In this chapter, I argue that it is important to acknowledge variations in the way human and nonhuman animals interact with others, variations that result from the different ways in which different groups behave and adapt to their environments. I also explore the implications for comparative cognition of acknowledging these variations. I start by, first, examining how studies in nonhuman primates have been used as a biological foundation for the core ideas used to describe the mother-infant interaction and how these biological foundations are used to support universal statements about mother-infant interaction. I describe the limitations of creating and applying these universal statements. I then focus on other forms of universal statements found in the study of mother-infant interaction: describing the mother-infant interaction only from the perspective of Western-urban families. Through several examples, I examine the complexities of comparative studies and the difficulties of aiming to find commonalities and individual differences among different primates. I will argue for the importance of acknowledging variation among the behaviors of mothers and infants and the ways they interact in various groups, cultures, societies, and species.