I just got done reading an excerpt from a book that sounds completely fascinating. It's all about pica—the overwhelming desire to eat dirt, starch, and other things that aren't food. Apparently, this phenomenon happens all over the world, primarily to pregnant women. In fact, says author Sera Young, in some cultures eating dirt is the go-to pregnancy "gotcha" symptom—the same way that every American knows to suspect a woman who pukes in the morning, or wants pickles with her ice cream.
That's really where a lot of the fascination comes from for me. Why is this tendency so specific to pregnant women? And why does the frequency of pica vary depending on location? Even though people do this all over the world, studies have shown some big differences between populations. For instance, Young writes, .01% of pregnant Danish women eat dirt, but 56% of pregnant Kenyan women do.
There's clearly some interesting overlaps between biology and culture happening here. Do the lower numbers of Danish pica practitioners, compared to Kenyan, reflect differences in genetics? Does this say something about the differences in diets between developed and undeveloped countries? (An interesting train of though, as Young points out that pica was widely known and accepted by American women in the rural South as late as the mid 20th-century.)
Or would more Danish women eat more dirt if it was a culturally accepted practice? Do more Danish women eat dirt, and just not want to admit it?
Young says the book delves into some of the biological and cultural "Why's". I'm looking forward to getting my hands on it and finding out more.
"Every day, twice a day, I take a chunk of earth from this wall and, well, I eat it."
Had I understood Mama Sharifa correctly?
We were sitting on a woven palm mat, in the only shade in her sunbaked yard, on a tiny Zanzibari island called Pemba. There were three of us: Mama Sharifa, Biubwa (my research assistant), and me. Our backs were against the dirt wall of her outdoor kitchen, our legs stretched out in front of us, discussing the things she eats during pregnancy.
With raised eyebrows, I looked to Biubwa to confirm that I had indeed understood her Swahili. Biubwa nodded. "Yes, she is saying she eats earth."
"But why?" I asked.
Mama Sharifa bent at the waist as much as her pregnant belly would allow to idly slap at a fly on her ankle. Then she looked away from us. "I just eat it, that's all." Her pink and orange kanga, a light cotton cloth frequently worn as a head covering, shifted over her shoulder and obscured her face, and I feared she would say no more on the matter.
But after a long pause, her arm reached out from under her kanga. She turned toward us, plucked a chunk of earth from the highest part of the wall she could reach, and displayed it in her open palm. I looked from the chunk of earth in her hand to her face and then back to her hand.
I smiled at her and repeated my question. "But why, Mama?"
She was giggling by then, out of what I've come to recognize as a combination of embarrassment and sheer inability to answer this question. She brushed at some dust on her long skirt, then stared off into the distance again. And then she locked eyes with me.
"I don't know. I really don't know. I just do it."
Columbia University Press: Craving Earth
Ironically, as I wrote this, I was eating an orange peel, pith and rind. That's not pica. But it was close enough to make me feel a little self-conscious.
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.