The Dirt on Dirt

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Updated on June 17, 2014

The prevailing opinion at MDA is that listening to one’s body is good policy. Natural instinct has been kind to us over the years – just as long as we listen to it. Oh, sure, some instinctual behaviors have little relevance nowadays and should be ignored (like our tendency to tribalize and shun newcomers for protection – made sense when we were living off the land in small inclusive clans competing for resources, but today it just causes war, racism, and nationalism), but most instincts are hard-wired into us for a reason. Consider salivation, which tells us delicious, wholesome food is to be had (I know I’m not the only one with an utterly Primal tendency to drool at the prospect of a rare steak), or our sense of fairness, which makes for a more harmonious environment (good for survival and for everyone involved). We like to stress the importance of listening to your body’s natural inclinations.

By definition, pretty much any instinctual behavior confers evolutionary advantages (otherwise it wouldn’t have been kept around for so long) – this is the basis of the Primal Blueprint, with our focus on living in accordance with our Primal ancestors (whose actions, behaviors, and diets were highly instinct-driven).

A series of recent studies examined a young child’s tendency to eat dirt, lick stuff on the ground, and put whatever he can find in his mouth. Is there some evolutionary benefit to be conferred from eating dirt? We have a rather unhealthy (or is it?) obsession with dirt, so we were interested to read the results.

Dirt vindicated, once again! Mud pies, it seems, aren’t just a tasty way for a fledgling baker to get his start in life. The ingestion of dirt introduces a number of bacteria and viruses that actually spur the development of our immune systems. And certain worms have been shown to redirect messed up immune systems that would normally result in autoimmune disorders, asthma, and allergies.

When he puts random things in his mouth, a child is letting his “immune system… explore his environment,” writes immunologist Mary Ruebush. That kid with a dirty mouth isn’t increasing his chances of getting sick; he’s actually giving his immune system “practice” figuring out what’s benign and what’s dangerous.

As we’ve discussed before, over-sterilization of our environments can actually be counterproductive. Scientists suspect that even as the increasing sanitization of developed countries has eliminated some health concerns – contaminated food and drinking water, for example – it has also introduced a whole host of other issues, including rising levels of multiple sclerosis, Type 1 diabetes, inflammatory bowel disease, asthma, and allergies – all potentially stemming from a reduced, or eliminated, exposure to bacteria early on. We’ve gotten “cleaner,” but in doing so we’ve eliminated both good and bad dirt. We’ve also strengthened the bad stuff. All those antibacterial products – Purell and the ubiquitous variants you see in purses, attached to kids’ wrists, in “fun size” – might actually be creating antibiotic-resistant strains of dangerous bacteria. Remember, evolution works both ways (and much more rapidly in bacteria).

That’s not to say we shouldn’t wash up. We should, especially if we’ve been touching dirty diapers, handling raw meat, or using the toilet. Just don’t go overboard with it. Basic soap and water are good enough.

And of course, it goes without saying that kids should have access to plenty of dirt growing up – if not for their immune systems, then for the fact that playing in the dirt is an awesome part of childhood that no kid should be without. It’s in line with the Primal spirit of play, too.

Oh, and you might want to ease up on the strict “wash your hands before dinner” rules – we might be doing more harm than good.