The study authors were amazed to find this season-sensing ability in an organism that lives for only about five hours in the lab before dividing. “It seemed like a very nonsensical idea to think that bacteria would care about something that’s happening on a scale that’s so much bigger than their lifetime,” said Luísa , a microbial chronobiologist at the John Innes Center in Norwich, England, and lead author of the new paper.
But cyanobacteria have an evolutionary incentive to pass on relevant information to their progeny: Each cell divides into two identical clones, and each of those does as well, ad infinitum. Carl Johnson, the senior paper author at Vanderbilt University, likened it to the way monarch butterflies migrate south for the winter but never make the return journey north — their offspring do that. “When you start thinking about more of a lineage, or as the colony or population,” he said, “then that kind of thing makes perfect sense.”
The discovery connects cyanobacteria to a plethora of much more complex organisms with seasonal rhythms, and it indicates that anticipating seasons may have emerged early in life’s evolution. It may have even predated the internal clocks that give an organism a sense of day and night. “This issue of dealing with seasonality may be very fundamental to why [biological] clocks exist in the first place,” said the cell biologist Mike Rust, who studies cyanobacteria’s internal rhythms at the University of Chicago and was not involved in the new research. Staying in sync with the seasons could be more ancient and more elemental to life than anyone suspected.
