The caregiving/care-seeking balance in captive common marmosets (Callithrix jacchus)

A hypothesis to explain differences in infant social development in species with multiple caregivers is described. The hypothesis states that the distribution of an infant's time and activities amongst the individuals in its group is determined by the balance between the relative amounts of care-seeking by the infant and caregiving by the other members of the group. This generates several predictions that are investigated by experimentally reducing the care available to a group of infant common marmosets (Callithrix jacchus), and comparing their interactions with caregivers with those of a control group of infants that experienced normal levels of care. The results bear out several of the predictions. Infants receiving less care than usual spend less time in non-care-seeking activities and there are some increases in care-seeking behaviour. Infants continue to seek care differentially from different caregivers, and no compensation among caregivers in their behaviour towards infants is found.