From sugar to starch: Detecting diet shifts during human evolution

What did our ancestors eat? It is a challenging question because feeding behaviors seldom fossilize. How, then, do we identify the foods and dietary preferences that fueled the origin and evolution of our human lineage? Here I evaluate three complementary methods and their inferential limits. First, mechanical testing of edible plant tissues—including rainforest fruits and underground storage organs—is useful for establishing the processing (chewing) abilities of hominin teeth and jaws. Second, stable isotope analyses of modern and fossil ecological analogs can distinguish between diets premised on below- or above-ground plant tissues, especially those in savanna-woodlands. Third, comparative genomics, exemplified by copy-number variation of the salivary amylase gene (AMY1), can detect signatures of dietary starch adaptation that persist in human populations today. No single method is decisive, but their convergence provides a rigorous, testable framework for reconstructing pivotal dietary transitions during human evolution.