Earlier this semester I talked about a few new kinds of assignments I was trying out in my evolutionary medicine class. I’ve got my students posting on the readings every week at the group blog, and there have been several great interactions. For instance, here is a thoughtful comment on one student’s post:
“…I have long wondered why a natural process, such as ovulation, is so painful and discomforting in a spectrum of ways to women across the board. Perhaps hormonal contraception modalities are not the ideal accommodation, but can you really blame the women who opt for it?
“I think perhaps it is our culture that is out of balance with our biology and needs a second review. Not only are women reaching ages of menarche earlier, experiencing higher levels of hormones, having fewer children to break the hormonal cycle, but our lifestyles just do not accommodate in alleviating this process. How are our stressful lifestyles adding to the premenstrual discomfort and feelings of inconvenience women have about their reproductive cycles?
“I understand that oral contraception stands in the way of natural ovulation and conception, but similarly, our culture stands in the way of our natural biological functioning. Should women have to live with discomfort and contemptuous feelings towards their bodies, supported by large cultural consensus that menses is ‘annoying so why not just stop it’? Is this ideology not also to be reproached?
“I only bring this up to suggest that perhaps the huge injustice to our bodies has been our cultural environment and not just the fix-its that we humans have come up with….”
You can check out the whole blog here.
But that’s not all! As part of their 20% projects, a few students have decided that the way they want to present their work is through writing a blog. First there’s The Daily Filling, a blog by a pre-dentistry student who is using her 20% time as a chance to integrate what we’re learning about evolutionary biology into a better understanding of dental health.
Here’s a neat passage from her post on sugar:
“I feel it is essential for readers to understand how humans have evolved to consume sugar more readily and how although it appears counter-intuitive that natural selection has not chosen against the side effects of sugar, it is not entirely Mother Nature’s fault. Sugar had historically been a rare substance for our ancestors to obtain–when it was ingested, it was readily stored and then used. New York Times states “humans evolved to crave sugar” and that apart from honey, there was rarely any food sweeter than carrots.
“If only they tried a Twinkie or two.
“Natural Selection has indirectly favored this genetic predisposition of craving sugar as a means of survival and reproductive success. What limits modern day humans is the excessive consumption of refined sugar spread throughout the day instead of at one sitting.
“From a dentition standpoint, it thus makes sense why our early Hominid ancestors lacked any cavities or tooth decay. When agriculture was discovered, the lactic-acid causing bacteria Streptococcus was found in more mouths across the world–found from eating all sorts of foods from carbohydrates to milk sugar (lactose) and sucrose. And, because brushing one’s teeth was a relatively novel idea at the time, the decay of teeth began.”
“So how does stress physiologically strain the cardiovascular system so much that it can give a perfectly healthy individual a heart attack?
“The obvious answer? – Stress. Though, it is far more complicated than that. From an evolutionary perspective, the stress response of our cardiovascular system is ideal. Say you are living 100,000 years ago. You and couple of your tribal peers go out hunting for a boar. You find one, have it in sight. You begin strategizing your method to catch it. But something unplanned happens – the boar starts charging you! Stress response activated: your digestive tract shuts down and your breathing rate surges. Your body inhibits the release of sex hormones, while others like epinephrine (adrenaline), norepinephrine and glucocorticoids spill into your bloodstream, activating the sympathetic nervous system. Heart rate increase to pump oxygen quicker throughout the body, glucose energy reserves are released, attention and response centers in the brain are heightened, and blood flow to skeletal muscles are top priority. With all this in place, you have a pretty good chance of escaping that charging boar intact.
“This heightened blood flow is well and great when we have the metabolic demand to match. However, like family member ‘A’, if these physiologic responses are chronic, you are continually diverting as much blood flow to your limbs, straining the heart and overlooking other areas of the body. This is when we see damaging effects.”
Finally, one of my students wanted to learn more about variety in the human diet by trying a number of diets herself (not the weight loss kind) for her blog Cuisine for Comfort. She has recently finished a rice-based diet and a typical Western diet – check out some of her daily posts that she has written, with pictures of her meals and descriptions of her health!
So go give these students a little love. They’re trying to make the blogosphere a little more sciencey, and are doing great work incorporating evolutionary medicine into their own interests, which is perfectly in line with the 20% project.
So, I haven’t had a chance to blog these last few weeks. Part of it is that I’ve been submitting papers, revising papers, teaching, and giving talks – the usual gig for a professor. Part of it, if I’m being honest, is the new workout program I’ve been on, and the extra three hours a week of physical therapy I’ve also been doing to rehab a shoulder injury. It’s hard to wake up at 5am when you have 12 hours a week of exercise as well as a full time job and childcare.
The real reason, I think, is that I’ve been mentally and emotionally sapped from the interviews I have been conducting over the last few weeks as the follow up to the Biological Anthropology Field Experiences Survey (you can still participate in the survey, and you can still do an interview). I’ve figured out that it helps to have a posse of people I can go to when sensitive topics are covered, which is why I am so glad I have fantastic collaborators. I’ve also lucked out with truly brilliant, thoughtful participants. I’m not sharing the details just yet, or my preliminary observations since the first wave of interviews are ongoing.
But I will say one thing. Many of the stories I have heard are unacceptable. And it is my mission now, mine and many other strong allies, to figure out how to change the culture and structure of field experiences so that these unacceptable things do not happen to anyone else.
My team does a lot together. We work out. We practice and scrimmage. We swap recipes and cook food together. We watch footage and we hold meetings. We try to listen and then talk all over each other. We squabble. We love.
