Parent-infant synchrony during social interaction exerts a critical influence on the healthy development of children. There is limited understanding of how synchrony may be influenced by mothers' history of childhood adversity. We evaluated the efficacy of a behavioral intervention, Massage+, on mother-infant synchrony among first-time mothers with childhood adversity. Adult pregnant women with adverse childhood experiences scores of ≥ 2 were enrolled in this longitudinal study. At birth, mothers and their full-term infants (N = 213) were randomized to the Massage+ group or the attention control group learning safe infant care. Mothers performed daily Massage+, which included talking to their infants, moderate touch stroking, looking at, and rocking their infant. At 3 months, mother-infant synchrony was microcoded for gaze, affect, vocalization, and touch from video recordings of a free-play interaction (N = 162). Compared with control dyads, the Massage+ dyads exhibited more co-occurring affect synchrony, touch synchrony, and maternal engagement with high infant arousal synchrony. Massage+ dyads also exhibited more sequential synchrony and faster time-to-first initiation of synchrony. When infants expressed positive arousal, Massage+ dyads were better able to increase the amount of synchrony, coordinate synchrony by mothers immediately responding to their infant's positive cues, and more quickly settle into synchrony. Encouraging positive affect is among the most critical early functions of synchrony. Future research warrants studying long-term benefits of Massage+ when implemented in real-world settings. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Intraspecific variation in social organization (IVSO) within primate populations can arise due to male mating competition. Verreaux's sifaka (Propithecus verreauxi) populations exhibit both single-male and multi-male groups, providing an opportunity to examine the relationship between male competitive ability and social organization. We predicted that males in single-male groups have traits for excluding competitors compared with dominant males in multi-male groups. We analyzed skeletal and muscular measurements, along with body mass and canine length, from 18 adult male sifaka studied at the Ankoatsifaka Research Station in Kirindy Mitea National Park, Madagascar, between 2007 and 2024. Multivariate patterns of limb morphology associated with fighting and chasing ability were summarized using principal component analysis (PCA), and the first two PCA-derived axes, together with body mass and canine length, were used as predictors in Bayesian logistic regression models of group membership. No morphological trait or PCA-derived component showed a consistent association with group type, with posterior credible intervals overlapping zero. Consequently, variation in male skeletal and muscular morphology alone is insufficient to explain IVSO. Together, these results indicate that although PCA-derived axes capture structured variation in overall limb configuration and proximal-distal functional trade-offs related to fighting and chasing ability, social organization is not determined by male morphology alone, underscoring the importance of female influence and dynamic behavioral and physiological pathways in shaping intraspecific variation in social organization.

Objectives Contest competition for mates and female reproductive energetics influence body size and sexual dimorphism across many primates; nevertheless, some monomorphic species defy these patterns. These deviations may reflect biological anthropology's focus on body mass and adult size as defining features of sexual dimorphism. Using ontogenetic data, we test whether sexual monomorphism in adult body mass necessitates monomorphism across all traits and evaluate whether mate competition and female energetics explain sex-specific developmental patterns and adult morphology in a monomorphic primate.Materials and Methods We built sex-specific growth curves using generalized additive mixed models to examine levels of sexual dimorphism in 14 morphological measurements across development in Verreaux's sifaka (Propithecus verreauxi) at Ankoatsifaka Research Station in western Madagascar.Results Sifaka exhibited male-biased dimorphism in upper arm and thigh circumference at adulthood and across growth, but not in other contest-related traits. Adult females had significantly longer hindlimbs and thighs and exhibited bimaturism and increased growth rate in these and several other traits.Discussion We found limited support for our hypotheses that female reproductive energetics or male-male contest competition drive adult size, sex differences, and growth trajectories in Verreaux's sifaka. However, male-male contest competition likely drives male-biased dimorphism in muscle mass, and longer female hindlimbs may represent an adaptation to infant carrying, reflecting a species-specific suite of dimorphic traits. This study demonstrates that sexual dimorphism exists at finer scales even in monomorphic species, and that adult size and sex differences are the result of a mosaic of selective pressures acting on individual traits.

