Darwin's Children

by Greg Bear

  Pathogen: disease-causing organism. There are many different varieties of pathogen: viruses, bacteria, fungi, protists (formerly known as protozoa), and metazoans such as nematodes.

  PERV: Porcine endogenous retrovirus. Ancient retroviruses found in the genome of pigs. See ERV.

  Phage: a virus that uses bacteria as hosts. Many kinds of phages kill their hosts almost immediately and can be used as antibacterial agents. Most bacteria have at least one and often many phages specific to them. Phages and bacteria are always in a contest to outrun each other, evolutionarily speaking.

  Phenotype: the physical structure of an organism or distinctive group of organisms. Genotype expressed and developed within an environment determines phenotype.

  Pheromone: a chemical message produced by one member of a species that influences the physiology and the behavior of another member of the same species. Whether or not this chemical message is consciously detected (smelled), pheromones have the same effect. Mammalian pheromones, in the form of “social odors,” that one member of a species is exposed to during interaction with another member of the species, cause changes in hormone levels and in behavior. See vomeropherin.

  Polyploidy: see chromosome.

  Protein: genes often code for proteins, which help form and regulate all organisms. Proteins are molecular machines made up of chains of twenty different types of amino acids. Proteins can themselves chain or clump together. Collagen, enzymes, many hormones, keratin, and antibodies are just a few of the different types of proteins.

  Proteome, Proteomics: the total complement of proteins within a cell or group of cells, or in an individual organism as a whole. Different tissues will produce different proteins from a standardized set of genes; gene activation in different tissues at different times causes variation in a cell's proteome. Knowing which genes have been activated can be traced through identifying proteins and other gene products. (See glycome and lipidome.)

  Provirus: the genetic code of a virus while it is contained within the DNA of a host.

  Radiology: imaging of the interior of a body using radiation, such as X-rays, PET scans (positron emission tomography), MRI (Magnetic resonance imaging), CAT scans (Computerized axial tomography), etc.

  Recombination: exchange of genes between or within organisms or viruses. Sexual reproduction is one such exchange; bacteria and viruses can recombine genes in many different ways. Recombination can also be done artificially in a laboratory.

  Retrotransposon, retroposon, retrogene: see movable elements.

  Retrovirus: RNA-based virus that inserts its code into a host's DNA for later replication. Replication can often be delayed for years. AIDS and other diseases are caused by retroviruses.

  RNA: ribonucleic Acid. Intermediate copy of DNA; messenger RNA (mRNA) is used by ribosomes as templates to construct proteins. Many viruses consist of single or doubled strands of RNA, usually transcribed to DNA within the host.

  SHEVA: fictional human endogenous retrovirus that can form an infectious virus particle, or virion; an infectious HERV. No such HERV is yet known. In Darwin's Radio and this novel, SHEVA carries first-order instructions between individuals for a rearrangement of the genome that produces a new variety of human. In effect, SHEVA triggers preexisting genetic “set-asides” that interact in time-proven ways to create a subtly different human phenotype.

  Sequencing: determining the sequence of molecules in a polymer such as a protein or nucleic acid; in genetics, discovering the sequence of bases in a gene or a length of DNA or RNA, or in the genome as a whole. Research into the sequence of the entire human genome has made huge strides, but our understanding of the implications of this growing knowledge is in its infancy.

  Sex chromosomes: in humans, the X and Y chromosomes. Two X chromosomes results in a female; an X and a Y results in a male. Other species have different types of sex chromosomes.

  Shiver: hypothetical activation of dormant endogenous retroviruses in women who have undergone SHEVA pregnancies. Recombination of exogenous and endogenous viral genes may produce new viruses with an unknown pathogenic potential.

  Transposon: see mobile elements.

  Vaccine: a substance that produces an immune response to a disease-causing organism. See antibody, antigen, immune response.

  Virion: infectious virus particle.

  Virus: nonliving but organically active particle capable of entering a cell and commandeering the cell's reproductive capacity to produce more viruses. Viruses consist of DNA or RNA, usually surrounded by a protein coat, or capsid. This capsid may in turn be surrounded by an envelope. There are hundreds of thousands of known viruses, and potentially millions not yet described. See exogenous virus, ERV.

