Supercontinent: Ten Billion Years in the Life of Our Planet
Harvard University Press, 2007
304 pp., $29.95
by Stephen O. Moshier
The Upper Crust
Nield explores sociological factors in the gradual acceptance of plate tectonics, suggesting that science is a kind of supercontinent. Just as plates are slowly shifted by a variety of forces, paradigm shifts in science can be preceded by decades of give and take between scientists. Wegener's idea was accepted earlier and more widely in Europe than in America. Frankly, American scientists were put off by Wegener's rather bombastic pronouncements (or at least the tone employed by his English translator). Nield suggests that European science was driven by inductive methods (allowing explanations to emerge from the data set), while American scientists practiced a democratic form of deduction called "multiple working hypotheses" (collection of data to deliberately test or reject numerous possible explanations). By American standards, Wegener and his cohort were jumping the gun. Also, Nield explains that scientific advances can stall or get sidetracked if scientific models become confused with reality. U.S. geographic surveyors were committed to a model of crust properties that was useful for correcting local gravity variations but carried the assumption that rocks do not flow over long periods of time. Europeans embraced a more dynamic model of the inner earth, making the idea of moving continents quite tenable. (While Nield doesn't disparage or completely neglect the role of U.S. scientists in the development of plate tectonics, I feel he ignores some important contributions from the New World to the emerging synthesis after World War II.)
The final third of the book is devoted to discoveries and theories about the earth before Pangaea. Nield uses the analogy of palimpsest texts to describe how geologists use ingenious geochemical methods to unravel the history of the earth's oldest rocks. The work has led to the "discovery" of supercontinents that preceded Pangaea: Ur some three billion years ago and Rodinia about one billion years ago. The influence of these Precambrian tectonic revolutions on the history of life is emerging from the supercontinent of science. Ur—with its marginal shallow seas—was a template for cyanobacteria growing layer upon slimy layer on the seafloor, converting carbon dioxide in the atmosphere into oxygen. Rodinia was an equatorial supercontinent, whose position and fragmentation may have promoted global cooling to the point of converting earth into a temporary snowball (or slushball, depending on the scientist). The appearance of multicellular life with three-layer bodies during the time of Rodinia's icy fragmentation about 650 million years ago implies some connection. "On the supercontinent of science, everything must fit together," the author reflects.
Nield considers how sometimes, in order to advance cultural or religious agendas, "scientific ideas about possible lost worlds have escaped the domain of science and taken on new life as myth." First there was the case of Lemuria, which was legitimized by Friedrich Engels and H. G. Wells as the missing nursery of humankind. Tamil religious scholars reasoned that Lemuria must be their mythic homeland Kumarikkanam. Spiritualist and Theosophy founder Helena Blavastsky claimed Lemuria as the paradise of pre-human ancestors who lived there with dinosaurs, before moving the whole kit and caboodle to another lost continent, Mu, in the south Pacific. Mu was promoted by a cottage industry of late 19th-century spiritualists on the basis of some wishful mistranslations of Mayan inscriptions. The account of ancient earth in the New Age Urantia Book refers to a supercontinent from which life originated one billion years ago, in embarrassing near-agreement with the scientific Rodinia.
Nield's commitment to philosophical naturalism is quite obvious throughout the book. He concludes on a blustering note, rejoicing in science's triumph over religion and mythology. Human hubris—the kind that inevitably follows from faith in an absolute creator, he contends—hinders the advance of knowledge, because "science tells us there is no absolute knowledge of any kind." Nield doesn't explain how scientific ancestors such as Isaac Newton, Robert Boyle, and (first Cambridge professor of geology) Adam Sedgwick—devout Christians all—managed somehow to overcome this handicap, not to mention the thousands of Christians and followers of other religious traditions in the sciences today. Nield compares the Tamil scholars' use of Lemuria to support their mythology with Christian creationists who, "By insisting on the literal truth of the creation myth told in the Old Testament and by vainly looking for evidence of the supernatural among the things of this world … espouse … both bad science and bad religion, demonstrating nothing more than ignorance on the one hand and lack of faith on the other." Ouch, he has a point there.