Sudden Infant Death Syndrome

Sudden Infant Death Syndrome (SIDS, also called crib death) is a fatal syndrome affecting sleeping human infants under a year old, characterized by a sudden cessation of breathing. It occurs with a frequency of ~0.5% in industrialized countries. Recent evidence indicates that at least some cases result from leaving the infant face down on bedding to sleep alone (to promote deep sleep). It has been suggested that SIDS' uniqueness to humans may relate to infant control of breathing that develops between 2-4 months of age (the age at which the majority of SIDS cases occur) related to speech breathing adaptations.

Cases of SIDS have not been reported in captive great apes. This could be explained in part because great ape mothers share their nest with young up to 5 years, even if the mother has another infant. Additionally, parent-infant co-sleeping is assumed to be the sleep arrangement of prehistoric hominids given it is the sleep arrangement found in all hunter-gatherer societies and 76% of nonindustrialized societies. In keeping with this, cultures where co-sleeping is the norm show very low rates of SIDS.