“…Scientists from various disciplines, such as economists and behavioural economists, psychologists and behavioural psychologists, biologists and evolutionary biologists, sociologists, anthropologists, ethnologists, political scientists, etc. have already used the norm of reciprocity as a basic motivational key factor for their investigations (Trivers, 1971;Axelrod, 1984;Cosmides and Tooby, 1989;Nowak and Sigmund, 1998;Komorita and Parks, 1999;Wedekind and Milinski, 2000;de Waal and Berfer, 2000;Sobel, 2005;Bicskei, Lankau and Bizer, 2016).…”