Peripheral forces: The growing impact of second-tier cities is narrowing the gap in research production [Comment]

International audience; Scientific production is undergoing a gradual process of democratization. Over the past 50 years, a growing number of cities and countries have joined the global scientific community, and are making a signifi-cant impact. A more balanced distribution of paper citations means greater equity between researchers regardless of their location. These changes have not gone unnoticed in traditional science hotspots, such as London, Paris and Tokyo, but those cities need not fear relinquishing their dominance in the foresee-able future. The observed spatial dispersal of knowledge production is driven by the emer-gence of new centres of higher education and innovation, not productivity losses at the top, and the newcomers have much ground to catch up.