K has been on a big kick reading books about sending students outside.  Obviously, I approve.  Being outdoors seems to make most humans happier, and people who spend time outside seem more likely to care about preserving our environment.  Plus, K even has scholastic reasons to ask students to sit contemplatively outside — it’s reasonable for students in a college-level biology course to practice fieldwork.

I try to get N outside a lot, too, but with her it’s probably not reasonable to use “learning to do fieldwork” as an excuse.  She’s a bit young to practice the extreme patience needed for successful fieldwork, so I thought it might be worthwhile summarizing a few of the recent studies on exposure to the world, allergies, and autoimmune disorders.

I should declare my conflict of interest upfront, though.  I’m extremely biased because I want you, dear reader, and your friends, and your family, to spend more time outside.  Unless you’re, I don’t know, living in a tent, roasting carrots & beats & whatnot over a firepit every evening… then you’re probably outside plenty.  It’s the rest of us, those who lead more normative modern lives, sleeping in air-conditioned homes, zipping about town inside our cars, hoofing it down concrete sidewalks, spending long hours pecking at our computers, who could use a bit more outdoor time.  I’ll try my best to keep this short so that you can rush outside and play, but if you feel antsy & want to go out now, go ahead!  I won’t begrudge your priorities!

The basic idea behind all of this was proposed by David Strachan in the article “Hay Fever, Hygiene, and Household Size.”  He observed that younger siblings were less likely to get asthma and proposed that the messy, disease-prone lifestyle of multi-child families was protecting those younger children.  As in, getting sick more often as a child, and having an absentminded older sister who tracks mud through the house, might lead to better health as an adult.

Which is a lovely theory.  At birth, our immune systems are relatively ignorant.  They instinctively know that they should destroy things — we are the product of untold millennia of selection for those who can survive routine infections — but they don’t know what they should destroy.  Exposure to pathogens trains our immune systems to recognize & attack those pathogens.  Repeated exposure to innocuous substances trains us to ignore those ever-present harmless components of our environment.

The modern world is very clean, though.  We wash our hands.  We eat less dirt.  We’re less likely to even walk barefoot through the dirt.  Most people in the United States don’t pull their drinking water from a river that another tribe upstream defecates into.  And that’s good.  We get sick less.  Children are more likely to survive to adulthood.  But it also means that many people’s immune systems encounter fewer pathogens than they “expect.”

If you’re in the market for a really evil social psychology experiment, I’ve got one for you: find a small child & every day explain to that child that he should expect to get into at least one fight per week at school.  Tell him, “There are so many bullies out there!  You’ll have to be ready for them!  Don’t let them catch you off guard.  One fight a week!  Maybe two!  It’s a jungle and they prey on the weak!”

Once that kid starts kindergarten, even if it’s in a total fluff district where his classmates are all sunshine and rainbows, he’s probably going to get into fights.  Because he’ll assume those fights are supposed to happen, so he’ll blow tiny slights way out of proportion… you used the blue crayon too long!  Pow!

The hygiene hypothesis purports that our immune systems are the same.  They expect fights, and so if we put them into too-clean environs, they become the bullies they’ve been warned about (bonus points if you’re thinking about the shipwrecked sailer from The Watchmen now).  Immune systems can rage against innocuous compounds — those are allergies.  Or, worse, they get so incredibly bored, they’re expecting fights and everyone is so incredibly nice, that they begin to attack their own hosts.  As in, our own bodies.

Fighting off foreign infections helps the immune system learn to distinguish self from other, but if there are too few outsiders, the immune system just starts wailing on a mirror.  Wondering why the kid on the other side can’t ever be knocked down.

Autoimmune disorders are the pits.

And for years it seemed like there was nothing to do, once you contracted an allergy, except avoid the thing that triggers your itching and snurfling.  Or, worse, triggers your anaphylactic shock, dizziness, maybe death from loss of breathing.

But there might be hope!

Recently, researchers have been testing whether you can retrain an immune system to ignore innocuous compounds.  For instance, peanuts: by eating a small amount of peanuts every day you might be able to train your immune system to just leave them be instead of going berserk trying to pick a fight.  Because it’s the immune system’s fit of rage that kills people, not the peanuts themselves.  If peanuts are always around, that familiarity might breed lassitude.

(NOTE: there are a lot of references for this, and theoretically the idea is sound.  But let’s say you or someone you know has a peanut allergy — please DO NOT try to cure yourself this way without contacting a medical professional & undertaking the project in a hospital setting.  If you want to look up more papers on this, go to PubMed and search for “oral immunotherapy,” but please note that very low doses of the allergens are used, and even with those very low doses some people can go into shock.)

Another strategy that seems to be working well is to introduce punching bags into classrooms… that way the battle-ready children have something to smack without disrupting anybody’s education.

Err, wait.  I mean, intentionally introducing parasites into the human body so that the immune system has something to attack & is less likely to inflame the bowels, joints, liver, etc.  Apparently the symptoms of several autoimmune diseases can be ameliorated by parasites; here is one recent reference but there are many others.

Of course, harboring parasites is often not fun.  But as long as the parasites make you less ill than your own body’s attacks against itself did, why not?  Because autoimmune disorders are horrible — attempting to treat them with parasites is way more reasonable than using tapeworms to lose weight.

And, as a new parent, I also spend time thinking about prevention.  I slather my pale baby with sunscreen before we play outside.  And I make her play outside — major lifestyle changes over the last few decades probably explain our current allergy epidemic, with the incidence of peanut allergies & celiac disease up to 1% or higher.  Huge numbers of people who’ll suffer from these ailments for their whole lives.

The most striking data on allergy prevention suggests that you should raise children on a farm.  For a lot of people, that’s not really feasible.  Even if K & I had the space, we wouldn’t raise animals — given that we can live well without subjugating any critters, I don’t think it’s the right thing to do.  But we can still take N to visit the pigs at our local farmed-animal sanctuary, and hopefully that’ll help a little.

Plus, we play outside.  Yes, the epidemiological data suggests that being outside on a farm helps most, but you can do pretty well just by getting out, running around, and playing in the dirt.

(Although even playing in the dirt is tricky.  It has to be clean dirt.  Bacteria are fine.  Some other soil parasites — a kid might get sick, but it’ll often be temporary sickness.  The whole thing about an immune system needing work to do means that nothing comes free.  But, ingesting petroleates would be bad.  Or heavy metals.  Halogenated aromatics.  And — yay pretend capitalism where businesses are allowed to impose negative externalities for free! — a lot of that dreck has been dumped for years.  Here in Bloomington we have a big tire factory & dirt on the properties downhill from it are poisoned.  Unless you have access to a good mass spec, your best bet for learning whether land is safe for a kid to grubble around on is to read up on its history.  Which is crummy to have to do, but the peculiar incarnation of capitalism indoctrinated by the U.S. has resulted in many horrors that still reverberate.)