A.J. Jacobs’ Drop Dead Healthy chapter: Germs, germaphobes, and the hygiene hypothesis.

The Germs That Don’t Kill You Will Make You Stronger

The Germs That Don’t Kill You Will Make You Stronger

Health and medicine explained.
April 18 2012 8:15 AM

Germ Porn, Hand-Washing, and the Hygiene Hypothesis

An excerpt from A.J. Jacobs’ new book, Drop Dead Healthy.

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I call up an immunologist named Mary Ruebush, author of Why Dirt is Good, a rallying cry for the Hygiene Hypothesis.

“The pendulum has swung,” she tells me. “The first few millennia of human evolution, there was no thought of cleanliness. Then when we realized there’s a link between cleanliness and disease, we went overboard.”

Like Tierno, she claims superior health. “I don’t remember having a cold or a headache, and I have absolutely no standards of hygiene whatsoever.” I suppress my instinct to say that I’m glad this is a phone interview.


 “My standard for hand-washing is this: If they look dirty or smell bad, then I wash them,” she says.

I tell her about how my son licked ice cream off the sidewalk. “Good for him,” she says. “He is going to be a healthy adult.”

When I get off the phone, I tell my wife about Ruebesh’s thesis. “That’s a wise woman,” she says.

Later that night, when she drops a cucumber slice on the floor, she bends down to pick it up and put it on Zane’s plate. “Hygiene Hypothesis!” she says gleefully. It’s her new catchphrase.


I decide to spend a week implementing Tierno’s Germ Battle Plan on myself. I promise my wife I’ll leave her and the kids out of it.

In his book The Secret Life of Germs, Tierno gives a list of antiseptic-living suggestions. On a Wednesday morning, I begin to implement them.

Wipe down the phones and remote controls weekly.

Does wiping them with moist paper towel really get the germs off? I wish I could boil my electronic equipment.

Soak all produce for five to 10 minutes in a solution of water, hydrogen peroxide, and vinegar.

“Hydrogen peroxide?” asks our babysitter, as I pour some into a bowl of apples. “Is that safe? I thought that’s what you use to dye hair.” It’s in the book, I tell her.

Wash underwear separately from other clothes to prevent a transfer of fecal residue.

Dry laundry in the sun, because the UV radiation kills germs.

A clothesline doesn’t work in New York, so I lay my shirts on the outside part of the air conditioner.

Remove showerheads and clean them with a wire brush to root out legionella, the cause of Legionnaire’s disease.

Put hypoallergenic sheets and pillowcases on your bed to keep the dust mites from snacking on your dead skin flakes, because dust mites can cause allergies.

The ones I bought are kind of slippery, but they make me feel better. Tierno himself takes his germ-proof sheets with him when he goes to a hotel. I put that on my list.

It’s been half a day, and I’m not even close to getting through my list. Though I do notice something strange. Aside from being busy, I have another feeling: righteousness.

Maybe it’s my imagination, but now I crave more order in every part of my life. I’m more annoyed when my wife is late to dinner. I’m more concerned when my son hangs around with the rambunctious elements in his class.

Does my punctiliousness have anything to do with my germ obsession? Perhaps not. But the brain is an odd place, and it’s possible that germaphobia has colored my moral view. I read a fascinating study arguing that the more obsessed you are with germs, the more politically conservative you become.

In the experiment, subjects were asked about their “moral, social, and fiscal” attitudes. “Merely standing near a hand-sanitizing dispenser led people to report more conservative political beliefs,” one of the scientists wrote. “Apparently, the slightest signal that germs might be present is enough to shift political attitudes toward the right.”

The professors speculate that that early humans often came into contact with other tribes that harbored dangerous germs. So humans evolved to have a feeling of disgust at The Other, which helped keep interactions to a minimum.

When I told one of my conservative friends this theory, he said it sounded absurd. But, he added, at least it gave him license to call liberals dirty.


From Drop Dead Healthy by A.J. Jacobs. Copyright © 2012 by A.J. Jacobs. Reprinted by permission of Simon & Schuster, Inc.