Course Hero. "A Short History of Nearly Everything Study Guide." Course Hero. 18 Jan. 2018. Web. 15 Jan. 2019. <https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/>.
Course Hero. (2018, January 18). A Short History of Nearly Everything Study Guide. In Course Hero. Retrieved January 15, 2019, from https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/
(Course Hero, 2018)
Course Hero. "A Short History of Nearly Everything Study Guide." January 18, 2018. Accessed January 15, 2019. https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/.
Course Hero, "A Short History of Nearly Everything Study Guide," January 18, 2018, accessed January 15, 2019, https://www.coursehero.com/lit/A-Short-History-of-Nearly-Everything/.
Bryson introduces the chapter by explaining how fossils form. Fossils are rare and dependent upon multiple factors for the replacement of organic material by rock to occur. As a result, the fossil record is inherently biased, not only toward creatures most likely to fossilize, such as shelled animals or those with vertebrae, but also toward specific areas of the world. As a result, "what we possess is the merest of sampling of all the life that Earth has spawned." For example, 95% of known fossils are of marine creatures, since they die in sediment. Therefore, the understanding of early life is biased and changes constantly with new discoveries and new ideas.
Bryson considers the fossil history of the trilobite, which appeared about 540 million years ago. This marine animal with three body parts lived for 300 million years, compared to the "one-half of 1 percent" of this time humans have survived. During the 19th century they were "almost the only known forms of early complex life," and their sudden appearance during a particular time period baffled scientists until the 1909 discovery of the Burgess Shale fossils by scientist Charles Doolittle Walcott. Walcott excavated approximately 60,000 fossils and argued life "began in primordial simplicity and moved inexorably, predictably onward to more and better." However, when in 1973 a graduate student named Simon Conway Morris revisited these same fossils, the story changed. Morris found a wide variety of life and many species that had not been documented before. He argued only a few survived to evolve into the species alive today. Science writer Stephen Jay Gould published a book on the idea, but scientists later realized many complex species of animals and plants did not arise during a so-called Cambrian "explosion" but propagated possibly much earlier and evolved over longer periods of time. In fact, Bryson says, complex organisms "existed at least a hundred million years before the Cambrian."
The main complaint with Gould's book was the belief "his conclusions were simply mistaken or carelessly inflated." Oxford academic Richard Dawkins argued the kind of early world Gould imagined would have required a fundamentally different evolutionary mechanism than the one in operation today. Later interpretations of the fossils by paleontologists Richard Fortey and Derek Briggs showed most of the Burgess Shale creatures did belong to still-living phyla (the plural of phylum, the classification level that groups together all classes of organisms with the same body plan). Based on their research, the Cambrian "explosion" was more likely to have been "an increase in size than a sudden appearance of new body types."
The interpretation of fossil evidence is a central aspect of paleontological science. As Bryson shows, paleontologists can become quite heated in their arguments, and specific fossils can become the subject of these debates. The scientific controversy surrounding the Burgess Shale fossils is a case in point. It stems from the publication of a science book written for the general public, Wonderful Life: The Burgess Shale and the Nature of History (1989) by Stephen Jay Gould. Stephen Jay Gould was a noted paleontologist from Harvard who wrote numerous scientific essays meant for a public audience. Wonderful Life hit the New York Times best-seller list and received multiple awards. By emphasizing the public nature of the debate over the book, Bryson suggests scientific controversy and interpretation is inherent even within science books meant for the general public.
The Burgess Shale controversy was ultimately settled. But the potential for revision of fossil-based theories based on new discoveries will continue to make them open to debate.