Primates are adept at dealing with fluctuating availability of resources and display a range of responses to minimize the effects of food scarcity. An important component of primate conservation is to understand how primates adapt their foraging and ranging patterns in response to fluctuating food resources. Animals optimize resource acquisition within the home range through the selection of resource-bearing patches and choose between contrasting foraging strategies (resource-maximizing vs. area-minimizing). Our study aimed to characterize the foraging strategy of a folivorous primate, Verreaux's sifaka (Propithecus verreauxi), by evaluating whether group home range size varied between peak and lean leaf seasons within a seasonally dry tropical forest in Madagascar. We hypothesized that Verreaux's sifaka used the resource maximization strategy to select high-value resource patches so that during periods of resource depression, the home range area did not significantly change in size. We characterized resource availability (i.e., primary productivity) by season at Kirindy Mitea National Park using remotely-sensed Enhanced Vegetation Index data. We calculated group home ranges using 10 years of focal animal sampling data collected on eight groups using both 95% and 50% kernel density estimation. We used area accumulation curves to ensure each group had an adequate number of locations to reach seasonal home range asymptotes. Neither 95% home ranges nor 50% core areas differed across peak and lean leaf resource seasons, supporting the hypothesis that Verreaux's sifaka use a resource maximization strategy. With a better understanding of animal space use strategies, managers can model anticipated changes under environmental and/or anthropogenic resource depression scenarios. These findings demonstrate the value of long-term data for characterizing and understanding foraging and ranging patterns. We also illustrate the benefits of using satellite data for characterizing food resources for folivorous primates.

Oxytocin pathways are hypothesized to play important roles in human-animal interactions and may contribute to some benefits of these interspecific social relationships. We explored the effects of naturalistic interactions between children and dogs on oxytocin release in both species, as well as associations between methylation of the oxytocin receptor gene (OXTRm), social behavior, and oxytocin response in this context. Children (N = 55) participated in a within-subjects design involving a) interaction with their pet dog, b) interaction with an unfamiliar dog, and c) a nonsocial control condition (solitary play). We used immunoassays to measure salivary and urinary oxytocin in both the children and dogs, behavioral coding to characterize dog-child interactions, and bisulfite sequencing to quantify methylation of the oxytocin receptor gene (n = 32 children). Child salivary oxytocin decreased moderately across time in all conditions, but the extent of this effect varied between conditions, with greater oxytocin output during interactions with dogs than the control condition. In the pet dog condition, children’s salivary oxytocin response was positively associated with the duration of visual co-orientation between the child and dog. Child urinary oxytocin did not deviate substantially from baseline in any condition. Children with higher levels of OXTRm had greater oxytocin output during interactions with their pet dogs, but lower oxytocin output in the control condition, and engaged in lower levels of affectionate interaction with dogs across conditions. Children’s pet dogs exhibited increases in salivary oxytocin, but we observed the opposite pattern in the unfamiliar dog, who exhibited decreases in both urinary and salivary oxytocin on average. Collectively, our results support the hypothesis that oxytocin pathways may shape and respond to social interactions between children and dogs, highlighting an important role for companion animals in child development.

Global warming is changing habitats and affecting biodiversity, and is expected to exacerbate aridification in many regions. Animals and plants in seasonally dry tropical forests often exhibit adaptations to cope with seasonal resource limitation. However, whether these adaptations will facilitate drought tolerance or increase drought vulnerability is unclear. Here, we combine long-term individual-based data on phenology, morphometrics, and demographics to investigate how drought impacts the food resources, health, reproduction, and behavior of a population of Verreaux's sifaka (Propithecus verreauxi), a critically endangered lemur inhabiting dry deciduous forests in Madagascar. Between December 2010 and May 2023, the population experienced 3 years of severe drought (2016, 2017, 2022). During green periods in severe drought, the availability of high-quality sifaka foods (young leaves, fruit) was significantly reduced and fruit tree mortality increased. This reduced availability of fruit persisted in the year after a drought, despite typical rainfall. Yet surprisingly, we found no negative effects on body condition or commonly-used metrics for reproductive success during drought years or years following a drought. Instead, sifaka exhibited significantly higher levels of subcutaneous body fat during severe droughts. We observed little change in sifaka behavior between drought and non-drought periods. However, they were more likely to lick dew during severe drought, and spent significantly less time feeding on young and mature leaves. They also significantly increased their time feeding on flowers and fruits, despite the reduced abundance of fruit in the habitat. Together, our results suggest that increased consumption of water-rich fruit and flowers during severe droughts could facilitate physiological mechanisms that help sifaka cope with water scarcity, including fructose-mediated fat storage, metabolic water production, and water conservation. These results provide new insights into how critically endangered animals may respond to climate change, suggesting that behavioral and physiological adaptations to seasonal resource limitation may buffer some mammals from the effects of severe drought or other extreme weather events.

