Diversity in Science Carnival: Pride Month 2011

Test the rainbow? (Flickr: nezume_you.

Diversity in Science CarnivalEven though the queer nerd is a long-established phenomenon, and a pretty common one these days, we’re not necessarily very visible in science, technology, engineering, or mathematics disciplines. Even cutting-edge fields can be surprisingly conservative, and a lot of us end up in industries or academic departments where people are still not asking or telling. And on the other hand, science often has a lower profile within the queer community than it deserves—how many queer scientist types have you seen on TV lately? Yeah, me neither.

(Maybe Willow Rosenberg? But she ditched computer science for magic, and she’s been off the air since 2003!)

As just one example of this, when Alberto Roca and I went looking for science-related videos on the “It Gets Better” project website, where queer adults can post their stories to encourage queer kids who are dealing with bullying, neither of us found much. Big tech companies like Microsoft, Pixar, Bayer, and Eli Lilly are well represented, but search for individuals’ videos labeled “science” and you get … not a lot.

So where are the examples of queer scientists for today’s nerdy gay, lesbian, bi, and trans kids to look toward?

Well, actually, we’re all over the place. For last October’s National Coming Out Day, Steve Silberman and Maggie Koerth-Baker put together a wonderful double feature at BoingBoing, compiling the personal stories of LGBT scientists, and presenting an in-depth interview with endocrinologist Neena Schwartz. Now, for the Pride edition of the Diversity in Science blog carnival, we have another array of voices from across the science blogosphere: queer and allied scientists and science fans, discussing everything from gay history to the science of sexuality to their personal experiences as sexual minorities in scientific workplaces.

The carnival commences after the jump!

Continue reading

Snake-eating opossums have evolved venom-resistant blood

The humble Virginia opossum can shrug off snakebites that would kill larger mammals. Photo by TexasEagle.

ResearchBlogging.orgIf you were going to pick the traits of a single animal to confer on a superhero, you probably wouldn’t pick the Virginia opossum. Possums are ubiquitous, scruffy, ratlike marsupials, their toothy grins giving the not entirely inaccurate impression that they don’t have much going on upstairs. Until recently, the nicest thing I could think to say about them is that they eat a lot of ticks.

Blood-sucking Lyme disease vectors are only a small part of the opossum’s eclectic diet, however. They also eat quite a few poisonous snakes, and this has apparently led them to evolve a trait I could call a superpower without exaggeration: opossum blood is resistant to snake venom.

This curious and useful ability was first documented by J.A. Kilmon in a 1976 paper [$a], in which Kilmon reported field observations and laboratory trials showing that opossums tolerate snakebites without visible ill effect. (If animal experimentation makes you queasy, you might want to go read something else about now. Perhaps a nice post about gerbils?)

A natural bite was observed in the field by a 160 cm eastern diamondback on an adult opossum, Didelphis virginiana. The opossum displayed no apparent distress and this suggested a remarkable tolerance by that animal to envenomation. In order to ascertain if an actual envenomation did take place, Mr. Seashole conducted field experiments by manually causing snakes to inflict actual bites on captured opossums. None of the bites caused visible signs of distress to the opossums.

Kilmon brought possums back to the lab, anesthetized them, hooked them up to heart monitors, and “inflicted” bites on them from diamondback and timber rattlesnakes, water moccasins, and at least one cobra. (Kilmon reports he used 15 snakes in total, but doesn’t break that number down by species.) “None of the five opossums,” he wrote, “developed observable local reactions other than trauma attributable to fang penetration and none developed observable systemic effect, exhibiting negligible alteration of heart rate and respiration.”

A timber rattlesnake—no big deal to an opossum. Photo by Tom Sprinker.

Finally Kilmon injected an anesthetized opossum with enough water moccasin venom to kill five fifteen-kilogram dogs, and observed no reaction beyond a brief drop in blood pressure and small spike in pulse rate—when the possum awoke, it was “apparently healthy.” Upon sacrificing and dissecting the animal, Kilmon found no evidence of organ damage.

Kilmon concludes his brief scientific report with a weird aside about the evolutionary history of opossums, which, had he been writing in 2011, would have made me think his research consisted mainly of skimming the Wikipedia entry for Didelphis virginiana. In the course of reporting the opossum’s taxonomic affiliations and known diet, Kilmon notes offhandedly,

This polyprotodont marsupial is a primitive but also very successful mammal. The opossums of varying species are the only marsupials surviving in the placental world, the predominant marsupial and monotreme mammals of Australia having probably survived due to their isolation. The opossum has remained unchanged for millions of years and probably reached his peak of evolutionary specialization several millions of years ago.

