" In science's pecking order, evolutionary biology lurks somewhere near the bottom, far closer to phrenology than to physics. For evolutionary biology is a historical science, laden with history's inevitable imponderables. We evolutionary biologists cannot generate a Cretaceous Park to observe exactly what killed the dinosaurs; and, unlike " harder" scientists, we usually cannot resolve issues with a simple experiment, such as adding tube A to tube B and noting the color of the mixture. "