Darwin's Children

by Greg Bear

  Mitch tried to find a little of Kaye in Sam's features, but there was too much eyebrow. Sam looked too much like Mitch.

  “He looks like Will, I think,” Stella said. She touched her mother's cheek, gripped her hand. “She has a scent. It's her, but different. I'm not sure I'd recognize her. Can you smell it?”

  Mitch shook his head. “Maybe she smells ill,” he said darkly.

  “No.” Stella bowed to sniff her mother from breast to crown. “She smells like smoke from a wood fire, and flowers. We need her to teach us. Mother, you could teach me so much.”

  Sam walked around the bed, gripping the covers and making sounds of discovery.

  Kaye's face did not change expression, but Stella saw the tiny freckles darken under her mother's eyes. Even now, Kaye could show her love.

  The memories fall away. We are shaped, but in ways we do not understand. Know that thinking and memory are biology, and biology is what we leave behind. The caller speaks to all of our minds, and they all pray; to all of our minds, from the lowest to the highest, in nature, the caller assures us that there is more, and that is all the caller can do. It is important that each mind be created with absolute freedom of will. That freedom is precious; it enriches and quickens that which the caller loves.

  Mind and memory make up the precious rind of the even more precious fruit.

  We are sculpted as the embryo is made; we die and cells die that others may take a shape; the shape grows and changes, visible only to the caller; ultimately all must be chipped away, having made their contributions.

  The memories fall away. We are shaped. There is no judgment, for in life there is no perfection, only freedom. To succeed or to fail is all the same—it is to be loved.

  To die, to fall silent, is not to be forgotten or lost.

  Silence is the beacon of past love and painful labor.

  Silence is also a signal.

  Mitch sat by Kaye as the doctors and nurses came and went. He watched her grow more at ease, if that was possible, while breath still came and heart still beat with a slow, pattering softness.

  He finished that night, before he napped off, by kissing her forehead and saying, “Good night, Eve.”

  Mitch slept in the chair. Quiet filled the room.

  The world seemed empty and new.

  Silence filled Kaye.

  In a dream, Mitch walked over the high rocky mountains, and met a woman on the snows.

  Lynnwood, Washington

  2002

  CAVEATS

  Much of the science in this novel is still controversial. Science usually begins with speculation, but must in time be confirmed by research, empirical evidence, and scientific consensus. However, all of the speculations found here are supported, to one degree or another, by research published in texts and in respected scientific journals. I have gone to great pains to solicit scientific criticism and make corrections where experts feel I have strayed over the line.

  No doubt errors remain, but they are my responsibility, not the responsibility of the scientists or other helpful readers listed in the acknowledgments.

  The theological speculations presented here are also based on empirical evidence, personal and culled from a number of key books. But that evidence is remarkably and uniquely difficult to present scientifically, since it is necessarily anecdotal. That does not make its truth any less apparent to the witnesses; it simply puts this type of life experience in the same category as other human events, such as love, abstract and creative thought, and artistic inspiration.

  All of these experiences are personal and anecdotal, yet almost universal; none are easily quantified or understood by current science.

  In answer to the obvious questions about evolution, do I support neo-Darwinian randomness or theistic external design? The answer must be neither. Do I support fundamentalist or Creationist views of our origins? I do not.

  My view is that life on Earth is constituted of many layers of neural networks, all interacting to solve problems in order to get access to resources and continue to exist. All living things solve problems posed by their environments, and all are adapted to attempt, with reasonable success, to solve such problems. The human mind is just one variety of this natural process, and not necessarily the most subtle or sophisticated. See my novel, Vitals.

  I also make a distinction between self-aware personality and mind. Human self-awareness is a psycho-social phenomenon resulting from feedback in modeling the behavior of one's neighbors, and, almost coincidentally, modeling one's own behavior to make sure we'll fit into social activities. One offshoot of this ability is the writing of novels.

