Rat Facts & Trivia: The Numbers Are All Wrong

• A female brown rat can mate up to 500 times during a single six-hour window of fertility.
• One female brown rat can produce seven litters a year — up to 60 young rats.
• Scientists examining a single rat's stomach found traces of more than 4,000 different items in it.
• A rat can pass through any gap wide enough for its head — the skull, not the body, is the limiting measurement.
• A rat's whiskers are a finer touch instrument than human fingertips.
• Rats really can swim up through household plumbing and emerge in a toilet bowl.
• Despite living alongside us for centuries, rats are poorly studied: veterinary scientist Chelsea Himsworth says science understands polar bear ecology better than rat ecology.
• Rats physically cannot vomit — emetic drugs including apomorphine, veratrine and copper sulfate produced no retching or vomiting at all. The popular version says rats can't vomit because of their anatomy — a long oesophagus and a weak diaphragm. The 2013 study found those anatomical constraints exist but are not the main reason: the rodents lack the brainstem circuitry that generates the reflex. It is also not a rat quirk — it appears to be a property of the whole order Rodentia, tested across rats, mice, voles, beavers, guinea pigs, nutria and mountain beavers.
• Tickled rats emit 50-kHz ultrasonic calls and perform spontaneous leaps that researchers named Freudensprünge — 'joy jumps'.
• Rat ticklishness switches off under stress — anxiety-inducing conditions suppressed both the tickle calls and the brain activity behind them.
• Rats learn to open a restrainer to free a trapped cagemate, and will not bother opening empty or object-filled restrainers.
• Given a choice between freeing a trapped companion and a restrainer full of chocolate, rats opened both — and then shared the chocolate.
• Rats that skip a good food option and then hit a worse one look back at the option they lost, and neurons in their orbitofrontal cortex represent the choice they should have made. Headlines said 'rats feel regret'. The researchers defined regret economically — recognising that a different action would have paid better — and measured behaviour and neural firing, not a subjective feeling. The paper's own wording is that 'regret-like processes' modify decision-making.
• The rat was the third mammal to have its genome sequenced to high quality, published in Nature on 1 April 2004.
• After invasive Norway rats were removed from Hawadax Island in Alaska's Aleutians in 2008, the shoreline ecosystem was fully recovered 11 years later.
• Rats introduced to islands eat seabird eggs and chicks, and are a leading driver of seabird population collapse.

“New York City has as many rats as people — roughly 8 million.” A statistical estimate built from the city's own lot-by-lot rat inspection data put the figure at about 2 million, roughly one rat for every four people. The 'one rat per person' line is folklore, not a count.

“Rats and their fleas caused the Black Death.” When researchers fitted transmission models to real mortality curves from nine European plague outbreaks between 1348 and 1813, the model that won was human ectoparasites — human fleas and body lice moving between people — not rats. Rats carry Yersinia pestis, but the medieval European epidemics do not look like rat-driven ones.

“A rat's orange front teeth are stained that colour by the iron in its enamel.” High-resolution imaging of incisors from seven rodent species, rats included, found the iron-rich enamel is a protective, acid-resistant shield — but the colour comes from a separate outer surface layer, and colour intensity tracks the thickness of that layer rather than the iron.

“You are never more than six feet from a rat.” The claim has circulated for a century with no traceable origin and no supporting data. Working from London rat estimates, even the pessimistic scenario puts your nearest rat about 5 m away, and the realistic one around 13 m — and rats cluster near food and cover rather than spreading evenly.

“The Norway rat is Norwegian.” The name is an 18th-century misattribution. Whole-genome data from wild brown rats worldwide traces the species out of southern East Asia; it reached Africa and Europe long before the Scandinavian ships it was named after.

Rats hit the screen as horror first. Willard (1971) turned a bullied clerk's rat colony into a murder weapon, and its sequel Ben (1972) produced the strangest chart entry in rat history: Michael Jackson's ballad "Ben," sung to a rat, became his first solo US number one, spending a week atop the Billboard Hot 100. Don Bluth's The Secret of NIMH (1982), adapted from Robert C. O'Brien's 1971 novel Mrs. Frisby and the Rats of NIMH, made lab rats the heroes. Pixar's Ratatouille (2007) finished the rehabilitation, winning the Academy Award for Best Animated Feature. Its afterlife was odder still: fans built Ratatouille: The TikTok Musical, which streamed from 1 January 2021 with Tituss Burgess as Remy and raised $2 million for The Actors Fund. Elsewhere: Master Splinter has led the Teenage Mutant Ninja Turtles since 1984; Rizzo joined the Muppets; games lean on rats as dread, from the plague swarms of A Plague Tale: Innocence (2019) to the Rat King boss of The Last of Us Part II (2020).

Magawa is the most decorated rat ever — though, strictly, an African giant pouched rat rather than a true Rattus. Born November 2013 at Sokoine University of Agriculture in Tanzania, he cleared minefields in Cambodia for the charity APOPO, finding 71 landmines and 38 items of unexploded ordnance. In September 2020 he received the PDSA Gold Medal, the highest animal award for gallantry; he retired in 2021 and died on the night of 8 January 2022, aged eight. His record fell to Ronin, who has located 109 landmines and 15 other war remnants since August 2021 and took the Guinness World Records title on 4 April 2025. Earlier still came Hector, launched by France on 22 February 1961 aboard a Véronique AGI rocket — the first rat in space, and he survived. And in September 2015, an anonymous New York rat dragging a pizza slice down subway stairs became Pizza Rat.