Lynn Margulis was an American biologist who completely altered the concept of how life arose on Earth. Born as the eldest of her siblings in Chicago, Margulis was not a class topper in Hyde Park Academy High School. She earned both her B.A. and M.A. degree from University of Chicago and then joined University of Wisconsin to study biology under Walter Plaut and Hans Ris. While pursuing research, she was offered a position as a research assistant and lecturer in Brandeis University. Throughout her career, she has scaled heights, the highest being the Distinguished Professor of Geosciences, a position she retained till her death. Margulis was married twice in her life. Although, she was a staunch evolutionist, she completely rejected the theory of modern evolutionary synthesis, which made her realize that she was more of a ‘neo-Darwinist’. Her theoretical paper on mitosing cells was rejected fifteen times before it was finally printed in and is now considered as the landmark argument in endosymbiotic theory. Margulis was a tenacious lady who defended her theory vehemently, even in the face of staunch criticism. Apart from her endosymbiotic theory, Margulis collaborated with James Lovelock, the British scientist on Gaia hypothesis. Apart from her scholarly articles, Margulis wrote a number of books interpreting scientific concepts for people in general.