The gut microbiome is a plastic phenotype; gut microbial composition is highly variable across an individual host's lifetime and between host social groups, and this variation has consequences for host health. However, we do not yet fully understand how longitudinal microbial dynamics and their social drivers may be influenced by ecological stressors, such as habitat degradation. Answering these questions is difficult in most wild animal systems, as it requires long-term collections of matched host, microbiome, and environmental trait data. To test if temporal and social influences on microbiome composition differ by the history of human disturbance, we leveraged banked, desiccated fecal samples collected over 5 months in 2004 from two ecologically distinct populations of wild, red-bellied lemurs (Eulemur rubriventer) that are part of a long-term study system. We found that social group explained more variation in microbiome composition than host population membership did, and that temporal variation in common microbial taxa was similar between populations, despite differences in history of human disturbance. Furthermore, we found that social group membership and collection month were both more important than individual lemur identity. Taken together, our results suggest that synchronized environments use can lead to synchronized microbial dynamics over time, even between habitats of varying quality, and that desiccated samples could become a viable approach for studying primate gut microbiota. Our work opens the door for other projects to utilize historic biological sample data sets to answer novel temporal microbiome questions in an ecological context.

Although research has shown that pets appear to provide certain types of social support to children, little is known about the physiological bases of these effects, especially in naturalistic contexts. In this study, we investigated the effect of free-form interactions between children (ages 8 -10 years) and dogs on salivary cortisol concentrations in both species. We further investigated the role of the child-dog relationship by comparing interactions with the child 's pet dog to interactions with an unfamiliar dog or a nonsocial control condition, and modeled associations between survey measures of the human -animal bond and children 's physiological responses. In both children and dogs, salivary cortisol decreased from pre- to post-interaction; the effect was strongest for children interacting with an unfamiliar dog (compared to their pet dog) and for the pet dogs (compared to the unfamiliar dog). We found minimal evidence for associations between cortisol output and behaviors coded from video, but children scoring higher on survey measures of the human -animal bond exhibited the greatest reductions in cortisol when interacting with dogs. Self-reported loneliness was not related to cortisol or the human -animal bond, but measures of both loneliness and the human -animal bond were higher among children who participated after the onset of the COVID-19 pandemic, relative to those who participated before the pandemic. This study builds on previous work that investigated potential stress-buffering effects of human -animal interaction during explicit stressors and demonstrates important physiological correlates of naturalistic interactions between children and dogs, similar to those that occur in daily life.

Primates exhibit diverse social systems that are intricately linked to their biology, behavior, and evolution, all of which influence the acquisition and maintenance of their gut microbiomes (GMs). However, most studies of wild primate populations focus on taxa with relatively large group sizes, and few consider pair-living species. To address this gap, we investigate how a primate's social system interacts with key environmental, social, and genetic variables to shape the GM in pair-living, red-bellied lemurs (Eulemur rubriventer). Previous research on this species suggests that social interactions within groups influence interindividual microbiome similarity; however, the impacts of other nonsocial variables and their relative contributions to gut microbial variation remain unclear. We sequenced the 16S ribosomal RNA hypervariable V4-V5 region to characterize the GM from 26 genotyped individuals across 11 social groups residing in Ranomafana National Park, Madagascar. We estimated the degree to which sex, social group identity, genetic relatedness, dietary diversity, and home range proximity were associated with variation in the gut microbial communities residing in red-bellied lemurs. All variables except sex played a significant role in predicting GM composition. Our model had high levels of variance inflation, inhibiting our ability to determine which variables were most predictive of gut microbial composition. This inflation is likely due to red-bellied lemurs' pair-living, pair-bonded social system that leads to covariation among environmental, social, and genetic variables. Our findings highlight some of the factors that predict GM composition in a tightly bonded, pair-living species and identify variables that require further study. We propose that future primate microbiome studies should simultaneously consider environmental, social, and genetic factors to improve our understanding of the relationships among sociality, the microbiome, and primate ecology and evolution.