  Self is not an illusion; it's real. But it's not unitary, it's not primary, and it's not always in charge.

  It seems apparent that God does not micromanage either human history or nature. Evolutionary freedom is just as important as individual human freedom. Does God interfere at all? Other than my affirming, along with many others, that the presence of something we could call God is made known—a kind of interference, undoubtedly—I do not know.

  As Kaye experiences her epiphany, she is made aware that her “caller” is not talking just to her, but to other minds within and around her. Epiphany is not limited to our conscious selves, or even to human beings.

  Imagine epiphany that touches our subconscious, our other internal minds—the immune system—or that reaches beyond us to touch a forest, or an ocean . . . or the vast and distributed “minds” of any ecological system.

  If the only honest approach to understanding both nature and God is humility, then surely this should help by making us feel humble.

  A SHORT BIOLOGICAL PRIMER

  Humans are metazoans, that is, we are made up of many cells. In most of our cells there is a nucleus that contains the “blueprint” for the entire individual. This blueprint is stored in DNA, deoxyribonucleic acid; DNA and its complement of helper proteins and organelles make up the molecular computer that contains the instructions necessary to construct an individual organism.

  Proteins are molecular machines that can perform incredibly complicated functions. They are the engines of life; DNA is the template that guides the manufacture of those engines.

  DNA in eukaryotic cells is arranged in two interwoven strands—the “double helix”—and packed tightly into a complex structure called chromatin, which is arranged into chromosomes in each cell nucleus. With a few exceptions, such as red blood cells and specialized immune cells, the DNA in each cell of the human body is complete and identical. Researchers currently estimate that the human genome—the complete collection of genetic instructions—consists of approximately thirty thousand genes. Genes are heritable traits; a gene has often been defined as a segment of DNA that contains the code for a protein or proteins. This code can be transcribed to make a strand of RNA, ribonucleic acid; ribosomes then use the RNA to translate the original DNA instructions and synthesize proteins. Some genes perform other functions, such as making the RNA constituents of ribosomes.

  Many scientists believe that RNA was the original coding molecule of life, and that DNA is a later elaboration.

  While most cells in the body of an individual carry identical DNA, as the person grows and develops, that DNA is expressed in different ways within each cell. This is how identical embryonic cells become different tissues.

  When DNA is transcribed to RNA, many lengths of nucleotides that do not code for proteins, called introns, are snipped out of the RNA segments. The segments that remain are spliced together; they code for proteins and are called exons. On a length of freshly transcribed RNA, these exons can be spliced together in different ways to make different proteins. Thus, a single gene can produce a number of products at different times.

  Bacteria are tiny single-celled organisms. Their DNA is not stored in a nucleus but is spread around within the cell. Their genome contains no introns, only exons, making them very sleek and compact little critters. Bacteria can behave like social organisms; different varie
ties both cooperate and compete with each other to find and use resources in their environment. In the wild, bacteria frequently come together to create biofilms; you may be familiar with these bacterial “cities” from the slime on spoiled vegetables in your refrigerator. Biofilms can also exist in your intestines, your urinary tract, and on your teeth, where they sometimes cause problems, and specialized ecologies of bacteria protect your skin, your mouth, and other areas of your body. Bacteria are extremely important and though some cause disease, many others are necessary to our existence. Some biologists believe that bacteria lie at the root of all life forms, and that eukaryotic cells—our own cells, for example—derive from ancient colonies of bacteria. In this sense, we may simply be spaceships for bacteria.

  Bacteria swap small circular loops of DNA called plasmids. Plasmids supplement the bacterial genome and allow them to respond quickly to threats such as antibiotics. Plasmids make up a universal library that bacteria of many different types can use to live more efficiently.

