From drains to bridges: The role of internationally mobile PhD students in linking non-mobile with foreign scientists

Studying and working abroad, internationally mobile scientists meet foreign scientists and become carriers of knowledge and foreign social capital. The benefits of scientific mobility may extend beyond those who experience it, benefiting non-mobile colleagues who collaborate with them. We investigate the role played by Colombian scientists who study abroad for a PhD in connecting non-mobile scientists with foreign scientists. Combining data from online CVs, scholarship programs, and Open Alex publications, we reconstruct the mobility path of 19,158 Colombian scientists and their co-authorship networks from 1990 to 2021. Our results show that coauthoring with mobile scientists increases the propensity of non-mobile scientists to collaborate with foreigners. While the diaspora has been seen as a brain drain, we find that not only returnees but also the diaspora itself can act as bridges connecting local and foreign scientists. However, foreign collaborations tend to be short-lived and sustained only by the mediation of a mobile scientist. Results also suggest that the largest effects stem from mobile scientists who have remained abroad or have a strong circulation pattern between countries (i.e., diaspora and intermittent scientists, respectively). Our paper contributes to the mobility literature by investigating the social capital spillovers generated by mobile scientists. It has also relevant policy implications. Our results call for increasing brain circulation while reducing brain drain by using flexible conditions to return to home countries and increasing the links between mobile and nonmobile scientists.