by Neil Shubin
The other mass extinctions in the fossil record do not appear to be caused by impacts. For detailed discussion of these other events, see Michael J. Benton, When Life Nearly Died: The Greatest Mass Extinction of All Time (New York: Thames & Hudson, 2003); Douglas H. Erwin, Extinction: How Life on Earth Nearly Ended 250 Million Years Ago (Princeton, N.J.: Princeton University Press, 2008); George R. McGhee, The Late Devonian Mass Extinction (New York: Columbia University Press, 1996); David M. Raup, The Nemesis Affair: A Story of the Death of Dinosaurs and the Ways of Science (New York: Norton, 1999); and Peter D. Ward, Rivers in Time (New York: Columbia University Press, 2002).
The meeting at Woods Hole, along with the interactions of Schopf, Raup, Gould, and Sepkoski, is in Sepkoski and Ruse, Paleobiological Revolution.
Sepkoski’s database is J. John Sepkoski Jr., A Compendium of Fossil Marine Animal Genera, Bulletins of American Paleontology, 364 (Ithaca, N.Y.: Paleontological Research Institution, 2002), http://strata.geology.wisc.edu/jack/.
His database revealed major patterns in the history of life in the oceans. These insights are detailed in J. J. Sepkoski Jr., “Patterns of Phanerozoic Extinction: A Perspective from Global Data Bases,” in Global Events and Event Stratigraphy, ed. O. H. Walliser (Berlin: Springer, 1996), 35–51; D. M. Raup and J. J. Sepkoski Jr., “Mass Extinctions in the Marine Fossil Record,” Science 215 (1995): 1501–3; D. M. Raup and J. J. Sepkoski Jr., “Periodicity of Extinctions in the Geologic Past,” PNAS 81 (1984): 801–5.
The work of David Jablonski was the subject of a wonderful piece by David Quammen, “The Weeds Shall Inherit the Earth,” Independent (London), November 22, 1998, 30–39. Original papers of Jablonski’s used in this chapter include D. Jablonski, “Heritability at the Species Level: Analysis of Geographic Ranges of Cretaceous Mollusks,” Science 238 (1987): 360–63; D. Jablonski and G. Hunt, “Larval Ecology, Geographic Range, and Species Survivorship in Cretaceous Mollusks: Organismic vs. Species-Level Explanations,” American Naturalist 168 (2006): 556–64; D. Jablonski, “Extinction and the Spatial Dynamics of Biodiversity,” PNAS 105, no. S1 (2008): 11528–35; and D. Jablonski, “Lessons from the Past: Evolutionary Impacts of Mass Extinctions,” PNAS 98 (2001): 5393–98.
The correlation of a rise in mammal diversity with the ecological vacuum produced by the end-Cretaceous extinction is supported most recently in R. W. Meredith et al., “Impacts of the Cretaceous Terrestrial Revolution and KPg Extinction on Mammal Diversification,” Science 334 (2010): 521–24.
EIGHT FEVERS AND CHILLS
Paul Tudge’s memorable flight over the Arctic was described in the original news accounts in 1986; see M. Lemonick, C. Tower, and D. Webster, “Unearthing a Fossil Forest,” Time, September 22, 1986. Original papers from the primary literature include J. F. Basinger, “Early Tertiary Floristics and Paleoclimate in the Very High Latitudes,” American Journal of Botany 76, no. S6 (1989): 158; J. F. Basinger, “The Fossil Forests of the Buchanan Lake Formation (Early Tertiary), Axel Heiberg Island, Canadian Arctic Archipelago: Preliminary Floristics and Paleoclimate,” in Tertiary Fossil Forests of the Geodetic Hills, Axel Heiberg Island, Arctic Archipelago, Geological Survey of Canada Bulletin no. 403, ed. R. L. Christie and N. J. McMillan (Ottawa: Geological Survey of Canada, 1991), 39–65; D. R. Greenwood and J. F. Basinger, “The Paleoecology of High-Latitude Eocene Swamp Forests from Axel Heiberg Island, Canadian High Arctic,” Review of Palaeobotany and Palynology 81, no. 1 (1994): 83–97; D. R. Greenwood and J. F. Basinger, “Stratigraphy and Floristics of Eocene Swamp Forests from Axel Heiberg Island, Canadian Arctic Archipelago,” Canadian Journal of Earth Sciences 30, no. 9 (1992): 1914–23; B. A. Lepage and J. F. Basinger, “Early Tertiary Larix from the Buchanan Lake Formation, Canadian Arctic Archipelago, and a Consideration of the Phytogeography of the Genus,” in Christie and McMillan, Tertiary Fossil Forests of the Geodetic Hills, 67–82.
