Why Does Everyone Hate Rats? (Update) | Freakonomics Radio

This episode explores the complex relationship between humans and rats, focusing on why rats are so widely despised and the efforts to mitigate their populations, particularly in New York City. The discussion begins with New York City's former Mayor Eric Adams, who in 2022 posted a job listing for a "Director of Rodent Mitigation," also known as the "rat czar." The job description, which called for a "swashbuckling attitude, crafty humor, and a general aura of badassery," reflected Adams' fervent anti-rat stance. Katy Corradi, the first person to hold this position, noted that the increased public attention on rats benefits the mitigation efforts. New York and other cities have seen a rise in rat populations, especially since the COVID-19 pandemic. Corradi emphasizes that rat mitigation is complicated, involving a holistic approach to their habitat and food sources. Her own childhood experience with rats, stemming from a property abutting railroad tracks, highlighted the need for ongoing maintenance to prevent rat harborage. Her professional path led her to rat mitigation through zero-waste programming in public schools, where she focused on improving waste management to reduce food access for rats. Sanitation is identified as the cornerstone of pest management. New York City, despite its many admirable qualities, is acknowledged as not being a particularly clean city, with abundant sidewalk trash and food waste creating an ideal environment for rats. While there's no definitive census, rat population estimates for New York City vary widely, with Corradi declining to endorse a specific number due to the futility and potential for misinterpretation. Corradi's role as director of rodent mitigation encompasses all rodents, but rats are the primary focus due to their "commensal" nature, meaning they "sit at the table with us" by exploiting urban spaces where humans are densest. She notes that while house mice might be more successful in some regards, rats are renowned for their adaptability and ability to thrive alongside humans. Rats are described as intelligent, savvy survivors, capable of learning and even exhibiting empathy and altruism. They are known to avoid new things in their environment and even send less dominant rats to test new food sources. Historically, rats have been exploiting urban spaces for centuries, with the brown rat (Rattus norvegicus) arriving in the 18th century. Bethany Brookshire, a science journalist and author of "Pests: How Humans Create Animal Villains," explains that the brown rat, despite its name, did not originate in Norway; the name was likely a jab at Norway by those who disliked rats. She notes that while people have disliked rats for centuries due to their impact on food supplies, the association of rats with disease is a more recent development, primarily emerging in the 18th or 19th century. The discussion delves into the plague, particularly the Black Death. While the plague is caused by the bacterium Yersinia pestis, spread by fleas that typically infect rats before spilling over to humans, scientists have challenged the long-held belief that rats were solely responsible for the Black Death. Nils Christian Stenseth, a professor of ecology and evolution, published research in 2018 suggesting that human ectoparasites like body lice and human fleas were more likely vectors for the rapid spread of plague during the Black Death. Ed Glaeser, an economist specializing in cities, corroborates this, explaining that rat-led plagues would spread more slowly because fleas only leave a rat once it dies. While rats might not have been the primary cause of the Black Death, they are believed to have played a critical role in the third bubonic plague explosion, which began in the 19th century and persists today in small numbers. The implication of rats in past disease outbreaks has significantly tarnished their global reputation. Brookshire argues that "blaming the rat is pretty much, you know, game over in terms of the rat's global reputation." Glaeser adds that while rats are a "negative externality" in cities, their role in disease transmission today is relatively minor. The economic impact of rats includes property damage (chewing wires, foundations, and food sources) and human costs related to public health and mental well-being. Leptospirosis, a bacterial illness transmitted through rat urine, is a public health concern, though reported cases in New York City are relatively low. However, studies have found novel viruses and pathogens on rats, raising concerns about their potential to mutate and jump hosts due to rats' close proximity to humans. Brookshire's book "Pests" explores how humans create "animal villains." She argues that the concept of a "pest" is subjective, reflecting human ideas about where animals belong and what they should be doing. She highlights how animals like pigeons, once crucial to human societies for food, messages, and fertilizer, have fallen from grace to be considered "rats with wings" as their utility diminished. The cultural perception of rats varies significantly. While Western cultures often associate rats with disgust and stress, other cultures, like that of the Karni Mata temple in Deshnoke, India, consider rats sacred as reincarnations of people. Brookshire suggests that the difference in perception is partly cultural, influenced by concepts like human dominion over animals. Humans often expect animals to disappear when their habitats are developed, becoming upset when they don't, especially if they thrive on resources humans value. This leads to a resentment of their "success because their success feels like our failure." Glaeser concludes that while the innate human reaction to rats is largely revulsion, particularly when associated with urban filth, the threat they pose today is probably small. He advocates for manageable rat control rather than complete eradication, acknowledging that rats are "our natural city partner" and suggesting a shift from horror to a view of them as urban cohabitants. New York City's current efforts, including a plan for citywide trash containerization by 2031, aim to continue the "war on rats." Recent reports indicate a decline in rat sightings, suggesting some success in mitigation efforts.