A great challenge for ecology in the coming decades is to understand the role humans play in eco-evolutionary dynamics. We define eco-evolutionary dynamics as the interplay between ecology and evolution on contemporary time scales. Emerging evidence shows that evolution can happen at much shorter time scales than originally believed. If, as the evidence indicates, such rapid evolutionary change affects ecosystem functioning and stability, it might have significant implications for ecological processes and human well-being on a contemporary scale. Humans are some of the most potent drivers of natural selection, with the potential to create unprecedented evolutionary consequences for Earth’s ecosystems. In human-dominated environments such as cities, selection pressures acting on traits can affect population dynamics by changing organisms’ rates of survival or reproductive success, leaving a genetic signature that might affect community dynamics and ecosystem functions. As cities expand rapidly around the globe, urbanization is becoming a dominant cause of human-driven eco-evolutionary change.