Direct evidence of milk consumption from ancient human dental calculus

Milk is a major food of global economic importance, and its consumption is regarded as a classic example ofgene-culture evolution. Humans have exploited animal milk as a food resource for at least 8500 years, but theorigins, spread, and scale of dairying remain poorly understood. Indirect lines of evidence, such as lipidisotopic ratios of pottery residues, faunal mortality profiles, and lactase persistence allele frequencies,provide a partial picture of this process; however, in order to understand how, where, and when humansconsumed milk products, it is necessary to link evidence of consumption directly to individuals and theirdairy livestock. Here we report the first direct evidence of milk consumption, the whey proteinb-lactoglobulin (BLG), preserved in human dental calculus from the Bronze Age (ca. 3000 BCE) to thepresent day. Using protein tandem mass spectrometry, we demonstrate that BLG is a species-specificbiomarker of dairy consumption, and we identify individuals consuming cattle, sheep, and goat milkproducts in the archaeological record. We then apply this method to human dental calculus fromGreenland’s medieval Norse colonies, and report a decline of this biomarker leading up to the abandonmentof the Norse Greenland colonies in the 15th century CE.