The Half-Life of Facts (12 page)

They were able to conduct a test using this network: They created an abstract contagion in a computer-based simulation—it could be a disease, a bit of gossip, a fact, or anything else—and had it spread in the cell phone network according to one basic assumption: The stronger the tie between two people, the more likely the contagion would spread from one person to another.

This is entirely reasonable. If you spend more time with someone who has a cold, you’re more likely to get sick. The more often you speak with someone, the more likely they are to tell you a bit of juicy gossip.

For each of one thousand simulations, the team would begin by randomly choosing a few people to start the contagion. Then, at each step, a weighted coin would be flipped for each neighboring person who could possibly become infected. The stronger the tie, the more weighted the coin would be toward infection. Through running the simulations they were able to see how long it took for everyone to become infected, as well as what happened along the way.

When they tested the network and ran this experiment, they discovered that weak ties aren’t that important to spreading knowledge.
While weak ties do in fact hold the network together, much as Granovetter suspected, they aren’t integral for spreading facts. Weak ties, while bringing together disparate social groups, aren’t strong enough to spread anything effectively.

But strong ties also aren’t that important. While they can spread a fact with ease, most of the time they are spreading it to people who already know it, because strong ties only exist in highly clustered groups of people who often all know similar things.

So Granovetter wasn’t quite right. Ultimately it’s the medium-strength ties that are the most important. They are that happy medium between ties that are too weak to spread anything and those too strong to be found in anything but socially (and informationally) inbred groups.

These are the types of ties that allow knowledge to spread, facts to disseminate, sometimes even errors to propagate. The people you trust a little bit but aren’t your closest friends, your work friends, or something a bit more than strangers but less than a good buddy: These people provide the ties that are the most important in allowing something to spread far and wide. They connect different enough social circles that the fact can infect a new group, but they are also strong enough to provide a good chance of spreading it.

We see hints of this when it comes to spreading the printing press and Gutenberg’s bundle of innovations. The key individuals in spreading new facts were other Germans in different towns. These individuals, who had the necessary knowledge and skills (and often some sort of connection to Gutenberg), were able to bring these innovations to new communities.

How facts spread and reach each of us is intimately tied to how we are connected to one another, and network science can provide us with a guide to understanding how this works. But just because a fact spreads doesn’t necessarily mean that it’s right. Just as quickly as truth can spread, so can facts that are wrong.

Errors are especially pernicious facts. Is there anything that science can say about how errors spread and persist in a population? To understand that we have to look at some of these errors,
starting with one that I fell victim to many years ago: the celebrated case of the brontosaurus.

.   .   .

AS
a child, I was a student of dinosaurs. When you’re a six-year-old boy, this is not really a choice—it’s some sort of biological imperative. I was well versed in the different types of sauropods and theropods, the dietary habits of these ancient giants, and even the recently popularized theory that they were warm-blooded rather than the slow, dim-witted, and cold-blooded dinosaurs known to previous generations.

We had a wonderful activity in my kindergarten class in which each of the eighth-grade students were paired with a kindergartner. They were assigned to interview us, to discuss our interests, hopes, and dreams, and then to write a storybook for us based on all of these findings. The subject matter for my book was never in any doubt. Dr. Sam Arbesman, paleontologist, was given the honor of being sent to South America to investigate rumors that a live dinosaur was there, and to capture it.

But despite this obsession with dinosaurs, there was one fact that I got wrong. It’s entirely basic, and yet no one had told me that I was incorrect: the name brontosaurus. The four-legged saurischian, with the long neck and tiny head, is one of the iconic creatures of my youth. In fact, it was the very species of dinosaur that my fictional self was sent to South America to capture. And yet its name is actually apatosaurus.

.   .   .

BY
the 1860s, dinosaur-fossil hunting was in full swing. Darwin had published
On the Origin of Species
the previous decade, and decades before that the argument that these fossils were the bones of creatures that perished in the deluge had been discarded. They were now bona fide monsters that had lived unbelievably long ago, and they were part of the pageantry of interconnected life explained by evolution.

Bestriding this wave of scientific discoveries were two American paleontologists: Edward Cope and Othniel Marsh. While entwined by history, they were highly unlike each other. Cope had little formal training in paleontology, and only received an honorary master’s at the same time he began a position at Haverford College. Marsh, on the other hand, had a doctorate from the University of Heidelberg, was a professor at Yale University, and was the curator of the Peabody Museum of Natural History.

Beginning in 1863, Marsh and Cope began something of a competition, though that term is not quite accurate. The phrase used by some—the Great American Dinosaur Rush—also doesn’t do it justice. This was no friendly rivalry over who might discover more new species. If you consider the depths of bribery, theft, and even ideological dispute to which both paleontologists sank, it is certainly more appropriate to call this conflict by its more common name: the Bone Wars.

Marsh and Cope were initially collaborators, but they soon had a falling-out. The proximate cause seems to be Marsh’s pointing out an error in the reconstruction of a swimming creature known as the elasmosaurus, a sort of Loch Ness monster. This, coupled with Marsh’s payment—behind Cope’s back—of diggers to divert all future fossil finds in their New Jersey area to him, cemented the beginnings of the war. The conflict was exacerbated by the fact that Marsh was a staunch Darwinist, while Cope adhered to an older theory known as neo-Lamarckism. Eventually the two became fierce rivals, resorting to nearly any stratagem in order to describe more dinosaur species.

