Research focused on the exceptional degree of sociality characterizing the human species and many of the other primates has demonstrated clear, adaptive benefits to strong social bonds. These positive benefits include increased health, longevity, and reproductive success, as well as associated reductions in stress, increased resilience, and enhanced social learning. Such multiple and critically important benefits of strong social relationships suggest that there are evolved mechanisms underlying these adaptive consequences. Deciphering the core aspects of developmental origins and the mechanisms accounting for persistence of bonds throughout the lifetime of highly social females, however, is difficult in the complex, multilayered societies found in exceptionally long-lived species such as our own. This research therefore will examine the developmental and longitudinal aspects of female social bonds in a primate model, that of wild chimpanzees, the closest living relatives of humans. These primates also are long-lived, transient during their lifetimes, and characterized by complexly structured societies and relationships, with females developing strong affiliative and preferential bonds in their natal communities, before emigrating to new communities as adults and forming social relationships in this context. Utilizing a unique research design employing microbiome signatures indicative of female movements between their natal and adult communities, as well as genetic, behavioral, and hormonal data related to social bonding, the project will circumvent research limitations for such highly social females and permit addressing hypotheses relevant to understanding the relationships between social bonds, health and well-being. This interdisciplinary, collaborative research applies distinctly transformative microbiome and autosomal genotype-based analyses with behavioral and endocrinological studies to explain patterns of female immigration and the basis for, benefits of, and persistence of female bonds through their lifespan. Specifically, this study will conduct next generation, direct-DNA microbial and autosomal sequencing of over 1000 wild female chimpanzees to determine natal community origins, immigration patterns, and longitudinal perspectives of female sociality and relationships. To test the hypothesis that female social relationships are adaptive, the research will apply hormone analyses (cortisol, a stress marker, and oxytocin, a marker for bonding) to a subset of habituated females. This natural laboratory permits examination of the relationships between microbial variation and host genetics, biogeography, and relatedness (kinship), which will contribute to understanding the factors driving social relationships, host-microbial diversity, and associated health consequences. The expansive and diverse datasets generated through the research will be broadly disseminated, facilitating future research in multiple scientific areas. Associated training and collaboration will focus on both US and international collaborators and students, thereby enhancing research capacity. And as the wild primates serving as the model study species are critically endangered, the microbiome and dispersal patterns data will find application in promoting the health of the species and informing conservation policy, particularly in increasingly fragmented habitats.