Katie Hinde

Harvard University

 

Mother’s milk contributes directly and indirectly to the developing mammalian neonate. Milk glycans, specifically milk oligosaccharides, indirectly contribute by influencing microbial colonization of the neonate’s intestinal tract. Certain milk oligosaccharides competitively inhibit the attachment of pathogenic bacteria to infant intestinal epithelium, whereas others provide nutritive substrates for beneficial commensals that serve essential immunological roles and contribute to the bioavailability of ingested nutrients. In humans, milk oligosaccharides (HMO) are substantially more abundant and diverse than described in other primates, revealing their derivation in the hominin lineage. We hypothesized that HMO profiles would reflect subsistence strategies, important for shaping nutritional and disease ecology. Breast milk samples, collected using standardized methods, from mothers in Argentina, Bolivia, Tibetans in Nepal, Namibia, Philippines, Poland, and the US (N=152) reveal that the abundances of particular classes of glycans, as well as individual isomers, show substantial variation across populations. As predicted, HMO profiles clustered as a function of subsistence strategy; pastoralists, horticulturalists, shop-foragers, and urban populations were significantly different from one another in their HMO profiles (p<0.0001). These results suggest that subsistence strategy was a key feature of the adaptively relevant environment that favored the co-evolution of certain HMO profiles and possibly commensal microbiota.