Mateo Peñaherrera-Aguirre, PhD, currently serves as a research associate in the School of Animal and Comparative-Sciences Research at the University of Arizona, USA. His lines of scientific research include the evolution of lethal coalitional aggression in human and nonhuman animals, socioecological correlates of sociopolitical complexity, social biogeography, cliodynamics, and multilevel selection. Dr Peñaherrera-Aguirre has coauthored 65 peer-reviewed journal articles, 59 book chapters, and 3 books.
Steven C. Hertler, PsyD, serves as assistant professor in Saint Elizabeth University’s (USA) Psychology Department teaching assessment, methodology, and physiological psychology. He reads and writes about history as it documents war, pestilence, migration, famine, and agricultural innovations, among other topics. Dr Hertler has coauthored 33 peer-reviewed journal articles, 16 book chapters, and 6 books.