by Neil Shubin
We’ve witnessed a number of different ideas about where the water of the planet came from. For a long time, it was thought that the main source was icy comets. That hypothesis was challenged when cometary water was sampled during a satellite visit to Hale-Bopp as it came close to Earth. These measurements revealed that the comet’s water had a different chemical signature than the water of Earth’s oceans. The comet hypothesis was in trouble until measurements were taken more recently of another comet: this one, Hartley 2, has more Earth-like water. Now a number of potential sources exist, and none are mutually exclusive: comets, asteroids, even squeezed or condensed from the constituents of early Earth. Reviews of the evidence are in N. H. de Leeuw et al., “Where on Earth Has Our Water Come From?,” Chemical Communications 46 (2010): 8923–25; M. J. Drake and H. Campins, “Origin of Water in the Terrestrial Planets,” Proceedings of the International Astronomical Union 1, no. S229 (2006): 381–94. The discovery of ocean-like water on a Kuiper belt comet, Hartley-2, is described in P. Hartogh et al., “Ocean-Like Water in the Jupiter-Family Comet 103P/Hartley 2,” Nature 478 (2011): 218–20. For images of potential water in the polar craters of Mercury, see NASA’s website: http://www.nasa.gov/mission_pages/messenger/multimedia/messenger_orbit_image20120322_3.html.
For the formation of the different planets of the solar system, and the relationships among them, see R. M. Canup, “Origin of Terrestrial Planets and the Earth-Moon System,” Physics Today, April 2004, 56–62.
FOUR ABOUT TIME
The origin of the moon has been the subject of a large number of scientific papers in recent years. For a sampling, with references, see R. M. Canup, “Formation of the Moon,” Annual Review of Astronomy and Astrophysics 42 (2004): 441–75; R. M. Canup and K. Righter, eds., Origin of the Earth and Moon (Tucson: University of Arizona Press, 2000); Canup, “Origin of Terrestrial Planets and the Earth-Moon System.”
For a history of the ways we keep time, see the work of Anthony Aveni, in particular Empires of Time: Calendars, Clocks, and Cultures (Boulder: University of Colorado Press, 2002).
The idea that clocks are embedded throughout the natural world is explored in detail in Macdougall, Nature’s Clocks.
A wonderful book on clocks, time, and our perception of time is Robert Levine, A Geography of Time: On Tempo, Culture, and the Pace of Life (New York: Basic Books, 1998). Michel Siffre’s cave experience is documented in his personal account, Beyond Time (New York: McGraw-Hill, 1964).
The story of Curt Richter’s life’s work can be found in his biographical memoir published by the National Academy of Sciences, in Biographical Memoirs, vol. 65 (Washington, D.C.: National Academy Press, 1994), http://www.nap.edu/catalog.php?record_id=4548.
The story of Seymour Benzer and the discovery of the molecular basis for circadian clocks, among other things, is in Jonathan Weiner’s wonderful Time, Love, and Memory: A Great Biologist and His Quest for the Origins of Behavior (New York: Vintage, 2000).
The starting point for learning more about biological clocks is John D. Palmer’s readable and often funny The Living Clock (Oxford: Oxford University Press, 2002). If you want more detail from the primary literature itself, then proceed to the papers in the following paragraphs.
The Benzer lab’s discovery of clock mutants is detailed in R. J. Konopka and S. Benzer, “Clock Mutants of Drosophila melanogaster,” PNAS 68 (1971): 2112–16. The trio of labs that cloned the gene and explored its biological ramifications were Jeffrey Hall’s (Brandeis), Michael Rosbash’s (Brandeis), and Michael Young’s (Rockefeller). The biology of these circadian clock mutants in diverse creatures is discussed in a number of papers, including Z. S. Sun et al., “RIGUI, a Putative Mammalian Ortholog of the Drosophila Period Gene,” Cell 90 (1997): 1003–11; H. Tei et al., “Circadian Oscillation of a Mammalian Homologue of the Drosophila Period Gene,” Nature 389 (1997): 512–16; M. W. Young and S. A. Kay, “Time Zones: A Comparative Genetics of Circadian Clocks,” Nature Reviews Genetics 2 (2001): 702–15; W. Yu and P. E. Hardin, “Circadian Oscillators of Drosophila and Mammals,” Journal of Cell Science 119 (2006): 4793–95; E. E. Hamilton and S. A. Kay, “SnapShot: Circadian Clock Proteins,” Cell 135 (2008); K. Lee, J. J. Loros, and J. C. Dunlap, “Interconnected Feedback Loops in the Neurospora Circadian System,” Science 289 (2000): 107–10; E. Tauber et al., “Clock Gene Evolution and Functional Divergence,” Journal of Biological Rhythms 19 (2004): 445–58; D. Bell-Pedersen et al., “Circadian Rhythms from Multiple Oscillators: Lessons from Diverse Organisms,” Nature Reviews Genetics 6 (2005): 544–56.
