Why Does Everyone Hate Rats?

New York’s mayor calls them “public enemy number one.” History books say they caused the Black Death — although that may be false. So is the rat a scapegoat? And what does our rat hatred say about us?

In the fall of 2022, a new job listing was posted on a New York City government website. It read, in part:

Do you have what it takes to do the impossible? A virulent vehemence for vermin? The ideal candidate is highly motivated and somewhat bloodthirsty, determined to look at all solutions from various angles, including improving operational efficiency, data collection, technology innovation, trash management, and wholesale slaughter.

It was a posting for the position of Citywide Director of Rodent Management, or “rat czar.” New York and many other cities have seen a rise in their rat populations, especially during Covid, and now they are fighting back. But is “wholesale slaughter” really the way to deal with rats? You couldn't get away with talking that way about most animals. What is it about the brown rat — Rattus norvegicus — that makes it so widely reviled?

Rats have been exploiting New York City’s urban space for at least a few hundred years. The ancestors of today’s rats are thought to have arrived in the 18th century on ships from Europe. But in the historical rat timeline, that is still relatively recent; genetically, they date back to the time of dinosaurs, and they've lived alongside humans ever since those humans started to congregate in cities, which present rats with delicious accumulations of food waste.

One reason that rats are so despised is because they spread disease — the most famous instance being the Black Death, a pandemic of bubonic plague in the 14th century that killed millions upon millions of Europeans. The standard epidemiological model of the Black Death is that humans were exposed to the plague by rats who had been bitten by diseased fleas — and if anything is going to give an animal species a bad reputation, it’s killing off half of Europe. The association between rats and plague remains strong today. In the opening credits of The Decameron, a new Netflix show set during the Black Death, a massive swarm of rats come together to spell out the title. And the recent remake of the film Nosferatu shows a pack of rats following the vampire, carrying the plague with them.

But scientists have recently challenged the claim that rats caused the Black Death. In 2018, Nils Christian Stenseth and some of his colleagues at the University of Oslo published a paper in the Proceedings of the National Academy of Sciences in which they presented a different model. “Despite the historical significance of the disease,” they wrote, “the mechanisms underlying the spread of plague in Europe are poorly understood. While it is commonly assumed that rats and their fleas spread plague ... there is little historical and archaeological support for such a claim.”

You can hear from Stenseth, along with New York City's rat czar Kathy Corradi and more rat experts, in this week's episode of Freakonomics Radio — the first in a three-part series about our most despised neighbors. You'll never look at a rat the same way again.

You can hear this week’s episode of Freakonomics Radio, “Why Does Everyone Hate Rats?”, on Apple Podcasts, Spotify, or wherever you listen to podcasts. A full transcript is available on our website.

Also on the Freakonomics Radio Network this week

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The primatologist discusses the thrill of observing chimpanzees in the wild, the value of challenging orthodoxy, and why dying is her next great adventure.
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The Economics of Everyday Things: School Photos

Picture day is an annual tradition for American families — and, for the companies that take the photos, a lucrative one. Zachary Crockett smiles for the camera.
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