I’m sad to report that Lynn Margulis died this evening*. I was lucky enough to take two classes with her when I was an undergraduate at UMass; Environmental Evolution and a Symbiosis seminar. Although she was best known for her work on the endosymbiotic theory–the now generally accepted idea that mitochondria, chloroplasts, and other organelles within eukaryotic cells were once free-living bacteria–her research and her courses covered essentially all the living and nonliving things on earth and the interactions among them.
Many fellow scientists thought the endosymbiotic theory was crazy when she proposed it, and she had a hard time getting her initial paper on the subject published. Throughout her career, she wasn’t afraid to promote other seemingly crazy ideas about symbiosis and evolution. Just a couple of years ago she facilitated the publishing of this paper claiming that insect larvae (e.g. caterpillars) evolved separately from their adult forms (e.g. butterflies) and that modern metamorphosing insects arose when velvet worms (phylum Onychophora) somehow hybridized with primitive arthropods. When I took my first class with her, she somehow intuited that I would one day become obsessed with gall-making insects, and she showed me a chapter in a book she had edited in which it was hypothesized that fleshy fruits arose when gall-making insects happened to induce galls in the reproductive tissues of plants, so that the genetic coding for gallmaking was incorporated into the plant’s heritable genome. The former idea of course generated an uproar in the scientific community; I think the latter wasn’t published prominently enough for everyone to get all upset about it. I don’t have the knowledge of genetics to comment on the plausibility of these ideas; I just think they’re fascinating to ponder. Lynn maintained that many of the most significant evolutionary events involved one organism acquiring the genome of another, rather than gradual change through natural selection, which she said mostly just maintains the status quo.
Lynn also helped James Lovelock develop the Gaia hypothesis, which proposes that all living things on earth, and the nonliving things with which they interact, form a self-regulating system, maintaining the environmental conditions that allow life to exist. Some elements of this hypothesis (Lynn insisted it deserves to be called a theory at this point) have gained acceptance in the scientific community, but there are many people who still don’t take it seriously–I can remember a few occasions where I was mocked by professors when I brought it up. I think this comes from simply not understanding it. To fully grasp the Gaia hypothesis requires in-depth knowledge of such diverse fields as microbiology, geology, meteorology, and chemistry, among others. In science there is a tendency toward extreme specialization, which can make it hard to see the big picture. As I learned about Gaia from Lynn, it seemed to me that the various elements of the system–like the carbon cycle or the greenhouse effect–are more or less established scientific fact, but people are unwilling or unable to put the effort into comprehending how they fit together.
Whatever we might think of Lynn Margulis’ ideas, her open-minded and eclectic approach to science (and to life in general) were admirable, and we would all do well to follow her example.
* Added 11/23/11: I did not anticipate that this post would be how much of the world is first hearing the news. Lynn apparently suffered a stroke last week, and her son, Dorion Sagan, posted on his Facebook page yesterday: “My mom just died peacefully in her sleep at home surrounded by family including my sister Jenny and son Tonio, and three granddaughters.”