The Concrete Jungle

Steve Winter/National Geographic/Getty Images
Leopard cubs at Sanjay Gandhi National Park, Mumbai, India, 2014

In 1965 the great British ecologist G. Evelyn Hutchinson, then Sterling Professor of Zoology at Yale, published an interesting little book, the very title of which was a good starting point for understanding the dynamics of life on Earth—life in the wild, life in the countryside, life in the city. Hutchinson called it The Ecological Theater and the Evolutionary Play. His title’s point was to distinguish environment from process and immediate interactions from trends of long-term change. Of course, an ecosystem also embodies processes: photosynthesis, herbivory, predation, and competition, among others. As creatures play those ecological roles, they interact, they struggle for survival, they strive to produce offspring, they succeed or they fail, and evolution is the broader result of such challenges, the grand arc of the tale, bending dramatically through time.

Evolution by natural selection, as Darwinians believed then, and had believed ever since Darwin stated it, moved “with extreme slowness.” He had stressed that point repeatedly in On the Origin of Species. “I do believe that natural selection will always act very slowly,” he wrote, and “we see nothing of these slow changes in progress, until the hand of time has marked the long lapse of ages.” Slow though evolution may be, with selection working on tiny incremental variations, “I can see no limit to the amount of change,” Darwin added, “which may be effected in the long course of time.” Another influential ecologist and a former student of Hutchinson’s, Lawrence Slobodkin, codified that idea of slowness in his (less poetically titled) book Growth and Regulation of Animal Populations, distinguishing there between “ecological time” (relatively short, reflecting little change in roles or relationships) and “evolutionary time,” measured in hundreds of millennia, time enough for incremental evolutionary change in one species or several to disrupt the ecological status quo.

Menno Schilthuizen is a Dutch biologist based at Leiden University, in a country whose population is more urban than rural. In other words, he inhabits the future. His new book, Darwin Comes to Town, implicitly answers Hutchinson and Slobodkin—and Darwin himself—alerting us to contrary evidence about the pace of evolution. By watching the evolutionary play as it runs in urban theaters, not just wildish ones, Schilthuizen and some colleagues—you might think of them as postmodern biologists, making the best of highly urbanized twenty-first-century landscapes—have noticed that evolution’s tempo can be surprisingly brisk.

Fast evolution in cities is the theme here, unfolding toward a suggestion that perhaps new species are being born in our time, while many older ones are being driven to extinction. For instance, has the Eurasian blackbird (Turdus merula) differentiated sufficiently—in certain urban environments where it enjoys warmer temperatures, abundant food scraps, and freedom from predators—to constitute a new species, which Schilthuizen would like to call Turdus urbanicus? Maybe, almost. “The…

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