The circadian clock and its evolution have been the subjects of a number of excellent reviews and books in the scientific literature. An entrée to this body of work can be found in the following papers: J. Dunlap, “Molecular Basis for Circadian Clocks,” Cell 96 (1999): 271–90; M. Rosbash, “Implications of Multiple Circadian Clock Origins,” PLoS Biology 7 (2009): 17–25; S. Panda, J. B. Hogenesch, and S. A. Kay, “Circadian Rhythms from Flies to Human,” Nature 417 (2002): 329–35.
The similarity of sleep mechanisms in diverse organisms is discussed in detail in C. Cirelli, “The Genetic and Molecular Regulation of Sleep: From Fruit Flies to Humans,” Nature Reviews Neuroscience 10 (2009): 549–60; and Panda et al., “Circadian Rhythms from Flies to Human.”
The use of the shells of invertebrate animals as timepieces to measure the length of days over time is found in Z. Zhenyu et al., “The Periodic Growth Increments of Biological Shells and the Orbital Parameters of Earth-Moon System,” Environmental Geology 51 (2006): 1271–77. The evolution of circadian clocks is discussed in D. A. Paranjpe and V. K. Sharma, “Evolution of Temporal Order in Living Organisms,” Journal of Circadian Rhythms 3 (2005): 7–17.
A general reference on sleep medicine is Meir H. Kryger, Thomas Roth, and William C. Dement, Principles and Practice of Sleep Medicine (Philadelphia: Saunders, 2005). A short but pithy review of the relationships between clocks and clinical conditions is in A. R. Barnard and P. M. Nolan, “When Clocks Go Bad: Neurobehavioural Consequences of Disrupted Circadian Timing,” PLoS Genetics 4 (2008).
The relationship of DNA replication, circadian clocks, and cancer is discussed in S. Mitra, “Does Evening Sun Increase the Risk of Skin Cancer?,” PNAS 108, no. 47 (2011): 18857–58; S. Gaddameedhi et al., “Control of Skin Cancer by the Circadian Rhythm,” PNAS 108 (2011): 18790–95; and S. Sahar and P. Sassone-Corsi, “Metabolism and Cancer: The Circadian Clock Connection,” Nature Reviews Cancer 9 (2009): 886–96.
The full story of the Hindostan grave markers is discussed in E. Kvale et al., “The Art, History, and Geoscience of Hindostan Whetstone Gravestones in Indiana,” Journal of Geoscience Education 48 (2000): 337–42. More information on the kind of rock that the stones are taken from, called rhythmites, is in B. W. Flemming and A. Bartholomä, Tidal Signatures in Modern and Ancient Sediments (Oxford: Blackwell Science, 1995).
FIVE THE ASCENT OF BIG
The discovery of the earliest living things, and Barghoorn’s life, are discussed in Elso Barghoorn’s biographical memoir, published by the National Academy of Sciences, in Biographical Memoirs, vol. 87 (Washington, D.C.: National Academy Press, 2005), http://www.nap.edu/html/catalog.php?record_id=11522.
A lively personal account of discovery of early life is written by one of Barghoorn’s students, now an eminence in his own right, J. William Schopf, Cradle of Life (Princeton, N.J.: Princeton University Press, 2001). A similarly excellent account is Martin Brasier, Darwin’s Lost World: The Hidden History of Animal Life (Oxford: Oxford University Press, 2009). The recognition of early fossils as the remnants of living things is challenging and often spawns debate, as it has between Schopf and Brasier. A review, and one side of these debates, is in M. D. Brasier et al., “Earth’s Oldest (c. 3.5Ga) Fossils and the ‘Early Eden Hypothesis’: Questioning the Evidence,” Origins of Life and Evolution of the Biosphere 34 (2004): 257–60. At the time of this writing, the oldest fossil evidence for life is either Schopf’s, described in his b
ook, or Brasier’s, found in D. Wacey et al., “Microfossils of Sulphur-Metabolizing Cells in 3.4-Billion-Year-Old Rocks of Western Australia,” Nature Geoscience (2011), doi:10.1038/ngeo1238.
Galileo’s discussion of size and gravity is in the definitive and readable text with translation by Stillman Drake and commentary by Stephen Jay Gould, Albert Einstein, and J. L. Heilbron, Dialogue Concerning the Two Chief World Systems: Ptolemaic and Copernican (New York: Modern Library, 2001).
The stories of van Leeuwenhoek were taken from Clifford Dobell, ed., Antony van Leeuwenhoek and His “Little Animals” (New York: Dover, 1960). The description of his likely microscope is reprinted in Clair L. Stong, The “Scientific American” Book of Projects for the Amateur Scientist (New York: Simon & Schuster, 1960).
