New scientific research has definitively revealed the true origins of Chicago’s viral “rat hole,” confirming with near certainty that the iconic sidewalk impression was left by an unlucky squirrel, not a rat, challenging years of local lore and offering a fascinating glimpse into the world of trace fossil analysis.
Chicago’s “rat hole” captivated the internet and local residents alike, an enigmatic sidewalk impression that became an unexpected urban shrine. For years, the prevailing theory was that an unfortunate brown rat had met its end in wet concrete, leaving behind a permanent, spread-eagled silhouette. However, recent rigorous scientific analysis has shattered this long-held belief, offering a more accurate—and perhaps even more charming—origin story: the culprit was almost certainly a squirrel.
The Unexpected Rise of an Urban Legend
The sidewalk impression in Chicago’s Roscoe Village neighborhood is believed to have been created some 20 to 30 years ago, likely in the early 2000s. It closely resembled the full-body outline of a rodent, complete with distinct markings for tiny claws, arms, legs, and even a tail. This led to its initial christening as the “Chicago Rat Hole” or affectionately, “Splatatouille.”
The impression catapulted to viral fame in early 2024 after comedian Winslow Dumaine posted a photo of it on X. This post ignited widespread public fascination, transforming the unassuming sidewalk spot into a peculiar local landmark. Curious tourists flocked to the site at all hours, leaving behind playful offerings such as Swiss cheese and coins, turning the “rat hole” into an impromptu shrine. However, this sudden surge in popularity also drew complaints from nearby residents about the constant traffic.
In April 2024, the site faced a brief moment of crisis when someone reportedly filled the impression with plaster. City workers ultimately intervened, removing the affected slab of sidewalk and transporting it to the City Hall-County Building for storage. Despite its physical absence from the sidewalk, a plaque honoring the impression reportedly remains at the original site, preserving its cultural legacy.
Unraveling the Mystery: The Scientific Investigation
The intriguing nature of the “rat hole” did not escape the attention of the scientific community. A team of researchers from institutions including the University of Tennessee, New York Institute of Technology College of Osteopathic Medicine, and the University of Calgary embarked on a mission to definitively identify the creature behind the impression. Their findings, published in the journal Biology Letters, challenged the long-held rat theory.
Given that the original impression had been removed, the researchers meticulously studied online photographs of the “rat hole.” They utilized visible scales within these images, such as coins left as offerings, to accurately estimate the imprint’s dimensions. Next, using the citizen science application iNaturalist, they identified eight small mammal species commonly found in Chicago as potential candidates:
- Muskrat
- House mouse
- White-footed mouse
- Eastern chipmunk
- Brown rat
- Three different species of squirrel
To compare, the team gathered precise measurements from 50 museum specimens for each of these eight species, encompassing various sexes and body sizes. Statistical analysis of this extensive data against the estimated dimensions of the sidewalk impression yielded a compelling conclusion.
The Squirrel Emerges as the True Artist
“We can affirmatively conclude that this imprint was not created by a rat,” stated Michael Granatosky, an evolutionary biomechanist at the University of Tennessee, Knoxville, in an interview cited by Associated Press. The analysis quickly ruled out the brown rat, whose forelimbs, hind paws, and digits were found to be consistently too stubby to match the impression.
Instead, the evidence strongly pointed towards squirrels. The researchers found an almost 99 percent chance that the imprint was made by an Eastern gray squirrel (Sciurus carolinensis) or a fox squirrel (S. niger). Given the high abundance of the Eastern gray squirrel in the Chicago area, it stands as the most probable suspect.
Behavioral patterns further supported the squirrel hypothesis. Concrete is typically wet during daylight hours, precisely when squirrels are most active, while rats are generally nocturnal. The absence of footprints around the impression suggested that the animal likely fell rather than walked into the wet cement. This theory is reinforced by accounts from longtime residents who recall a tree formerly standing near the site of the impression, suggesting a squirrel might have misjudged a leap or slipped from a branch.
While some might wonder about the lack of a bushy tail imprint, the researchers noted that hair often lacks the rigidity required to create deep, well-defined impressions in concrete, making its absence unsurprising.
Beyond the Sidewalk: Paleontology and Public Engagement
The scientific inquiry into the “rat hole” may seem whimsical, but it serves a serious purpose. It offers a practical demonstration of the methods employed in paleontology, particularly in the challenging field of identifying trace fossils. “What if this impression was a fossil? Paleontologists would go about identifying the organism that created the fossil in the same way,” explained Elizabeth Carlen, a biologist at Washington University in St. Louis, to CNN.
The study highlights the complexities of connecting an impression to its maker, even with a relatively recent and clear outline. Granatosky pointed out that despite the impression being a modern example, pinpointing the exact species proved difficult, often narrowing it down only to the genus level. This underscores the challenges faced by paleontologists when dealing with ancient and often fragmented evidence.
Embracing the fun and educational aspect of the discovery, Granatosky is developing a lesson plan for children, aiming to make scientific methodology accessible to a broader audience. “It’s so rare to get such a fun story,” he remarked to Amanda Heidt at Science News, emphasizing how the project effectively communicates the process of data analysis in an engaging manner.
In light of their findings, the research team has proposed a fitting new name for the iconic landmark: the “Windy City Sidewalk Squirrel,” a moniker that more accurately reflects its likely origins and the scientific evidence at hand. Perhaps, as Article 1 mused, “Scrat Hole” could also be a playful alternative. Regardless of its name, the Chicago impression will forever be a testament to urban whimsy, scientific curiosity, and the surprising stories hidden in plain sight.
