Lynn Margulis : the Woman Who Transformed the Meaning of Self and Evolution

I discovered Lynn Margulis years ago as the scientist who brought endosymbiosis (from ??endo???: inside and ??symbiosis??, mutually beneifical?: the idea that our cells and plant cells are constituted by the engulfment of protobacteria by ancestral cells) from heretic theory to recognised scientific truth. As she fought to make us humans recognize our selves as hybrid bodies, and to see the evolution in the light of collaboration rather than mere violent competition, her life, wisdom, courage and grit have continuously inspired me. To me, she is as important as Darwin in defining our place in the book of Life, if not more. Yet, she’s generally unknown. Books on the microbiome always introduce Leuwenhoek, Metchnikoff and Pasteur as the fathers of microbiology and probiotics. Lynn Margulis often gets forgotten, yet she proved true the concept that our very own cells are chimeras with microbes since long before we were humans. It’s been a long time I’ve wanted to write a tribute to that amazing and crucial personality.

??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?? - Richard Dawkins. ??This is one of the great achievements of twentieth-century evolutionary biology.??

The World Before Margulis

Darwin was revolutionary when he drew a little sketch in his leather notebook, commenting ??organized beings represent a tree?? around 1840. He was not exactly the first to think this way though, Augier organized his Arbre Botanique in 1801 in the same form, and Lamarck made a tree of dots in 1809 titled ??to show the origin of different animals?? (The Tangled Tree). But Darwin was the one who came out with a constructed argument detailed in his book On the Origin of Species in 1859, which entailed a lot of fuss, throwing Christianity into discomfort, putting Man as just another animal in the Tree of Life.

A century later, the advent of molecular phylogenetics brought scientists to study DNA and RNA. Carl Woese looked at RNA as an evolutionary clock that could help inform the origins of life, some 4 billion years ago, thanks to the 16s ribosomal subunit contained by all living cells, and that microbiologists know well as they are ubiquitous and highly variable, thus used to identify species. These studies re-shaped the Tree of Life thanks to the discovery of Archae as organisms singularly distinct from bacteria, that helped to investigate the origin of life itself, in a primitive Earth.

Lynn Margulis’s Life Work

Margulis entered the public scientific stage in 1967 with her paper On the Origin of Mitosing Cells (under the name of Lynn Sagan as she was then married with Carl Sagan, the famous divulgator of the Cosmos, and whose Wikipedia page doesn’t even mention Lynn, sic). In this publication, she makes a case for eukaryotic cells (our cells, but also the cells of all fungi and plants?: structured cells with a nucleus, by opposition to prokaryotic cells, simpler ones like bacteria) as ??compound individuals??.

Let’s explain. Mitochondria are cell organites present in almost all animal cells, in high numbers (300 to 2000 per cell, representing about 25% of the cell volume) and producing the energy for the cell, thanks to a chemical reaction involving oxygen. Interestingly, mitochondria are the shape and size of bacteria, and are not coded for by the DNA in our chromosomes. And they replicate by dividing, just like bacteria.

Margulis was not the first to emit the hypothesis that mitochondria had bacterial origins – with a protobacterium engulfing another one a couple billion years ago, maybe to eat it, maybe to infect it, but ended up benefitting from the production of energy in-house. The Russian Merezhkowsky (a known pedophile rapist of 26 little girls) born in 1855 had spoken of ??symbiogenesis?? about chloroplasts, and though he claimed the paternity of the idea, he had read about it from Anton de Bary and Andreas Schimper who studied lichens and spoke of chloroplasts (organites in plant cells that transform sunlight and carbon dioxide into sugars, the plant energy form) in the 1880s as ??reminiscent of symbiosis??. In 1927, Ivan Wallin published Symbionticism and the Origin of Species where he added mitochondria to the endosymbiosis theory.

Endosymbiosis is thus an idea that emerged in the 19th century, but by the 1960s, these ideas were in disrepute and forgotten. Lynn Margulis heard about them as anecdotes (and ackowledged in her writings these previous authors) and followed the thread, adding another idea, that flagella could have evolved from spirochetes and given centrioles (cell structures that allow the migration of chromosomes to the ends of a cell for division). This last idea was not proven, but her Life Work focused on demonstrating scientifically the soundness of the endosymbiosis theory.

Thanks to RNA, she proved that the mitochondria of wheat do not resemble wheat?: they are genetically alien, but co-opted into the service of wheat.

In 1971, she published Origin of Eukaryotic Cells, proposing an evolutionary change of paradigm.

In the 70s, friend with James Lovelock, the man who named the world, she supported the Gaian theory?: the concept of our planet as a self-regulating entity. They co-authored the article Atmospheric homeostasis by and for the biosphere?: the gaia hypothesis, presenting the biosphere as an active adaptive control system supporting Earth’s homeostasis (balance within livable ranges). Indeed, microorganisms are a potent regulating force for the atmosphere, producing gases. Early Earth bacteria are at the origin of most of the oxygen in the air we breathe. This work came at the premices of the environmental movement and brought a new eye to seeing our planet not as an insensitive rock and mere floor for life, but almost as a being in itself, needing care and nurture for it to continue to offer and balance the conditions for life.

