Lynn Margulis
1938-
American Geneticist
American geneticist Lynn Margulis is noted for her investigations of the intricate, fundamental systems by which life creates and maintains itself on Earth. She is often regarded as the co-creator, with James Lovelock (1919- ), of the Gaia hypothesis, an idea suggesting that the earth is an ecosystem, or the sum of many ecosystems.
Margulis was born in Chicago in 1938, the eldest of four daughters. At age 14 she enrolled in an undergraduate program at the University of Chicago, where she was introduced to the natural sciences. After graduating, she pursued an M.S. in zoology and genetics at the University of Wisconsin. In 1965 she received her Ph.D. in genetics from the University of California at Berkeley. In 1970 she moved to Massachusetts, where over the next 22 years she raised four children and taught at Boston University. She now teaches at the University of Massachusetts.
Margulis is considered an expert on the biological kingdom Protoctista, which includes an estimated 250,000 algae, seaweeds, amoebas, and other little known life forms. In the 1960s she began looking for DNA where no one had thought it could be found—outside the nucleus of the algae cell. She found it, and her discovery supported a revolutionary theory of symbiosis in the origin of the cell.
Margulis is also considered the co-author of the Gaia hypothesis. The Gaia hypothesis suggests that certain conditions that sustain life are regulated by life itself. More specifically, she contends, the atmosphere and all life on Earth act as a single integrated physiological system.
The strongest evidence for the Gaia hypothesis comes from the study of atmospheric chemistry. Her work in reconstructing early life on the planet revealed that bacteria produce and remove all types of atmospheric gases. The composition of the earth's atmosphere differs from our nearest neighbors, Mars and Venus. Both of these planets have carbon dioxide-rich, steady-state atmospheres that remain in equilibrium. However, our atmosphere on Earth is very different. Loaded with reactive gases, our atmosphere contains oxygen, nitrogen, and methane, among others, which are violently reactive to one another. There is no way to explain this by chemistry alone.
James Lovelock, a British atmospheric chemist, felt that the presence of reactive gases is evidence that atmospheric gases on Earth are actively regulated. Margulis agreed and suggested the atmosphere is an extension of life itself. If the surface of Earth were not covered with oxygen-emitting algae and plants, methane producing bacteria, hydrogen-producing fermenters, and countless other life forms, its atmosphere would long ago have reached the same steady state of Mars and Venus.
Magulis suggests that another argument for Gaia comes from the study of astronomy. According to accepted models, the sun is 30 to 70percent hotter today than it was in the early days of the earth's history. If the earth's temperature was consistent with this increase in solar radiation, we would now be at a boiling point. However, the temperature of Earth has remained stable and conducive to life for all of this time. She concludes that growing populations of gas-producing organisms have actively maintained surface temperatures within a range suitable for life.
Ultimately, Margulis notes, "it doesn't matter whether the Gaia hypotheses is supported or not." The fact that it has generated new thoughts and new work is the best evidence of its value. She also points out that although soil erosion, loss of nutrients, methane production, ozone depletion, deforestation, and the loss of species diversification may all be Gaian processes, our human habits and behaviors have accentuated them to the point of near catastrophe. It is possible that our lack of environmental policies and our overpopulation will stress the system to such an extent that the earth will roll over into another steady-state regime, which may or may not include human life.
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