Friday’s HBES meetings started with a plenary by anthropologist Brian Hare from Duke. Let me just say that I like the starting days with plenaries. No presenters have to “pay dues” with crappy earlier spots that everyone sleeps through. People get up for good plenaries, & this was no exception. Hare did his undergrad at Emory, working in Yerkes Primate Center, I think. He did he Ph.D. at Harvard with Richard Wrangham, then did a postdoc at Max Planck with Michael Tomasello. He’s now at Duke where the runs the Hominoid Psychology Research Group & Duke Canine Cognition Center. He works with lemurs at the Duke Lemur Center & supervises students in Africa at a bonobo sanctuary. This talk compared chimp & bonobo behavior, starting with a video demonstrating how a chimp named “Yoyo” solves a logic problem to get a peanut out of a cylinder by spitting water into it until the peanut floats to the top (males would have peed in it, says Hare). Hare outlines several tests of the “cooperative species hypothesis,” examing ape tolerance constraints, reputation formation, active punishment, altruism & helping, collaboration, negotiation, reciprocity, & decision making. Chimps & bonobos can be dsitinguished in these respects, as the chimp/bonobo genome mapping has recently placed their split at 3 million years ago with no interbreeding. Using a term coined by a colleague, Hare says we can’t understand our “Pan-cestors” if we don’t understand our two closest relatives.
Experiments to detect cooperation indicate chimps know how to recruit help by using paradigm wherein a chimp has to use a key to let in a partner to get to a food item. Chimps are aware that a joint effort is necessary, as the partner get obviously pissed if the chimp in the inner room is allowed to get the food without needing to let the partner in to help. Chimps also remember an effective partner over in ineffective one if they have to choose.
In another set of experiment, chimps solve a cooperative negotiating experiment without overt communication in only 5 minutes 95% of the time. There are two rooms with two sets of bananas each, with ropes leading to each that need to be pulled in concert. In one room, one plate has 3 bananas, the other in the same room has 1 banana. In the other room, each plate has 2 bananas. The dominant chimp tries to go to the plate with the most bananas but gets not assistance from the other chimp unless he relents & goes into the other room to cooperate so they each get 2 bananas, suggesting implicit negotiation.
Experiments with bonobos find they are more tolerant of strangers than chimps even though bonobos don’t cooperatively gather food in the wild. Hare shares anecdotes of observing captive chimp & bonobo groups merged. Integrating chimps is a nightmare he says. The stress & fear of merging is what most causes chimps to jump the fence & says having a chimp clinging to your leg in fear is a singular experience. Bonobos on the other hand can be merged with little formality or foreplanning, much to Hare’s surprise. Additionally, not only do bonobos share, but they share will unlock doors to let groupmates AND strangers in to eat with them, even when cooperation is not necessary. Bonobos may share with strangers to make new friends & expand their social network.
Next I went to a session on behavioral economics moderated by Douglas Kenrick. Ashley Arsena, a grad student from Kristina Durante’s lab at UT San Antonio, gave a talk on “The effect of ovulation on women’s variety seeking & loss aversion.” Interestingly, she found that nearer ovulation, women prefer more variety in nail polish colors. Ovulating women are also less loss averse, as measured by the selling prices they set for items in an economic experiment (they set them lower so they will sell rather than higher to try to retain them). An audience member questioned why women would want to signal a variety of nail polish during ovulation. We had a similar discussion this semester in discussing why women buy so many cosmetics & perfumes, when guys scarcely seem to care & don’t know subtle shades of difference. It seems more related to intra-sexual competition, & Ryan Earley ancedotally mentioned he thinks he sees similar behavior in fish. When one female is brighter than others, other females bristle, but the males seem to care less. We hope to enlist an EvoS student to test this soon.
Chris Rodeheffer discussed the “lipstick effect,” which is apparently a commonly seen boom in women’s cosmetics sales during economic hardships. Women purchase luxury rather than cheap cosmetics when primed with economic uncertain in experimental conditions. The lipstick effect is a female functional response to diminished access to quality mates, whether or not the females have access to their own resources. No lipstick effect is observed in men–in economic uncertainty, men don’t buy shit.
I zipped over to catch the last talk in the women’s reproductive strategies session & caught Stephanie Cantu giving a talk on whether scarcity of men leads women to choose careers over having babies. U.S. Census, Department of Labor, & Centers for Disease Control data all indicate that there are more women in high paying jobs when there are fewer men with high paying jobs available. Experimental research suggests that perceptions of the mating market predict whether women would hypothetically choose career or family.
