Cities are often thought of as organisms or ecosystems, but the authors of a new study find that metaphor lacking. "The one thing that we know about organisms whether it be elephants or sharks or frogs, is that as they get large, they slow down. They use less energy, they don't move as fast. That is a very important point for biological scaling. In the case of cities, it is actually the opposite. As cities get larger they create more wealth and they are more innovative at a faster rate. There is no counterpart to that in biology."
