Your genome is the same right now as it was yesterday, last week, last year, or the day you were born. But your microbiomes—the combined genes of all the trillions of microbes that share your body—have shifted since the sun came up this morning. And they will change again before the next sunrise.
Christoph Thaiss from the Weizmann Institute of Science has discovered that the communities of microbes in out guts vary on a daily cycle. Some species rise to the fore during daylight hours and recede into the background at night, while others show the opposite pattern.