Microcosmos: Four Billion Years of Microbial Evolution

"Lynn Margulis was a force of a nature for those of us who had the pleasure of knowing her. She was one of the great enthusiasts of biology, especially microbiology, of the last century. Her major contribution wasn’t in her own discoveries so much as in popularizing and explaining the concept of symbiosis to the public and to her fellow biologists. Lynn had, at one time, been married to the late Carl Sagan, who was an astronomer. Dorion Sagan, who is the co-author of this book, is her son. Lynn rediscovered the concept of symbiosis. The idea is very simple. It’s that every eukaryote has one or sometimes two organelles — that’s a membrane-bound body within the cell. For us, it’s mitochondria. All animals and all plants have mitochondria. Mitochondria are where the energy is made in animals. It’s the place where we respire our oxygen. Mitochondria originally were a type of photosynthetic bacterium that didn’t make oxygen. The other organelle is a chloroplast. The chloroplast in all plants is derived, originally, from another bacterium — a blue-green alga — which can make oxygen. The central idea in Microcosmos is that these organelles were carried along through life virtually unchanged. They are, as it were, the nanomachines that were derived by microbes, literally 3 billion years ago, and have been moved on into other body parts of higher plants and animals virtually intact. Yes, that’s another area where Lynn tried very hard to make inroads. The co-operative part of it is that microbes form consortia. The consortia have partners that give something into the pool and withdraw something from the pool of their partners. This idea of microbes together forming collective consortia leads to a symbiotic association later. It’s actually a very important concept, because if you think about it, that’s exactly what happens in each of us individually, in our guts. Get the weekly Five Books newsletter We have microbes that form a consortium and for each of us, it’s a unique consortium that helps us with the digestion of our food and obtaining nutrients from what we eat. If the microbes in our guts were a single species we wouldn’t be here, we would probably be dead. That idea of microbes as social organisms was actually popularized by Lynn a long time ago, but it took me a long time to really appreciate what she was saying. It came out very early. People can go back and read Lynn’s books, and they’ll still find them inspiring. Virtually everybody that ever read one of her books understood the importance of these concepts. We’re just starting to really understand them now, in terms of human health. She had a good style of writing and Dorion became a professional writer. She wasn’t a great experimentalist, that was not her forte. Her forte was communicating ideas, and she did a magnificent job. She did it in a way that was very accessible, and the concepts don’t go away. We’re still learning the rules of how microbes talk to each other and how they communicate with each other and form consortia, and how they form symbiotic associations. I’m very interested in what I call the global electronic marketplace, which is how the planet moves major materials — such as oxygen and carbon dioxide and nitrogen gases — across the planet to interact with microbes very far away and forms a planetary circuit. My work is primarily about going from the very, very small nanostructures within these mitochondria and chloroplasts to how when you build upon billions, trillions and quadrillions of these processes they really influence the planet. I am trying to understand how nature works from the very, very small structures to very large outcomes of planetary change."