Joachim Singelmann is Emeritus Professor of Sociology and Demography at the University of Texas at San Antonio, from where he retired in 2021. Prior to joining UTSA in 2011as chair of Demography, he served as the David J. Kriskovich Distinguished professor of Sociology and Director of the Louisiana Population Data Center at Louisiana State University. His areas of research include economic sociology and demography with emphasis on inequality between social classes, men and women, race and ethnic groups, and urban vs. rural settings. His previous positions were in the Population Division of the United Nations, and faculty appointments at the Universität Duisburg-Essen, Germany, the University of California San Diego, and Vanderbilt University. He was a visiting fellow at Wissenschaftszentrum Berlin (WZB), a well-known social science research center. He published five books, and his articles have appeared in the leading U.S., European, and Latin American social science journals. Dudley L. Poston, Jr., Ph.D. is Emeritus Professor of Sociology at Texas A&M University, College Station, USA. He retired from Texas A&M in May 2019. Prior to his retirement he also held the positions of Adjunct Professor of Demography, People’s (Renmin) University of China; Adjunct Professor of Sociology, Fuzhou University; and Adjunct Professor of Demography, Nanjing Normal University. In his 49+ years as a sociology faculty member at University of Texas at Austin (1970-1988), Cornell University (1988-1992) and Texas A&M University (1992-2019), he chaired the doctoral committees of 65 graduate students. During his career he taught demography and statistics classes to around 1,000 graduate students and around 5,000 undergraduate students. He has published 22 books and over 380 journal articles, book chapters and related reports.