Adoption among nonhuman primates (hereafter primates) has been widely reported, particularly in chimpanzees, renowned for their higher intelligence and well-developed cognition. In contrast to adoption in other Old World monkeys, this case of adoption in golden snub-nosed monkeys (Rhinopithecus roxellana) involves two infants associated with three units characterized by distinct social structures and reproductive functions. Consequently, this case extends beyond traditional hypotheses on allomaternal care and adoption—such as enhancing the fitness of adoptive mothers, fostering maternal behaviors, and improving fitness through social and individual interactions—to necessitate an association with the complex social structure characterized by hierarchical, multilevel composition, akin to human society, and intense sexual selection that frequently results in infanticide. Specifically, adopting an infant with a genetic link to the dominant male of the adopting female may reduce the risk of infanticide against her offspring that do not share a biological link with the dominant male. This adoption pattern suggests that golden snub-nosed monkeys may possess more sophisticated intelligence and cognition, characteristics supported by more developed brain structure and facial muscles than the other Old World monkeys.

Post-traumatic stress disorder (PTSD) is a severe psychiatric disorder, affecting approximately 25–35% of individuals exposed to significant psychological trauma. Despite extensive research, the underlying biological mechanisms of PTSD remain poorly understood, and the effectiveness of trauma-focused psychotherapeutic interventions is limited. To date, animal studies investigating trauma responses have primarily relied on rodent models, with the potential contributions of non-human primates relatively neglected. In this study, matched-control observations were employed to examine maternal caregiving behaviors, prosocial interactions, and responses to alarm calls in free-ranging golden snub-nosed monkeys (Rhinopithecus roxellana) before and after an infanticide event. Results indicated a significant decrease in prosocial behaviors among some mothers, accompanied by significant increases in caregiving behaviors, heightened responsiveness to alarm calls, and indications of low mood. These findings provide evidence of trauma-related behavioral changes in golden snub-nosed monkeys, underscoring their utility as a model for studying PTSD given the similarity to trauma responses observed in humans. Overall, this study provides a foundation for further investigation into the evolutionary and biological aspects of PTSD, as well as the interactions between species-specific trauma responses. Future research should explore the use of non-human primate models to deepen our understanding of PTSD mechanisms.

Background: Understanding the nasopharyngeal (NAS) and rectal (INT) microbiomes is critical to maintain host health. However, their functional roles in shaping microbial network structure and niche differentiation remain unexplored in most animal species, especially endangered primates. Here, we compared the NAS and INT microbiomes of golden snub-nosed monkeys (Rhinopithecus roxellana) using full-length 16S rRNA amplicon sequencing and metagenomics, focusing on taxonomic composition, functional profiles (KEGG, CAZy, PHI), and microbial co-occurrence networks. Results: Our results indicate that microbial community structure and diversity (Shannon evenness) differ significantly between the two niches. Taxonomically, both sequencing approaches consistently show that, at the relative-abundance level, NAS is dominated by genera such as Dolosigranulum and Vibrio, whereas the INT is characterized by Campylobacter, Helicobacter, and Aerococcus. Notably, metagenomic analysis indicates a relatively high abundance of potential pathogens, including Helicobacter pylori and Chlamydia psittaci. LEfSe analysis shows Dolosigranulum and Campylobacter are key microbial markers for the NAS and INT niches, respectively. KEGG pathway analysis reveals that the NAS microbiome is enriched in valine/leucine/isoleucine degradation and glutathione metabolism, while the INT microbiome is enriched in amino sugar and nucleotide sugar metabolism and ribosome pathways. At the CAZy level, all 29 differentially abundant families (e.g., GH13_29, GH103, AA3_2) were enriched in the NAS. Distinct pathogen–host interaction profiles further reflect niche-specific adaptations. Exploratory Spearman-based co-occurrence networks (in which no genus–CAZy edge survived Benjamini–Hochberg (FDR) correction) linked core commensals to KEGG pathways and CAZy families (e.g., GT35, GH0). In the INT, Campylobacter and Helicobacter form high-connectivity modules associated with pathways such as those involving the two-component system and ABC transporters. Conclusions: The nasopharyngeal and rectal microbiomes in golden snub-nosed monkeys differ not only taxonomically but also functionally, exhibiting clear spatially specialized functional differentiation. Given the small sample size (n = 8), these findings provide preliminary evidence for niche-specific microbial and functional partitioning and suggest that the nasopharynx may harbor a relatively high abundance of potential zoonotic pathogens. This study provides a basis for further exploration with a larger sample size.