In an effort to better understand variation in jealous response cross-culturally, the researchers of this study surveyed 11 different populations, eight of which were small-scale societies on five different continents (Mayangna, Shuar, Tsimane, Himba, Hadza, Karo Batak, Mosuo, and Yasawa) and three of which were in urban settings (Los Angeles, CA, "urban India" (online), and Okinawa, Japan). Looking at the differences between sexual and emotional infidelity, researchers found that greater paternal investment and lower frequency of extramarital sex are associated with more severe jealous response.