If you’ve ever lived in a city, you’re pretty familiar with the fact that, at any one moment, there’s a lot going on. Too much, in fact. It’s ground zero for the FOMO disease. The party at the Standard. A stroll along the High Line. A gallery opening (and another and another and another). Baseball. Basketball. Brunch and dinner. After-work drinks with your co-workers. You get the picture. But did you ever consider the fact that something truly spectacular is happening right under your nose amidst all the exhaust fumes and traffic jams?
Menno Schilthuizen’s new book, Darwin Comes to Town (Picador, $27.00), dives into the phenomenon of urban evolution. Working its way from peppered moths to human beings, the book details the way cities alter the genetic make up of its inhabitants. It’s highly readable. It’s informative. It’s a great conversation starter. Most importantly, by the time you finish it, you’ll never look at asphalt streets and concrete corners the same way. You might even appreciate those pigeons a bit more.
SCIENTIFIC INQUIRER: Your book deals with the way urban environments can drive evolutionary change among organisms living there. You cite countless examples of adaptation. If you had to select one that perfectly embodies urban evolution, which would you choose and why?
MENNO SCHILTHUIZEN: My favorite example would be the urban blackbird in Europe, which is one of the best studied cases and also a species that has been urbanizing for 200 years already. That’s why we can see such an advanced stage of urban adaptation, which ranges from changes in appearance, migration, and breeding timing, to evolved personality and even song.
SCINQ: Why do you believe many people choose to exclude human beings, the cities they create, and its effects on its surroundings from being a part of nature? It seems like they consider humans as existing above nature.
MS: It may stem from the old idea that “nature” is noting more than the facilities that a Creator provided for His favorite creation, Man. Those engrained ideas will only slowly be replaced by a scientific worldview in which humans are just one (albeit quite extraordinary) species among many.
SCINQ: Do factors like city size and density influence urban evolution?
MS: The bigger and denser a city is, the greater the effects of, for example, the urban heat island, or pollution. Also, there are indications that bigger cities change faster than smaller ones. So, the drive to evolve is probably stronger there and also changes course more frequently.
SCINQ: Which is more sensitive to the changes that occur in cities, interspecies evolution or intraspecies?
MS: I’d say it is interspecies evolution, simply because, for example, predator-prey interactions provide two independently evolving units, whereas in intraspecies evolution, like male-female interaction, evolution has to work with a single genome, which means “compromises”.
SCINQ: You mention that the notion of preadaptability is a little controversial. Why is that?
MS: The notion itself is not very controversial, but rather the term, because it can be mistakenly interpreted as meaning that evolution can “think ahead”. Therefore, some authors prefer the term “predisposition”.
SCINQ: Urban evolution seems to spur rapid changes, faster than the classical textbook definition of evolution indicates. Does epigenetics play a role at all, particularly in species that revert back to their original phenotype after a few generations?
MS: For the few cases where urban evolution is seen to reverse (like in the peppered moth), it is certain that this change is purely genetic, rather than epigenetic. However, there probably is an important role for epigenetics in many other cases, though this has not yet been properly studied.
SCINQ: Humans have lived in urban environments for thousands of years, though obviously not in numbers like today. Are there any clues from ancient DNA that might indicate small genetic changes?
MS: There are some data that indicate that in early cities, humans evolved resistance against infectious disease more quickly than in rural areas. Obviously, in cities, it’s much easier for infections to spread.
SCINQ: What would you like your readers to take away most after reading your book?
MS: That evolution is a process that happens everywhere, all the time. It is going on in your bathroom, your garden, and the streets right outside your front door.
IMAGE CREDIT: Gijs Versteeg; Manfred Schulenberg; Benjamin J. de Benutzer; Ben Sale
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