Roller derby is the most brutal, yet most fun, sport I have ever played. The degree of contact between skaters is high, as we hold on to our teammates’ hips, shoulders, arms, sometimes whatever we can grab to provide stability, form a wall, or sometimes throw one of our players at an opponent. We need to trust and respect each other, to listen and communicate. Despite its violence, derby is my safe space: there are no anonymous peer reviews, no opaque promotion and tenure policies. My experience has been that the greater your effort, the greater your results, and compared to the stressful experience of academia where the uncontrollable factors are what can ruin your research trajectory, this is an exhilarating feeling. I love my team and I know they love me, warts and all.
I don’t know everything going on in my teammates’ lives outside of derby, but because of the camaraderie formed by doing something dangerous, competitive, and gloriously fun together, we are very close. We know our menstrual cycles aren’t synchronizing, despite occasional coincidences in timing. But perhaps there are other ways we are physiologically in sync.
Protect your jammer!
To my mind, the most important job a blocker can do is hold back the opposing jammer as long as possible to help their jammer get lead and make a scoring pass. Related goals include playing offense to help your jammer through, and protecting her from the worst hits. As someone who jams pretty often, I am most at ease when I know my blockers are keeping the other jammer from making it through the pack, because it frees me up from worrying about where she is, so I can do what I need to do to score.
A roller derby pack is not unlike a microbial community. Diversity of strategies and skills are key – some of our blockers are better at containment, some at big hits, others at offense, even if pack coordination is the primary goal. And a diverse microbiome tends to be correlated with better health outcomes, provided the main bacterial types are the “good” kind (think Lactobacillus, found in cultured food like yogurt, but also our guts and our vaginas). This diversity is what makes it possible for the “good” bacteria to outcompete the “bad.”
In a paper out today at the new open access journal PeerJ, Meadow et al (2013) explore the ways in which the contact sport of roller derby provides a great test scenario for understanding variation in and transmission of skin microbes. One of the authors is a former skater, and their materials and methods indicate they understand the sport well. My favorite quote:
“Flat track roller derby is a contact sport; blockers are allowed to initiate contact with another player tocompete for track position using any of the following body parts: upper arm (shoulder to elbow), torso, hips, “booty” (official WFTDA nomenclature), and mid to upper thigh” (Meadow et al 2013: 3, emphasis mine).
The authors used a tournament happening at Eugene, Oregon with the Emerald City Roller Girls (the host, from Eugene), DC Roller Girls (Washington, DC) and Silicon Valley Roller Girls (San Jose, CA). They were able to test a few conditions: the teams’ microbial communities before playing, after playing one bout, and after playing two bouts, to see change over time and over contact with different team microbial communities. They sampled from the upper arm, because it’s probably the body part with the most universal exposure across players.
Meadow et al (2013) hypothesized that individual skin microbial communities would be similar within teams, but after bouts opposing teams would also bear some similarities, given the substantial skin contact involved in the sport.
Bacteria that skates together, stays together
The authors found that team membership predicted individuals’ skin microbial communities. They also found a significant difference in the composition of each team’s microbial communities, but also that their microbial communities of each individual within a team became more similar, after bouts.
Differences between individuals did not seem to be predicted by the amount of time each skater played in a bout. The way they measured time played was to assign each skater 2 minutes of playing time for every jam they were in. 2 minutes is the maximum amount of time a jam can take, and is by no means the average, so skating time, which can be anywhere from 10 seconds to 2 minutes per jam, was not well represented. Further, they didn’t differentiate between jammer and blocker positions in each jam, which carry very different kinds of contact risk. This was perhaps the only methodological wrinkle for me, and the authors are careful to note it themselves as well. And unless the authors planned to take copious observational data and ask for post-bout stats, it would have been hard for them to do better than what they did. What this means though, is that their lack of a correlation is just as likely a false negative as it is accurate.
Finally, the Meadow et al (2013) found that Emerald City skaters’ microbial communities were similar to the track where the tournament was held, which also happens to be their practice track. The authors then point out (I may have LOLed):
“it is perhaps unsurprising that EC players share some of their microbiome with the track surface since they shed skin cells and frequently come into direct contact with the floor” (Meadow et al 2013: 12-13).
Bacterial hugs, on and off the track
There are a lot of reasons each of these roller derby teams have microbial community similarities. They are from the same geographic region, they probably practice and live in the same area, some skaters may even live together. There is a high amount of skin contact when they practice, scrimmage and bout together. And, as the authors also point out, exercise produces changes in microbial communities, and these are all pretty highly ranked teams, with elite athletes (Emerald City is ranked 58th, DC Rollers are 48th, and Silicon Valley is 74th out of 161 teams as of this writing… <cough cough> my own Twin City Derby Girls are 72nd).
The authors suggest direct contact is the most effective means of bacterial transmission, given the present evidence, which means the skin contact of roller derby is the best predictor for team and post-bout similarities. It would be interesting to test their hypotheses among other sports, or at different times of the year, and to compare hand microbial communities to upper arm communities. Or what about shifts along the menstrual cycle or with or without hormonal contraceptive use? I would also wonder about non-skating teammates and coaches: coaches get quite a lot of sweaty contact from their team, but not with their opponents. How much of a shift might happen to their microbial communities between bouts?
In any case, I like to think of the similarity I share with my teammates in terms of skin microbial communities to be like an all-day bacterial hug. Even when I’m not with them, they’re with me. As a jammer, I couldn’t ask for better protection from my pack.
Check out this video that lead author James Meadow shared with me from the tournament where they sampled skaters (a little hokey, but then, I did just talk about being hugged by my team via bacteria).
Meadow et al. (2013), Significant changes in the skin microbiome mediated by the sport of roller derby. PeerJ 1:e53; DOI 10.7717/peerj.53