Archive for October 2018

Bones in the Paris catacombs

Man-made calcium deposits

Paris is a shockingly large city. There are many fine vantage points from which to view the panorama, including the Montparnasse Tower, Sacré Coeur, the Eiffel Tower, or the bell towers of Notre Dame. I’m sure everyone who looks out over the vast expanse of Paris has a different impression; mine has been, overwhelmingly, “Gosh, that’s a lot of limestone.” With very few exceptions, the buildings of Paris are uniformly beige, limestone being the preferred building material—and not just for the buildings either, but for bridges, sidewalks, and monuments. As far as the eye can see in every direction, the earth is covered with stone. A splash of green, like a park, or gray, like the Seine, seems strangely out of place. All that stone had to come from somewhere, but it never occurs to most people to wonder where that might have been. Most of it was quarried locally, and what’s particularly interesting about this is that the empty spaces left when the limestone was removed—mind-bogglingly huge volumes of space—are largely still vacant, hidden beneath the city streets.

The Other French Empire

On visits to Paris and during the years I lived there, I spent a good bit of time underground. I took countless trips on the Paris Métro, of course, and I’ve spent several enjoyable afternoons exploring the public portion of the vast Paris sewer system, not to mention visiting the archeological crypts near Notre Dame. But these are merely the tip of the iceberg. Underneath Paris the real action—so to speak—is in the hundreds of kilometers of abandoned limestone quarries, part of which have been turned into a depository for the bones of millions of former citizens. As with all the underground attractions in Paris, only a portion of the catacombs is officially open to the public; this visitor-friendly section is known as the Denfert-Rochereau Ossuary, or simply the Catacombs.

Unlike the many lavish museums, cathedrals, and tombs in Paris, the entrance to the catacombs is a simple black door in a small building that you could easily miss if you blinked while walking by it. On our first visit, it took some time to find it because we were expecting something much more prominent. After we paid our entrance fee, we passed a sign reminding visitors that flash photography is strictly forbidden, then descended a long spiral staircase and entered a small gallery of photographs and drawings. Leaving the gallery, we began walking through long, dark, damp tunnels whose only significant features were signs at intervals stating when they had been built. Tourists zipped past us, talking loudly and snapping flash photos. I began to feel like the day would have been better spent sitting in a café drinking coffee and eating croissants. But then we passed through a larger chamber with a sign over the entrance to a dark hallway that said: “Arrête! C’est ici l’empire de la mort.” (“Stop! This is the empire of death.”).

Dem Bones, Dem Bones, Dem Dry Bones

Beyond that sign was another world—and one of the creepiest things I’ve ever seen. What at first appeared to be walls built of small stones were in fact huge, orderly piles of human bones. Tibias and femurs by the thousands were stacked neatly, interspersed with rows of skulls, which were sometimes arranged quite artistically in a cross or other pattern. There were no intact skeletons; the goal of the arrangement had clearly been maximum compactness. I could only assume that the ribs, spines, and other bones filled in the spaces behind the walls of large leg bones. Most of the stacks of bones rose to a height of about 5 ft. (1.5m), and while some were just a couple of yards deep, there was at least one area where the bones stretched back for a good 20 yards (18m), as you could see from the narrow gap left on top. The tunnels of bones stretched on and on; many side passages were blocked with locked gates, but even the path designated for tourists was about a mile (1.5km) long.

The bones began accumulating in the catacombs in 1786, just as momentum for the Revolution was building in Paris. Real estate was scarce while the cemeteries were becoming severely overcrowded. The government decided to reclaim the large swaths of land used for cemeteries by relocating the remains of the departed citizens to the empty limestone quarries, whose tunnels were at that time on the outskirts of town. The process of disinterring the bones from the cemeteries, moving them solemnly into the quarries, and arranging them there took several decades. No attempt was made to identify or separate individual bodies, but each set of bones was marked with a plaque signifying the cemetery they came from and the year in which they were moved. By the time the relocation was finished in 1860, an estimated five to six million skeletons had been moved to the catacombs.

The Outer Limits of the Twilight Zone

Even so, the bones filled only a tiny percentage of the empty quarries. As far as I know, none of the modern maps of the catacombs are exhaustive, but explorers have estimated that there are at least 185 miles (300km) of tunnels in the entire network of catacombs—that’s in addition to the 1,300 miles (2,100km) of sewer tunnels and 124 miles (199km) of subway tracks in the Métro system, though the three systems crisscross and interconnect at various points. Among a certain Paris subculture, exploring these forgotten tunnels is considered a sport. Despite the best efforts of maintenance workers to seal off illicit entrances and police patrols that slap heavy fines on trespassers, the maze of tunnels is so extensive that it is simply not possible to keep ahead of the so-called cataphiles.

The catacombs are eerie—quiet (except for the sounds of water dripping from the ceiling and tourists chatting), dark (except for the dim floodlights and camera flashes), and in many ways, downright depressing. It’s hard not to notice that the bones of these millions of people are all pretty much the same. The skull of a revolutionary may be resting on the leg of an aristocrat; noble and corrupt, young and old, wealthy and poor, all are indistinguishable now. It can give you an entirely new perspective on the concept of human equality. It also, needless to say, gives visitors a very keen sense of their own mortality. It made me wonder fleetingly whether, centuries from now, someone might walk by my bones among millions of others and think, “Gosh, that’s a lot of calcium.”

