For anthropological and paleontological advice, I thank Michael K. Brett-Surman, Ph.D., and Rick Potts, Ph.D., both of the National Museum of natural History, Smithsonian Institution; Philip Lieberman, Ph.D., Brown University; Robin Ridington, Ph.D., Professor Emeritus, University of British Columbia; Gary J. Sawyer [no relation] and Ian Tattersall, Ph.D., both of the American Museum of natural History; Milford H. Wolpoff, Ph.D., University of Michigan, and the various experts listed in the Acknowledgments to my earlier book, Hominids.
For advice on genetics and disease, I thank George R. Carmody, Ph.D., Department of biology, Carleton University; Peter Halasz; Hassan Masum, a Ph.D. candidate at Carleton; Alison Sinclair, Ph.D.; and Edward Willett. For advice on the other medical matter that figures in the plot, I thank endocrinologist Christopher Kovacs, M.D., Health Sciences Centre, Memorial University of Newfoundland.
For information about and access to the Sudbury Neutrino Observatory, I thank Art McDonald, Ph.D., and J. Duncan Hepburn, Ph.D.
For drawing to my attention theories that human consciousness is an electromagnetic phenomenon, I thank Norm Nason. Two such theories, similar in most particulars, have recently and independently been developed by Johnjoe McFadden, Ph.D., School of biomedical and Life Science, University of Surrey, and Susan Pockett, Ph.D., Department of physics, University of Auckland. For those interested in reading more about them, McFadden presents a general account of his version in the closing chapter of his book Quantum Evolution: The New Science of Life (HarperCollins UK, 2000; W. W. Norton USA, 2001), and Pockett devotes her entire book The Nature of Consciousness: A Hypothesis (Writers Club Press, 2000) to her version of this theory.
There was much discussion in Humans, the previous book in this trilogy, about paleomagnetic evidence showing that Earth’s magnetic field has previously collapsed very rapidly. Since that research figures again in this book, I invite the curious to check the original study by Robert S. Coe and Michel Prévot, “Evidence suggesting extremely rapid field variation during a geomagnetic reversal,” in Earth and Planetary Science Letters, 92:292–98 (1989), and the follow-up by Coe, Prévot, and Pierre Camps, “New evidence for extraordinarily rapid change of the geomagnetic field during a reversal” in Nature, 374:687–92 (1995). For other advice related to magnetic reversals, I thank Grant C. McCormick and Ariel Reich, Ph.D.
Huge thanks to my lovely wife, Carolyn Clink; my editor David G. Hartwell and his associate Moshe Feder; my agent Ralph Vicinanza and his associates Christopher Lotts and Vince Gerardis; Tom Doherty, Linda Quinton, Jennifer Marcus, Jenifer Hunt, Irene Gallo, and everyone else at Tor Books; and Harold and Sylvia Fenn, Robert Howard, Heidi Winter, Melissa Cameron, David Leonard, Steve St. Amant, and everyone else at H. B. Fenn and Company.
Many thanks, also, to the friends and colleagues who let me bounce ideas off them or otherwise provided input, including Linda Carson, Marcel Gagné, James Alan Gardner, Al Katerinsky, Herb Kauderer, and Robert Charles Wilson. Beta testers for this novel were Ted Bleaney, Carolyn Clink, David Livingstone Clink, Richard Gotlib, Peter Halasz, Howard Miller, Ariel Reich, Alan B. Sawyer, Sally Tomasevic, Edo van Belkom, and David Widdicombe.