite statistically significant. The results do seem to vary somewhat with which contraceptive is being tested. But with the average American woman’s BMI at 28, it seems as though today’s oral contraceptives may not be effective for a majority of our country’s population.

There are two other major issues to consider regarding the effects of hormonal contraceptives on health. The first is that hormonal contraceptives negatively impact bone mineral density. Last year, one of my undergrads Emily Marzolph wrote a wonderful Honors paper for me entitled “Moderate changes to bone mineral density due to hormonal contraceptives during adolescence may undermine wide array of skeletal mass diversity.” In her literature review, she found significant evidence that hormonal contraceptives, particularly the progestin-only injection Depo-Provera, lower bone mineral density rates (e.g., Cromer et al 2005, Prior et al 2001). However, to put these results in context, Emily also looked at what we know of interpopulational variation in bone mineral density; this turns out to be quite significant as well. Analyzing these data qualitatively, it appears that the reduction in bone mineral density caused by hormonal contraceptives is still within the range of variation seen across populations (Arabi et al 2004, Hou et al 2007). Here’s a free dissertation topic for you: someone ought to do a meta-analysis of this literature, or a cross-populational analysis of new data, that examines the differential effects of ethnicity, environment and hormonal contraceptives on bone mineral density! Who knew you could get free dissertation advice from a blog?

The second health issue I want to mention is the potential increase in systemic inflammation with the use of hormonal contraceptives (one of my other undergraduates, Katherine Tribble, found this article for our lab’s weekly journal club). Morin-Papunen et al (2008) looked at women at thirty one years of age in the Northern Finland Birth Cohort, born in 1966. They grouped these women into levonorgestrel-releasing intrauterine device (IUD) users, oral contraceptive users, and no hormonal contraception use. Morin-Papunen et al (2008) found oral contraceptive usage was correlated with increased C-reactive protein concentrations — this is a biomarker for inflammation that is associated with cardiovascular disease. Compared to IUD users, oral contraceptive users also had more insulin resistance, higher blood pressure, raised lipids and insulin levels, despite having a smaller waist and lower waist-hip ratio (a larger waist or higher waist-hip ratio is often associated with these results). Further, most of these results actually strengthened when factors like BMI, household income, and alcohol consumption were controlled for. Another interesting point, third generation hormonal contraceptives, which are lower concentrations of synthetic hormones than the second generation, actually had higher serum levels of insulin, CRP, total cholesterol and other lipids, compared to users of second generation contraceptives.

So in addition to the factors you already knew about, you may want to avoid hormonal contraceptives if your BMI is over 25 and are using them for contraception; or, if you are already at risk for osteoporosis or cardiovascular disease (or want to reduce your risk for these things).

In the second post, I’ll discuss what it means to have a normal menstrual cycle, and how this relates to the prevalence of hormonal contraceptives.

References

Arabi, A., Nabulsi, M., Maalouf, J., Chouchair, M., Khaliffe, H., Vieth, R., & Elhajjfuleihan, G. (2004). Bone mineral density by age, gender, pubertal stages, and socioeconomic status in healthy Lebanese children and adolescents Bone, 35 (5), 1169-1179 DOI: 10.1016/j.bone.2004.06.015

Brunner Huber, L., & Hogue, C. (2005). The Association Between Body Weight, Unintended Pregnancy Resulting in a Livebirth, and Contraception at the Time of Conception Maternal and Child Health Journal, 9 (4), 413-420 DOI: 10.1007/s10995-005-0015-5

Burkman RT, Fisher AC, Wan GJ, Barnowski CE, & LaGuardia KD (2009). Association between efficacy and body weight or body mass index for two low-dose oral contraceptives Contraception, 79 (6), 424-427.

Cromer BA, Lazebnik R, Rome E, Stager M, Bonny A, Ziegler J, & Debanne SM (2005). Double-blinded randomized controlled trial of estrogen supplementation in adolescent girls who receive depot medroxyprogesterone acetate for contraception. American journal of obstetrics and gynecology, 192 (1), 42-7 PMID: 15672001

Hou YL, Wu XP, Luo XH, Zhang H, Cao XZ, Jiang YB, & Liao EY (2007). Differences in age-related bone mass of proximal femur between Chinese women and different ethnic women in the United States. Journal of bone and mineral metabolism, 25 (4), 243-52 PMID: 17593495

Morin-Papunen L, Martikainen H, McCarthy MI, Franks S, Sovio U, Hartikainen AL, Ruokonen A, Leinonen M, Laitinen J, Järvelin MR, & Pouta A (2008). Comparison of metabolic and inflammatory outcomes in women who used oral contraceptives and the levonorgestrel-releasing intrauterine device in a general population. American journal of obstetrics and gynecology, 199 (5), 5290-2147483647 PMID: 18533124

Prior JC, Kirkland SA, Joseph L, Kreiger N, Murray TM, Hanley DA, Adachi JD, Vigna YM, Berger C, Blondeau L, Jackson SA, & Tenenhouse A (2001). Oral contraceptive use and bone mineral density in premenopausal women: cross-sectional, population-based data from the Canadian Multicentre Osteoporosis Study. CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne, 165 (8), 1023-9 PMID: 11699697