Despite an ancient warning from the Buddha, we still like to pretend that we’re one self—a unified biological animal that persists through time. Sure, we know that our biological processes are dictated by circadian rhythms. What we overlook is that we’re really the sum of billions of different components, and some of those “parts” have their own clocks.

The Buddha might not have had a microscope, but his keen insight into human psychology translates well to biology. That’s the word from a new study, published in Science Advances, that found the bacterium Bacillus subtilis is run by its own circadian rhythms.

Also known as “grass bacillus,” B. subtilis thrives in the gastrointestinal tracts of humans as well as grass-feeding ruminants. You can easily and cheaply purchase bottles of this bacterium as a probiotic due to its supposed immune system-boosting properties. The strain is found in soil, though you probably want to secure it by other means, making it a favorite of supplement companies. The European Food Safety Authority rates it as “Qualified Presumption of Safety.”

For this study, the European research team chose B. subtilis thanks to previous observations that, like humans, it seems to follow a 24-hour circadian clock. It also responds to red and blue lights (again, like humans), causing the researchers to believe that it entrains to environmental conditions. The team discovered this by enzymatically inducing bioluminescence in order to stare into this mysterious world.

Lead author, Professor Martha Merrow from Munich’s Ludwig Maximilans University, says

“We’ve found for the first time that non-photosynthetic bacteria can tell the time. They adapt their molecular workings to the time of day by reading the cycles in the light or in the temperature environment.”[…]