Friday, November 30, 2007

PoE: Bibliography "I"

This is the Bibliography "I" page for authors' surnames beginning

[Left: William Irvine's, "Apes, Angels & Victorians: The Story of Darwin, Huxley, and Evolution" (1955).]

with "I" which I may refer to in my book outline, "Problems of Evolution."

© Stephen E. Jones, BSc. (Biology)



Ingram, J. , 2001, "The Barmaid's Brain: And Other Strange Tales from Science," Aurum Press: London, Reprinted, 2005.
Inwood, B. & Gerson, L.P., eds, 1994, "The Epicurus Reader," Hackett Publishing Co: Indianapolis IN.
Irvine, W., 1955, "Apes, Angels and Victorians: The Story of Darwin, Huxley, and Evolution," McGraw-Hill: New York NY.
Isaac, B., ed., 1990, "The Archaeology of Human Origins: Papers by Glynn Isaac," Cambridge University Press: Cambridge UK
Isaacs, A., Daintith, J. & Martin, E., eds, 1991, "Concise Science Dictionary," [1984], Oxford University Press: Oxford, Second edition.

PS: See `tagline' quotes below, from these above books. I do not necessarily agree with everything that I emphasise (bold).

Stephen E. Jones, BSc. (Biology).
My other blog: TheShroudofTurin

"Scientists spend a lot of time pointing out the similarities between us and our closest relatives, the chimpanzees. There are two species of chimp, the common chimp that Jane Goodall has studied for decades and the lesser known bonobo, or pygmy chimp. Both are genetically very similar to humans (the common chimp closer), so much so that some scientists think of humans as just another chimp (see Jared Diamond's The Third Chimpanzee). But let's face it: there is world of difference between a human and a chimp. The most obvious is mental, notwithstanding the linguistic achievements of chimpanzees like Kanzi, the chimp trained by Sue Savage-Rumbaugh who apparently understands complicated English sentences (there are even structures in the chimp brain that hint at some sort of organization for language) or the reasoning exhibited by chimps who are smart enough to pile up boxes to reach bananas suspended from the ceiling. They're smart, but they're not Homo sapiens smart. And the difference between us and the chimps is more than just mental: physically and developmentally we're completely different animals. And yet there's that genetic similarity-the genes of the two species are more than 98 per cent identical." (Ingram, J., "The Barmaid's Brain: And Other Strange Tales from Science, London : Aurum, 2001, pp.105-106. Emphasis original).

"My favourite inhabitant of that [ultramicroscopic] world is a virus, but not one that preys on human beings. They too are marvellous, but the virus that first captured my imagination-and still holds it-was something called a bacteriophage, a `bacteria-eater.' Now simply called phage ... the existence of these specialized parasites was first deduced early in the twentieth century. They were not even seen; their presence was inferred. ... Felix d'Herelle, the pioneer of the research, could only have seen a bacteriophage near the end of his life-the first photos using the electron microscope were taken in the early 1940s. ... seeing a phage is a revelatory experience, not only confirming the portrait painted by the biochemistry (the criminal suspect turns out to look just like the artist's composite drawing) but also reinforcing the idea that nature is endlessly inventive-and savage." (Ingram, 2001, pp.201-202).

"There are many bacteriophages, one or more for every kind of bacterium. They have been studied, not so much because they are interesting in and of themselves, but because they are relatively simple objects that can shed light on how genes work. The one that is probably the most intensively studied in a virus called T4 that parasitizes E. coli, the bacterium with the misfortune of being known mostly for its association with human feces-water quality tests search for the presence of coliform bacteria as an index of exposure of that water to human waste." (Ingram, 2001, p.202)

"Under ideal laboratory conditions an E. coli cell can divide every twenty minutes. Obviously, as has been pointed out many times before, that can't possibly be happening in the natural habitat (your intestine) or the earth would be swamped by these bacteria in a couple of days. Nonetheless coliform bacteria represent a highly evolved, incredibly efficient life form; thus any organism that would target it must be highly evolved as well, and the T4 bacteriophage fits the bill. In fact it is speculated that T4 probably appeared on the planet shortly after its bacterial hosts, which puts its arrival at something like three and a half billion years ago. Its modus operandi substantiates the view that it is anything but primitive." (Ingram, 2001, pp.202-203)

"A T4 phage looks a little like the Apollo lunar lander.