  Bacteria and nearly all other organisms can be attacked by viruses. Viruses are very small, generally encapsulated bits of DNA or RNA that cannot reproduce by themselves, Instead, they hijack a cell's reproductive machinery to make new viruses. In bacteria, the viruses are called bacteriophages, (“eaters of bacteria”) or just phages. Many phages carry genetic material between bacterial hosts, as do some viruses in animals and plants.

  It is possible that viruses originally came from segments of DNA within cells that can move around, both inside and between chromosomes. Viruses are essentially roving segments of genetic material that have learned how to “put on space suits” and leave the cell.

  SHORT GLOSSARY OF SCIENTIFIC TERMS

  Antibody: molecule that attaches to an antigen, inactivates it, and attracts other defenses to the intruder.

  Antibiotics: a large class of substances manufactured by many different kinds of organisms that can kill bacteria. Antibiotics have no effect on viruses.

  Antigen: intruding substance or part of an organism that provokes the creation of antibodies as part of an immune response.

  Bacteria: prokaryotes, tiny living cells whose genetic material is not enclosed in a nucleus. Bacteria perform important work in nature and are the base of all food chains.

  Bacteriophage: see phage.

  Chromosome: arrangement of tightly packed and coiled DNA. Diploid cells such as body cells in humans have two sets of twenty-two autosomes as well as two sex chromosomes; haploid cells such as gametes—sperm or ova—have only a single set of chromosomes. The total number of chromosomes varies between apes and humans. Chromosome numbers for so-called ancestral species such as Homo sapiens neandertalensis and Homo erectus are not known; any DNA extracted from even relatively recent (~20,000 years) fossil specimens is generally limited to mitochondrial DNA. Polyploidy—having extra sets of chromosomes—results in infertile offspring or totally precludes reproduction between organisms and can often define a barrier between species. This should prevent successful mating between SHEVA individuals and older variety humans. Apparently, it does not. This puzzles scientists, and further research is in order.

  Cro-Magnon: early variety of modern human, Homo sapiens sapiens, from Cro-Magnon in France. Homo is the genus, sapiens the species, sapiens the subspecies.

  DNA: Deoxyribonucleic acid, the famous double-helix molecule that codes for the proteins and other elements that help construct the phenotype or body structure of an organism.

  ERV or endogenous retrovirus: virus that inserts its genetic material into the DNA of a host. The integrated provirus lies dormant for a time. ERVs may be quite ancient and fragmentary and no longer capable of producing infectious viruses.

  Exogenous virus: virus that does not insert its genes into host DNA on a long-term basis. Some viruses, such as MMTV or mouse mammary tumor virus, seem to be able to choose whether to insert or not insert their genetic code into host DNA. See ERV.

  Exon: region of DNA that codes for proteins or RNA.

  Frithing: also, flehman. Sucking air over the vomeronasal organ to detect pheromones. See vomeronasal organ.

  Gene: the definition of a gene is changing. A recent text defines a gene as “a segment of DNA or RNA that performs a specific function.” More particularly, a gene can be thought of as a segment of DNA that codes for some molecular product, very often one or more proteins or parts of proteins. Besides the nucleotides that code for the protein, the gene also consists of segments that determine how much and what kind of protein is expressed, and when. Genes can produce different combinations of proteins under different stimuli. In a very real sense, a gene is a tiny factory and computer within a much larger factory-computer, the genome.

  Genome: sum total of genetic material in an individual organism. In humans, the genome appears to consist of approximately thirty thousand genes—half to one-third the number predicted at the time of the publication of Darwin's Radio.

  Genotype: the genetic character of an organism or distinctive group of organisms.

  Glycome: the total complement of sugars and related compounds in a cell. Sugars can form links with proteins and lipids to make glycoproteins and glycolipids.

  Herpes: HSV-1 or -2. Herpes simplex virus types responsible for cold sores and genital herpes. Though herpes viruses are not retroviruses they can lie dormant in nerve cells for years, and often reactivate in response to stress. Chicken pox and its recurrent form, shingles, or herpes zoster, are also related to herpes.

