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The Function of Chimpanzee Greeting Calls Is Modulated by Their Acoustic Variation

Signalling plays an important role in mediating social interactions in many animal species. For example, during approaches certain species produce ‘greetings’, which can take the form of vocal or visual signals, which reduce the probability of …

Systematic Mapping of Developmental Milestones in Wild Chimpanzees

Postnatal development is protracted relative to lifespan in many primates, including modern humans (Homo sapiens), facilitating the acquisition of key motor, communication and social skills that can maximize fitness later in life. Nevertheless, it …

Early Maternal Loss Affects Diurnal Cortisol Slopes in Immature but Not Mature Wild Chimpanzees

$$In mammals, early life adversity negatively affects survival and reproductive success. A key causal mechanism is proposed by the biological embedding model which posits that adversity experienced early in life has deleterious consequences on …

Patterns of Urinary Cortisol Levels during Ontogeny Appear Population Specific Rather than Species Specific in Wild Chimpanzees and Bonobos

Compared with most mammals, postnatal development in great apes is protracted, presenting both an extended period of phenotypic plasticity to environmental conditions and the potential for sustained mother-offspring and/or sibling conflict over …

Information Transfer Efficiency Differs in Wild Chimpanzees and Bonobos, but Not Social Cognition

Several theories have been generated to understand the socio-cognitive mechanisms underlying the unique cooperative abilities of humans. The ‘interdependence hypothesis' posits first, that the cognitive dimension of human cooperation evolved in …

Maternal Cannibalism in Two Populations of Wild Chimpanzees

Maternal cannibalism has been reported in several animal taxa, prompting speculations that the behavior may be part of an evolved strategy. In chimpanzees, however, maternal cannibalism has been conspicuously absent, despite high levels of infant …

Maternal Effects on Offspring Growth Indicate Post-Weaning Juvenile Dependence in Chimpanzees (Pan Troglodytes Verus)

In animals with altricial offspring, most growth occurs after birth and may be optimized by post-natal maternal care. Maternal effects on growth may be influenced by individual characteristics of the mothers, such as social status, individual …

Long-Term Repeatability in Social Behaviour Suggests Stable Social Phenotypes in Wild Chimpanzees

Consistent individual differences in social phenotypes have been observed in many animal species. Changes in demographics, dominance hierarchies or ecological factors, such as food availability or disease prevalence, are expected to influence …

Measuring Personality in the Field: An in Situ Comparison of Personality Quantification Methods in Wild Barbary Macaques (Macaca Sylvanus)

Repeatable Glucocorticoid Expression Is Associated with Behavioural Syndromes in Males but Not Females in a Wild Primate

Behavioural syndromes are a well-established phenomenon in human and non-human animal behavioural ecology. However, the mechanisms that lead to correlations among behaviours and individual consistency in their expression at the apparent expense of …