The afternoon plenary by Laura Glynn was about maternal brain fogs. Studies find improved spatial memory in pregnant rats, but humans self-report impaired memory during postpartum periods. Experimental studies find that pregnant women also score lower in memory than non-pregnant women. In fact, memory goes down further with each pregnancy in multiparous mothers. They control for sleep, so it does not seem to be an effect of this type of stressor. I asked about multiples (my wife birthed triplets), if there was any data regarding whether it was a child effect or pregnancy effect. There is no data on the brains of mother of multiples, but Glynn suspects it is a child effect, so mother of multiples will be like multiparous women (bad news for my wife). Consistent with this fetal cells are found in injured areas of maternal brains, suggesting they lesion these areas.
Next I went to part of a Darwinian psychiatry session (maybe Dan Glass will be blogging more about these?). P. Andrews gave a talk on whether anti-depressants do more harm than good. Only 5% of serotonin is in the brain, he said. 95% is made in the gut & distributed around the body. SSRIs, which are intended to target serotonin in the brain, actually affect it system-wide. Serotonin is under the body’s homeostatic system, so when SSRI keep serotonin in the synapses longer, the body dampens down production. But this tension is like a coiled spring being pulled. When a person goes off serotonin, the coil spring back harshly, often overshooting the original set-points & causing a relapse of depression worse than the original symptoms. When SSRIs are prescribed to people with sub-clinical depression, this spring affect leads to real depression, hence the higher prevalence of depression in our society than ever before (depression is the common cold of psychiatric disease). A better course of action would be to prescribe such patients a placebo, which would not produce this relapse reaction.
Another excellent talk in this session was given by E.H. Hagen, regarding “Tobacco & cannabis vs. helminths in Center African foragers.” He only had data analyzed for tobacco, but it seems to suggest support for a “pharmacophagy hypothesis,” which suggests that recreational drug use is an adaptation to fight parasites. Apparently, nicotine used to be commonly used to deworm livestock. In an experiment among the Aka foragers of Central Africa, Hagen found highly worm-infested men (women don’t smoke as much) smoked significantly less after a worm treatment relative to controls & less worm-infested men. Though he didn’t frame it in this paradigm, smoking behavior seems to be part of the “behavioral immune system” other talks would discuss. Smoking, it seems, is more prevalent among men in countries with higher parasite loads.
After the poster session was a performance by evolution rapper Baba Brinkman that I thought was going to be hokey but which was really excellent. What impressed me was that not only is Baba as geekily informed as anyone else at the conference, demonstrating detail & topical relevance in rhyming on recent hypotheses, his performance was really excellent. David Buss introduced Brinkman & suggested that intro students are often bored until he plays Brinkman for them.
Brinkman says the first thing he found evolutionary biologists & rappers have in common is a belief in common descent from Africa & covered “I’m A African” by Dead Prez in homage. The 2nd thing they have in common is sex. I was blown away when Brinkman’s sex rhyme discussed different types of animal sex & even referenced one of my faves (see my previous post on the topic), the corkscrew penis of the Argentian wood duck.
Brinkman raps about the correlation between adolescent growth spurt/maturation & the homicide/teen pregnancy rates in low SES communities, as pointed out in Wilson & Daly’s classic Homicide. “I was a 13-year-old white, suburban Canadian & didn’t understand ‘How I Could Just Kill a Man’ until Wilson & Daly,” Brinkman said of his introduction to Cypress Hill AND evolutionary psychology.
Batesian mimicry is the same as posturing as a thug for Mobb Deep, says Brinkman. There are perfect evolutionary lessons in rap lyrics without even changing too much, most of the time. For instance, “bling” is analogous to peacock tailfeathers that you can’t carry until you’re fit enough to bear the cost of someone trying to rip you off.
Brinkman even had a rap for the “behavioral immune system”/”parasite-driven wedge” hypothesis. I about shit in a bowl over that. Finally, he admitted he sends his lyrics to the experts to get proofed. Instead of fixing one, he played the voicemail message from David Buss informing him there is new evidence suggesting that one of his lyrics might not be supported & need to be changed. Geekily awesome!
Check out Brinkman’s CD “Rap Guide to Evolution.”