[Right (click to enlarge): T4 bacteriophage, National Science Foundation]

It has a geometric head, a tail, and a set of tail fibres that spread out and attach to the surface of the bacterium. In function, however, it is more like a completely self-contained robotic spacecraft - fully preprogrammed.

The manufactured appearance-the unlifelike symmetry-is surprising at first look, probably because we think of microscopic infectors as tiny worms, or even miasmic gases, concepts left over from centuries ago. But the forces that dominate this world (where objects are millionths of a metre in size or less) are powerful short-range chemical bonds, and structures are nakedly molecular. For instance, a molecule will attract or repel others depending on the haze of electric charge surrounding its projections or the shape and orientation of tiny crevasses on its surface. A second molecule might fit like a hand in a glove or it might never make contact. This isn't to say that life in our world isn't dictated by the same kind of chemistry-it is. But other forces, especially gravity, play a dominant role. In the world of the phage, chemistry is it." (Ingram, 2001, p.204)

"In the absence of prey, the T4 phage simply drifts with the tide-it is not capable of seeking out E. coli. In drift mode the tail fibres are stowed, pinned up alongside the tail. However, when the virus comes into contact with the surface of the bacterial cell, the tail fibres immediately swing down and spread out, and are the first parts of T4 actually to touch the E. coli cell. They will attach wherever they contact a specific receptor molecule that's part of the external coat of the bacterium. However, the bond between one tail fibre and its receptor is weak, too weak to anchor the virus. There are six such fibres and at least three must make contact before capture is complete. That doesn't happen immediately because the receptors are distributed across the surface of the bacterium like occasional repeating tiles in a mosaic. This is the first step of what phage scientists call the `phage mating dance.' T4 walks across the surface of its intended victim, tail fibres attaching, then detaching, until finally it makes sufficient, and permanent, contact." (Ingram, 2001, pp.204-205)

"Once anchored, a remarkable series of events ensues. The virus adjusts its position so that the tail is positioned over a thin portion of the surface of the bacterium. Tail fibres attached to the flat base plate of the tail extend and pin the virus down (no escape now) and suddenly the base plate itself mysteriously changes shape from hexagonal to star-shaped. This triggers a rearrangement of the molecules of the outer sheath of the tail; the sheath contracts, the tail fibres bend and the virus is pulled down closer to the cell surface. The core of the tail actually penetrates partway through the multilayered outer envelope of the bacterium, an event likely made easier by enzymes in the base plate that chop up some of the surface molecules in that envelope." (Ingram, 2001, p.205)

"Now the head of the virus sits just above the cell. The head is a rigid hollow case in the shape of an icosahedron, a regular twenty-sided geometric figure. It contains the genes of the phage, more than one hundred and fifty of them, all linked together in one long thread of DNA. Long of course is a relative term, but the phage DNA, stretched out, would measure several hundred times the dimensions of the head. No one is yet sure exactly how that much DNA is packed into that tiny space, a space made tinier by the fact that special packing molecules are stuffed in there as well. But at this point in the phage mating dance, the DNA isn't going to be locked inside the head much longer." (Ingram, 2001, pp.205-206)

"When the hexagonal base plate changed its shape, it opened up a channel wide enough for a single DNA double helix to pass through. Now the huge string of phage DNA, its entire genome, snakes its way through the tail, through the bacterial surface envelopes, the rigid cell wall and into the interior. It's all over in less than a minute, this process that some researchers have likened to throwing a potful of spaghetti-one enormous strand-into a colander and having the end of that strand find its way through a hole and then feed itself through completely. The energy to do that has to come from somewhere, but it's not yet clear where. One thing is certain: once the phage DNA has entered the E. coli cell the poor bacterium is not long for this world. And it is about to suffer the indignity of contributing through its death to the multiplication of the phage." (Ingram, 2001, p.206)