  Vomeronasal organ (VNO, also known as Jacobson's organ): consisting of two pitlike openings in the roof of the mouth or in the nasal septum, this organ, in non-human mammals, provides a pathway that links pheromones to a hormone response and to sex differences in behavior. “Frithing” is a term used to describe sucking in air over the pit-like entrance to this organ, which is in the roof of the mouth in some animals. Cats can sometimes be observed curling their upper lip when smelling something funky; this is also called the flehman response, usually associated with examination of urine, marking scents, etc. Snakes perform similar sampling by drawing in scents from the air on their flicking tongues. Humans have vomeronasal pits, though they are very small and somewhat difficult to find; they may play a role in mate choice and other behaviors. A 1995 journal article warned plastic surgeons to preserve the human vomeronasal organ during reconstructive surgery, lest damage lead to loss of sexual interest and subsequent litigation.

  Vomeropherin: a marketing term for a pheromone detected by the human vomeronasal organ (the same as a mammalian pheromone detected by the mammalian VNO).

  Xenotransplant: transplant of nonhuman tissues and organs into humans. Xenotransplants in the past have involved baboon and other ape organs. Most xenotransplant research now focuses on pig tissues and organs. Xenotransplants could be risky because of the existence of latent viruses within the donor tissues. (See ERV, herpes, PERV.) The case of Mrs. Carla Rhine described in this novel is unlikely in real life; Mrs. Rhine's maladies come from the unfortunate combination of a relatively rare evolutionary viral event and transplantation. Nevertheless, the possibilities of viral contamination or viral recombination within human recipients of animal tissues is very real, and demands further research.

  ACKNOWLEDGMENTS

  Special thanks to Mark Minie, Ph.D., and Rose James, Ph.D.; Deirdre V. Lovecky, Ph.D.; Dr. Joseph Miller; Dominic Esposito of the National Cancer Institute; Dr. Elizabeth Kutter; Cleone Hawkinson; Alison Stenger, Ph.D.; David and Diane Clark; Brian W. J. Mahy, Ph.D., Sc.D., director of the Division of Viral and Rickettsial Diseases at the Center for Disease Control; Karl H. Anders, M.D.; Sylvia Anders, M.D.; Howard Bloom and the International Paleopsychology Project; Cynthia Robbins-Roth, Ph.D., James V. Kohl, Oliver Morton, Karen Anderson, Lynn Caporale, and Roger Brent, Ph.D.

  A BRIEF READING LIST

  A concise, elegantly written and conservative view of neo-Darwinian evolutionary theory is available in Richard Dawkins's River out of Eden: A Darwinian View of Life, BasicBooks, 1995. Dawkins is one of our best science writers and an excellent whetstone for anyone wishing to challenge institutionalized views of biology and evolution. It is my belief that he is wrong on many points, but he defines the debate in ways few others can.

  Published more recently, and going into more detail, Ernst Mayr's summing up of a life's work, What Evolution Is (2002, Perseus Books) makes another clear and unyielding statement of the paradigm of modern Darwinism. There will probably be no finer exponents of the old view of Darwinian evolution.

  The new view is emerging even as we speak.

  Stephen Jay Gould is unfortunately no longer with us. I recommend all of his learned and impassioned books and essays, but in particular the flawed, and for that reason no less fascinating and instructive, Wond
erful Life (Norton, 1989).

  A good bridge to a larger understanding of the turmoil in evolutionary theory is Niles Eldredge's Reinventing Darwin: The Great Debate at the High Table of Evolutionary Theory, Wiley, 1995. Eldredge and Gould are currently credited with a particular view of evolutionary leaps known as punctuated equilibrium, but the idea can be traced back at least to masters such as Ernst Mayr, and even back to Darwin. Wherever it comes from, punctuated equilibrium was one of the key stimuli to my writing Darwin's Radio. Gould and Eldredge should not be blamed for my elaborations, however.

  Peter J. Bowler's The Non-Darwinian Revolution: Reinterpreting a Historical Myth (1988, Johns Hopkins) is scholarly and entertaining at once.

  A fine introduction to genetics is Dealing with Genes: The Language of Heredity by Paul Berg and Maxine Singer, 1992, University Science Books. Though a decade old, its information is still useful and its attitude is forward-looking. It could prepare the reader for the following books.

