The 'gazillions' of lizards in Cincinnati could actually guard us from Lyme disease

For more than 70 years, thousands of common wall lizards, known as Lazarus lizards, have scurried across sidewalks and lurked in gardens in Cincinnati.

They're all over the city, but the reptiles aren't from here. They're an invasive species and native to Europe. The lizards came to the Midwest thanks to a 10-year-old boy from Walnut Hills and a sock full of lizards.

In 1951, George Rau Jr., the stepson of Fred Lazarus Jr. (who founded the retail chain Lazarus, which would later become Macy's), smuggled 10 Italian lizards home from a family trip in Lake Garda, Italy. He then set them loose in his backyard.

Many pass off the origin story as local lore, but in 1989, when Rau Jr. was an adult, he wrote to the Cincinnati Museum of Natural History explaining his role in the eventual lizard population boom. That same year, he also told The Enquirer he smuggled the lizards through customs and brought them back to his East Side home.

Cincinnati's vast lizard population has attracted researchers, such as Ohio Wesleyan University biology professor Eric Gangloff. He and his team of student researchers, dubbed the Lizard League, have studied Lazarus lizards since 2020, and they've learned the population isn't just getting larger, but so are the lizards.

Gangloff and his team traveled to Cincinnati this month for a four-day research outing. They typically observe lizards at Alms, Ault, Mt. Storm and Mt. Echo parks. Here's what they have learned about the lizards.

Cincinnati's Lazarus lizard population could be in the 'millions'

One question many may have is whether Rau Jr.'s smuggled lizards actually sparked the population.

Gangloff said it's true that all of Cincinnati's lizards came from the initial introduction of 10 back in the 1950s, calling the phenomenon "remarkable."

"We do know from our analysis of their DNA, to genomic analyses, that all of the lizards here are the result of a single introduction. So they all stem from that one origin. It doesn't look like there are multiple introductions or anything like that. They're all pretty closely related," he said.

As for how many lizards make up the total population: Gangloff and his team can't quite nail that down.

"Oh, God. I wish I had a better population estimate − the gazillions, to use a scientific number," he said.

His team is estimating the population by using the capture-mark-recapture method, meaning a portion of the population is captured, marked and released. Later, another portion will be captured, and the number of marked individuals within the sample will be counted.

"Every year they're moving out. There were some studies done in the 1990s on population densities, and they can achieve remarkably high densities. To give you an honest answer, it's in the hundreds of thousands, if not millions, across the city," Gangloff said.

Cincinnati's Lazarus lizards are getting larger

National Geographic, which interviewed Gangloff, first reported the lizards are getting bigger in size.

"Not only are they absolutely bigger, but they proportionally have longer limbs as well, and that's true for both males and females," Gangloff told The Enquirer.

It's not necessarily unusual to see this pattern in lizards. Gangloff said the Italian wall lizard, another species that has been introduced to North America, has also since changed its body size.

"So it seems like it's not necessarily unique to just this species. It's not like a one-off kind of thing," he said. "It seems like there's some broader pattern there whereby these European lizards are introduced in places in North America. And then there are subsequent changes that are not exactly the same, but similar across these differentials."

Since the lizards have gradually gotten larger, it's unlikely the growth has been a noticeable change for Cincinnati residents. However, if you vacation in France and spot wall lizards there, Gangloff said the size difference will be increasingly noticeable.

He said these changes could be an evolutionary result to help them better escape house cats and other urban predators.

The lizards are 'world champion' lead toxicity tolerators

Aside from the apparent size change, Gangloff and his students have noticed a difference in how the reptiles respond to different environmental conditions. In March, the team told National Geographic they found during experiments that despite the"prolonged exposure to heavy metals in the city, the lizards seem unaffected."

Gangloff and his collaborator, Tulane University School of Science & Engineering Assistant Professor Alex Gunderson, even found at Tulane that these lizards are like "world champion lead toxicity tolerators."

"We found levels of lead in lizard blood that are way higher than what would land you or me or any other mammal really sick in the hospital or lethal," he said.

