The article says:

Why is beauty a productivity-enhancing attribute for males in non-quantitative subjects? Generally, it is difficult to disentangle the reasons behind why beauty improves productivity (Hamermesh and Parker, 2005). However, relative to other students, attractive men are more successful in peer influence, and are more persistent, a personality trait positively linked to academic outcomes (Dion and Stein, 1978, Alan et al., 2019). In addition, attractive individuals are more socially skilled, have more open social networks, and are more popular vis-à-vis physically unattractive peers (Feingold, 1992). Importantly, possession of these traits is significantly linked to creativity (Soda et al., 2021). In our setting, the tasks faced by students in non-quantitative subjects, for instance in marketing and supply chain management, are likely to be seen as more ”creative”, and significantly contrast the more traditional book-reading and problem-solving in mathematics and physics courses, the latter presumably perceived as more monotonous. Together with the large use of group assignments in non-quantitative courses, these theoretical results imply that socially skilled individuals are likely to have a comparative advantage in non-quantitative subjects.