"It's simple really. Among the hundred-and-fifty-plus genes in the phage DNA are those that direct (through the molecules they make) the shutdown of almost all E. coli activities. However, the cellular machinery formerly used to make E. coli membranes, enzymes, structural protein molecules-the machinery that maintained the bacterium's pulse of life-remains unscathed and is instantly converted to creating new phages. The now commandeered bacterial cell becomes a factory floor for phage parts. As the minutes tick by scaffolds for building new heads appear here, tail fibres there, baseplates over here. It might appear simple, but in fact some of these parts are composed of several different kinds of molecules. David Coombs, a phage biologist at the University of New Brunswick, has called the base plate alone `one of the most challenging biological structures ever studied in molecular detail.' Some phage parts spontaneously self-assemble from their components, but others must be engineered together under the guidance of yet more molecules." (Ingram, 2001, pp.206-207)

"A hint of the subtlety of engineering involved can be seen in the manufacture of new phage DNA. Naturally it's assembled using the machinery that E. coli used to make its own DNA. But what is it made out of? Pieces of E. coli DNA that were disorganized, then dismembered, mere minutes after the phage gained access to the interior of the cell. The phage manages to scavenge about twenty viruses' worth of DNA from host DNA. But the phage DNA is different in one important respect: one of the four DNA subunits is decorated with small molecules that identify it as uniquely phage. It's suspected this protects the phage DNA from enzymes inside the cell that normally attack and destroy any pieces of foreign DNA that they happen upon. It may even protect the intruder's DNA from its own DNA-destroying chemicals. Because such recognition is a molecular touch-and-feel sort of process, DNA with these unusual decorations escapes." (Ingram, 2001, p.207)

"Assembly continues in an ordered but rapid fashion. Fully mature heads are built around head scaffolds (which are then discarded), then stuffed with a complete set of genes. Tail fibres bond to base plates, tail cores to sheaths, base plates to tails, and before the half hour is out hundreds of new phages are ready to be released. One final enzyme is manufactured which chews away the bacterial envelope from the inside and the progeny viruses escape to begin the routine all over again." (Ingram, 2001, p.207)

"How do any E. coli survive in the face of such diabolical evolutionary design? They might come up with alterations to the receptors that the tail fibres recognize, which would literally make them `invisible' to the phage, but there's good evidence that the phages can simply respond by altering their tail fibres to make them visible again. E. coli also makes a variety of defensive DNA-destroying enzymes, but T4 can evade many of those by decorating its own DNA, although there's likely an ongoing battle here, with E. coli cells swapping defence genes among themselves." (Ingram, 2001, pp.207-208)

"Perhaps the most effective defences are what are called `guests' hiding in the E. coli DNA. These are genes left behind in the E. coli chromosome by other phages or in some case by some unknown visitor. These alien genes will not permit the T4 to reproduce inside the E. coli cell, but this act of defiance is a noble one for the bacterium, because the bacterium dies in the process, reminiscent of the infamous phrase from the Vietnam War, `We had to destroy the village to save it.' In this molecular version, however, death of the bacterium does insure that no new viruses will be produced from it." (Ingram, 2001, p.208)

"Do you want to be happy? Of course you do! Then what's standing in your way? Your happiness is entirely up to you. This has been revealed to us by a man of divine serenity and wisdom who spent his life among us, and showed us, by his personal example and by his teaching, the path to redemption from unhappiness. His name was Epicurus. ... The fundamental obstacle to happiness, says Epicurus, is anxiety. No matter how rich or famous you are, you won't be happy if you're anxious to be richer or more famous. No matter how good your health is, you won't be happy if you're anxious about getting sick. You can't be happy in this life if you're worried about the next life. You can't be happy as a human being if you're worried about being punished or victimized by powerful divine beings. But you can be happy if you believe in the four basic truths of Epicureanism: there are no divine beings which threaten us; there is no next life; what we actually need is easy to get; what makes us suffer is easy to put up with. This is the so-called 'four-part cure', the Epicurean remedy for the epidemic sickness of human anxiety; as a later Epicurean puts it, `Don't fear god, don't worry about death; what's good is easy to get, and what's terrible is easy to endure.'" (Hutchinson, D.S., "Introduction," in Inwood, B. & Gerson, L.P., eds, 1994, "The Epicurus Reader," Hackett Publishing Co: Indianapolis IN, p.vii. Emphasis original).

