PSTC Faculty Associate Stephen McGarvey, a Professor of Epidemiology and Anthropology and the Director of the International Health Institute, has spent most of his career studying the nutritional and health transitions in low- and middle-income countries, focusing particularly on Samoan populations and how demographic and economic factors contribute to their rising rates of non-communicable diseases. His recent work has used advances in genomic science to study Samoan population health, including a 2016 publication in Nature Genetics that examined genetic contributors to high levels of obesity among Samoans.

In “Evolutionary history of modern Samoans,” recently published in the Proceedings in the National Academy of Sciences (PNAS), McGarvey and colleagues used archaeological records and genome sampling of Samoans to understand the relationship between rare genetic variants and the small population size of the initial Samoan settlement. This study differs from his past work because it considers the role of the earliest Samoan population in modern health outcomes. McGarvey remarked, “Our past studies emphasized the concrete associations of specific gene variants, or combinations of them, with health conditions, or risk factors mainly for cardiometabolic diseases such as obesity, hypertension, type 2 diabetes, and blood lipids. This new report suggests that due to Samoan population history, genetic influences stemming from small founding population sizes must be strongly considered.”

Regarding environmental conditions that may explain the small size of early Samoan populations, McGarvey explained that the population “may have been susceptible to natural selection forces related to any number of environmental stressors,” including “food availability in the new floral and faunal assemblies of that time and place, infectious diseases, and local and regional climatic events and trends such as cyclones, sea level changes and climate changes in the last 3,000 years. These shape the genetic variation of Samoans in ways we don’t understand and will influence biological susceptibility to a range of infectious and non-communicable diseases in the past and the contemporary time.”

He also reflected on the consequences of this recent study on future inquiries into population health. “The new and growing fields of genomic medicine and public health genetics must contain more and widely representative genomic information from all over the world, and not just from European and European-derived populations. The Samoan findings point to the critical importance of a deeper ethical engagement in genetic/genomic studies.”