AbstractBackgroundAlthough treatment for opioid use disorder (OUD) often yields high adherence during pregnancy, the risk of returning to opioid misuse during postpartum is high. There are currently no relapse prevention programs tailored to this unique time period.ObjectivesUsing a prospective cohort study, we seek to identify hormones and/or infant caregiving approaches as predictors of postpartum opioid misuse. As a first step in dissemination of results, this report contains a detailed account of the protocol, as well as recruitment, retention, compliance, and participant satisfaction.PopulationParticipants were individuals with OUD (OUD+) and those without (OUD−) who were followed from late pregnancy (≥gestational week 36) to postpartum month five.MethodsFrom childbirth to postpartum week 12, participants completed daily surveys (capturing use, craving, interactions with infant) and weekly face-to-face visits (including collection of biological samples for hormone assays). Follow-up visits using the same procedures occurred at postpartum month four and five.Preliminary ResultsA total of 50 OUD+ and 21 OUD− participants enrolled, 93% notified the study staff of childbirth, 87% completed at least one postpartum clinic visit, and 73% completed through postpartum month five. Compliance with procedures ranged from 66% for saliva samples and daily surveys to 78% for weekly surveys, generally with lower compliance among OUD+ and at later study time points. Participants, regardless of group and time point, reported high study satisfaction (e.g., on a scale where 0 is “not at all” and 3 is “extremely”, on average participants reported 2.9±0.4 for their willingness to complete this study again).ConclusionsThis prospective cohort study was well tolerated despite the challenging postpartum period. Data collected will provide ample opportunities to identify novel risk/protective factors to inform the development of new relapse prevention intervention programs specific to the needs of those with OUD during early postpartum.SynopsisUsing a novel protocol with daily surveys plus weekly face-to-face visits with biological sample collection from late pregnancy through 12 weeks postpartum, we report on the compliance with data collection methodologies over time between those with and without opioid use disorder. We observed fairly high levels of retention (e.g., 75% completed through postpartum week 12) and compliance (e.g., 69% of weekly dried blood spots were collected) with very high satisfaction (e.g., on a scale where 0 is “not at all” and 3 is “extremely”, on average, participants reported 2.9±0.4 for their willingness to participate again). These observations suggest that both those with and without opioid use disorder are willing and able to participate in an intensive, multi-method, prospective study during the early postpartum period.

Oxytocin and cortisol are hormones that can influence cognition and behavior, but the relationships between endogenous concentrations and individual differences in cognitive and behavioral phenotypes remain poorly understood. Across mammals, oxytocin has important roles in diverse social behaviors, and in dogs, it has been implicated in human-oriented behaviors such as social gaze and point-following. Cortisol, an end-product of the hypothalamic-pituitary-adrenal (HPA) axis, is often studied in relation to temperament and emotional reactivity, but it is also known to modulate executive functions. In this study, we measured basal fecal cortisol (n = 247) and plasma oxytocin (n = 249) in dog puppies from a pedigreed population (Canine Companions (R)). We collected cognitive and behavioral data from these subjects (n = 247), including measures of human-oriented social cognition, memory, inhibitory control, perceptual discriminations, and temperament. Oxytocin concentrations were estimated to be very highly heritable (h2 = 0.90-0.99) and cortisol concentrations were estimated to be moderately-highly heritable (h2 = 0.43-0.47). Bayesian mixed models controlling for relatedness revealed that oxytocin concentrations were positively associated with spatial working memory and displayed a negative quadratic relationship with behavioral laterality, but no credible associations were seen for social measures. Cortisol concentrations exhibited a negative linear relationship with performance on an inhibitory control task and a negative quadratic relationship with bold behavioral reactions to a novel object. Collectively, our results suggest that individual differences in oxytocin and cortisol concentrations are under strong genetic control in dogs and are associated with phenotypic variation in aspects of temperament, behavioral laterality, and executive function.

Measuring glucocorticoids is one of the most reliable and widely used techniques to monitor stress responses, however invasive techniques to collect plasma samples may not be applicable for wild populations. Monitoring excreted glucocorticoids is an effective noninvasive technique that researchers have used increasingly over the past two decades, and it has allowed the investigation of glucocorticoids in a variety of species with a range of activity patterns. Many species exhibit predictable circadian patterns of glucocorticoid secretion in accordance with their daily activity pattern. There remains a gap in our understanding of how excreted glucocorticoid metabolites vary throughout the day and across species, despite the utility of this information when developing sampling protocols and analyzing data. We investigated circadian patterns of glucocorticoid excretion in a cathemeral primate species, Eulemur rubriventer (red-bellied lemur), in Ranomafana National Park, Madagascar. We collected fecal samples from 10 individuals throughout the day and analyzed fecal glucocorticoid levels across three time points (Early, Midday, and Late), and again across two time points (Morning and Afternoon). We also investigated whether activity pattern, sex (as a control variable), and other traits associated with gut passage rate (diet, body mass) could help predict the presence and timing of circadian patterns of fecal glucocorticoid metabolites across mammal species. We found that fecal glucocorticoid metabolite levels in E. rubriventer fluctuate throughout the day, with lowest levels in the morning and peak levels in the afternoon. None of the variables that we tested predicted whether daily fecal glucocorticoid metabolites changed significantly throughout the day, nor when levels were likely to peak, across species. We stress the importance of controlling for sampling time and reporting these results as standard practice in studies of fecal glucocorticoid metabolites.

