Men Eat Dirt Too

Women make cookies of dirt, salt, and vegetable shortening in Port-au-Prince, Haiti (file picture).

Photograph by Ariana Cubillos, AP

Christine Dell'Amore

for National Geographic News

Published October 19, 2012

Turns out pregnant women aren't the only ones who eat dirt. A new study reveals a surprising incidence of pica—craving and consuming nonfood substances—among men.

Conducted in Madagascar, where pica is common, the research is the first to identify a population where the practice is highly prevalent among men, the scientists say. In fact, the men in the study ate nonfood items at least as much as pregnant women and adolescents, whom previous case studies had shown to be the main pica practitioners.

(See "Stop Food Cravings Through Imaginary Eating?")

So why this sudden appearance of pica-practicing men?2012-10-19

"My guess, which is not substantiated, is that prior research study designs may have ignored men in their study samples as an artifact of studying pregnant women," said study author Christopher Golden, an eco-epidemiologist and National Geographic Society Conservation Trust grantee. (National Geographic News is part of the Society.)

Pica researcher Laura Beatriz López, nutrition director at the University of Buenos Aires, agreed.

"Traditionally studies of geophagy [eating earth] and pica have focused on describing the prevalence in children and pregnant women," López wrote in an email, which has been translated from Spanish.

"Personally, I think the work is pioneering," she said, because it reveals "such a high prevalence of pica in men and also found no significant differences with women."

Pica for Better Health?

Golden and colleagues—advised by Cornell nutritional anthropologist Sera Young—surveyed pica behaviors in a random sample of 760 people in 16 villages of Madagascar's Makira Protected Area in 2009. (See Madagascar pictures from National Geographic magazine.)

The study subjects—male and female—identified eating 13 nonfood substances, including sand, soil, chicken feces, uncooked rice, raw cassava root, charcoal, salt, and ash, according to the new report, which appeared Wednesday in the journal PLOS ONE.

More than 53 percent of the survey respondents reported engaging in pica. For adult men alone, that number was 63 percent.

Bucking the stereotype, less than one percent of nonpregnant women said they ate any nonfoods only during pregnancy.

Why Eat Dirt, Chalk, or Uncooked Rice?

Many people reported eating nonfoods for their healing powers, especially for stomach troubles, Golden said. And many believed that pica would bring good luck for better overall health. (Explore an interactive of the human body.)

Previously, scientists had suggested people practice pica for two reasons: to fulfill a deficiency of trace minerals in their diet and to cleanse and deworm the intestinal tract.

The nutrition theory would make sense for pregnant women and children, whose dietary needs are greater those of the rest of the population.

Even so, there's no evidence that the human body can actually absorb trace minerals from soil, said Golden, adding that pica "may not serve any health purpose."

The University of Buenos Aires's López added that the cultural norms of Madagascar contribute to the high rate of eating inedible substances. For instance, many Malagasy don't consider eating raw starches, such as uncooked rice, to be a form of pica.

(See video: "Clay Eating Discouraged.")

Eating Inedibles Stigmatized, Underreported

Pica, study co-author Golden emphasized, "is not exclusive to rural populations in developing countries."

For example, many Americans do it, Golden said, and he speaks from experience. "A close college friend of mine," he said, "is a frequent consumer of chalk.

"It is very prevalent, yet stigmatized, and thus underreported."

Added Cleveland Clinic psychologist Susan Albers by email: "Pica is an eating disorder that gets far less attention and research than other eating disorders such as anorexia and bulimia, yet it is important, as it can lead to significant health consequences, due to the possibility of consuming toxic substances.

"We've seen more attention on men and eating disorders over the last few years," Albers said. "This study notes the importance of further research on men and pica and making sure they are adequately represented in the sample."

Study co-author Golden said he isn't quite ready to label pica an eating disorder, since it's not yet clear whether the practice is harmful. But he agreed that more pica research is needed, especially among men.

The new Madagascar study may be a big step in that direction. To Golden, the discovery "opens up this whole field of research, to have fellow researchers acknowledge both men and women in their studies."

Two-Ton "Alien" Horned Dinosaur

Eighty million years ago, Xenoceratops inhabited a frost-free Canada.

Illustration courtesy Julius Csotonyi

Ker Than

for National Geographic News

Published November 9, 2012

A newly identified species of spiky-headed dinosaur that roamed Canada 78 million years ago is the oldest known large, horned reptile ever discovered in North America.

"In terms of large-bodied ones that look like Triceratops, this is definitely the oldest," said biologist Michael Ryan, lead author of the new study describing the dinosaur, published online Thursday by the Canadian Journal of Earth Sciences.

The newfound plant-eater has been named Xenoceratops foremostensis—Latin for "alien horned-face from Foremost," the small Canada town where someXenoceratops fossils were found in 1958.

Like its more famous cousin Triceratops—which lived 15 million years later, during the dinosaurs' last days—Xenoceratops had long spearlike horns thrusting from its brow and a shieldlike frill extending back from its skull. But unlike Triceratops, Xenoceratops also had horns on its frill.

(Read about another Triceratops ancestor found in Canada.)

Like No Other Dinosaur

The new dinosaur is known from fragments of fossilized skull and horn found in Alberta, Canada. Ryan and his team recently found 78-million-year-old bones during a dig, and that led them to search the collection of the Canadian Museum of Nature in Ottawa for other fossils from the same time period.

There, the team found the 1958 fossils, which had long since been filed away. The museum fossils dated to the same period as Ryan's team's bones, and appeared to belong to the same unidentified species of dinosaur.

"In the museum we found ... two large pieces of the frill, including one spike. As soon as I saw them, I recognized it as being different from every other horned dinosaur," said Ryan, who heads the vertebrate paleontology division of theCleveland Museum of Natural History in Ohio.

Measuring approximately 20 feet (6 meters) long and more than 2 tons,Xenoceratops was average-size for a horned dinosaur—African elephant-sizeTriceratops was half again as large. But the new dino would have been among the largest ceratopsids alive 80 million years ago.

Living alongside Xenoceratops would have been predators related toTyrannosaurus rex as well as duck-billed dinosaurs and ankylosaurs—dinosaurs resembling giant armadillos with big club tails.

In the late Cretaceous period, they all would have known a very different Alberta from the current, cool Canadian province, Ryan said. In the then subtropical region, "there were probably wet and dry periods, but there would never have been snow or frost."

Today, the area around Foremost is prairie country, he said, and inhabited by the modern analog of horned dinosaurs: cattle.