"`Don't worry about death.' While you are alive, you don't have to deal with being dead, but when you are dead you don't have to deal with it either, because you aren't there to deal with it. `Death is nothing to us,' as Epicurus puts it, for `when we exist, death is not yet present, and when death is present, then we do not exist.' [Epicurus, Letter to Menoeceus, text 4, section 125] Death is always irrelevant to us, even though it causes considerable anxiety to many people for much of their lives. Worrying about death casts a general pall over the experience of living, either because people expect to exist after their deaths and are humbled and terrified into ingratiating themselves with the gods, who might well punish them for their misdeeds, or else because they are saddened and terrified by the prospect of not existing after their deaths. But there are no gods which threaten us, and, even if there were, we would not be there to be punished. Our souls are flimsy things which are dissipated when we die, and even if the stuff of which they were made were to survive intact, that would be nothing to us, because what matters to us is the continuity of our experience, which is severed by the parting of body and soul. It is not sensible to be afraid of ceasing to exist, since you already know what it is like not to exist; consider any time before your birth-was it disagreeable not to exist? And if there is nothing bad about not existing, then there is nothing bad for your friend when he ceases to exist, nor is there anything bad for you about being fated to cease to exist. It is a confusion to be worried by your mortality, and it is an ingratitude to resent the limitations of life, like some greedy dinner guest who expects an indefinite number of courses and refuses to leave the table." (Hutchinson, 1994, p.viii-ix).

"`Don't fear god.' The gods are happy and immortal, as the very concept of `god' indicates. But in Epicurus' view, most people were in a state of confusion about the gods, believing them to be intensely concerned about what human beings were up to and exerting tremendous effort to favour their worshippers and punish their mortal enemies. No; it is incompatible with the concept of divinity to suppose that the gods exert themselves or that they have any concerns at all. The most accurate, as well as the most agreeable, conception of the gods is to think of them, as the Greeks often did, in a state of bliss, unconcerned about anything, without needs, invulnerable to any harm, and generally living an enviable life. So conceived, they are role models for Epicureans, who emulate the happiness of the gods, within the limits imposed by human nature. `Epicurus said that he was prepared to compete with Zeus in happiness, as long as he had a barley cake and some water.' If, however, the gods are as independent as this conception indicates, then they will not observe the sacrifices we make to them, and Epicurus was indeed widely regarded as undermining the foundations of traditional religion. Furthermore, how can Epicurus explain the visions that we receive of the gods, if the gods don't deliberately send them to us? These visions, replies Epicurus, are material images travelling through the world, like everything else that we see or imagine, and are therefore something real; they travel through the world because of the general laws of atomic motion, not because god sends them. But then what sort of bodies must the gods have, if these images are always streaming off them, and yet they remain strong and invulnerable? Their bodies, replies Epicurus, are continually replenished by images streaming towards them; indeed the `body' of a god may be nothing more than a focus to which the images travel, the images that later travel to us and make up our conception of its nature." (Hutchinson, 1994, pp.ix-x).

"If the gods do not exert themselves for our benefit, how is it that the world around us is suitable for our habitation? It happened by accident, said Epicurus, an answer that gave ancient critics ample opportunity for ridicule, and yet it makes him a thinker of a very modern sort, well ahead of his time. Epicurus believed that the universe is a material system governed by the laws of matter. The fundamental elements of matter are atoms, which move, collide, and form larger structures according to physical laws. These larger structures can sometimes develop into yet larger structures by the addition of more matter, and sometimes whole worlds will develop. These worlds are extremely numerous and variable; some will be unstable, but others will be stable. The stable ones will persist and give the appearance of being designed to be stable, like our world, and living structures will sometimes develop out of the elements of these worlds. This theory is no longer as unbelievable as it was to the non-Epicurean scientists and philosophers of the ancient world, and its broad outlines may well be true." (Hutchinson, 1994, pp.ix-x).

