LynnMargulis
A conversation with Lynn Margulis is an effective way to change the way you think
about life. Not just your life. All life. Scientists today recognize five groups of life:
bacteria, protoctists (amoebas, seaweed), fungi (yeast, mold, mushrooms), plants,
and animals. Margulis, a self-described “evolutionist,” makes a convincing case that
there are really just two groups, bacteria and everything else.
That distinction led to her career-making insight. In a 1967 paper published in the
Journal of Theoretical Biology, Margulis suggested that mitochondria and plastids
—vital structures within animal and plant cells—evolved from bacteria hundreds of
million of years ago, after bacterial cells started to collect in interactive commu-
nities and live symbiotically with one another. The resulting mergers yielded the
compound cells known as eukaryotes, which in turn gave rise to all the rest—the
protoctists, fungi, plants, and animals, including humans. The notion that we are all
the children of bacteria seemed outlandish at the time, but it is now widely sup-
ported and accepted. “The evolution of the eukaryotic cells was the single most
important event in the history of the organic world,” said Ernst Mayr, the leading
evolutionary biologist of the last century. “Margulis’s contribution to our understand-
ing the symbiotic factors was of enormous importance.”
Her subsequent ideas remain decidedly more controversial. Margulis came to
