Monday, November 29th 2010
The science blogosphere has been having a big dust-up about two issues: the GQ Rock Stars of Science, and the Science Cheerleaders (here is Scicurious’s take, which is one of the best ones). This got me thinking about how and why I decided to become a scientist.
My parents made it very clear to me, directly and in no uncertain terms, that I could do anything, and this was incredibly important. When I had to do a project on the Constitution my mother suggested I do it on the 19th Amendment. When I had to do a project on an athlete I wrote about Flo Jo. When I had to do a project on a scientist I wrote on Marie Curie. (When I had to do a project on animals I chose flamingos, but that is off topic.) I was very sensitive to issues of sexism from a young age, to the point that I reveled in mastering skills I wasn’t supposed to master, like math and science. (I will say some of this was beaten out of me by junior and senior year in high school, to the point that I was afraid of math and “harder” sciences beyond biology, despite being in gifted programs and special math classes when I was younger. But the oppression side of things can be discussed another time.)
I remember reading the Jurassic Park series when I was in junior high and high school: the young girl with the computer skills in the movie version impressed me (even as I was annoyed that that wasn’t how it happened in the book). In one of the later books, a female scientist whose name I no longer remember needed to take a quick shower. Rather than being all girly about it she grabbed some dish soap to use as shampoo, gruffly saying something that sounded, to me, brilliantly scientific, like “it has the same chemical composition as the main ingredient in shampoo.” This character was instantly cool to me, and I honestly wanted to be just like her.
When I was in college, the director of my lab and person with whom I had the most contact in my early years was female. The lab technician in that lab was also a woman. It was really important having the two of them around as I awkwardly fumbled my way through my teen years. I read the papers of other women in my field, and I knew some of them had walked the halls of my school. They all made me feel it was possible. It is no accident I am in a scientific discipline that actually has a decent number of women (at least compared to many others).
At least in my own history, in my own making as a scientist, it was support and encouragement from my family, and an emphasis on female role models who were strong and independent, that made me feel it all was possible. I wonder about the Science Cheerleaders issue: is it that the climate has gotten better for women, or worse, that implicit in the Science Cheerleaders is objectification of these scientists? Is this really third wave feminism, where women can “have it all,” or does this make things harder for young women who want to be scientists, because now they feel they have more to live up to?
When I was graduating college and thinking about careers, if I felt I had to be fashionable, attractive, and show a considerable amount of skin to be respected as a scientist, I probably would have chosen something else. I saw women being who they were — which was as beautiful and variable as you find in all professions — and I wanted to join them. The fact that I am fashionable now (and that is a generous reading of my fashion sense) is simply a bonus of finally having a living wage.
Monday, November 15th 2010
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.
This week I broadly introduced the field of behavioral endocrinology, and focused on male behavioral endocrinology as a way to apply it. Of course a week on male behavior can’t go without Robert Sapolsky’s essay The Trouble with Testosterone, and students wrote some very thoughtful posts reflecting on that reading. Next time we’ll cover stress, and the week after that female behavioral endocrinology.
This week, though, it’s all about the testosterone. I spent a fair bit of time in lecture trying to parse out what the relationship between hormones and behavior really is: 1) the relationship goes both ways, meaning behavior impacts hormone levels at least as much as hormones impact behavior, and 2) hormones rarely make anyone do anything, but in some cases they can increase your willingness. It’s as though the hormone opens the door to a particular behavior, but doesn’t push you through.
Also, the last week of the course covers cognitive sex differences (or not), so you will notice an absence of that type of material here. Don’t worry, you can do mental rotation tests in a few weeks!
Aggression
I wanted to link to several stories about testosterone and aggression from the mainstream media. Testosterone and aggression relationships have been covered, with at least some degree of complexity, the New York Times and TIME. The New York Times article is of course by Natalie Angier, a rather wonderful science writer who wrote Woman: an Intimate Geography.
I also found two other links: this student paper on testosterone and aggression from Bryn Mawr. I hope work like this shows my students the kinds of sophisticated thinking they are also capable of, and starts some fun conversations. This one from the website About Gender also has a thoughtful take on this often-exaggerated relationship.