Algae and the rise of oxygen are discussed, and well referenced, in Andrew Knoll’s Life on a Young Planet, cited above. The importance of oxygen for the evolution and history of life is discussed in two other engaging books: Nick Lane, Oxygen: The Molecule That Made the World (Oxford: Oxford University Press, 2003); and Peter D. Ward, Out of Thin Air: Dinosaurs, Birds, and Earth’s Ancient Atmosphere (Washington, D.C.: Joseph Henry Press, 2006). A general review of oxygen over geological time (looking at more recent events) is in R. A. Berner et al., “Phanerozoic Atmospheric Oxygen,” Annual Review of Earth and Planetary Sciences 31 (2003): 105–34.
The timing of the rise of oxygen, called the Great Oxygenation Event, appears as not a single increase but several scattered over hundreds of millions of years. Scientific papers include L. R. Kump, “The Rise of Atmospheric Oxygen,” Nature 451 (2007): 277–78; A. Bekker et al., “Dating the Rise of Atmospheric Oxygen,” Nature 427 (2004): 117–20; and H. Holland, “The Oxygenation of the Atmosphere and Oceans,” Philosophical Transactions of the Royal Society B 361 (2006): 903–15.
Befitting such a complicated situation as the rise of oxygen, there are a number of different hypotheses for its cause. The one discussed here is outlined in L. R. Kump and M. E. Barley, “Increased Subaerial Volcanism and the Rise of Atmospheric Oxygen 2.5 Billion Years Ago,” Nature 448 (2007): 1033–37.
The Darlington-Barbour “dropping the frogs off the roof of the MCZ” story was the stuff of legend when I was a graduate student there in the 1980s. That, and the adventure with the crocodile, are discussed in the National Academy of Sciences’ biographical memoir of Philip Darlington written by his Harvard colleague E. O. Wilson, in Biographical Memoirs, vol. 60 (Washington, D.C.: National Academy Press, 1991), http://www.nap.edu/catalog.php?record_id=6061.
J. B. S. Haldane’s essay “On Being the Right Size” was originally published in 1926 and is available at http://www.physlink.com/Education/essay_haldane.cfm.
The study of the relationship between size and other biological features is known as allometry. The literature in the field is vast, but a number of reviews can get one up to speed pretty rapidly. After Haldane’s paper, there is the seminal paper of Stephen Jay Gould, produced when he was a college student. It remains an important contribution over forty-five years later: “Allometry and Size in Ontogeny and Phylogeny,” Biological Reviews of the Cambridge Philosophical Society 41 (1966): 587–638. The history of the concept is in J. Gayon, “History of the Concept of Allometry,” American Zoologist 40 (2000): 748–58. A general book in the field, with extensive references, is William A. Calder, Size, Function, and Life History (Mineola, N.Y.: Dover, 1996). The eminent biologist John Tyler Bonner has written an outstanding volume for general audiences on the consequences of size: Why Size Matters: From Bacteria to Blue Whales, rev. ed. (Princeton, N.J.: Princeton University Press, 2011).
The challenges for small creatures moving about in fluids are captured in E. M. Purcell, “Life at Low Reynolds Number,” American Journal of Physics 45 (1977): 3–11. Went’s musings on the importance of size for our abilities are in F. W. Went, “The Size of Man,” American Scientist 56 (1968): 400–413.
Preston Cloud’s worldview, written for a general audience, is in his Cosmos, Earth, and Man: A Short History of the Universe (New Haven, Conn.: Yale University Press, 1980). His National Academy biographical memoir holds the trajectory of this career and anecdotes discussed herein; see Biographical Memoirs, vol. 67 (Washington, D.C.: National Academy Press, 1995).
A general review, with lots of references, of the factors that control size in flies is in S. Oldham et al., “Genetic Control of Size in Drosophila,” Philosophical Transactions of the Royal Society B 355 (2000): 945–52.
A review of size-control genes and their similarity in flies and people is in J. Dong et al., “Elucidation of a Universal Size-Control Mechanism in Drosophila and Mammals,” Cell 130 (2007): 1120–33.
The cost of size, particularly that resulting from living in an oxygen-rich environment, is outlined in Q. Zeng and W. Hong, “The Emerging Role of the Hippo Pathway in Cell Contact Inhibition, Organ Size Control, and Cancer Development in Mammals,” Cancer Cell 13 (2008): 188–92; D. Pan, “The Hippo Signaling Pathway in Development and Cancer,” Developmental Cell 19, no. 4 (2010): 491–505; and C. Badouel, A. Garg, and H. McNeill, “Herding Hippos: Regulating Growth in Flies and Man,” Current Opinion in Cell Biology 21, no. 6 (2009): 837–43.
