Shit happens, except when it doesn’t. And when it doesn’t, we get worried. Over the centuries, constipation has gone by many delicate euphemisms, but the problem itself refuses to budge.

The Egyptian Ebers Papyrus, one of the oldest books in the world, promoted a theory of disease that begins with toxic, undigested food poisoning the body from the gut outward. Doctors no longer believe that, but we’re still worried about constipation. Even though most people who feel constipated never seek a doctor’s opinion on it, it still accounts for 8 million physician visits every year in the United States. The connections between the Ebers Papyrus and the modern health care industry are about culture as much as they are about the gut. Constipation is a social disease. It exists in your head and your heart, as well as in your colon.

To get a sense of what it means for constipation to be cultural, look no further than current estimations of the prevalence of constipation in the public. There are an awful lot of people who feel like they are constipated even though their doctors disagree. The rate of constipation in North America could be anywhere from 2 percent to 27 percent, according to a systematic review of the literature published in 2004. But the studies with the highest estimates tend to collect the data from patients’ self-reports, said Dr. Peter Higgins, associate professor of internal medicine at the University of Michigan and an author of that review paper. “If you look at physician discharge billing codes, it’s more like 1.2 percent to 4 percent,” he told me.

It’s the first day of this week’s series on gut science. We’ve also made a video about what poop can tell us about our health, and there’s more to come later in the week.

Unlike constipation, poop is purely biological. What you eat reaches your colon in a couple of hours but can take up to a week to make it out the other end. In the meantime, your colon is absorbing liquid, sucking up whatever nutrients it can as it uses muscle contractions to push along the stuff it can’t use.

That stuff is made up almost entirely of water — 75 percent. Of the rest, most is bacteria, dead and alive, plus indigestible fiber and other parts of food your body couldn’t break down during digestion. You will poop whether you eat or not, Higgins told me. “People are surprised by that. Your stomach secretes fluid every day, your pancreas secretes a large amount of fluid every day, your small bowel secretes fluid; you secrete in the neighborhood of 10 liters of fluid into your gut and then reabsorb most of that in the process of dissolving, emulsifying, grinding and reabsorbing nutrients,” he said.

AVG. POOPS PER WEEK DEMOGRAPHIC WOMEN MEN White 7.2 9.3 Hispanic 7.5 8.6 Black 5.6 6.9 How often Americans poop White and Hispanic samples from Texas in 1995, black sample from North Carolina in 1987 Source: Digestive diseases and Sciences

Given that the secretion is happening constantly and you are (hopefully) eating every day, your rate of pooping should be reasonably regular. Studies suggest that almost everybody poops at least a couple of times a week (though what’s “normal” varies quite a bit from person to person). Because normal is a spectrum, though, it’s difficult to define precisely where normal pooping ends and constipation begins.

Doctors use diagnostic criteria for constipation, where patients have to experience two or more of six symptoms:

Straining during at least 25 percent of defecations Lumpy or hard stools in at least 25 percent of defecations Sensation of incomplete evacuation in at least 25 percent of defecations Sense of obstruction in at least 25 percent of defecations Manual maneuvers needed to facilitate at least 25 percent of defecations Fewer than three defecations per week

But you can see how even that detailed guide is pretty imprecise. Have you ever paid enough attention to your poops to know what is happening 25 percent of the time versus, say, 15 percent? That’s why, when patients come in and tell Higgins that they are constipated, his first question is, “What do you mean by that?”

FREQUENCY OF POOPING SHARE Every 2 days or less 7.5% Once a day 54.9 1-2 times per day 34.2 >2 times per day 3.4 How often Dutch men poop Source: American Journal of Epidemiology, 2010

That imprecision matters because it gets in the way of our understanding something pretty basic: How has constipation changed over time? If even the highly quantified world of modern medicine isn’t super clear on this point, it’s safe to say that our knowledge of the constipation of the Ancients is even worse.

But here is something we do know: Since at least the Renaissance, Western cultures have fretted about their own bowels while looking back to an imagined past where mankind pooped in peace and harmony. According to James Whorton, professor emeritus of medical history and ethics at the University of Washington School of Medicine, modern life has long been considered the ultimate cause of constipation. Take, for instance, a bit of doggerel poetry from mid-1600s England:

And for to make us emulate,

The good old Father doth relate

The vigour of our Ancestors,

Whose shiting far exceeded ours.