  Lynn Margulis and Dorion Sagan have published an excellent critique of neo-Darwinianism in Acquiring Genomes: A Theory on the Origins of Species, 2002, BasicBooks. Margulis is a pioneer in thinking about cooperative and symbiotic systems, and she and her son Dorion make up the single most stimulating popular writing team in modern biology.

  More radical still, but just as polite and level-headed as Margulis, is Lynn Caporale, whose Darwin in the Genome: Molecular Strategies in Biological Evolution (2003, McGraw-Hill) is a clear and thoughtful examination of how genomics will shape and mutate the debate on evolution.

  Lamarck's Signature: How Retrogenes are Changing Darwin's Natural Selection Paradigm, by Edward J. Steele, Robyn A. Lindley, and Robert V. Blanden (1998, Perseus Books) focuses on one possible cause and arbiter of genomic variation.

  A key text in modern biology is Retroviruses, edited by John M. Coffin, Stephen H. Hughes, and Harold E. Varmus, 1997, Cold Spring Harbor Laboratory Press. Mostly for professionals, this rigorous and pioneering collection of monographs is filled with useful information.

  Of particular relevance to my two novels is Lateral DNA Transfer by Frederic Bushman, 2002, Cold Spring Harbor Laboratory Press, is an important synopsis of what is currently known about DNA transfer through viruses, transposons, plasmids, etc. I think it is one of the most significant biology books published in the last decade.

  James V. Kohl's The Scent of Eros (1995; reprinted in a revised edition, 2002, Continuum) is a rich source of information on pheromones, human communication through smell, and the influence of scent on sexuality.

  There's a wealth of fine writing on these topics in many other popular science books, textbooks, and magazines. Searching on author names and topics in online bookstores can be a good way to leapfrog through diverse subjects. Which leads us to a very small sampling of Web sites.

  Searching on key words in Web engines such as Google (“HERV,” “Retrotransposon,” “Barbara McClintock,” “Homo erectus,” “Mitochondria,” etc.) can lead the curious reader into a combination paradise and mine field of articles peer-reviewed and otherwise, research goals and updates, opinions, and quite a few rants of varying degrees of erudition. Caveats abound—there are dozens if not hundreds of Creationist and other religiously motivated, anti-evolution sites that seem to discuss evolution and genetics with some lucidity, for a while. Generally speaking, the science here is dubious at best.

  Nevertheless, searching on Google is how I located excellent articles by Luis P. Villarreal. In particular, I was influenced by Villarreal's “The Viruses That Make Us: A Role For Endogenous Retrovirus In The Evolution Of Placental Species,” available on the Web at http:// darwin.bio.uci.edu/ ~faculty/ villarreal/ new1/ erv-placental.html

  (Dr. Villarreal, Eric Larsson, and Howard Temin should not, however, be blamed for all the uses their ideas are put to in this novel.)

  James V. Kohl's Web site, www.pheromones.com, provides a number of links to articles and other sites that discuss the biology of smell. The Web site of the Molecular Sciences Institute, www.molsci.org, is filled with interesting news and developments. The International Paleopsychology Project, www.paleopsych.org, is a clearing house of fascinating ideas with many links to other Web sites.

  Periodically, I will post bibliographical updates on www.gregbear.com, as well as comments from readers about the theoretical underpinnings of the Darwin novels.

  Also by Greg Bear

  Hegira

  Beyond Heaven River

  Strength of Stone

  Psychlone

  Blood Music

  Songs of Earth and Power

  Eon

  Eternity

  Legacy

  The Forge of God

  Anvil of Stars

  Queen of Angels

  / (Slant)

  Heads

  Moving Mars

  Dinosaur Summer

  Foundation and Chaos

  Star Wars: Rogue Planet

  Darwin's Radio

  Vitals

  Collection

  The Collected Stories of Greg Bear

  Editor

  New Legends

  Darwin's Children is a work of fiction. Names, places, and incidents either are products of the author's imagination or are used fictitiously.

  A Del Rey® Book

  Published by The Random House Ballantine Publishing Group

  Copyright © 2003 by Greg Bear