This study examines the genetic history of ancient and modern Andean populations to the unique environmental conditions of the Atacama Desert over the past 7,000 years, with a focus on the effects of chronic arsenic exposure and the agricultural transition. Modern Andean populations exposed to arsenic in drinking water exhibit an enhanced capacity to metabolize this element, positioning this region as a valuable natural model for studying human adaptation to toxic environments. By functionally testing non-coding genetic variants from these populations, I identified higher enhancer activity associated with some of these unique Andean variants in a liver cell line, suggesting potential protective mechanisms against this environmental toxin. In parallel, I examined changes in oral microbiome composition across the agricultural transition in coastal populations, assessing how the shift to agro-maritime subsistence affected oral health and the emergence of oral pathogens such as Tannerella forsythia. These analyses demonstrate how ancient microbiome diversity may also reflect dietary patterns and lifestyle changes within the same time periods. Additionally, I reconstructed the maternal genetic history of ancient coastal groups using mitochondrial genomes, revealing both the persistence of early lineages and the presence of rare haplogroups that link these populations to some of the earliest lineages during the colonization of the Americas.
Together, these multidisciplinary analyses provide an integrative perspective on how humans have adapted genetically, microbially, and functionally to life in coastal environments marked by chronic arsenic exposure and dietary shifts.