New data shows that cities might be one of the most powerful forces shaping evolution today. Some species are naturally pretty well suited to life in the city (e.g. raccoons, rats), but others have been forced to adapt to keep pace. New species of subterranean mosquito, fish that are resistant to human pollutants, finches that can more easily draw from bird feeders and even more versatile, long-limbed lizards that can climb tall buildings are just a few examples from the past few years.We tend to think of evolution as something that’s over. Something that’s done with. But that’s not always the case. In fact, everything around us is still evolving, and humans are becoming a much larger factor in that shift.These new results in the journal Science document dozens of examples of these changes, pulling from more than 192 studies across the world to demonstrate evolution that has been specifically molded to suit urban environments.What’s most interesting about urban areas is that they are an ecological niche that is totally engineered by humans. But they are prime targets for creatures for a few reasons. The first is that humans are really good at creating food for other things. We throw lots of stuff away, we’re profoundly wasteful, and we keep loads of relatively unguarded food in our homes.Combine that with a boosted mutation rate thanks to urban pollution, the isolating effects of highways and other city structures, and the introduction of really evolutionarily wonky things like bird feeders, and you’ve got a perfect recipe for ecological shifts in hundreds of cities across the globe.“I actually don’t like cities that much, but being a professor with a young family, I’m now kind of stuck in one of North America’s largest cities,” study co-author Marc Johnson told the CBC in an interview. “I started realizing there’s pretty amazing biology all around us, and we have very little understanding of how the development of cities and urbanization in general, which is happening throughout the world, is influencing not only the ecology but also the evolution of the organisms that live around us and sometimes even with and in some cases on or in us.”It’s important to note that these creatures are largely adapting to circumstance. When human beings started building stuff, we weren’t too keen on protecting the life that was already there. In the process, we kinda messed up a few things, and these animals have had to make these changes just to survive us. Not us hunting them, not us eating them, just… us being near them and living the way we do.“If it can’t adapt to the change in that urban environment, it will go extinct,” he says. “If it can adapt to the change in that environment, that may allow it to persist and then to have consequences for other members of the community and maybe the entire ecosystem.”One of the more unusual findings, according to Johnson, is that humans are evolving too. Especially in urban areas. The genes that protect against leprosy for example, are most prevalent in the world’s oldest cities. We’ve been evolving to compensate for greater density for a while. Not enough to form a new species, like some of these animals, but enough that it’s left indelible genetic markers.Every day I think things can’t get any more bizarre, and almost every day I’m even more amazed by how amazing the natural and biological world really is. Let us know what you like about Geek by taking our survey.