I've been really bothered by coverage of the supposed meteorite in southeastern Peru and of villagers getting sick. People have been way too quick to leap to mass hysteria as the explanation for the strange events. An article at Space.com today is the latest example:

Initial suspicions of an airplane crash quickly spiraled into widespread reports that a meteorite had plummeted to Earth and left a smoking, boiling crater whose supposedly noxious fumes were reported to have sickened curious locals who went to peer at the hole.

Despite doubts expressed by geologists that the crater was actually caused by a meteorite and firm explanations that a meteorite would not even emit fumes and that the "sickness" was likely a case of mass hysteria....

Some health officials suggest that the symptoms described by the locals, the large number of people reporting symptoms, and the apparently rapid spread have all the hallmarks of a case of mass hysteria.

"Those who say they are affected are the product of a collective psychosis," Jorge Lopez Tejada, health department chief in Puno, the nearest city, told the Los Angeles Times.

This psychosis could have begun as a result of fear of the meteorite and the mysterious "disease" on the part of the residents and spread as official and media reports seemed to confirm it and give it credence.

Whoa, time out. Geologists say that meteorites can't cause people to become sick, therefore the people must be delusional. Isn't that putting the theory before the observation? It's also a little weird that the "large number" of reports is used to cast doubt on them. In most areas of science, a large number increases our confidence. Why can't we just say, There were reports of people reporting a flash in the sky and a big hole in the ground and getting sick, that's weird, so let's investigate. I bet if a meteorite had crashed down in a meeting of planetary scientists and everyone had gotten sick, the commentariat wouldn't put it down to mass hysteria. Somehow, because it's a remote Peruvian village we can distrust the eyewitness accounts.

I must not lead a very interesting life because I've never seen the type of delusion attributed to these villagers. I've certainly seen people get obsessively worried, and I've certainly been obsessively worried myself, but overreaction is not the same as delusion. I remember well the information vacuum of 9/11, when people passed along rumors about waves of attacks on bridges, power lines, and so on. But no one ever claimed to have actually seen those secondary attacks, and the rumors were almost always accompanied by a disclaimer, "I've heard a rumor that...." In my experience, people are level-headed during extreme events. It's the ordinary events, like not getting a parking spot, that upset them.

Historically, cases of mass hysteria are very rare. The classic, the Salem witch trials, involved a perfect storm of social divisions, political uncertainty, religious fundamentalism, and perhaps genuine medical conditions. I have yet to see evidence of any of these in the Desaguadero case. The 1938 Orson Welles "Wars of the Worlds" broadcast doesn't quite live up to its infamy. If you turn on the radio and hear eyewitness accounts of an invasion, organizing patrols of your neighborhood might well be the prudent response. Few people did even that, let alone panic, as sociologist David Miller has argued:

The next day, newspapers across the country carried stories of terrorized people hiding in basements, panic flight from New Jersey and New York, stampedes in theaters, heart attacks, miscarriages, and even suicides. During the months that followed, these stories were shown to have little if any substance, yet today the myth of War of the Worlds stampedes and suicides persists as part of American folklore....

In the days following the show, newspaper columnists and public officials expressed dismay at the "incredible stupidity," "gullibility," and "hysteria" of listeners. Many popular accounts claim that the broadcast was interrupted several times for special announcements that a play was in progress. Listeners, however, had apparently been too panicked to notice them. These extreme psychogenic assumptions are, for the most part, unwarranted and inaccurate. For example, other than Mercury Theater's one-minute introduction (which most listeners missed), the station break at the middle of the broadcast, and the signoff, there were no announcements, special or otherwise, to indicate that a play was on the air....

In summary, the quantitative mass hysteria studies fail to show that the unusual and unverified experiences are widespread. In some instances, these experiences are reported by a very small portion of an available population, and in no instance are they reported by a majority. The quantitative studies also fail to clearly substantiate the hysterical nature of unusual and unverified experiences. Some studies have relied almost totally on the judgment of law enforcement or medical authorities that the reported experiences are of a hysterical nature.

If people can persist in talking on their cellphones while driving, I have no doubt they're capable of mass hysteria, too. But that is almost as last a resort as supposing that a meteorite really did fall and it really did make them ill.

Update (September 28th): New Scientist has the latest, according to which it really was a meteorite and people really did get (mildly) sick, though not nearly as many as reports had indicated.