New York City’s white-footed mice live in the city’s parks and wooded areas, but they’re no country mice. They deal with all the dangers of urban living, like disease, pollution, and overcrowding. And as it turns out, the mice may actually be evolving in response to their urban lifestyle.

Scientist Jason Munshi-South wanted to figure out if the pressures of city living had caused the mice to evolve, Carl Zimmer writes at National Geographic. So he caught a bunch, sequenced their genes, and compared them to the genes of their rural cousins.

He and his colleagues found, Zimmer reports, a “handful of genes that evolved due to natural section.” And some of them seem to have evolved in response to the pressures of city life:

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Some of them are known to be involved in recognizing pathogens, and others help launch an immune system attack against them. Others help to detoxify pollutants. These genes not only evolved relatively quickly — in just the past couple centuries at most — but also repeatedly. In park after park, the same adaptations were favored by natural selection.

The scientists now have to follow up to find out if those genes actually change the mice in significant ways. But if that pollution-detoxifying gene exists, look for overprotective NYC-dwelling parents to ask for it to be spliced into their children’s DNA.