Biology subjects

Rincon, A. V.

Publications and source records attributed to Rincon, A. V..

2 recordsLinked to original sources

bioRxiv2019

Testosterone and cortisol are negatively associated with ritualized bonding behavior in male macaques

Neuroendocrine research on the formation of social bonds has primarily focused on the role of nonapeptides. However, steroid hormones often act simultaneously to either inhibit or facilitate bonding. Testosterone is proposed to mediate a trade-off between male mating effort and nurturing behavior; therefore, low levels are predicted during periods of nurturing infant care and social bonding. In species where social bonding and support regulates hypothalamic-pituitary-adrenal axis activity, we also expect glucocorticoid levels to be low during bonding periods. We investigated how immunoreactive urinary testosterone (iuT) and cortisol (iuC) were related to triadic male-infant-male interactions - a ritualized male bonding behavior - as well as infant care in male Barbary macaques (Macaca sylvanus). We collected >3000 hours of behavioral observation data during full-day focal animal follows from 14 adult males and quantified iuT and iuC from 650 urine samples. As predicted, both iuT and iuC were negatively correlated with rates of triadic interactions within-subjects in the hours preceding urination. We found no relationship between iuT and iuC with triadic interactions between-subjects. Infant care was weakly positively correlated to iuT and iuC within-subjects, but not between-subjects. The observed negative relationship between iuT and triadic interactions may be beneficial to lower competitive tendencies between adult males and to not inhibit bond formation. Lowered iuC could reflect increased bonding and perceived social support as triadic interactions predict future coalition formation in this species. Additionally, lowered iuC may be reflective of buffered tensions between males. The positive relationship of iuT and iuC with infant care suggests that the handling of infants in may be less nurturing but rather protective or competitive in this species. Measuring steroid hormones in relation to bonding and nurturing can help us interpret behaviors within the ecological contexts that they occur.

animal behavior and cognition↗

bioRxiv2019

Oxytocin increases after affiliative interactions in male Barbary macaques

Mammals living in stable social groups often mitigate the costs of group living through the formation of social bonds and cooperative relationships. The neuropeptide hormone oxytocin (OT) has been proposed to promote both bonding and cooperation although only a limited number of studies have investigated this under natural conditions. Our aim was to assess the role of OT in bonding and cooperation in male Barbary macaques (Macaca sylvanus). First we tested for an effect of affiliation - grooming and triadic male-infant-male interactions - with bond and non-bond partners on urinary OT levels. Secondly we aimed to test whether grooming interactions (and thus increased OT levels) increase a males general propensity to cooperate in polyadic conflicts. We collected behavioral data via full-day focal animal protocols on 14 adult males and measured endogenous OT levels from 139 urine samples collected after affiliation and non-social control periods. Urinary OT levels were higher after grooming with any partner. By contrast, OT levels after male-infant-male interactions with any partner or with bond partners were not different from controls but were higher after interactions with non-bond partners. Previous grooming did not increase the likelihood of males to support others in conflicts. Collectively, our results support research indicating that OT is involved in the regulation of adult social bonds, including in non-reproductive contexts. However, our male-infant-male interaction results go against previous studies suggesting that it is affiliation with bond rather than non-bond partners that trigger the release of OT. Alternatively, OT levels may have been elevated prior to male-infant-male interactions thus facilitating interaction between non-bond partners. The lack of an association of grooming (and by extension increased OT levels) and subsequent support speaks against an OT linked increase in the general propensity to cooperate, yet further studies are needed for a more direct test including the possibility of partner-specific contingent cooperation.

animal behavior and cognition↗