Yanomamo Warriors Dancing (IMAGE) University of Utah Caption Men from one Yanomamo village in the Amazon 'dance' in a neighboring village to show off their military prowess, weaponry and group cohesion after they were invited to a feast to form a coalition between the two communities. This photo dates from the late 1960s. A new study from the University of Utah and University of Missouri shows how the Yanomamo, whom once gained status by killing, formed 'bands of brothers-in-law' alliances between villages rather than fighting in more closely related 'bands of brothers' from a single village. Credit Napoleon Chagnon Usage Restrictions Credit required License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.