SIX CONNECTING THE DOTS
The theory of plate tectonics was sprung by a network of scientists around the globe. There are several excellent resources on the history of the theories of continental drift and plate tectonics, notable among them Naomi Oreskes and H. E. Le Grand, eds., Plate Tectonics: An Insider’s History of the Modern Theory of the Earth (Boulder, Colo.: Westview Press, 2003); Naomi Oreskes, The Rejection of Continental Drift: Theory and Method in American Earth Science (New York: Oxford University Press, 1999); and David M. Lawrence, Upheaval from the Abyss: Ocean Floor Mapping and the Earth Science Revolution (New Brunswick, N.J.: Rutgers University Press, 2002).
Eduard Suess’s quotation and life story are taken from his obituary, written by an American eminence in earth science, Charles Schuchert of Yale, Science, June 26, 1914, 933–35.
Alfred Wegener’s life, work, and impact are discussed in Roger M. McCoy, Ending in Ice (Oxford: Oxford University Press, 2006).
The oral history project in which Marie Tharp talks of her work is at http://www.aip.org/history/ohilist/22896_1.html.
One of the classics, describing the accumulation of evidence in support of the theory, is a short book, written over thirty years ago, that is well worth a read to expand the treatment in this chapter: Seiya Uyeda, The New View of the Earth (San Francisco: W. H. Freeman, 1978). Consult also Philip Kearey and Frederick J. Vine, Global Tectonics (London: Blackwell Science, 1996).
Frederick Vine’s paper is F. J. Vine and D. H. Matthews, “Magnetic Anomalies over Oceanic Ridges,” Nature 199 (1963): 947–49.
A short biography of John Tuzo Wilson is at http://gsahist.org/gsat/gt01sept24_25.htm. For insights into the discoveries discussed in this chapter, see J. T. Wilson, “A Revolution in Earth Science,” Geotimes 13 (1968): 10–16; and J. T. Wilson, “Did the Atlantic Close and Then Re-open?” Nature 211 (1966): 676–81. You can watch Wilson describe his theories of faults at http://www.youtube.com/watch?v=OmrXy65O6fY as well as his approach to science at http://www.youtube.com/watch?v=fdSwEFyurDY.
The link between mammalian biology (placentation, size, and metabolism) and tectonic change is found in the work of Paul Falkowski and his colleagues: P. Falkowski et al., “The Rise of Oxygen over the Past 205 Million Years and the Evolution of Large Placental Mammals,” Science 309 (2005): 2202–4. For other proposed effects of oxygen on the history of life, see also Ward, Out of Thin Air, and Berner et al., “Phanerozoic Atmospheric Oxygen,” for perspective on the importance of oxygen and its links to other planetary processes.
SEVEN KINGS OF THE HILL
William Smith, his map, and his struggles are the topic of Simon Winchester’s Map That Changed the World (New York: Viking, 2001). John Phillips’s ideas and work are in Jack Morrell, John Phillips and the Business of
Victorian Science (London: Ashgate, 2005). See Phillips’s Treatise on Geology (Surrey: Ashgate Media, 2001) for a firsthand account of his views.
For one-stop intellectual shopping on the ideas and writings of Cuvier, see M. J. S. Rudwick, Georges Cuvier, Fossil Bones, and Geological Catastrophes: New Translations and Interpretations of the Primary Texts (Chicago: University of Chicago Press, 1999).
Histories of the concept of extinction are found in a number of highly readable accounts, including Walter Alvarez, T. rex and the Crater of Doom (New York: Vintage, 1999); David Sepkoski and Michael Ruse, eds., The Paleobiological Revolution (Chicago: University of Chicago Press, 2009); and M. J. S. Rudwick, The Meaning of Fossils: Episodes in the History of Paleontology (Chicago: University of Chicago Press, 1985).
Details of Norman Newell’s career were taken from his obituary in the Journal of Paleontology 80 (2006): 607–8. Papers of his relevant to extinction include “Crises in the History of Life,” Scientific American 208 (1963): 76–92; and “Mass Extinctions at the End of the Cretaceous Period,” Science 149 (1965): 922–24.
The fifty volumes of the Treatise on Invertebrate Paleontology remain available at the University of Kansas Paleontological Institute (http://paleo.ku.edu/pdf/brochure.pdf).
Newell was one of several calling out loud for the reality of mass extinction. Another passionate voice was Otto Schindewolf: see his “Über die möglichen Ursachen der grossen erdgeschichtlichen Faunenschnitte,” Neues Jahrbuch für Geologie und Palaöntologie. Monatshefte (1954): 457–65.
The impact hypothesis for the end-Cretaceous event is discussed in Alvarez’s book written for a general audience, T. rex and the Crater of Doom. The original scientific paper describing the impact hypothesis is L. W. Alvarez et al., “Extraterrestrial Cause for the Cretaceous-Tertiary Boundary Extinction,” Science 208 (1980): 1095–108.