Altogether, Margulis authored or co-authored 19 different books, many of them with her son Dorion Sagan, including these three to help disseminate the beautiful novel understanding of life : Microcosmos, Four Billion Years of Microbial Evolution in 1986, which ideas you can find in my previous blog Is Your Vision of the Evolutionary Tree Stuck in the 19th Century??; What Is Life?? and Origins of Sex. In 1998 she also wrote Symbiotic Planet, exploring the relationship between Gaia and her work on symbiosis.

Her Struggles as a Woman (and opponent to neo-Darwinism)

Lynn was born in 1938, in a world where women didn't hold leadership positions. When I read The Tangled Tree, retracing the history of evolution through the lens of microbiology, I was shocked to see the absence of women names. In the past century, probably nearly a hundred names of people who made the history of evolution were made. Of them, just three women. Lynn Margulis, Barbara McClintock, and Linda Bonen (only refereed to as a technician in Woese’s lab, although she made RNA fingerprinting possible). There’s even a picture with a woman referred to only as ??a microbiologist??. Anonymous. There were no women role models in science when Lynn Margulis grew up.

As a precocious child, she entered university at 15 and graduated at 19. She conducted her doctorate while working as a research associate and lecturer at Brandeis University while raising two sons.

After her second divorce, she commented?: ??I quit my job as a wife twice. It’s not humanly possible to be a good wife, a good mother, and a first-class scientist. No one can do it – something has to go.?? Would a man meet the same expectations??

??I quit my job as a wife twice. It’s not humanly possible to be a good wife, a good mother, and a first-class scientist. No one can do it – something has to go.?? - Lynn Margulis

She struggled to obtain funding to pursue her research. The scientific community plainly called her crazy. Her revolutionary paper was rejected by 15 journals before being published. One reviewer even wrote to her ??Your research is crap. Do not bother to apply again.??

??Your research is crap. Do not bother to apply again.?? - a reviewer to Lynn Margulis

She has been called ??science’s unruly mother??, a ??vindicated heretic??, a ??scientific rebel??, and generally a maverick and an outsider.

Yet, in the second part of her career, she earned public recognition, including the William Procter Prize for Scientific Achievement and the Golden Plate Award of the American Academy of Achievement.

Impacts On Our Sense of Identity

Part of the reason her work attracted such hostility is that it touched to our most intimate sense of self. The one that is protected in the heart of our cells. After Copernicus’s blow to human’s ego, Darwin’s revelation that we are but animals in close kin to other animals, Lynn Margulis’s third civilization narcissistic blow is to revise our sense of self as an aggregate of beings, a combination, a chimera. Like lichens are not just algae or fungi, but a specific combination of these (and bacteria!) with their own metabolic workings, humans cell constituents include ancestral bacteria, and live as an ecosystem in constant interaction with microbiomes.

??We are all of us walking communities of bacteria. The world shimmers, a pointillist landscape made of tiny living beings.?? - Lynn Margulis.

??All organisms visible to the unaided eye are chimaeras… all cells, protists, fungi, plants, and animals have multiple ancestry.?? - Lynn Margulis

Since Pasteur, we considered microorganisms as ??lower life forms?? and saw germs as causing diseases. And with Margulis we had to welcome them into our very identity. Although it’s a gorgeous show of the genius of life’s ability to reorganize itself to grow in complexity, it’s a humbling perspective.

??From a planetary point of view, mammal’s main role seems to be fertilizing plants and carrying mitochondria.?? - Lynn Margulis

Impacts on Evolution and Our Worldview

What does the neo-Darwinistic perception of an aggressive, competitive world entails?? It grounds the belief in the need to be selfish to survive and reproduce, which contributes in the paternalistic, consumerist civilization that’s currently self-distructing through pushing beyond planetary limits. To create a group, we need trust, collaboration, and the belief that these qualities are already a part of us.

Lynn offered a new explanation of evolutionary forces?: it’s not small random mutations that explain variations?: ??New mutations don’t create new species?; they create offspring that are impaired.?? ??Rather, the important transmitted variation that leads to evolutionary novelty comes from the acquisition of genomes??. From symbiosis.

??The evolutionary biologists believe the evolutionary pattern is a tree. It’s not. The evolutionary pattern is a web – the branches fuse?? - Lynn Margulis.

Lynn proposed a philosophically deeply different view of evolution compared to the aggressive competitive dominant view since Darwin. Where Darwin saw nature as ??tooth and claw?? in the survival of the fittest, she saw a kinder, cooperative world, based on symbiosis, on microbes merging for mutual gain. Combination of beings as a true creative life force.

??Life did not take over the globe by combat, but by networking?? - Lynn Margulis.

Even if the truth is necessarily a combination of the competitive forces of the survival of the fittest and the cooperative fusion of organisms, I believe it is a strong symbol that it was Lynn Margulis, a woman, who laboriously pushed beyond a pillar of paternalism by seeing and showing the beauty of symbiosis as an evolutionary and creative life force.

Conclusion

Had you heard of Lynn Margulis and endosymbiosis before reading this article?? I would love for you to comment about this, to understand how much she made her way to the microbiome community. And I’d love to encourage further conversations – what about your colleagues, partner, friends, kids, have they heard of her?? How do they envision evolution?? Do they want to hear her story?of grit, rebellion and victory in changing humanity’s perspective on its origins and constitution ?

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