Whorton documented that poem in “Inner Hygiene,” his book on the history of constipation in Western popular culture. More than just nostalgia, though, the belief that modern lifestyles caused constipation was viewed as a medical emergency, on the scale of what we think of the obesity epidemic today, Whorton told me.

That’s because constipation was, itself, a theory of disease. The ideas documented in the Ebers Papyrus, which dates to the 16th century B.C., persisted all the way through the 1930s, in the guise of “autointoxication” — accidental self-poisoning that begins in the bowels. Constipation, then, could literally cause any disease, from cancer to schizophrenia. And this emphasis on constipation as the cause of all disease got stronger in the late 19th century, after scientists began to understand the germ theory of disease, Whorton said. Suddenly, there was a scientific explanation for what everybody already thought to be true. Bacteria lived in your poop. Bacteria caused disease. Clearly, the longer your poop sat in your body, the more at risk you were of getting sick.

FREQUENCY OF POOPING SHARE <2 times per week 1.0% 3-4 times per week 8.0 5-7 times per week 76.8 >1 to <3 times per day 11.8 3 times per day 1.8 >3 times per day 0.8 How often Londoners poop Source: British Medical Journal, 1965

You can see this fear at play in the over-the-counter medications sold during the 19th and early 20th centuries. There isn’t an organized database of patent medicines. Even if there were, it would be difficult to cleanly categorize what each medication was “for” because they were frequently sold with multiple cure-all claims. But “a majority were laxatives of one kind or another,” said Edward Shorter, professor of history of medicine and psychiatry at the University of Toronto. Advertisements for these medicines called constipation “the monarch of all diseases,” claimed it was the “shortest road to old age, wrinkles and decay” and promised that “a clean colon is more important than a clean face.” A major feature of this time period was the idea that laxatives should be taken preventatively, not just as a treatment for existing constipation. After all, if constipation caused disease, you’d be better off if you never had it. People were encouraged to give their children daily doses of laxatives, such as castor oil. (A fun bit of history to ask your grandparents about at the next family holiday party!)

Eventually, Shorter said, the medical field lost interest in constipation as a source of disease and became more concerned about issues such as inflammation. But constipation, and the fears that surrounded it, are still important because of how they presaged pervasive popular ideas about health. Take, for instance, current beliefs about the dangers of modernity and the supposed inherently healthier lives of people who lived in the past or who live today under “more primitive” conditions. That idea existed long before the first human entered a CrossFit gym.

FREQUENCY OF POOPING SHARE <2 times per week 8.3% 3-5 times per week 40.8 1 time per day 41.7 2-3 times per day 8.1 >4 times per day 1.1 How often Korean college students poop Source: International Journal of Nursing Studies, 2005

One of the people who bought into that hypothesis was Denis Burkitt, an Irishman who worked as a surgeon and Christian missionary in Uganda in the 1950s and ’60s and who is kind of the patron saint of bran muffins as health food. Burkitt became convinced that the people he treated in Uganda were much healthier than those in the United States and Europe and that the cause of their health was dietary fiber (and the healthy poops said fiber facilitated). Diseases of modernity, from varicose veins to cancer, could be attributed to a lack of fiber, Burkitt believed. And he promoted diets that were more fibrous and more “ancestral” as a cure-all. Far from being written off as a quack, Burkitt was a respected scholar who has a lymphoma named after him. He’s the primary reason doctors began recommending bran-heavy, high-fiber diets in the 1970s — and still do, even though, today, there’s little evidence that either bran or fiber has an impact on health. (Although they will, probably, make you less constipated.)

And patients are still concerned about the state of their poops, even if doctors are less so, Higgins told me. Look at the advertising for probiotics, he said. “They use code words like ‘good health’ or ‘good gut.’ They make these vague cultural references about regularity. They’re doing a dog whistle for the kind of 19th-century view of how your bowel should function.”

On the plus side, though, Higgins said that modern, over-the-counter laxatives aren’t really dangerous. You’d have to work very hard to hurt yourself with something like milk of magnesia or Activia yogurt. So there isn’t much of a downside to that disconnect between the frequency of constipation that patients report and the frequency reported by doctors. “You probably have perceptions of what’s normal that you’ve inherited from your parents or grandparents — perceptions that aren’t medical,” he said. “But if you’re happier with daily bowel movements instead of every other day, well, great. That’s fine.”