Doctoral Dissertation Research: The influence of the social environment on the infant skin microbiome

Understanding the impact of human-environment interactions on early life development is a key area of interest for biological anthropology. The microbiome—the microorganisms (and their genes) that live in and on us—mediates many of these interactions, with effects on human biology and health. For example, early life diet and contact with other people shapes the infant microbiome, which directly impacts host physiology, including nutritional status and immune system function. Despite these important connections, we have only a basic understanding of how the microbiome is first established. Contact with mothers plays a role; however, unlike other great apes, humans are cooperative breeders, and mothers rely on alloparents (additional caregivers) for substantial infant care. As such, human infancy is highly social, and contact with alloparents, including through behaviors like holding and carrying, likely provides additional routes for alloparents to share skin microbes with infants. The proposed project takes a comparative approach to investigate how allocare influences the infant skin microbiome, with a focus on the factors that shape alloparent-infant social networks. Skin microbiome samples will be collected from infants, mothers, and alloparents in two populations in Veracruz, Mexico that display variation in patterns of allocare. Questionnaires will address allocare practices and additional exposures likely to influence the infant skin microbiome. Results of 16S rRNA bacterial gene sequencing will provide data on infant skin microbial community diversity and composition. Statistical models and social network analysis will quantify infant social environments, identify potential routes for microbial sharing, and test the effect of allocare on the infant skin microbiome (while controlling for potential additional microbial exposures). This project offers a novel perspective on the benefits of allocare to infants, and the results can help inte