Diversity™ heaps limitless miseries upon the host nation. You don’t need social science studies to tell you that, (you can just go to a diverse part of town and experience the joylessness, tension, annoyances, stress, and general aesthetic dreariness for yourself), but when the ¡SCIENCE! is available it sure is fun to rub it in libfruit faces.
Happiness in modern society: Why intelligence and ethnic composition matter
Recent developments in evolutionary psychology suggest that living among others of the same ethnicity might make individuals happier and further that such an effect of the ethnic composition on life