"We happen to have a great deal of evidence about the Epicurean philosophy of nature, which served as a philosophical foundation for the rest of the system. But many Epicureans would have had little interest in this subject, nor did they need to, if their curiosity or scepticism did not drive them to ask fundamental questions. What was most important in Epicurus' philosophy of nature was the overall conviction that our life on this earth comes with no strings attached; that there is no Maker whose puppets we are; that there is no script for us to follow and be constrained by; that it is up to us to discover the real constraints which our own nature imposes on us. When we do this, we find something very delightful: life is free, life is good, happiness is possible, and we can enjoy the bliss of the gods, rather than abasing ourselves to our misconceptions of them." (Hutchinson, 1994, p.x).

"Like nearly everything else, evolution was invented, or almost invented, by the Greeks. From Heraclitus and Anaximander came the suggestion that animal species are mutable; from Aristotle, the idea of a graded series of organisms, the idea of continuity in nature or the shading of one class into another, and a model of evolutionary process in the development of the germ into the plant. From both the Stoics and the Epicureans, and particularly from Lucretius, came the doctrine that man is a part of nature and that his origins are animal and savage rather than godlike and idyllic." (Irvine, W., 1955, "Apes, Angels and Victorians: The Story of Darwin, Huxley, and Evolution," McGraw-Hill: New York NY, pp.84-85).

"Already in The Origin of Species Darwin is haunted by the mystery of genetics. If variations cause evolution, what causes variations? He attacks the problem in the first and second chapters, and finally at length in the fifth. The discussion is cautious and sensible but also vague and occasionally confused. He sometimes talks as though natural selection not only sifts variations but causes them. Later, when taken to task for these lapses by Lyell and Wallace, he rectified many passages but allowed a few to remain, even in the last edition of his book. In general, he holds that variations arise through unknown hereditary factors within the organism, through use and disuse, the correlation of parts, and changes in environment. Domestic animals are extremely variable because man has introduced them into many and diverse regions. The domestic duck cannot rise from the ground because it has long ceased to need or use its wings. Significantly, its young can still fly. In short, he is often, so to speak, a Buffonian or a Lamarckian on the genetic level. At his best, he simply acknowledges a complete ignorance of the whole subject." (Irvine, 1955, p.92).

"You could not see natural selection at work. Therefore it was a mere empty speculation. But in a more particular sense the sore point was natural selection itself. It seemed to substitute accident-or, as some felt, mechanism-for intelligent purpose in the natural order. ... Natural selection was an ingenious hypothesis but of course it could not be taken seriously. It omitted its own ultimate and governing factor. The American Asa Gray, a warm and sincere Darwinian, held that, so far from representing chance, natural selection embodied a blind necessity totally incompatible with theism, unless the stream of variations themselves could be conceived as guided by design. [Gray, A. "Design versus Necessity," in "Darwiniana," D. Appleton & Co: New York NY, 1876, pp.75-76] ... When Asa Gray pleaded that variations might be divinely guided, Darwin ... felt that the more divine guidance in variations, the less reality in natural selection." (Irvine, 1955, p.108).

"At the end of his life, he [Darwin] spoke out frankly in the `Autobiography:' As usual, he explained himself with a history. His religion had wasted away before his science in a war of attrition so gradual that, in his own words, he `felt no distress' and hardly realized that a shot had been fired. Soon after his return to England, while yet hesitating between an evolutionary and a theological biology, he had discovered -no doubt with astonishment-that he had become a complete skeptic about Revelation. His ideas of progress and evolution-secondarily, his humanitarianism-had been decisive. He saw that scriptures and mythology were part of the evolution of every people. `The Old Testament was no more to be trusted than the sacred books of the Hindoos,' [Darwin, C.R. in Barlow, N., ed., "The Autobiography of Charles Darwin," W.W. Norton & Co: New York, 1958, p.85] not only because of `its manifestly false history of the world' but because of `its attributing to God the feelings of a revengeful tyrant.' [Ibid, p.85] He rejected Christian miracles because they were similar to those in other mythologies, because they rested on dubious and conflicting testimony, and because they contradicted the uniformitarianism he had learned from Lyell. He also rejected the divinity of Jesus and doubted the supremacy of Christian ethics. `Beautiful as is the morality of the New Testament, it can hardly be denied that its perfection depends in part on the interpretation we now put on metaphors and allegories:' [Ibid, p.86]" (Irvine, 1955, p.109).