Business sense?
This press release (at least, I think that’s what it is) suggests that male CEOs with higher testosterone concentrations are more likely to drop deals or attempt hostile takeovers. The whole piece struck me as odd, in its phrasing, and in the fact that an article on hormones was accepted in a journal called Management Science. So I decided to look up the article on which the press release is based (Levi et al 2010).
It’s a mess, and here’s why: THEY DON’T ACTUALLY MEASURE TESTOSTERONE CONCENTRATIONS. They use age as a proxy for testosterone, saying that testosterone is higher in young men, and because younger men do these more reckless behaviors, it is because of Teh Evul Testosterone. Further, as far as I can tell, the way they use age as a variable is that you are “young” if you are under forty five years old, and “old” if you are over that age. Age significantly impacts testosterone, but the amount of variation unrelated to age is also considerable. And when it is so easy to measure testosterone — we’re talking about getting someone to spit for you a handful of times — it seems silly to use a proxy so far removed as to be almost meaningless. It also ignores the many other factors related to age that might make someone reckless, like brain development and experience.
Et cetera
Greg Laden has a short, tongue-in-cheek blog post about Testosterone and Humor: he reviews a rather earnest article by a dermatologist who hypothesizes that humor develops from aggressive behavior (that, perhaps, it is a kind of verbal aggression?). Go read the weirdness.
Ed Yong at Not Exactly Rocket Science has two interesting posts on testosterone. In Prejudice vs. Biology I think Ed does a marvelous job demonstrating what I was trying to explain above: testosterone and other hormones might open the door to a behavior, but you (or you and your pre-conceived notions of hormones) are the one who decides whether to walk through. His other post looks at a study of the differential effects of testosterone and estrogen on economic decisions in postmenopausal women and found… nothing. I loved that this study actually looked at women, not men. The authors of the study even go so far as to suggest that some of the results that have found correlations between hormones and economic behavior are a result of publication bias. Go, go on and read!
Your dose of random
A lot of posts and articles have caught my eye recently. I’ll share some this time and maybe save a few for my next Around the Web.
Ever wonder how to get more young people to be more responsible about their reproductive health? Perhaps we need to understand the adolescent brain better to come up with more targeted campaigns.
The Shadow Scholar is a rather disturbing read by a pseudonymous writer for hire who helps college students cheat. Related to this (in my mind), is the story of how students lack basic research skills. On a more positive note, some perspective on why being hardworking (and, you know, not cheating) is more important than being smart.
Related to the last Around the Web on sexual differentiation and variation, this post by sex-positive Alice Dreger answers a young girl’s question who is worried that her clitoris is too big.
Finally, though we’ve already covered parenting, I wanted to share with you this neat story about adoption in sea lions. Read the story. Revel in the cute babies.
Next time I’ll write about stress and social disparities.
Reference
Levi, Maurice, Li, Kai, & Zhang, Feng (2010). Deal or no deal: hormones and the mergers and acquisitions game Management Science, 56 (9), 1462-1483
Friday, November 12th 2010
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 two of five. Part one can be found here.
What is a normal menstrual cycle? Are you normal? Am I? Women spend a lot of time worrying about this, and most of them seem to assume they fall outside of normal. So, I’d like to spend a little time unpacking the concept of normal reproductive functioning in the second part of this series.
What is normal?
Recently, in the beginning of an evolutionary medicine volume, I read in the editors’ opening comments that there is “nothing biologically normal” about monthly menses, as a way to put forward the idea that women should take continuous oral contraceptives (Stearns and Koella 2008, p. 4). This led me to wonder what it means to be biologically normal. That offhand, and troubling, statement about there being “nothing biologically normal” about month-long cycles and frequent menses, makes an entire population of women feel as though they are, then, biologically “abnormal.” I don’t think this is useful.
My understanding of biologically normal is that the body varies and is responding to its environment in a way that we would consider to be adaptive. It is normal for the female reproductive system to allocate resources in response to its environment.
Women from industrial populations are at the far end of the spectrum of variation in reproductive function, but we have not fallen off the end of the continuum. On the one hand, I appreciate the attempt of the authors to introduce the idea that American physiology is not the global standard that we should use to evaluate all human populations. However, any body that responds appropriately to its ecology is, by the definition I’ve always learned, normal.
