12 Days of Women in STEM: Lynn Margulis

“Lynn Margulis is one of those rare scientists whose research  fundamentally altered the way we view the world.”

Eric Goldscheider

American (r)evolutionary biologist Lynn Margulis is most known for her theory  on endosymbiosis, which fundamentally transformed the understanding of the  evolution of eukaryotic cells. Her theory is now accepted as scientific norm and  is taught in schools the world over, but in the 1960’s and 70’s after the  publication of her paper: “On the Origin of Mitosing Cells” Margulis had to fight  hard for its acceptance in the minds of her fellow scientists. The paper was  rejected from 15 journals prior to publication in the Journal of Theoretical  Biology in 1967.  

“Lynn Margulis’s name is as synonymous with symbiosis as Charles Darwin’s is with evolution.”

Jan Sapp

Often described as a scientific rebel, Margulis herself said that she was a bad  student who was often punished by being made to stand quietly in a corner of  the classroom. Nevertheless she was accepted as a student at the University of  Chicago Laboratory Schools in 1952 at the age of 15 and in 1957 she earned  her BA in Liberal Arts from the University of Chicago.  

She went on to study biology at the University of Wisconsin and graduated with  an MS in Genetics/Zoology in 1960. Her PhD research in zoology was  completed on the job following her leaving the University of California, Berkeley  for an early job offer as a research associate and lecturer at Brandeis  University. Over the span of her career, she was awarded an extra 15 (honorary)  doctoral degrees by various educational institutions. 

Margulis academically settled at Boston University in 1966 and continued to  teach biology there for 22 years before moving to the University of  Massachusetts, Amherst as a Distinguished Professor of Botany in 1988. She  held her post as DP within the university until her death in 2011, transferring  through the Department of Biology before settling in the Department of  Geosciences.  

It was as a junior faculty member at Boston University in 1966 that she wrote  her theoretical paper “On the Origin of Mitosing Cells”, now considered a  landmark scientific publication. Margulis theorised that energy-producing cell  organelles like mitochondria and chloroplasts (in animal and plant cells,  respectively) once existed independently as free-living bacteria. The theory  was at best ignored and at worst heavily criticised by other scientists until  experimental evidence could be obtained through new genetic techniques.  Margulis fiercely backed her theory throughout the years of doubt and was  later in her career quoted saying: “I don’t consider my ideas controversial. I consider them right”.  

“I greatly admire Lynn Margulis’s sheer courage and stamina in sticking by the endosymbiosis theory, and carrying it through from being an unorthodoxy to an orthodoxy. This is one of the great achievements of  twentieth-century evolutionary biology.”

Richard Dawkins

In 1978, researchers Robert Schwarz and Margaret Dayhoff laid the foundations  for experimental evidence of the endosymbiosis theory by demonstrating the  descent of mitochondria from bacteria and chloroplasts from cyanobacteria.  Margulis’s theory was widely accepted in the early 1980s when clear  differences in the genetic material of mitochondria and chloroplasts on the one  hand and nuclei on the other were observed.  

Margulis remained a controversial character throughout her life, her ideas often  sparking scientific debate. Though a self-confessed Darwinist, Margulis took  issue with the view of natural selection and evolution through only competition,  and argued that symbiosis should be included as a major driver of evolutionary  change, saying: “Natural selection eliminates and maybe maintains, but it  doesn’t create”. Her proposal that symbiosis between organisms can explain  most genetic variation however is considered a fringe idea. Employing her  famed tenacity in the face of opposition Margulis also defended Robert  Whittaker’s five kingdom classification system, successfully ensuring its  survival following intense criticism. 

In addition to her fame as a scientist, Lynn Margulis also made a name for  herself in science education and communication, publishing over 20 books.  These were often co-authored with her and astronomer Carl Sagan’s son  Dorion Sagan, a popular science writer in his own right. 

Margulis was awarded numerous prizes throughout her career, notably she was  recognised as one of the 50 most important women in science in 2002, 9 years  before her death. Lynn Margulis rests in the area around Puffers Pond, her  favourite local fieldwork site in Massachusetts – surrounded by billions of the  symbiotic cellular relationships she fought so hard to shed light on.