Parent-offspring facial resemblance increases with age in rhesus macaques

Chemical signatures of social information in Barbary macaques

Primates are well-known for their complex social lives and intricate social relationships, which requires them to obtain and update social knowledge about conspecifics. The sense of smell may provide access to social information that is unavailable in other sensory domains or enhance the precision and reliability of other sensory cues. However, the cognition of social information in catarrhine primates has been studied primarily in the visual and auditory domain. We assessed the social information content of body odor in a catarrhine primate, the Barbary macaque (Macaca sylvanus), in three semi-free ranging groups at Affenberg Salem, Germany. In particular, we related socially relevant attributes (identity, genetic relatedness, rank, sex, age, group membership) to chemical profiles of body odor. We applied non-invasive active sampling via thermal desorption tubes and analyzed samples by gas chromatography-mass spectrometry. We found robust evidence for individual odor signatures and limited support for kin signatures. Chemical profiles were also related to group membership, but little to rank, sex or age. The detected associations between chemical profiles and socially relevant attributes form the theoretical foundations for olfactory information transfer, highlighting the potential of body odor to provide valuable social information in this highly visually oriented primate.

Unveiling facial kinship: The BioKinVis dataset for facial kinship verification and genetic association studies

Facial image-based kinship verification represents a burgeoning frontier within the realms of computer vision and biomedicine. Recent genome-wide association studies have underscored the heritability of human facial morphology, revealing its predictability based on genetic information. These revelations form a robust foundation for advancing facial image-based kinship verification. Despite strides in computer vision, there remains a discernible gap between the biomedical and computer vision domains. Notably, the absence of family photo datasets established through biological paternity testing methods poses a significant challenge. This study addresses this gap by introducing the biological kinship visualization dataset, encompassing 5773 individuals from 2412 families with biologically confirmed kinship. Our analysis delves into the distribution and influencing factors of facial similarity among parent-child pairs, probing the potential association between forensic short tandem repeat polymorphisms and facial similarity. Additionally, we have developed a machine learning model for facial image-based kinship verification, achieving an accuracy of 0.80 in the dataset. To facilitate further exploration, we have established an online tool and database, accessible at http://120.55.161.230:88/.

Cryptic kin discrimination during communal lactation in mice favours cooperation between relatives

Breeding females can cooperate by rearing their offspring communally, sharing synergistic benefits of offspring care but risking exploitation by partners. In lactating mammals, communal rearing occurs mostly among close relatives. Inclusive fitness theory predicts enhanced cooperation between related partners and greater willingness to compensate for any partner under-investment, while females are less likely to bias investment towards own offspring. We use a dual isotopic tracer approach to track individual milk allocation when familiar pairs of sisters or unrelated house mice reared offspring communally. Closely related pairs show lower energy demand and pups experience better access to non-maternal milk. Lactational investment is more skewed between sister partners but females pay greater energetic costs per own offspring reared with an unrelated partner. The choice of close kin as cooperative partners is strongly favoured by these direct as well as indirect benefits, providing a driver to maintain female kin groups for communal breeding.

The interplay between father-adolescent phenotypic resemblance and interparental conflict in predicting harsh discipline

Phenotypic resemblance refers to the degree of physical and behavioral similarity between parent and child. Evolutionary approaches to the determinants of parenting have consistently found father-child phenotypic resemblance to serve as a risk factor for harsh discipline, but we still know little about the mechanisms underlying these associations. To address this gap in the literature, the present study employed a mediated moderation model to understand how interparental conflict and dysfunctional child-oriented attributions for children's misbehavior can help explain associations between father-child phenotypic resemblance and harsh discipline during the period of adolescence. Participants included 151 parents of adolescents (Mage = 12.3, range = 12-14) recruited from a northeastern region in the United States. Fathers reported on father-child phenotypic resemblance, interparental conflict, dysfunctional child-oriented attributions, and harsh discipline. Structural equation modeling analyses revealed a significant moderating role of interparental conflict in amplifying associations between phenotypic resemblance and harsh discipline in a for-better-and-for-worse manner over a 1-year period. In support of mediated moderation, we further found that the interaction between phenotypic resemblance and interparental conflict in predicting harsh discipline was partially accounted for by increases in dysfunctional child-oriented attributions over a 1-year period, which in turn, was associated with harsh discipline concurrently. Findings are discussed within evolutionary and developmental frameworks. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Parent-offspring facial resemblance increases with age in rhesus macaques

Kin recognition is a key ability which facilitates the acquisition of inclusive fitness benefits and enables optimal outbreeding. In primates, phenotype matching is considered particularly important for the recognition of patrilineal relatives, as information on paternity is unlikely to be available via social familiarity. Phenotypic cues to both paternal and maternal relatedness exist in the facial features of humans and other primates. However, theoretical models suggest that in systems with uncertainty parentage it may be adaptive for offspring to conceal such cues when young, in order to avoid potential costs of being discriminated against by unrelated adults. Using experienced human raters, we demonstrate in a computer-based task that detection of parent-offspring resemblances in the faces of rhesus macaques (Macaca mulatta) increases significantly with offspring age. Moreover, this effect is specific to information about kinship, as raters were extremely successful at discriminating individuals even among the youngest animals. To our knowledge, this is the first evidence in non-humans for the age-dependent expression of visual cues used in kin recognition.