Monday, November 15th 2010

Around the web: male behavior

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!


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?

ResearchBlogging.orgThis 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.


Levi, Maurice, Li, Kai, & Zhang, Feng (2010). Deal or no deal: hormones and the mergers and acquisitions game Management Science, 56 (9), 1462-1483

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Wednesday, November 10th 2010

Around the web: sexual differentiation and identity

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 taught my students about sexual differentiation in humans. We also watched the PBS special Sex: Unknown. This film documents the botched circumcision, gender reassignment surgery, social and hormonal conditioning, then later gender reversal of Bruce, turned Brenda, turned David. They also interview David’s mother, Anne Fausto-Sterling, a few scientists (to set up a sense of “controversy”) and a transgender man. Overall I think it’s a very well done, devastatingly sad film.

One of the things I always take away from this film when I watch it is how malleable gender is, and how gender is something that is up to the individual who supposedly possesses it, not parents or doctors. I think my students got the second message, but not the first. They found David’s story — an XY male who was gender reassigned due to the botched circumcision, but that gender reassignment ultimately failed — as confirmation that sex is not malleable, and that it’s binary. We had a hard time defining gender and sex and making sure to parse them out. And despite what we learned in the film, about the large number of people born with genitalia that is not obviously male or female (more than those born with cystic fibrosis and Down’s syndrome combined), most thought there are only two sexes.

While I think sex is more determined, in some obvious and very interesting ways, compared to gender, I have a feeling that sex is still more malleable than we would like to admit. We have so much interesting comparative evidence in other animals of hormonal organizational effects that are not permanent. So, while the majority of people likely are male or female, I think the awareness the intersex movement brings, for us to acknowledge more variation rather than bin people into two categories, is an important one.

Sex determination, sex and gender identity

First, from Ed Yong: Sex runs hot and cold (look, even the amazing Ed Yong conflates sex and gender! It’s ok, we all do it sometimes). Here is some of that comparative evidence I mentioned — environmental stimuli impacting sex determination in jacky dragons. A very cool read. Also check out the comments; one of them contains a useful citation.

I also found a few others in Discover Magazine: Of Mice and Men is interesting, as it chronicles the importance of pheromones in sex determination and sex behavior in mice. This bleeds over, at least a little, into our class’s next topic of behavioral endocrinology. Transsexual brains also looks at sex identity, by examining the brains of transgender folk. They found differences between transgender and not-transgender male brains in parts of the brain that are probably determined in utero.

Related to this story was another in Scientific American Mind. I had a hard time finding a link that would allow you to read the full text, but this one should work. The article is called the Third Gender, and similar to the previous link, it looks at transgendered folks as a way to think about sex and gender differently and flexibly. An interesting read.

Next, the basic story of sexual differentiation often implies that male factors are needed to produce males, whereas females are just produced so long as there are no male factors around. Not so fast! Rather than seeing female sex determination as a passive process, this article suggests a more active role. This complicates the story, but that is rarely a bad thing!

Finally, a rather sad story, but one I thought worth sharing regarding our conversation on sex and gender: Afghan Boys are Prized, so Girls Live the Part. This is a New York Times story about families in Afghanistan dressing their daughters as sons in order to improve their status. Once the girls hit puberty, they generally have to go back to being girls, but for those years that they dress as boys they enjoy all the privileges of being male. You need to read this story.

Nothing random to share in this Around the Web, but I’m saving a few good ones for the next post. You should just read what I’ve linked here!

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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:

Cooperates Defects
Cooperates 6 months | 6 months 0 years | 10 years
Defects 10 years | 0 years 3 years | 3 years

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:

Cooperates Defects
Cooperates 3 candies | 3 candies 0 candies | 5 candies
Defects 5 candies | 0 candies 1 candy | 1 candy

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?


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…

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