Colbert’s discovery in Antarctica was also the subject of news accounts of the time; see “New Life for Gondwanaland,” Time, March 22, 1968. You can hear Colbert himself tell you of his Antarctica work at http://www.youtube.com/watch?v=UNe5SGkQP7Q. The discovery of Lystrosaurus from Antarctica is described in E. Colbert, “Lystrosaurus from Antarctica,” American Museum Novitates 2535 (1974): 1–44, http://digitallibrary.amnh.org/dspace/bitstream/handle/2246/5462//v2/dspace/ingest/pdfSource/nov/N2535.pdf?sequence=1.
The faint-young-sun paradox—the notion that a warming sun hasn’t correlated to an overheated Earth—is first discussed by C. Sagan and G. Mullen, “Earth and Mars: Evolution of Atmospheres and Surface Temperatures,” Science 177 (1972): 52–56.
A wealth of classic papers on carbon, climate, and atmosphere, including Arrhenius’s from 1896, are republished and discussed in David Archer and Raymond Pierrehumbert, eds., The Warming Papers (Hoboken, N.J.: Wiley-Blackwell, 2011).
The famous BLaG paper is R. A. Berner, A. C. Lasaga, and R. M. Garrels, “The Carbonate-Silicate Geochemical Cycle and Its Effect on Atmospheric Carbon Dioxide over the Past 100 Million Years,” American Journal of Science 283 (1983): 451–73. One seminal paper that preceded this (in science there are often many) is J. C. G. Walker, P. B. Hays, and J. F. Kasting, “A Negative Feedback Mechanism for the Long-Term Stabilization of Earth’s Surface Temperature,” Journal of Geophysical Research 86 (1981): 9776–82. More recently, an update of the model is in R. A. Berner and Z. Kothavala, “Geocarb III: A Revised Model of Atmospheric CO2 over Phanerozoic Time,” American Journal of Science 301 (2001): 182–204.
Maureen Raymo and her coauthors, W. F. Ruddiman and P. N. Froelich, launched a debate with the original publication of their uplift-climate hypothesis in M. E. Raymo, W. F. Ruddiman, and P. N. Froelich, “Influence of Late Cenozoic Mountain Building on Ocean Geochemical Cycles,” Geology 16 (1988): 649–53; M. E. Raymo and W. F. Ruddiman, “Tectonic Forcing of Late Cenozoic Climate,” Nature 359 (1992): 117–22; and M. E. Raymo, “The Himalayas, Organic Carbon Burial, and Climate in the Miocene,” Paleoceanography 9 (1994): 399–404. This idea has very deep historical roots, deriving from some elements in T. C. Chamberlin’s work of the late nineteenth century: T. C. Chamberlin, “An Attempt to Frame a Working Hypothesis of the Cause of Glacial Periods on an Atmospheric Basis,” Journal of Geology 7 (1899): 545–84, 667–85, 751–87. See also Raymo’s commentary in M. E. Raymo, “Geochemical Evidence Supporting T. C. Chamberlin’s Theory of Glaciation,” Geology 19 (1991): 344–47. For a general volume containing a number of different perspectives, see W. F. Ruddiman, ed., Tectonic Uplift and Climate Change (New York: Plenum Press, 1997). See also J. C. Zachos and L. R. Kump, “Carbon Cycle Feedbacks and the Initiation of Antarctic Glaciation in the Earliest Oligocene,” Global and Planetary Change 47 (2005): 51–66, for references.
