Scientists usually study natural selection at a single level, such as genes or individuals or even a population, says (SFI External Professor) and biophysical complexity researcher Maya Paczuski -- but it takes place at all these levels simultaneously, and what happens at each scale resonates through the web of life in ways we're just beginning to comprehend. Paczuski, founder of the University of Calgary's Complexity Science Group, talked to Wired.com on the expansion of evolutionary theory to include complexity and emergence. These phenomena don't replace the classic mechanisms of genetic mutation and natural selection, but work with them; and accompanying this expanded conception of evolution is the multi-scale perspective espoused by Paczuski. "One of the things that complexity theory teaches us is that you have emergent properties -- like ecosystems -- so you have to think of selection happening at many different scales. That problem hasn't been addressed in any coherent way in scientific literature. It's one of the great complex problems of the future."