Why do mothers cradle babies on their left?

Many explanations have been put forward for the observed preference of mothers to cradle babies on the left side. These include handedness, the importance of the maternal heartbeat, left breast sensitivity, socio-psychological factors, and advantages in monitoring the infant. We propose that protection and facilitation of affective communication is at the core of cradling; and explore the relation between left-cradling and the role of the right hemisphere in early mother-infant interaction. Left-cradling not only directs maternal communication to the infant's right hemisphere but also facilitates affective feedback to the maternal right brain. The underlying neuro-linguistic mechanisms proposed in this article may be important in the early course of child language development and may also serve to illuminate our understanding of the evolution of human language.