Many of us are lucky enough to live in a society where we can, at many times, eat whatever food we would like, whenever we would like. Not so for the Hadza community, that lives near the Serengeti. They are one of the last hunter/gatherers that live solely off what they can find or kill all year round. Scientists have been studying this community of foragers for quite some time for everything from sleeping patterns to how they find their food, as this gives some clues as to how our species used to live and thrive. Recent studies have shown that the gut microbiota (microbes that live in the gut) in this community go through a seasonal shift. These seasonal shift/pattern is predictable and not seen in people that do not live as hunters/gatherers. As one researcher, Dr. Sonnenberg, from the study has said "an abrupt change in diet will lead to an abrupt change in the gut microbiome, on the order of a day or two,” but no one expected to ever find a predictable seasonal shift continuously occurring.
Source: New York Times: https://www.nytimes.com/2017/08/24/science/gut-bacteria-hadza-diet-health.html?rref=collection%2Ftimestopic%2FMicrobiology&action=click&contentCollection=science®ion=stream&module=stream_unit&version=latest&contentPlacement=1&pgtype=collection