The titi and owl monkeys of South America live in socially-monogamous groups where the male and female establish a pair bond and share parental duties. Why do males of these species mate in a monogamous relationship presumably foregoing other reproductive opportunities? And why are titi and owl monkey males such good fathers, investing heavily in the care of offspring that they cannot be certain they sired? Relying on ecological, behavioral and genetic data collected during 28 years from wild populations in Argentina, Peru and Ecuador. This lecture will discuss the role of food distribution, mate guarding and infant care in the evolution of pair-bonds, monogamy and paternal care. Recorded on 02/14/2025. (#40382)