Yanomamo Practicing Combat (image) University of Utah Share Print E-Mail Caption In this mid-1960s photo, men from two Yanomamo villages in the Amazon engage in nonhostile combat to determine the strength and fighting prowess of potential alliance partners. A new study from the University of Utah and University of Missouri indicates the Yanomamo -- who engaged in killing to gain status in past decades -- often formed alliances with men in different villages when they attacked and killed people in other communities, then married their allies' sisters or daughters. The idea is they fought like a 'band of brothers-in-law' more than a closely related 'band of brothers,' fathers and sons from a single community. Credit Napoleon Chagnon Usage Restrictions Credit required. Share Print E-Mail 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.