Higher social tolerance in wild versus captive common marmosets: the role of interdependence.

Social tolerance in a group reflects the balance between within-group competition and interdependence: whereas increased competition leads to a reduction in social tolerance, increased interdependence increases it. Captivity reduces both feeding competition and interdependence and can therefore affect social tolerance. In independently breeding primates, social tolerance has been shown to be higher in captivity, indicating a strong effect of food abundance.

Personality method validation in common marmosets (Callithrix jacchus): Getting the best of both worlds.

Animal personality, consistent interindividual differences in behavior through time, has been intensively studied across animal taxa and particularly in nonhuman primates. Two different methods have been used to study personality: questionnaires filled out by trusted raters, following the research tradition in human personality psychology, and behavioral observations or testing, based on the behavioral ecology research tradition. Systematic research of cross-method validity has, however, brought equivocal results.

The cooperative breeding perspective helps in pinning down when uniquely human evolutionary processes are necessary.

The cultural group selection (CGS) approach provides a compelling explanation for recent changes in human societies, but has trouble explaining why our ancestors, rather than any other great ape, evolved into a hyper-cooperative niche. The cooperative breeding hypothesis can plug this gap and thus complement CGS, because recent comparative evidence suggests that it promoted proactive prosociality, social transmission, and communication in Pleistocene hominins.

Preschool children fail primate prosocial game because of attentional task demands.

Various nonhuman primate species have been tested with prosocial games (i.e. derivates from dictator games) in order to better understand the evolutionary origin of proactive prosociality in humans.

Group service in macaques (Macaca fuscata), capuchins (Cebus apella) and marmosets (Callithrix jacchus): a comparative approach to identifying proactive prosocial motivations.

Proactive, that is, spontaneous, prosociality reflects a psychological interest in the welfare of others and has been reported in callitrichid monkeys, capuchin monkeys (Cebus apella), and humans, but not in chimpanzees. One explanation for the co-occurrence of proactive prosociality in these species is that it is linked to shared infant care (cooperative breeding); alternatively, it might merely reflect unusually high social tolerance or be mediated by advanced cognitive abilities. To date, distinguishing between these alternative explanations is difficult, partly because available evidence is restricted to only a handful of species and partly because methodological differences thwart comparisons across studies.

Dissociation between seeing and acting: insights from common marmosets (Callithrix jacchus).

Perception-based measures often reveal much earlier competencies than action-based approaches. We explored this phenomenon generally labeled as "knowledge dissociation" in 28 common marmoset monkeys (Callithrix jacchus) using a paradigm where subjects had to localize a food item dropped down an opaque tube. Experiments 1 and 2 assessed common marmoset monkeys' gravity bias in an action based version of the tubes task.

Cognitive consequences of cooperative breeding in primates?

Several hypotheses propose that cooperative breeding leads to increased cognitive performance, in both nonhuman and human primates, but systematic evidence for such a relationship is missing. A causal link might exist because motivational and cognitive processes necessary for the execution and coordination of helping behaviors could also favor cognitive performance in contexts not directly related to caregiving. In callitrichids, which among primates rely most strongly on cooperative breeding, these motivational and cognitive processes include attentional biases toward monitoring others, the ability to coordinate actions spatially and temporally, increased social tolerance, increased responsiveness to others' signals, and spontaneous prosociality.