Oxytocin is a pleiotropic neuropeptide that plays roles in biological processes ranging from birth, lactation, and social bonding to immune function, cardiovascular repair, and regulation of appetite. Although measurements of endogenous oxytocin concentrations have been performed for more than 50 years, the ability to measure oxytocin accurately poses notable challenges. One potential solution for overcoming these challenges involves measurement of oxytocin's carrier molecule - neurophysin I (NP-1) - as a surrogate biomarker. NP-1 is secreted in equimolar concentrations with oxytocin but has a longer half-life, circulates in higher concentrations, and can be measured using a sandwich immunoassay. We report experiments that 1) analytically validate a commercially available NP-1 sandwich immunoassay for use with human plasma and urine samples, 2) confirm the specificity of this assay, based on detection of NP-1 in plasma from wild-type but not oxytocin knockout mice, 3) demonstrate that NP-1 concentrations are markedly elevated in late pregnancy, consistent with studies showing substantial increases in plasma oxytocin throughout gestation, and 4) establish strong correlation between NP-1 and plasma oxytocin concentrations when oxytocin is measured in extracted (but not non-extracted) plasma. The NP-1 assay used in this study has strong analytical properties, does not require time-intensive extraction protocols, and the assay itself can be completed in < 2 h (compared to 16-24 h for a competitive oxytocin immunoassay). Our findings suggest that much like copeptin has become a useful surrogate biomarker in studies of vasopressin, measurements of NP-1 have similar potential to advance oxytocin research.

The COVID-19 pandemic caused by the SARS-CoV-2 virus brought many primatology research programs and conservation efforts to a halt. After Madagascar closed its borders during March 2020, many on-site international project leaders and researchers returned to their home countries when their programs were delayed or canceled. Madagascar remained closed to travelers until November 2021, when it reopened to international flights. The 20-month absence of international researchers allowed many local Malagasy program staff, wildlife professionals, and community leaders to step into new leadership roles and responsibilities. Many programs that already had strong Malagasy leadership and meaningful collaborations with local communities flourished, while others either swiftly strengthened these attributes or faced challenges from pandemic-related travel restrictions. Here, we describe how the coronavirus pandemic events of 2020-2021 initiated long-overdue shifts in outdated models of internationally led primate research and education projects in communities living alongside primates at risk of extinction. We discuss the benefits and challenges of pandemic-induced changes within five primatological outreach projects, as well as how we can use these experiences to improve community-led environmental education and conservation awareness in the future.

Fathers contribute substantially to infant care, yet the mechanisms facilitating paternal bonding and interactions with infants are not as well understood as they are in mothers. Several hormonal changes occur as males transition into parenthood, first in response to a partner's pregnancy, and next in response to interacting with the newborn. These changes may prepare fathers for parenting and help facilitate and maintain paternal care. Experimental studies with monkeys and rodents suggest that paternal care requires elevated estradiol levels, which increase when a male's partner is pregnant and are higher in fathers than non-fathers, but its role in the expression of paternal behaviors throughout infant development is unknown. To assess estradiol's role in paternal care, we analyzed the relationship between paternal estradiol metabolites and 1) offspring age, and 2) paternal care behavior (holding, carrying, huddling, playing, grooming), in wild, red-bellied lemurs (Eulemur rubriventer). We collected 146 fecal samples and 1597 h of behavioral data on 10 adult males who had newborn infants during the study. Estradiol metabolites increased four-fold in expectant males, and in new fathers they fluctuated and gradually decreased with time. Infant age, not paternal behavior, best predicted hormone levels in new fathers. These results suggest that hormonal changes occur in expectant males with facultative paternal care, but they do not support the hypothesis that estradiol is directly associated with the day-to-day expression of paternal care. Future research should explore estradiol's role in facilitating behaviors, including infant-directed attention and responsiveness, or preparing fathers for infant care generally.