You’re the top!

So, this has been in my running/fiddling with code/writing playlist for a while.

Naturally that’s got me thinking I should take a crack at the challenge proposed by Ask Me Another, and update those highly period-specific lyrics:

You’re the top!
You’re a Pixar feature.
You’re the top!
You’re a Whedon creature.
You’re a two-page endnote in a D.F. Wallace tome.
You’re a NASA rover,
A four-leaf clover,
You’re the microbiome.
You’re a dream,
You’re mid-cent’ry style,
You’re the gleam in Don Draper’s smile.
I’m the nominee for the G.O.P.—flip flop!
But if, baby, I’m the bottom, you’re the top!

Yeah, okay, that probably still needs some work. If you can do better, show me in the comments.◼

Science online, dilated pupils edition

pupils 2007 An apt pupil. Photo by thraxil.
  • So. Freaking. Cool. NASA successfully landed a car-sized, nuclear-powered, laser-equipped exploratory rover on Mars—for a fifth of the cost of the 2012 Olympic Games.
  • Meanwhile, in the life sciences. Thousands of ecologists converge on Portland, Oregon for the Ecological Society of America meeting. Check Dynamic Ecology and EEB & Flow for coverage.
  • What is the difference between wheelchair racing and cycling, when you think about it? The line between human athletic achievement and technological advancement is fuzzier than you might think.
  • Next: NOM announces that pupil dilation is a “lifestyle choice.” A new approach to testing sexual orientation measures pupil dilation. See also good discussion by Scicurious and Deborah Blum.
  • Yet another microbiome. Examining the bacteria living on the surface of plant roots might be as informative as examining the ones living inside plant roots.
  • Commitment to innovation? Apparently the fundamentalist textbooks for Christian schools are now opposed to set theory.
  • FACT: Wearing a bike helmet all day = 80% reduced risk of death by meteor. How to clearly explain risk, with an illustrative story.
  • Because we only think they think they’re people. Why it’s important to avoid anthropomorphizing when discussing the sexual habits of non-human animals.
  • Cool! Google Scholar will now identify new articles for you to read based on your own publication list.
  • That … sounds like a problem. Some of the world’s most important food-producing regions are living on non-renewable water.

“The Hobbit: An Unexpected Journey”

Against my better judgement (okay, not really) I’m starting to get excited about the upcoming prequel to The Lord of the Rings.

By adding Bilbo Baggins to his filmography, I think Martin Freeman is officially defining his career in the role of the Universal English Everyman, the straight man to wonders: John Watson, Arthur Dent, even Tim, his breakout role on the original version of The Office. Next up: Newton Pulsifer from Good Omens?◼

Is corn the new milk? Evolutionarily speaking, that is.

colorful fall corn

Corn. (Flickr: srqpix)

ResearchBlogging.orgIt is a widespread misconception that, as we developed the technology to reshape our environment to our preferences, human beings neutralized the power of natural selection. Quite the opposite is true: some of the best-known examples of recent evolutionary change in humans are attributable to technology. People who colonized high-altitude environments were selected for tolerance of low-oxygen conditions in the high Himalayas and Andes; populations that have historically raised cattle for milk evolved the ability to digest milk sugars as adults.

A recent study of population genetics in Native American groups suggests that another example is ripening in the experimental fields just a few blocks away from my office at the University of Minnesota: Corn, or maize, may have exerted natural selection on the human populations that first cultivated it.

The target of this new study is an allele called 230Cys, a variant of a gene involved in transporting cholesterol. 230Cys is known only in Native American populations, and it’s associated with abnormally low production of HDL cholesterol (that’s the “good” kind of cholesterol) and thereby increased risk for obesity, diabetes, and heart disease. In Native American populations, the genetic code near 230Cys shows the reduced diversity associated with a selective sweep, which suggests that, although it’s not particuarly helpful now, this variant may have been favored by selection in the past.

One of the biggest dietary changes in the history of Native American humans was the domestication of corn, which provided a staple crop to support settlements across North and South America long before Europeans arrived. However, a staple crop is something of a double-edged sword: it can provide a more predictable food source than hunting and gathering—but if the crop fails, it means famine. It’s been proposed that the 230Cys variant makes people who carry it better at storing food as fat, which might come in handy for ancient farmers who had to weather bad harvests every few years.

2011.08.27 - Corn!

Corn on display at the 2011 Minnesota State Fair. (Flickr: jby)

So the new study looks for an association between frequencies of 230Cys and corn-based agriculture in Native populations from Central and South America. The study’s authors—a big international team from universities in Brazil, Argentina, Mexico, Chile, Costa Rica, France, and Great Britain—first show that there’s a strong correlation between the frequency of Cys230 in Native populations and the length of time that domestic corn has been grown by those populations, as determined by the radiocarbon date of maize pollen found in archeological sites. That is, 230Cys is more common in Native populations that have a longer history of growing corn.

