Why Does Everyone Hate Rats? (Update)

What It Covers

Freakonomics Radio examines why rats are universally despised, tracing their history from medieval plague carriers to modern urban pests. New York City's rat czar Kathy Curati, science journalist Bethany Brookshire, and Harvard economist Ed Glaser challenge assumptions about rats, disease, and human psychology behind pest hatred.

Key Questions Answered

• •Rat control strategy: Sanitation is the primary lever for rat population management, not extermination. Rats require two things to thrive — food access and harborage. Removing garbage, containerizing trash, and eliminating overgrown brush eliminates the conditions rats need. NYC's Department of Sanitation reported a 20% year-over-year decline in rat sightings using this approach.
• •Black Death misattribution: A 2018 PNAS study by University of Oslo ecologist Niels Christian Stenseth analyzed plague death rates across London, Barcelona, and Florence from the 1300s–1700s. The data shows human ectoparasites — body lice and human fleas — spread the Black Death faster than the rat-flea transmission model allows, largely exonerating rats from Europe's most infamous pandemic.
• •Rat population measurement: No reliable census method exists for urban rat populations. Any specific figure cited — whether 3 million or 8 million for New York City — is an estimate without scientific validation. Policymakers and residents should treat published rat population numbers skeptically, as they function more as political talking points than measurable benchmarks.
• •Cultural relativity of pest status: Whether an animal is labeled a pest reflects human values, not biology. The Karni Mata temple in Deshnoke, India houses 25,000 sacred black rats fed fruit, vegetables, and whole wheat bread. Pigeons shifted from valued messengers and fertilizer sources to "rats with wings" only after technology made their utility obsolete — demonstrating that pest status is assigned, not inherent.
• •Disease risk calibration: Leptospirosis, the most cited rat-transmitted illness in NYC, produced only 24 confirmed human cases in 2023 across a population of over 8 million. Novel viruses found on rats in a Columbia University study represent a theoretical future risk, but current documented public health impact from rats in developed cities remains statistically minor compared to other urban health threats.