"Darwin's matter was as English as his method. Terrestrial history turned out to be strangely like Victorian history writ large. Bertrand Russell. and others have remarked that Darwin's theory was mainly `an extension to the animal and vegetable world of laissez faire economics' [Russell, B., "Religion and Science," Home University Library: London, 1935, pp.72-73] As a matter of fact, the economic conceptions of utility, pressure of population, marginal fertility, barriers in restraint of trade, the division of labor, progress and adjustment by competition, and the spread of technological improvements can all be paralleled in The Origin of Species. But so, also, can some of the doctrines of English political conservatism. In revealing the importance of time and the hereditary past, in emphasizing the persistence of vestigial structures, the minuteness of variations and the slowness of evolution, Darwin was adding Hooker and Burke to Bentham and Adam Smith. The constitution of the universe exhibited many of the virtues of the English Constitution." (Irvine, 1955, p.98).

"Understanding the literature on human evolution calls for the recognition of special problems that confront scientists who report on this topic. Regardless. of how the scientists present them, accounts of human origins are read as replacement material for genesis [sic]. They fulfil needs that are reflected in the fact that all societies have in their culture some form of origin beliefs, that is, some narrative or configurational notion of how the world and humanity began. Usually, these beliefs do more than cope with curiosity, they have allegorical content, and they convey values, ethics and attitudes. The Adam and Eve creation story of the Bible is simply one of a wide variety of such poetic formulations." (Isaac, G., in Isaac, B., ed., 1990, "The Archaeology of Human Origins: Papers by Glynn Isaac," Cambridge University Press: Cambridge UK, p.96).

"We are conscious of a great change in all this, starting in the eighteenth and nineteenth centuries, The scientific movement which culminated in Darwin's compelling formulation of evolution as a mode of origin seemed to sweep away earlier beliefs and relegate them to the realm of myth and legend. Following on from this, it is often supposed that the myths have been replaced by something quite different. which we call `science'. However. this is only partly true: scientific theories and information about human origins have been slotted into the same old places in our minds and our cultures that used to be occupied by the myths, the information component has then inevitably been expanded to fill the same needs. Our new origin beliefs are in fact surrogate myths, that are themselves part science, part myths." (Isaac, 1990, p.96).

"abiogenesis The origin of living from nonliving matter, as by *biopoiesis. See also spontaneous generation." (Isaacs, A., Daintith, J. & Martin, E., eds., "Concise Science Dictionary," [1984], Oxford University Press: Oxford UK, Second Edition, 1991, p.1. Emphasis original).

"biogenesis The principle that a living organism can only arise from other living organisms similar to itself (i.e. that like gives rise to like) and can never originate from nonliving material. Compare spontaneous generation." (Isaacs, et al., 1991, p.74. Emphasis original).

"biopoiesis The development of living matter from complex organic molecules that are themselves nonliving but self-replicating. It is the process by which life is assumed to have begun. See origin of life." (Isaacs, et al., 1991, p.74. Emphasis original).

"Darwinism The theory of *evolution proposed by Charles Darwin (1809-82) in On the Origin of Species (1859), which postulated that present-day species have evolved from simpler ancestral types by the process of *natural selection acting on the variability found within populations. On the Origin of Species caused a furore when it was first published because it suggested that species are not immutable nor were they specially created - a view directly opposed to the doctrine of *special creation. However the wealth of evidence presented by Darwin gradually convinced most people and the only major unresolved problem was to explain how the variations in populations arose and were maintained from one generation to the next. This became clear with the rediscovery of Mendel's work on classical genetics in the 1900s and led to the present theory known as neo-Darwinism." (Isaacs, et al., 1991, p.183. Emphasis original).

