Lynn Margulis, the rebel of biology, from Paria to prophet

And that was the scenario where a young scientist named Lynn Margulis (1938-2011) dared to challenge the entire establishment of evolutionary biology by proposing an idea that seemed taken from science fiction and that, however, would revolutionize our understanding of the tree of life.

On one side of the ring we had the powerful neo-Darwinists-Darwin’s intellectual heirs-who had refined the theory of evolution until they made it what they called the “modern synthesis.” He defended the existence of random mutations and natural selection, a clean, orderly and progressive story of evolutionary development.

In the other corner a brilliant woman, stubborn and with an extraordinary scientific intuition: Lynn Margulis. In 1967, with just 29 years, he launched an intellectual challenge that would shake the foundations of biology with an apparently absurd idea. It was a permanent symbiotic relationship, a kind of “cell marriage” that transformed both parties forever.

The heresy of symbiogenesis

To truly understand how radical Margulis was we must place ourselves in the scientific context of the sixties, when molecular biology began to emerge with the discovery of DNA. The consensus among the evolutionists was practically monolithic: evolution proceeded exclusively through small random mutations on which natural selection acted favoring those organisms better adapted to their environment. Any other proposal was considered a scientific heresy and heretics were not well received in academic circles where dogma. Darwinist reigned supreme Lynn Margulis did not denied natural selection, but argued that cooperation and symbiosis also played a crucial role in evolution, especially in the great evolutionary jumps. His theory – called “serial endosimbiosis” – proposed that complex cellular structures, such as mitochondria, that generate energy in our cells and chloroplasts, which allow photosynthesis in plants, had originally been independent bacteria and were incorporated by more stable cells, generating permanent symbiotic relationships.

If this sounds for science fiction, imagine how it sounded for the orthodox scientists of the time, who had built entire careers about the preeminence of competition and natural selection as the only engine of evolution. The idea that cooperation could be an evolutionary mechanism as important as competition was simply unacceptable.

It is not surprising then that when Margulis sent his original manuscript – “the origin of eukaryotic cells” – to more than a dozen scientific journals, they all reject it and some without even reviewing it. The scientific establishment was not prepared to consider that a young scientist could be proposing such a radical addition to evolutionary theory.

The battle for recognition

The rejection did not stop Margulis who was convinced of the validity of his theory and possessed the type of determination that distinguishes the great scientific revolutionaries.

After multiple attempts and rejections, he finally found a home for his manuscript in the ‘Journal of Theoretical Biology’. A somewhat marginal magazine for the standards of the time, but that was willing to consider unconventional ideas.

Thus began a battle of decades for the scientific recognition that would test not only their ideas but also his personal tenacity.

Despite the initial ostracism, Margulis continued to build his case with scientific meticulousness and an obstinacy worthy of admiration. Advances in electronic microscopy revealed that mitochondria and chloroplasts had their own different DNA from the nuclear DNA of the host cell and, surprisingly, similar to bacterial DNA.

In addition, these organelles reproduced independently through a process of division similar to bacterial fission, exactly as Margulis’s theory predicted. Subsequent biochemical studies showed that mitochondria used protein synthesis mechanisms more similar to bacteria than to the rest of the eukaryotic cell.

The transformation of Margulis’s status within the scientific community was gradual, but inexorable as the evidence in favor of endosimbiosis accumulated. The recognition came in the form of numerous awards and honors including the National Medal of Science of the United States in 1999 and its election as a member of the National Academy of Sciences.

Lynn Margulis died in 2011 leaving a monumental scientific legacy that goes far beyond endosimbiotic theory. Its history represents one of the most inspiring examples of how intellectual perseverance can eventually succeed over scientific dogmatism. It also reminds us that science, although it aspires to objectivity, is inevitably influenced by dominant paradigms and that true advances often come from those who dare to question the established truths.

For new generations of scientists, the history of Lynn Margulis offers invaluable lessons about the importance of intellectual independence, the value of challenging the dominant paradigms and the need for perseverance against rejection.

It also illustrates how good ideas eventually triumph if they are backed by solid evidence regardless of how revolutionary or initially unpopular they are.