The reason Stearns and Koella (2008), and Eaton et al (1994; 2002), and others have been advocating continuous hormonal contraceptive use in industrial populations is that it may decrease reproductive cancer rates. The relatively higher incidence of reproductive cancers in industrial populations is a consequence of our flexibly responsive bodies being in an environment of low energy constraint. Once upon a time, we were eating less and moving more. Age at menarche (that’s when we get our first menstrual period) used to be much later, menses itself wasn’t particularly heavy or cumbersome, and few cycles were ovulatory (meaning that an egg is released for possible fertilization). Soon after reaching menarche (as in, within a few years) a woman has her first child. She breastfeeds intensively for the first few years, but continues to breastfeed at least occasionally for four years, maybe more. At some point towards the end of breastfeeding, or sometimes not even until breastfeeding was done, she would resume cycling, and in a few cycles likely get pregnant again.
This pattern would continue, with some variations based on miscarriages, increasing age, seasonal variation in food availability, and other issues, until the woman hit menopause. Of course, for many women, their lives ended around that point or even before, but plenty of women survived to be grandmothers, if observation of current forager populations is any indication. This means that for most of a woman’s reproductive life she was pregnant or breastfeeding, and cycling only occasionally. Strassmann (1997) has a great analysis of this and comparison between populations: the punchline is that an industrialized woman of today has around 400 menstrual cycles, while our ancestors, if modern foragers are an indication, had 50-100.
Now let’s look at today’s industrialized woman: like men, she eats more and moves around less, largely because she is in school or working rather than getting her own food. She hits menarche earlier, and menses are more frequent and copious than her ancestors, which creates lots of tissue remodeling in the endometrium (the lining of the uterus). Many of her cycles are ovulatory, necessitating frequent tissue remodeling for the ovaries. She may cycle for years before having her first child, even decades, and with those frequent cycles come a higher exposure to endogenous (coming from within the body rather than outside it, as in a pill) sex steroids like estradiol and progesterone. Even if she breastfeeds for years, she will likely resume menstrual cycling sooner than her ancestors because she is better fed. She will probably have fewer pregnancies and births than her ancestors, which means more cycles in between pregnancies. She will most likely make it to menopause and beyond; because she is so much more likely to make it past menopause we are far more likely to notice the negative effects of all that hormone exposure, in the form of reproductive cancers.
So while I disagree with the idea that there is “nothing biologically normal” about frequent menstrual cycles, I certainly agree that they are not doing us any favors. But is it the reproductive system that is at fault or the lifestyle? Should we artificially suppress the system in order to promote health, or make changes to the way we live? I want to complicate things further and ask if it is actually true that continuous oral contraceptive use would actually reduce reproductive cancer risk, and if so, at what age should it be administered? Currently, I’m not convinced that getting women on to oral contraceptives for their entire reproductive years is wise. But that’s for another post.
The third part of this series will address population variation in reproductive function, and how this impacts the efficacy and side effect incidence of hormonal contraceptives.
References
Eaton SB, Pike MC, Short RV, Lee NC, Trussell J, Hatcher RA, Wood JW, Worthman CM, Blurton-Jones NG, Konner MJ, Hill KR, & Bailey R (1994). Women’s reproductive cancers in evolutionary context Quarterly Review of Biology, 69 (3), 353-367
Eaton, S.B., Strassmann, B.I., Nesse, R.M., Neel, J.V., Ewald, P.W., Williams, G.C., Weder, A.B., Eaton III, S.B., Lindeberg, S., Konner, M.J., Mysterud, I., & Cordain, L. (2002). Evolutionary health promotion Preventive Medicine, 34, 109-118
Stearns S, and Koella J, editors. 2008. Evolution in health and disease. 2nd ed. Oxford: Oxford University Press.
Strassmann, BI (1997). The biology of menstruation in Homo sapiens: Total lifetime menses, fecundity, and nonsynchrony in a natural-fertility population Current Anthropology, 38 (1), 123-129 ISI: A1997WD24700015
