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Cities Are One Big Evolutionary Experiment

Urbanization has unintended consequences on city-dwelling creatures, from the peppered moths of the Industrial Revolution to today’s pesticide-resistant bed bug.
Rapid development spells unintended consequences for winged denizens.
Rapid development spells unintended consequences for winged denizens.Courtesy of Jason Munshi-South and Marc Johnson

Historically, the most convincing case for evolution came from the the parts of the natural world left largely untouched by humans. It was, after all, on the isolated Galapagos Islands off the coast of Ecuador that finches—and their many different beaks—helped shape Charles Darwin’s famous theory back in the 1800s.

Even at the time, though, evidence for evolution could be found inside bustling and rapidly growing cities. Look no further than the peppered moths. Their white-and-black-speckled wings once helped them blend in with similarly colored trees. But as the Industrial Revolution covered those trees with soot, the moths with all-black wings (a genetic mutation) survived and passed on their genes. The moths eventually evolved to become all black in certain parts of England.