In the midst of all of this, Othniel Marsh published his discovery of the brontosaurus in 1879. Its full taxonomic name is
Brontosaurus excelsus
, essentially meaning in Latin “most sublime thunder lizard.” Two years earlier, in 1877, he also submitted a paper entitled “Notice of New Dinosaurian Reptiles from the Jurassic Formation,” in which he described a slightly smaller dinosaur (it was clearly a juvenile, or child, dino) that he called apatosaurus. This name means “deceptive lizard,” due to Marsh’s observation that its bones looked
similar to those of another species. Marsh, in these descriptions, even managed to get a dig in against Cope, noting that his findings related to these species were superior to Cope’s, whose “[c]onclusions based on such work will naturally be received with distrust by anatomists.”

The brontosaurus discovery went on to be supplemented with a complete skeleton, beautiful to behold and the harbinger of its fame in popular culture. The apatosaurus, on the other hand, languished as a tiny collection of bones that included not much more than a pelvic bone and a shoulder blade.

Marsh and Cope continued their respective breakneck paces of dinosaur discovery, lashing out at each other over and over. Cope even went so far as to purchase a controlling interest in the distinguished scientific journal
American Naturalist
in order to make it easier for him to publish his discoveries. Despite their vitriol and animosity, they actually didn’t fight any more about the brontosaurus.

But in 1903, an error was found by the paleontologist Elmer Riggs. This time it was Marsh who had gotten something wrong. While Cope didn’t have the satisfaction of knowing this (both had already died several years earlier), it was a rather large error. Riggs argued that the brontosaurus was in fact simply a version of the apatosaurus. Due to the error, the brontosaurus no longer formally existed. Since it had been discovered after the apatosaurus, the apatosaurus name received precedence. And while the name brontosaurus was much more impressive, the title apatosaurus was now the correct one due to being first.

Despite this problem, many paleontologists persisted in using brontosaurus. Why confuse the public when it was a rather minor issue?

Then, in 1978, two other paleontologists, J. S. McIntosh and David Berman, noticed something even bigger that was amiss: The original brontosaurus had been graced with the wrong head! It had the head of another large, plant-eating dinosaur. They recognized that a skull, misidentified as belonging to a different species, in fact belonged to the apatosaurus. After this discovery was made
they realized it was time to set this error straight; scientists began to agitate for a switch to the name apatosaurus.

But this did nothing to diminish the appeal of the name brontosaurus. This dinosaur was already out of the bag. The brontosaurus was featured in popular books of all types, including those from which I gained much of my childhood dinosaur expertise. The United States Postal Service even included it as one of four dinosaur stamps in 1989, nearly a century after the discovery of the misclassification and two decades after the beginning of the discontent in the paleontological community. I only learned of the misclassification in the early 1990s, through Stephen Jay Gould’s essay “Bully for Brontosaurus,” when he argued that the postal service did the right thing, even though the name was technically incorrect.

Since then, apatosaurus has been gaining currency, although rather slowly, as seen here in a Google Ngram:

Figure 7. The number of uses of word
brontosaurus
(black) versus
apatosaurus
(gray) over time. Data courtesy of Google Books Ngrams and the Cultural Observatory.

But is this always how erroneous facts persist? Sadly, it seems that this is often the case, that there are many examples of errors that have stuck around for far longer than they should have.

.   .   .

IN
chapter 9
we’ll examine why people refuse to change their knowledge, or at least neglect to update their mental databases of facts. But how does a novel fact, even a wrong one, spread and persist in the population? Are there regularities to how errors spread?

One of the strangest examples of the spread of error is related to an article in the
British Medical Journal
from 1981. In it, the immunohematologist Terry Hamblin discusses incorrect medical information, including a wonderful story about spinach. He details how, due to a typo, the amount of iron in spinach was thought to be ten times higher than it actually is. While there are only 3.5 milligrams of iron in a 100-gram serving of spinach, the accepted fact became that spinach contained 35 milligrams of iron. Hamblin argues that German scientists debunked this in the 1930s, but the misinformation continued to spread far and wide.

According to Hamblin, the spread of this mistake even led to spinach becoming Popeye the Sailor’s food choice. When Popeye was created, it was recommended he eat spinach for his strength, due to its vaunted iron-based health properties.

This wonderful case of a typo that led to so much incorrect thinking was taken up for decades as a delightful, and somewhat paradigmatic, example of how wrong information could spread widely. The trouble is, the story itself isn’t correct.

While the amount of iron in spinach did seem to be incorrectly reported in the nineteenth century, it was likely due to a confusion between iron oxide—a related chemical—and iron, or contamination in the experiments, rather than a typographical error. The error was corrected relatively rapidly, over the course of years, rather than over many decades.

Mike Sutton, a reader in criminology at Nottingham Trent University, debunked the entire original story several years ago
through a careful examination of the literature. He even discovered that Popeye seems to have eaten spinach not for its supposed high quantities of iron, but rather due to vitamin A. While the truth behind the myth is still being excavated, this misinformation—the myth of the error—from over thirty years ago continues to spread.

Ultimately, the reason these errors spread is because it’s a lot easier to spread the first thing you find, or the fact that sounds correct, than to delve deeply into the literature in search of the correct fact.

Michael Mauboussin, the chief investment strategist of Legg Mason Global Asset Management, in an article about fact-checking, relates his own experience with this sort of error propagation. While working on his book
Think Twice
, he came across an equation in a book about statistics that calculated the value of wines from the Bordeaux region. The problem was, when Mauboussin tried it, it didn’t work. It turned out that his source was riddled with errors, ranging from one number that was ten times too small to another that contained a rounding error, completely changing the meaning of the equation. Only when Mauboussin tracked down the original scientific paper did he find the correct version.