For a recent paper seeking to put the different lines of evidence together, see C. Garzione, “Surface Uplift of Tibet and Cenozoic Global Cooling,” Geology 36 (2008): 1003–4. For a discussion of the geochemical issues related to the Raymo hypothesis, see S. E. McCauley and D. DePaolo, “The Marine 87Sr/86Sr and d18O Records, Himalayan Alkalinity Fluxes and Cenozoic Climate Models,” in Ruddiman, Tectonic Uplift and Climate Change, 428–65.
A classic map of carbon dioxide levels over time is R. A. Berner, “Atmospheric Carbon Dioxide Levels over Phanerozoic Time,” Science 249, no. 4975 (1990): 1382–86.
The interval prior to 45 million years ago was a hot one (known as the PETM, Paleocene-Eocene Thermal Maximum), and many have looked at the plants, carbon dioxide, and other factors at this time. An entrée to this literature includes F. A. McInerney and S. L. Wing, “The Paleocene-Eocene Thermal Maximum: A Perturbation of Carbon Cycle, Climate, and Biosphere with Implications for the Future,” Annual Review of Earth and Planetary Sciences 39 (2011): 489–516; A. Sluija et al., “Subtropical Arctic Ocean Temperatures During the Palaeocene/Eocene Thermal Maximum,” Nature 441 (2006): 610–13; J. C. Zachos et al., “A Transient Rise in Tropical Sea Surface Temperature During the Paleocene-Eocene Thermal Maximum,” Sci
ence 302 (2003): 1151–54; J. P. Kennett and L. D. Stott, “Abrupt Deep-Sea Warming, Palaeoceanographic Changes, and Benthic Extinctions at the End of the Palaeocene,” Nature 353 (1991): 225–29; and S. L. Wing et al., “Coordinated Sedimentary and Biotic Change During the Paleocene-Eocene Thermal Maximum in the Bighorn Basin, Wyoming, USA,” in Conference Programme and Abstracts: CBEP 2009, Climatic and Biotic Events of the Paleogene, 12–15 January 2009, Wellington, New Zealand, ed. C. P. Strong, Erica M. Crouch, and C. J. Hollis (Lower Hutt, N.Z.: Institute of Geological and Nuclear Sciences, 2009), 156–62.
The paper describing the importance of new patterns of ocean circulation to Antarctica’s climate is J. P. Kennett, “Cenozoic Evolution of Antarctic Glaciation, the Circum-Antarctic Ocean, and Their Impact on Global Paleoceanography,” Journal of Geophysical Research 82 (1977): 3843–60. The timing of the freezing of Antarctica and its relationship to oceanic circulation are the subject of J. Anderson et al., “Progressive Cenozoic Cooling and the Demise of Antarctica’s Last Refugium,” PNAS 108 (2011): 11356–60.
Nate Dominy’s papers on color vision and fruit include N. Dominy and P. W. Lucas, “Ecological Importance of Trichromatic Vision to Primates,” Nature 410 (2001): 363–66; N. Dominy, “Fruits, Fingers, and Fermentation: The Sensory Cues Available to Foraging Primates,” Integrative and Comparative Biology 44 (2004): 295–303; N. Dominy and P. W. Lucas, “Significance of Color, Calories, and Climate to the Visual Ecology of Catarrhines,” American Journal of Primatology 62 (2004): 189–207.
The mobile field kit designed by Dominy and his colleagues is described in P. W. Lucas et al., “Field Kit to Characterize Physical, Chemical, and Spatial Aspects of Potential Primate Foods,” Folia Primatologica 72, no. 1 (2001): 11–25.
NINE COLD FACTS
For background on the military history of Project Iceworm and Camp Century, see E. D. Weiss, “Cold War Under the Ice: The Army’s Bid for a Long-Range Nuclear Role, 1959–1963,” Journal of Cold War Studies 3, no. 3 (Fall 2001): 31–58.
