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 communities 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 supported 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 understanding the symbiotic factors was of enormous importance.”
Her subsequent ideas remain decidedly more controversial. Margulis came to view symbiosis as the central force behind the evolution of new species, an idea that has been dismissed by modern biologists. The dominant theory of evolution (often called neo-Darwinism) holds that new species arise through the gradual accumulation of random mutations, which are either favored or weeded out by natural selection. To Margulis, random mutation and natural selection are just cogs in the gears of evolution; the big leaps forward result from mergers between different kinds of organisms, what she calls symbiogenesis. Viewing life as one giant network of social connections has set Margulis against the mainstream in other high-profile ways as well. She disputes the current medical understanding of AIDS and considers every kind of life to be “conscious” in a sense.
Margulis herself is a highly social organism. Now 71, she is a well-known sight at the University of Massachusetts at Amherst, where she is on the geosciences faculty, riding her bike in all weather and at all times of day. Interviewer Dick Teresi, a neighbor, almost ran her over when, dressed in a dark coat, she cycled in front of his car late at night. On the three occasions that they met for this interview, Teresi couldn’t help noticing that Margulis shared her home with numerous others: family, students, visiting scholars, friends, friends of friends, and anybody interesting who needed a place to stay.
Most scientists would say there is no controversy over evolution. Why do you disagree? All scientists agree that evolution has occurred—that all life comes from a common ancestry, that there has been extinction, and that new taxa, new biological groups, have arisen. The question is, is natural selection enough to explain evolution? Is it the driver of evolution?