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on June 11, 2003, and again in a slightly revised form on June 5, 2004.


Source: Interesting Thing of the Day

Six degrees of separation diagram

Is it a small world after all?

At family reunions, my mother used to joke about the fact that actress Shirley Jones (of “The Partridge Family” fame) never showed up. Apparently someone had figured out that Jones was a distant relation by marriage, and more than once I heard of plans by one of my cousins to invite her to a reunion just for fun. Whether an invitation was ever actually sent I don’t know, nor can I recall the exact chain of relatives that supposedly connected me to Jones. But I always enjoyed the thought of being related, however distantly, to a celebrity. I imagined showing up at a dinner or award ceremony where I’d be introduced to the rich and famous: “This is Joe Kissell, my third cousin-in-law, once removed.” I didn’t suspect it at the time, but if a prominent sociological theory is correct, I may have indirect social connections to millions or even billions of people.

The theory in question, of course, is that of “Six Degrees of Separation”—roughly, the notion that anyone can form a chain of personal contacts leading to any other person, with no more than six links in the chain. Nearly everyone has heard of this idea, thanks to John Guare’s 1990 play “Six Degrees of Separation” and the “Six Degrees of Kevin Bacon” game that became popular in the late 1990s. But what many people don’t realize is that this game has its roots in serious sociological research, and that work is currently underway to establish the validity of the theory scientifically.

Network (of) Associates

The late Stanley Milgram, a Harvard social psychologist, performed an experiment in 1967 to determine the extent of social networks in the United States. In his study, it took an average of six steps for a letter sent to a random resident of Omaha, Nebraska to reach a target person in Boston—using only personal contacts to form a chain. This was the origin of the “six degrees of separation” idea, but Milgram’s small experiment was hardly conclusive, restricted as it was to a very small sample size (and with all participants within the United States).

Nearly four decades later, as part of the Small World Research Project at Columbia University, sociologists attempted a modern version of the experiment using email. The project worked like this. You registered on Columbia’s website, providing demographic information about yourself and answering a range of questions to help the researchers make sense of their results. You were then presented with the name and location of a target person somewhere in the world. The idea was to send a specially formatted email message to someone you know who you think is closer to the target (in one way or another) than you were. When this next person in the chain received your message, the process repeated until, the researchers hoped, a chain formed all the way from you to the target person. Among other things, the experiment hoped to determine what the average length of such a chain is, providing some statistical validation or refutation of the “six degrees” notion.

Connect Four

The experiment ended after a couple of years, producing some very interesting results (only some of which were ever published). In all, more than 60,000 people from 166 countries participated in the experiment’s first round. Although over 24,000 chains were started, only 384 of them successfully reached their targets. Most of the unsuccessful chains were broken simply because someone along the way chose not to participate. The high number of incomplete chains skews the otherwise impressive results: the successful chains required an average of only four links. However, when they factored in how long the broken chains most likely would have been, had they been completed, the researchers estimated that people are separated by five to seven degrees—with shorter chains expected between people living in the same country. In other words, there’s apparently nothing magical about the number six, but it does happen to be pretty close to the average number of social links most people have to most other people, at least among the 4.2 billion or so of us with internet access.

One of the main goals of this project was to determine which factors people consider in trying to form associative links. Every time participants selected a new message recipient, a form asked why they chose that person—for example, due to geographic proximity or a shared profession or hobby—as well as what their relationship to the person is (friend, coworker, relative, etc.). The experiment found that participants considered geographic proximity and similarity of occupation to be primary factors in choosing how to continue a chain. And although people most frequently chose friends as the next link, professional relationships were much more likely to lead to a successful chain. I participated in a couple of chains in the experiment’s first round, and although I consider myself relatively well-connected, neither of my chains successfully found its target. But the question is not whether there is a link between any two people; it’s how you go about finding it. Email may or may not be the best discovery method, though it certainly does have a kind of efficiency that casual conversation or letter writing do not.

Supposing it turns out that everyone on the planet is indeed connected to everyone else by no more than six steps, so what? Sooner or later, given the sheer number of people on Earth and the ways in which people form networks, the six-degrees-of-separation theory must become nearly certain mathematically. But does that actually mean anything? Will it lead to world peace, or will it just facilitate the spread of viruses—biological or digital? I don’t know, but I’m sure it will lead to something. I mean, Weird Al Yankovic knows a guy who knows a guy who knows a guy who knows a guy who knows a guy who knows Kevin Bacon…and I know a guy who knows Weird Al! Meanwhile, Kevin Bacon is only two degrees from Shirley Jones. I’ll be expecting to see them all at the next family reunion.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on May 10, 2003, and again in a slightly revised form on June 21, 2004.

Image credit: By Daniel Walker [GFDL or CC BY-SA 3.0], from Wikimedia Commons


Source: Interesting Thing of the Day