From urban archeology to urban ecology: In Saturday's New York Times, there's a fascinating article about botanists' and zoologists' newfound interest in city environments. "Until recently," writes reporter Alexander Stille, "the only real environments thought worth studying were in 'pristine' nature, remote areas as far as possible from the footprint of human beings. Cities, by contrast, were seen as unnatural, nonenvironments, whose parks and gardens, ornamental plants and scraggly sidewalk trees and weeds were of as little interest to ecologists as house cats and lap dogs are to big game hunters." In the last 25 years, though, those assumptions were shaken by the discovery that "virtually all 'pristine' environments bore clear signs of human intervention: fires, the hunting of animals, the harvesting of plants, herbs, nuts or fruits." Meanwhile, cities contain much more biodiversity than previously assumed, undermining the conventional wisdom on everything from urban planning to invasive species.