Genius Foods

been sold a lie about bacteria: without them, we wouldn’t be
here.
You’re now familiar with mitochondria, the cellular
organelles responsible for combining glucose (or ketones, a
by-product of fat metabolism) with oxygen to create energy.
These important structures didn’t always work for us. As the
theory goes, they were once bacteria floating about the
world, when one mitochondrion became engulfed by
another bacterium. Rather than digest it, the much larger
host cell was able to exploit its new friend’s energy-
producing capabilities for survival—a serious advantage 1.5
billion years ago as the world was becoming increasingly
oxygenated. In return, the mitochondrion got protection
from the elements and an unlimited all-you-can-eat buffet—
but they could never, ever leave. It was perhaps the earliest-
ever case of Stockholm syndrome.
Over time the mitochondrion and its host cell began to
depend on each other, joining the ranks of famous
partnerships like Batman and Robin, Han Solo and
Chewbacca, and Bert and Ernie (well, maybe not quite like
Bert and Ernie). This was the birth of the complex
eukaryotic cells that ultimately gave rise to multicellular
organisms like us. Even after all these years, it’s striking to
realize that our mitochondria can still multiply inside our
cells and hold on to their own, completely separate set of
DNA—a throwback to their lives as bachelorettes.
We would be nowhere without bacteria. And though our
modern form is vastly more complex than in those early
years as single-celled organisms, our communion with
bacteria today is no less important. There are countless