The discovery of the causes for the ice ages, as well as the hidden climatic records in ice, have been the subject of fantastic general science books: John Imbrie and Katherine Palmer Imbrie, Ice Ages: Solving the Mystery (Cambridge, Mass.: Harvard University Press, 1986); Richard B. Alley, The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future (Princeton, N.J.: Princeton University Press, 2002); and Doug Macdougall, Frozen Earth: The Once and Future Story of Ice Ages (Berkeley: University of California Press, 2006). All three are science writing at its best: authoritative, captivating, and well referenced. Detailed studies of ice cores, of the type described in Alley’s Two-Mile Time Machine, reveal a complex set of cycles and oceanic events, each with their own names—Dansgaard-Oeschger cycles, Bond cycles, Heinrich events, and MacAyeal cycles. Climate can fluctuate wildly based on changes to glaciers, ocean circulation, and prevailing winds. Our understanding of the global extent and interworkings of the variables is a work in progress, aided by the increasing resolution available to geologists mapping chemical and physical changes to oceans and glaciers.
The impact of the ice ages on one part of human history is discussed in Brian Fagan, The Little Ice Age: How Climate Made History, 1300–1850 (New York: Basic Books, 2001). For a beautiful account of how ice ages have affected both the landscape and life, see: E. C. Pielou, After the Ice Age: The Return of Life to Glaciated North America (Chicago, University of Chicago Press, 1991).
The work of Libby and Urey is discussed in Macdougall’s superb Nature’s Clocks.
An account of Dorothy Garrod can be found in P. J. Smith, “Dorothy Garrod as the First Woman Professor at Cambridge University,” Antiquity 74 (2000): 131–36.
The importance of climate change and Natufian culture on the development of agriculture is the subject of debate, with the classical view in O. Bar-Yosef, “The Natufian Culture in the Levant, Threshold to the Origins of Agriculture,” Evolutionary Anthropology 6, no. 5 (1998): 159–77; and O. Bar-Yosef and A. Belfer-Cohen, “The Origins of Sedentism and Farming Communities in the Levant,” Journal of World Prehistory 3 (1989): 447–98. Other views—including contrary ones—are discussed in M. Balter, “The Tangled Roots of Agriculture,” Science 327 (2010): 404–6.
The ways that diet, particularly the origin of agriculture, has influenced the structure of our genome are discussed in Spencer Wells, Pandora’s Seed: The Unforeseen Cost of Civilization (New York: Random House, 2010). Jonathan Pritchard’s seminal article on selection in the human genome is B. F. Voight, S. Kudaravalli, X. Wen, and J. K. Pritchard, “A Map of Recent Positive Selection in the Human Genome,” PLoS Biology 4, no. 3 (2006). See also P. Sabeti et al., “Genome-wide Detection and Characterization of Positive Selection in Human Populations,” Nature (2007): 913–88; and D. J. Wilson et al., “A Population Genetics-Phylogenetic Approach to Inferring Natural Selection in Coding Sequences,” PLoS Genetics 7, no. 12 (2011).
TEN MOTHERS OF INVENTION
The role of climate change in the origin and early evolution of humans and their closest relatives is evaluated in National Research Council and Committee on the Earth System Context for Hominin Evolution, Understanding Climate’s Influence on Human Evolution (Washington, D.C.: National Academies Press, 2010), http://www.nap.edu/catalog.php?record_id=12825#toc. This volume contains an extensive set of references on the climate reconstruction. See also T. E. Cerling et al., “Woody Cover and Hominin Environments in the Past 6 Million Years,” Nature 476 (2011): 51–56.
The hominid fossils from Chad are described in M. Brunet, “A New Hominid from the Upper Miocene of Chad, Central Africa,” Nature 418 (2002): 145–51; and M. Brunet et al., “New Material of the Earliest Hominid from the Upper Miocene of Chad,” Nature 434 (2005): 752–55. A recent analysis of bipedalism in early Kenyan finds is in B. Richmond et al., “Orrorin tugenensis Femoral Morphology and the Evolution of Hominin Bipedalism,” Science 319, no. 5870 (2008): 1662–65. General books on the hominin fossil record include Ann Gibbons, The First Human (New York: Doubleday, 2006); and Donald C. Johanson and Kate Wong, Lucy’s Legacy: The Quest for Human Origins (New York: Harmony Books, 2009).