Gangloff and Gunderson, along with other contributors, published a study in January showing the amount of lead in the lizards' blood didn't really affect their ability to run long distances or their cognitive function.

The researchers put the lizards on "little lizard treadmills" and tested how long they could run without getting exhausted, and to much surprise, there was no effect. They also tested the reptiles' ability to run on a balance beam, due to lead affecting cognitive function, and even though that's a cognitively demanding task, the team found no effect again.

Gangloff said the lizards are likely exhibiting adult neurogenesis or the process of generating new neurons from neural stem cells. He currently has students in the lab experimenting with their hypothesis that, unlike humans or other mammals, adult lizard brains can regenerate neurons.

"A few parts of our brain, you can generate neurons, but mostly for us, if a neuron is gone, it's gone," he said.

The experiment involves students dosing animals with known quantities of lead to increase the levels, and then they'll look at "neuro death" and the lizards' capacity to regenerate those neurons.

Although adult neurogenesis is a hypothetical explanation for the Cincinnati lizards' lead resistance, since not many have been tested for this specific trait, Gangloff mentioned that the Anole lizard also thrives in urban environments. Those are also being studied by researchers in Chile because they are "super, super resistant to lead" and even have higher levels of lead than Cincinnati's lizards.

But how are the Cincinnati-based lizards getting lead in their bloodstream? According to Gangloff, it's easier than you'd think.

Lead levels are ubiquitous in urban environments, such as the ones Lazarus lizards thrive in due to industrial processes, lead gasoline and, obviously, lead paint on homes. Gangloff also noticed higher levels of lead were found in lizards found alongside roads than in parks.

"Suggesting that roads are definitely part of this, the thing about lead is it just doesn't go away. It gets into the environment, just like it's inert, and it just stays. Even if we stopped using gasoline 20 years ago on these roadways, there's still going to be lead there," Gangloff said.

Wall lizards have been 'super effective' at killing off the bacterium that causes Lyme disease

The findings and data that researchers are collecting from the Queen City could also lead to lessening serious health implications, such as Lyme disease, a bacterial infection that's transmitted through the bite of an infected tick.

"Out West, there's a lizard species where if a tick bites the lizard and the tick carries the bacterium that causes Lyme disease, the lizard can neutralize that bacterium, so it makes the tick less harmful if they go and bite the human," Gangloff said.

Sean Giery, an assistant professor at Ohio University, worked alongside Gangloff in May and tested this with the Lazarus wall lizards. The lizards were "super effective" at killing off the bacterium that causes the disease because of a protein within the lizards, per Gangloff.

Cincinnati's Lazarus lizards prefer higher temperatures

Gangloff's team also found the lizards from Cincinnati prefer "much, much higher temperatures" (about 3-4 degrees Celsius warmer) than any of the populations they've studied. The team puts the lizards in thermal gradients with cool and warm ends, and sees what temperatures the lizards select.

"(It's) really kind of intriguing and surprising, because the weather, the climate in Cincinnati, isn't necessarily warmer, so there's something going on there that suggests they're preferring warmer temperatures," he said.

Where can you find Lazarus lizards in Cincinnati?

According to the National Geographic article, Cincinnati has the "perfect lizard habitat," noting the city's hilly geography and weather as contributing factors for the lizards becoming "permanent residents," as declared by the Ohio Division of Wildlife.

Gangloff and his team of students observe the lizards all over the city. The reptiles can be found throughout Cincinnati's luscious parks, but they can also be found on random stone walls.

"There's one site where it used to be an old schoolhouse that's torn down, and there's like a city block that's just this old stone wall that's great," Gangloff said. "There's just no shortage of places to find these guys in the city."

However, Gangloff saw the most lizards close to downtown Cincinnati.

"There's an abandoned lot along River Road, kind of west of downtown, and there's this stone wall that's probably about two meters high, and maybe not even 40-50 meters long, if that," he said. "And it's just this random place that's packed with lizards and it backs up to a forest.

I couldn't tell you exactly why, but that one site has this huge density of lizards, and if you go out there in the morning, the sun comes up, and it just seems like the wall is coming alive as the animals emerge from it. It's pretty neat."