The other day, I read a fascinating piece on the relationship between politics, culture, and disease (thanks to the astonishingly smart Amanda Pustilnik for pointing me at it in the first place.) The basic idea was this: could cultural behaviors like xenophobia, washing practices, and a focus on physical attractiveness be tied to risks of disease?

Our moment-to-moment psychological reactions to the threat of illness, they suggest, have a huge cumulative effect on culture. Not only that—and here’s where Thornhill’s theory really starts to fire the imagination—these deep interactions between local pathogens and human social evolution may explain many of the basic differences we observe between cultures.

How does your culture behave toward strangers? What kind of government do you live under? Who are your sexual partners? What values do you share? All of these questions may mask a more fundamental one: What germs are you warding off?

The hypothesis (for which there seems to be decent evidence) is that in warm, pathogen-ridden climates, humans need to be wary of outsiders with new diseases and need to inbreed to enhance immunities (such as the way Tay-Sachs, common in Ashkenazi Jewish populations, may confer immunity to Tuberculosis); also that physical appearance gives clues about whether a prospective mate is immunocompromised.

On the surface, this leads me to a few conclusions:

• Plastic surgery is bad for our collective health, because it masks poor immunoefficiency.
• To fix banana republic dictators and tribal wars we first need to improve health conditions
• Can the conservatism of “red states” in the US be explained by climate? (something they cite this in the study.)

It seems like a useful line of thinking, particularly as the twin horsemen of climate change (which increases weather-related disasters and the spread of some diseases) and antibiotic-resistant pathogens come riding rough-shod across modern society.

Correlation is not causality

Many of my friends were quick to question the integrity of such a study, or at least to encourage healthy skepticism. My interest in this is certainly biased; I think we are subject to more biological forces than we realize.

At Blitzweekend Montreal in late 2008, I gave a talk on viral marketing. In researching the talk, I looked at organisms which effectively control their host—from fungi to parasites to other diseases.

Perhaps the most commonly cited of these is toxoplasma gondii, a parasitic protozoan that can significantly alter the behavior of its host. In humans, it makes males more aggressive and females more sexually promiscuous.

Consistent and significant differences in Cattell’s personality factors were found … men were more likely to disregard rules and were more expedient, suspicious, jealous, and dogmatic … infected women, by contrast … were more warm hearted, outgoing, conscientious, persistent, and moralistic.

In some countries the majority of the population—up to 80 percent—is infected with Toxoplasmosis. Consider what something like this means to geopolitics, or tribal warfare. Also, thanks, cats.

And yet we humans are convinced we’re sentient and autonomous, and often try to rationalize away many things that can be explained by natural selection or biological processes.

Stand back; I’m going to try science

As we try to understand the jungle-surplus wetware on which our brains run, it’s easy to get distracted by the latest fad. This is why I love science: everything is a fad, an idea, a hypothesis. It needs to be tested, refuted.

One of my favorite recent examples is the theory of the rise and fall of urban crime.

• In 1982, New York mayor Rudi Giuliani credited his “zero tolerance” policy for the drop in crime.
• Then in 1999, the Freakonomics guys said the Roe v. Wade was responsible for the drop.
• And in 2013, it looks like it was lead poisoning from leaded gasoline (with much better correlation, and a causal clinical explanation, and evidence that violent criminals have elevated levels of lead in their bodies.)

Clearly, we’re still trying to explain things, getting closer and closer to the truth. We’re distracted by confirmation bias, but eventually, we home in on better and better models to explain our world.

The moral mind

Last year, the book I cited the most was Jonathan Haidt, whose “five dimensions of the moral mind” TED talk is one of the most fascinating pieces of research I’ve ever seen.

Over several years, Haidt and his team conducted an investigation into the fundamental dimension of moral reasoning, concluding that humans have several “primitive” moral dimensions including fairness, freedom from harm, respect for authority, tribal affinity, and purity.

Think of these as sliders on an equalizer. We all—sociopaths aside—have them, but they’re adjusted differently for each of us. If tribal affinity trumps freedom from harm, you start waterboarding terrorists; if fairness trumps respect for authority, you get soft jail terms. And so on.

These dimensions don’t fall along political lines (although their settings do.) Haidt’s “purity” dimension, for example, includes conservative religious messages like “don’t have sex before marriage” and “don’t eat pork” but also liberal-leaning “avoid GMO foods” and “clear your mind through Zen meditation.”

Haidt found that these dimensions varied by region. In The Righteous Mind, he points out that while the purity dimension didn’t seem important to him as a Westerner, a trip to India showed him that cleanliness is sacred in part because of the life-threatening consequences of not being clean. Now Thornhill’s research suggests that regional biological pressures shape culture.

Putting the pieces together

I’d love to see a comparison of Thornhill and Haidt’s research. Perhaps the geopolitical landscape is simply the biological landscape, seen through the lens of human culture.

Now that would have a serious impact on world peace and the funding of healthcare.