Social contributions to the foraging behavior of young wild golden lion tamarins (Leontopithecus rosalia): Age-related changes and partner preferences.

In cooperatively breeding species, group members other than the parents contribute to the care of the young. The costs and benefits to caregiving may vary with the type of care provided and with caregiver characteristics such as age, sex, reproductive status, and foraging ability. Here I examine the relative contributions of parents, helpers and same-aged twins to the foraging and feeding activities of the young in a longitudinal study of wild golden lion tamarins, specifically with regard to direct food transfer, tolerance for coforaging or cofeeding by immatures and signaling young as to the location of profitable prey-foraging sites.

Sibling sex, but not androgens, shapes phenotypes in perinatal common marmosets (Callithrix jacchus).

When offspring share a womb, interactions among fetuses can impart lasting impressions on phenotypic outcomes. Such intrauterine interactions often are mediated by sex steroids (estrogens and androgens) produced by the developing fetuses. In many mammals, intrauterine interactions between brothers and sisters lead to masculinization of females, which can induce fitness consequences.

Is tolerance really teaching?

Kline succeeds in demonstrating the value of an approach that integrates information from various scientific and social disciplines, but her framework does not uniformly provide clarity. Specifically, inclusion of situations in which knowledgeable individuals do not actively donate information is misguided. Passive tolerance by demonstrators should continue to be excluded from definitions of teaching, in order to focus on situations in which selection has favored behaviors that are specifically geared to promoting learning in others.

Progressive parenting behavior in wild golden lion tamarins.

Young primates in the family Callitrichidae (the marmosets and tamarins) receive extensive and relatively prolonged care from adults. Of particular note, callitrichid young are routinely provisioned until well after weaning by parents and helpers, which is in stark contrast to typical juvenile primates, who must acquire most of their food independently once they are weaned. Adults of some callitrichid species produce a specialized vocalization that encourages immature group members to take proffered food from the caller.

Parenting behaviour: babbling bird teachers?

One of humankind's most distinctive characteristics is our extended and complex period of child dependency. New research on a noisy African bird may help to shed light on how our unusual parenting behavior evolved.