Early life environments shape the development of the microbiome, which in turn influences human biology and health outcomes. Since physiological development relies on microbiome maturation during infancy, there is growing interest in the environmental, cultural, and behavioral factors that impact early life microbial exposures. Drawing on theoretical frameworks from evolutionary medicine and community ecology, this talk presents recent findings that common birth practices—including antibiotic exposure and newborn bathing—are associated with differences in the composition of the skin microbiome in the first days of life. In line with previous work that identified an impact of C-section birth on the infant microbiome and health outcomes, these findings point to potential evolutionary mismatches in microbiome development that stem from variation in the birth environment. Applications of these findings to medical and public health interventions, including strategies to mitigate mismatches, will also be discussed.
