Friday, December 11, 2009

Can we be too clean?

As reported in the 3 December issue of Nature, a group of British researchers have shown that baby pigs raised outside in the dirt have healthier immune systems that baby pigs raised indoors.

I mentioned this to my spouse and she just smirked and said, "I could have told you that fifty years ago."

In fact, she did tell me that fifty years ago. She always said, "Let the kids get dirty, it will boost their immune systems."

At the time, I wrote off what she said as an excuse for the fact that she always felt she had something more important to do than be a fastidious housekeeper.

"Get 'em out of the playpen," she said, "let 'em crawl around on the floor." "But the floor's dirty," I said, "they'll lap up germs." "All the better for their immune system," she said.

As it turned out, our kids were never sickly, and maybe the baby pigs explain why.

Some years ago, the Binney & Smith Company introduced Magic Scent Crayolas, with aromas such as chocolate, licorice, cherry and blueberry. Parents complained that the foody scents might entice the kids to eat their crayons. So the crayon-makers changed to nonfood scents, such as dirt, smoke, leather and lumber, forgetting, apparently, that dirt is one of the things kids are most likely to put in their mouths. In announcing the change, a spokesperson for Crayola got one thing right. "Kids love dirt," she said.

Kids love dirt, indeed. Against the wishes of fastidious parents and the conventions of modern civilization, kids love getting dirty. Non-dirt floors are a rather recent development in human history -- not to mention playpens -- and all those millions of years that our soapless ancestors sat in the dirt eating unwashed food with unwashed hands may have left their mark on the immune system we are born with. It is probably worth noting that "human" and "humus" come from the same ancient Indo-European root, dhghem, meaning "earth."

Cleanliness may be next to godliness, but too much cleanliness may not be best for kids and pigs.