"Evolution The gradual process by which the present diversity of plant and animal life arose from the earliest and most primitive organisms, which is believed to have been continuing for at least the past 3000 million years. Until the middle of the 18th century it was generally believed that each species was divinely created and fixed in its form throughout its existence (see special creation). Lamarck was the first biologist to publish a theory to explain how one species could have evolved into another (see Lamarckism), but it was not until the publication of Darwin's On the Origin of Species in 1859 that special creation was seriously challenged. Unlike Lamarck, Darwin proposed a feasible mechanism for evolution and backed it up with evidence from the fossil record and studies of comparative anatomy and embryology (see Darwinism; natural selection). The modern version of Darwinism, which incorporates discoveries in genetics made since Darwin's time, probably remains the most acceptable theory of species evolution. More controversial, however, and still to be firmly clarified, are the relationships and evolution of groups above the species level." (Isaacs, et al., 1991, pp.251-252. Emphasis original).

"mutation A sudden random change in the genetic material of a cell that may cause it and all cells derived from it to differ in appearance or behaviour from the normal type. An organism affected by a mutation (especially one with visible effects) is described as a mutant. Somatic mutations affect the nonreproductive cells and are therefore restricted to the tissues of a single organism but germline mutations, which occur in the reproductive cells or their precursors, may be transmitted to the organism's descendants and cause abnormal development. Mutations occur naturally at a low rate but this may be increased by radiation and by some chemicals (see mutagen). Most (the gene mutations) consist of invisible changes in the DNA of the chromosomes, but some (the chromosome mutations) affect the appearance or the number of the chromosomes. An example of a chromosome mutation is that giving rise to *Down's syndrome. The majority of mutations are harmful, but a very small proportion may increase an organism's *fitness; these spread through the population over successive generations by natural selection. Mutation is therefore essential for evolution, being the ultimate source of genetic variation." (Isaacs, 1991, p.455. Emphasis original).

"natural selection The process that, according to *Darwinism, brings about the evolution of new species of animals and plants. Darwin noted that the size of any population tends to remain constant despite the fact that more offspring are produced than are needed to maintain it. He also saw that variations existed between individuals of the population and concluded that disease, competition, and other forces acting on the population eliminated those individuals less well adapted to their environment. The survivors would pass on any inheritable advantageous characteristics (i.e. characteristics with survival value) to their offspring and in time the composition of the population would change in adaptation to a changing environment. Over a long period of time this process could give rise to organisms so different from the original population that new species are formed. *See also* adaptive radiation. *Compare* punctuated equilibrium." (Isaacs, 1991, p.458. Emphasis original).

"neo-Darwinism (modern synthesis) The current theory of the process of *evolution, formulated between about 1920 and 1950, that combines evidence from classical genetics with the Darwinian theory of evolution by *natural selection (see Darwinism)*. It makes use of modern knowledge of genes and chromosomes to explain the source of the genetic variation upon which selection works. This aspect was unexplained by traditional Darwinism." (Isaacs, et al., 1991, pp.459-460. Emphasis original).

"origin of life The process by which living organisms developed from inanimate matter, which is generally thought to have occurred on earth between 3500 and 4000 million years ago. It is supposed that the primordial atmosphere was like a chemical soup containing all the basic constituents of organic matter: ammonia, methane, hydrogen, and water vapour. These underwent a process of chemical evolution using energy from the sun and electric storms to combine into ever more complex molecules, such as amino acids, proteins, and vitamins. Eventually self-replicating nucleic acids, the basis of all life, could have developed. The very first organisms may have consisted of such molecules bounded by a simple membrane. " (Isaacs, et al., 1991, p.491. Emphasis original).

"Special Creation. The belief, in accordance with the Book of Genesis, that every species was individually created by God in the form in which it exists today and is not capable of undergoing any change. It was the generally accepted explanation of the origin of life until the advent of *Darwinism. The idea has recently enjoyed a revival, especially among members of the fundamentalist movement in the USA, partly because there still remain problems that cannot be explained entirely by Darwinian theory. However, special creation is contradicted by fossil evidence and genetic studies, and the pseudoscientific arguments of creation science cannot stand up to logical examination." (Isaacs, et al., 1991, pp.646-647. Emphasis original).

"spontaneous generation The discredited belief that living organism can somehow be produced by nonliving matter. For example, it was once thought that microorganisms arose by the process of decay and even that vermin spontaneously developed from household rubbish. Controlled experiments using sterilized media by Pasteur and others finally disproved these notions. Compare biogenesis. See also* biopoiesis" (Isaacs, et al., 1991, pp.652-653. Emphasis original).

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