I don’t think he could’ve gotten away with that last sentence in an evolutionary biology journal. It’s true that the common ancestor of opossums and placental mammals (i.e., us) diverged quite a long time ago, that opossum-like critters are known from the fossil record going back that far, and that many opossum traits are thought to be shared with early mammals. But that doesn’t mean opossums “remained unchanged for millions of years.” The lineage leading to modern opossums has been evolving exactly as long as the lineage leading to modern humans—and if the opossum’s lifestyle hasn’t led it to such evolutionary heights as the wheel, war, New York and so forth, then it also hasn’t left the opossum unchanged.

As it happens, a pretty good illustration of this point is the paper that led me to Kilmon’s morbid little study in the first place. Mammalogists Sharon Jansa and Robert Voss have just published a study of one blood protein that may underlie opossums’ resistance to venom. The venom of pit vipers like rattlesnakes and water moccasins targets the blood clotting system—one of the unpleasant effects of a snake bite is internal hemorrhage. So Jansa and Voss examined the evolution of a venom-targeted clotting protein called von Willebrand Factor, or vWF, comparing it across the entire family of opossums, the didelphidae.

Photo by Maggie Osterberg.

Since the evolutionary origin of the family, the vWF of opossum species that prey on snakes has accumulated more changes than vWF in non-snake-eating species. That’s circumstantial evidence for the effect of natural selection continuously acting on vWF over millions of years. Jansa and Voss picked out several specific changes that are unique to snake-eating opossums, and found that they’re associated with a region of vWF that is known to bind with one of the toxins in pit viper venom.

The authors suggest that opossums may have been engaged in a evolutionary “arms race” against snake venom toxins since they first developed a taste for rattlesnake. In other words, not only is the opossum not unchanged since the early history of mammals, one of the traits that has changed continuously since then may be the very feature that piqued Kilmon’s interest.


Jansa, S., & Voss, R. (2011). Adaptive evolution of the venom-targeted vWF protein in opossums that eat pitvipers. PLoS ONE, 6 (6) DOI: 10.1371/journal.pone.0020997

Kilmon, J., Sr. (1976). High tolerance to snake venom by the Virginia opossum, Didelphis virginiana. Toxicon, 14 (4), 337-40 DOI: 10.1016/0041-0101(76)90032-5

What to wear to Pride (if you’re a huge nerd)

Drift happens, and it’s fabulous. Photo by jby.

After the big gay post came out Tuesday, there was really only one shirt I could wear to the Twin Cities Pride parade. You, too, can have the thrill of explaining the Wright-Fisher model of drift and mutation in front of a gay bar—this design is available for purchase, with your choice of American Apparel shirt colors.

Science online, toxic newt eggs edition

A rough-skinned newt. Photo by matt knoth.

Don’t forget—Diversity in Science carnival contributions are due Monday!

And finally, a video sent to me by Dave Giordano, describing field studies of nesting behavior in tropical birds.

The intelligent homosexual’s guide to natural selection and evolution, with a key to many complicating factors

San Francisco Pride, 2008. Photo by ingridtaylar.

This is a cross-posting of my latest contribution to the Scientific American guest blog. Since the original went up at SciAm, P.Z. Myers has pointed out a few more complicating factors. If you read one paper to follow up on what I’ve written here, I’d suggest Nathan Bailey and Marlene Zuk’s excellent 2009 review [PDF], which is posted in PDF format by none other than The Stranger.

ResearchBlogging.orgJune is Pride Month in the United States, and in communities across the country, lesbian, gay, bisexual, and transgendered Americans are celebrating with carnivals, parades, and marches. Pride is a rebuke to the shame and marginalization many LGBT people face growing up, and a celebration of the freedoms we’ve won since the days when our sexual orientations were considered psychological diseases and grounds for harrassment and arrest. It’s also a chance to acknowledge how far we still have to go, and to organize our efforts for a better future.

And, of course, it’s a great big party.

I’m looking forward to celebrating Pride for the first time in my new hometown of Minneapolis this weekend–but as an evolutionary biologist, I suspect I have a perspective on the life and history of sexual minorities that many of my fellow partiers don’t. In spite of the progress that LGBT folks have made, and seem likely to continue to make, towards legal equality, there’s a popular perception that we can never really achieve biological equality. This is because same-sex sexual activity is inherently not reproductive sex. To put it baldly, as the idea is usually expressed, natural selection should be against men who want to have sex with other men–because we aren’t interested in the kind of sex that makes babies. An oft-cited estimate from 1981 is that gay men have about 80 percent fewer children than straight men.