The team also used genetic data from the vicinity of Cys230 to estimate the age of the allele, and found that it probably originated between 19,000 and 7,000 years ago—which is to say, all the copies of Cys230 in the population genetic sample are descended from a single mutation that occurred after humans colonized the Americas. The lower age estimate is also pretty close to how long ago native populations are thought to have first begun farming maize.

That data makes a pretty good case for 230Cys having arisen as an adaptation to the diet created by Native American corn-based agriculture. But it’s not the whole story, by a long shot. Although 230Cys is strongly associated with metabolic disease in today’s modern, mostly famine-free, lifestyle, it only explains about four percent of variation in blood cholesterol levels. Moreover, it’s not clear to me that agriculture based on maize should be more prone to famine than agriculture based on wheat or rice—so why didn’t European and Asian populations evolve their own versions of 230Cys? It seems much more probable that there are a lot of other genes involved in determining how human bodies respond to modern-day feasting or prehistoric famine.

And, in fact, a 2010 study of world-wide human population genetics found evidence of selection associated with both climate and with diet type across the genome. That study found genetic markers with strong associations to climate and diet in close proximity to genes connected to blood glucose levels, diabetes risk, cancer risk, and, yes, blood cholesterol levels. The climate and dietary categories examined in that study are very broad, however, so it’s hard to know what, specifically, helped create the natural selection suggested by the observed associations between gene variants and evironments.

Corn and 230Cys may be the most recently described specific case of recent human evolution in response to agricultural technology—but we can expect to find a lot more stories like this one as we dig deeper into human population genetics.◼


Acuña-Alonzo, V., T. Flores-Dorantes, J. K. Kruit, T. Villarreal-Molina, O. Arellano-Campos, T. Hünemeier, A. Moreno-Estrada, M. G. Ortiz-López, H. Villamil-Ramírez, P. León-Mimila, & et al. (2010). A functional ABCA1 gene variant is associated with low HDL-cholesterol levels and shows evidence of positive selection in Native Americans. Human Molecular Genetics, 19, 2877-85 : 10.1093/hmg/ddq173

Hancock, A. M., D. B. Witonsky, E. Ehler, G. Alkorta-Aranburu, C. Beall, A. Gebremedhin, R. Sukernik, G. Utermann, J. Pritchard, & G. Coop (2010). Human adaptations to diet, subsistence, and ecoregion are due to subtle shifts in allele frequency. Proc. Nat. Acad. Sci. USA., 107, 8924-8930 : 10.1073/pnas.0914625107

Hünemeier, T., C. E. G. Amorim, S. Azevedo, V. Contini, V. Acuña-Alonzo, F. Rothhammer, J.-M. Dugoujon, S. Mazières, R. Barrantes, M. T. Villarreal-Molina, & et al. (2012). Evolutionary responses to a constructed niche: Ancient Mesoamericans as a model of gene-culture coevolution. PLoS ONE, 7 : 10.1371/journal.pone.0038862

Rainbow flags over the ‘burbs

Rainbow Flag Photo by Mktp.

Over at The Atlantic, there’s a nice piece about how the conversation-centric campaign against the proposed anti-gay-marriage amendment to Minnesota’s state constitution is playing out in communities outside the famously queer-friendly Twin Cities. It comes across as pretty hopeful, I’d say.

[Wendy] Ivins recalls a discussion she had one night with a neighbor who argued, “There are more important issues to deal with, like the economy.”

Ivins’ husband, Gary, stepped in. “I’m not an economist,” he said. “I can’t solve the economy. I’m not a military strategist, so I can’t do that. I’m a doctor — and this I do know: Every human being deserves the right to be treated the same as everybody else, and the ability to marry and spend your life with someone is a fundamental right. This is on our ballot right now; it’s important to us right now that we do something about this.”

“The person backed down a bit,” Ivins says. “It’s all about civil rights, injustice. But it’s simpler than that. It’s about individual families—what does it mean personally to you?”

That’s right out of the Minnesotans United for All Families playbook, that is. For more detail (and, yes, the inevitable references to Lake Wobegone), go read the whole thing.◼

New blog on the block

Awesome Bitches Dissertating is a blog by two queer University of Minnesota doctoral students (one of whom is a friend of mine) who have achieved the “All but Dissertation” stage of grad school, and wanted an online venue to vent about academic bureaucracy, the exquisite pain of dissertation writing, and, yes, the appropriate use of the word “bitch.”

Science online, solve for x edition

Ocean Latte Save your Starbucks card, and have a cup of ocean instead. Photo by nicadlr.