Robert Merton’s insights into invention are in R. K. Merton, “Singletons and Multiples in Scientific Discovery: A Chapter in the Sociology of Science,” Proceedings of the American Philosophical Society 105, no. 5 (1961): 470–86; and R. K. Merton, “Priorities in Scientific Discovery: A Chapter in the Sociology of Science,” American Sociological Review 22, no. 6 (1957): 635–59.
Stigler’s law is in Stephen Stigler, “Stigler’s Law of Eponymy,” in Science and Social Structure: A Festschrift for Robert K. Merton, ed. Thomas F. Gieryn (New York: New York Academy of Sciences, 1980), 147–58.
For an account of how plants have influenced the history of life, see David Beerling, The Emerald Planet: How Plants Changed Earth’s History (Oxford: Oxford University Press, 2007); and William C. Burger, Flowers: How They Changed the World (Amherst, N.Y.: Prometheus Books, 2006).
Steven Stearns’s work on recent selection in humans is in S. C. Stearns et al., “Measuring Selection in Contemporary Human Populations,” Nature Reviews Genetics 11 (2010): 611–22.
ACKNOWLEDGMENTS
My inspiration to enter science derived from growing up watching Apollo space missions on TV, visiting natural history museums, and reading writers such as Carl Sagan and Jacob Bronowski. And, as I grew, my parents, Seymour and Gloria Shubin, supported each hobby of the week—from rock collections and colonial pottery to telescopes and meteorites—no questions asked. They nurtured a child’s curiosity, allowing it to transform into that of an adult scientist.
Sadly, my friend and mentor, Professor Farish A. Jenkins, Jr., passed away just as this book was going to press. He found wonder in the process of discovery and, accordingly, it is only befitting that this narrative is bookended by stories with him.
Kalliopi Monoyios, who created all the original art for the book, is everything you could want in a scientific i
llustrator: a student of the natural world who has a keen eye, sharp critical sense, and compelling aesthetic vision. Kapi helped transduce complex ideas and text into simple visuals. I had the privilege of having her in my lab for the past eleven years: she has now fledged to form her own freelance studio (www.kalliopimonoyios.com) and can be followed on her blog (blogs.scientificamerican.com/symbiartic).
I am fortunate to have worked in the field with remarkable people: Farish A. Jenkins Jr., Bill Amaral, Paul Olsen, Ted Daeschler, Jason Downs, Chuck Schaff. One of the joys of writing this book was reliving moments we shared in Greenland, Morocco, Canada, and Ellesmere Island.
Members of my lab past and present have been influential to and patient with my writing: Randy Dahn, Marcus Davis, Adam Franssen, Nadia Fröbisch, Andrew Gehrke, Andrew Gillis, Christian Kammerer, Justin Lemberg, Kapi Monoyios, Joyce Pieretti, Igor Schneider, Becky Shearman, Natalia Taft, and John Westlund.
For insights, comments, and responses to pesky queries, I thank Bill Amaral, James Bullock, Robin Canup, Sean Carroll, Michael Coates, Anna Di Renzio, John Flynn, David Gozal, Lance Grande, David Jablonski, Susan Kidwell, Andy Knoll, Michael LaBarbera, Dan Lieberman, Daniel Margoliash, Paul Olsen, Kevin Righter, Callum Ross, David Rowley, Paul Sereno, Michael Turner, Mark Webster, and Mike Young. Elena Skosey-Lalonde assisted with the fact-checking during summer breaks from the University of Chicago Laboratory Schools. Fred Ciesla patiently answered questions about the origin of planets many mornings after dropping our daughters off at kindergarden. Nate Dominy kindly shared stories and details of his work in Uganda. Lawrence Krauss graciously commented on the big bang and stellar formation, thereby saving me from embarrassing mistakes. Seymour Shubin, Michele Seidl, Kalliopi Monoyios, Andrew Gehrke, Joyce Pieretti, and John Westlund read and commented on drafts of the text. Thanks to all. The errors that remain are, of course, my own.