  HERV: human endogenous retrovirus. Within our genetic material are many remnants of past infections by retroviruses. Some researchers estimate that as much as one third of our genetic material may consist of old retroviruses. No instance is yet known of these ancient viral genes producing infectious particles (virions) that can move from host to host, in lateral or horizontal transmission. Many HERV do produce viruslike particles within the cells and body, however, and whether these particles serve a function or cause problems is not yet known. All HERV are part of our genome and are transmitted vertically when we reproduce, from parent to offspring. Infection of gametes by retroviruses is the best explanation so far for the presence of HERV in our genome. ERV, endogenous retroviruses, are found in many other organisms, as well.

  Homo erectus: general classification for fossils of the genus Homo dated chronologically and evolutionarily prior to Homo sapiens. Homo erectus was a very successful human species, surviving for at least a million years. Calling any of these fossils “ancestral” is problematic both scientifically and philosophically, but it's a simple and easily understood description of a complex relationship. There are many interpretations of these relationships in the literature, but growing sophistication in genetics will probably lead to a general shaking out and clarification over the next ten to twenty years.

  Immune response (immunity, immunization): the provoking and marshaling of defensive cells within an organism to ward off and destroy pathogens, disease-causing organisms such as viruses or bacteria. Immune response may also identify nonpathogenic cells as foreign, not part of the normal body complement of tissues; transplanted organs cause an immune response and may be rejected. Autoimmune diseases such as multiple sclerosis and various forms of arthritis may occur or reoccur in response to viral activation due to stress. In humans, ERV activation has been suggested as a cause of some autoimmune diseases.

  Intron: region of DNA that generally does not code for proteins. In most eukaryotic cells, genes consist of mingled exons and introns. Introns are clipped out of transcribed messenger RNA (mRNA) before it is processed by ribosomes; ribosomes use the code contained in lengths of mRNA to assemble specific proteins out of amino acids. Bacteria lack introns.

  Lipids: organic compounds such as fats, oils, waxes, and sterols. Lipids make up many of the structural components of cells, including much of the cell wall or membrane.

  Lipome: the total complement of lipids within a cell. Lipids may also form alliances with sugars and proteins (see gly
come and proteome).

  Mitochondrion, mitochondria: organelles within cells that process sugars to produce the common fuel for cells, adenosine triphosphate, or ATP. Generally regarded as highly adapted descendants of bacteria that entered host cells billions of years ago. Mitochondria have their own loops of DNA constituting a separate genome within every cell. Mitochondrial DNA, being shorter and simpler, is often the target of choice for fossil analysis.

  Modern human: Homo sapiens sapiens. Genus Homo, species sapiens, subspecies sapiens. Homo sapiens sapiens could be read as “Man who is wise, who knows.” Also, “Man who is discreet, who savors.”

  Mobile element: movable segment of DNA. Transposons can move or have their DNA copied from place to place in a length of DNA using DNA polymerase. Retrotransposons contain their own reverse transcriptase, which gives them some autonomy within the genome. Mobile elements have been shown by Barbara McClintock and others to generate variety in plants; but some believe these are, more often than not, so-called selfish genes which are duplicated without being useful to the organism. More and more, geneticists have found strong evidence that mobile elements contribute to variation in all genomes and help to regulate both embryonic development and evolution.

  Mutation: alteration in a gene or segment of DNA. May be accidental and unproductive or even dangerous; may also be useful, leading to the production of a more efficient protein. Mutations may lead to variation in phenotype, or the physical structure of an organism. Random mutations are usually either neutral or bad for the health of the organism.

  Neandertal: Homo sapiens Neandertalensis. Possibly ancestral to humans. Modern anthropologists and geneticists are currently engaged in a debate about whether Neandertals are our ancestors, based on evidence of mitochondrial DNA extracted from ancient bones. More than likely, the evidence is confusing because we simply do not yet know how species and subspecies separate and develop.