Focusing on the selective benefit or detriment associated with particular human traits and behaviors gets my scientific dander up, because it’s so easy for the discussion to slip from what is “selectively beneficial” to what is “right.” A superficial understanding of what natural selection favors or doesn’t favor is a horrible standard for making moral judgements. A man could leave behind a lot of children by being a thief, a rapist, and a murderer–but only a sociopath would consider that such behavior was justified by high reproductive fitness.

And yet, as an evolutionary biologist, I have to admit that my sexual orientation is a puzzle.

Continue reading

Hello, SciAm readers!

If you’ve just arrived here on account of my contribution to the Scientific American guest blog, welcome! I hope you’ll have a look through the archives, and consider adding me to your regular online reading. Allow me to suggest a few posts that should give you an idea about what’s going on here:

Only a week left to contribute to the Diversity in Science blog carnival

Diversity in Science CarnivalThere’s just a week left to send in your posts for the Pride edition of the Diversity in Science Blog Carnival. The carnival will be right here at Denim and Tweed on 30 June, so I need submissions by the 27th so as to have time to put it all together.

Let me add a point I don’t think I’ve made before: blog carnivals are traditionally about aggregating links to blog posts, but you don’t have to write a thousand-word essay to contribute. You can send in photos, videos, even favorite songs—or send links to other folks’ work (credited appropriately!) that you think the DiS audience would appreciate. Carnivals celebrate by aggregating, and we’re interested in all kinds of media.

You can submit posts and other material directly to me by e-mailing a link, or use the handy online form Alberto Roca has set up at MinorityPostdoc.

Thanks to all the folks who have contributed so far!

Science online, (don’t) feel the beat edition

Whitetail deer: adorable forces of ecological destruction. Photo by HerpShots.

There’s just a few days left to submit your posts for the Pride Month 2011 edition of the Diversity in Science Carnival.

  • But how will we identify vampires now? A new artificial heart design is simpler than other models, pumping blood without creating a pulse.
  • Schadenfreude. The production company responsible for the anti-science hack film “Expelled: No Intelligence Allowed” has gone bankrupt.
  • So we’ll have those sharks any day now, right? Living cells engineered to produce green fluorescent protein become the first-ever biological lasers.
  • Not mentioned: liberals more likely to accept lousy pay. Why academia might, in fact, have a liberal bias.
  • In some cases, yes. Are invasive species as bad as we’ve been led to believe?
  • Say it ain’t so, Stephen Jay. To demonstrate that a historic (and racist) study of human skull size was biased by systematic manipulation of data, Stephen Jay Gould systematically manipulated data.
  • Save a serviceberry bush—eat venison! A multi-decade experiment provides strong evidence that too many deer are bad for forests.
  • Not by running with scissors. How the cave-dwelling isopod lost its eyes

From the archive: Evolution’s Rainbow

White-throated sparrow Photo by hjhipster.

No new science post this week, because I’m taking my time to put together a (hopefully) particularly good, detailed article for the near future. In the meantime, let me suggest something from the D&T archives for Pride month, in advance of the Diversity in Science carnival in a couple weeks. Specifically, my review of Joan Roughgarden’s survey of sexuality across the animal kingdom, Evolution’s Rainbow:

This interest in the evolutionary context of diversity would eventually become much more personal. In 1998, [Roughgarden] came out as transgendered, taking the name Joan after decades spent establishing her scientific reputation under the name she was given at birth, Jonathan. In addition to the challenges inherent to gender transition, Roughgarden’s expertise intersects with her identity in one awkward question: in a biological world shaped by natural selection, how can we explain the evolution of lesbians, gay men, and transgendered people—individuals who are not interested in sexual activity that passes on their genes?

Roughgarden’s answer was to begin a program of research questioning the dominant way of thinking about sex in an evolutionary context. In 2004, she presented her conclusions comprehensively in the book Evolution’s Rainbow, calling for biologists to re-think they way they understood and described sexual behavior throughout the animal kingdom. As another biologist with an admitted personal interest in the question, I’ve found Evolution’s Rainbow to be a great starting point for thinking about sexuality in an evolutionary context.

For in-depth looks at three examples of “alternative” animal lifestyles and the reception Roughgarden’s ideas met in the broader evolutionary biology community, go read the whole post.