Katherin Amato

KATHERINE R. AMATO, Northwestern University, Evanston, Illinois, was awarded funding in October 2017 to aid research on ‘A Comparative, Evolutionary Context for Human-gut Microbe Interactions.’ Among other factors, human brain expansion is believed to have depended upon a shift in energy allocation from the gut to the brain as well as increased fat stores to buffer against energy shortage. Gut microbes may have partly facilitated these metabolic changes since they degrade dietary fiber to produce a range of short-chain fatty acids (SCFAs). SCFAs provide energy to host tissues and alter metabolic programming. Reduced fiber intake alters the gut microbiome (GM) and favors production of SCFAs that fuel non-gut tissue and promote fat deposition. The reduction in fiber intake over human evolution therefore could have supported human brain expansion by altering human metabolism via the GM and SCFAs. To explore this hypothesis, here we compared the GM of humans and wild non-human primates consuming both high- and low-fiber diets. Humans exhibited distinct GM composition from other primates regardless of diet, but non-human primates consuming low-fiber diets had GMs that were more compositionally similar to those of humans. Assays are currently being completed to describe patterns in GM SCFA gene content and production. However, these data suggest that the relationship between fiber intake and the GM is critical for understanding the evolutionary trajectory of the human GM and its impact on human physiology.