Thursday, April 23, 2015

Big Gaps In Evolution Explained

 

Saltation, symbiosis, self-organization


Punctuated equilibrium

 The theory of punctuated equilibrium was proposed in the early 1970s by palaeontologists Stephen Jay Gould and Niles Eldredge, soon to be joined by Stephen Stanley. It postulates that, instead of undergoing continuous evolutionary change, species remain in a state of unchanging equilibrium for most of their existence. But these long periods of stability or stasis are occasionally punctuated by brief bursts of rapid evolution in which new species emerge – so quickly geologically speaking (i.e. within a few tens of thousands of years) that no finely graded sequence of intermediate forms is preserved in the fossil record.

 Standard evolutionary theory recognizes that a new species may branch off from an existing one very quickly – a process known a quantum speciation – but only in special circumstances; punctuated equilibrium suggests that rapid speciation is the rule rather than the exception. Most evolutionists are vigorously opposed to this theory, and continue to attribute the lack of transitional fossils to the imperfection of the fossil record. There have been heated and sometimes nasty debates between gradualists and punctuationists. Gradualists have called punctuationism ‘evolution by jerks’, while punctuationists have called gradualism ‘evolution by creeps’!
Punctuationists argue that rapid speciation events occur in small populations that have become geographically isolated. This has the advantage that it is easier for genetic traits to become fixed in a population, the smaller it is. At the same time, however, random genetic drift is greatest in small populations, which makes the accumulation of favourable mutations more unlikely. The theory also claims that speciation happens so fast that there is no time for nonadaptive mutations to be eliminated by natural selection. It holds that, rather than individual organisms being selected, entire new species survive or perish depending on their degree of adaptation to the environment they find themselves in. Critics maintain that species (or allopatric) selection cannot account for the degree of adaptation observed in the fossil record.
Punctuationism was originally put forward as a radical alternative theory to neo-Darwinian gradualism, which Gould declared to be ‘effectively dead, despite its persistence as textbook orthodoxy’. However, from the early 1980s, in the face of criticism, punctuationists began to moderate their statements. Gould (who died in 2002) eventually acknowledged that new anatomical traits are generated by the standard neo-Darwinian mechanism – natural selection acting on random mutations over long periods of time in large, relatively stable populations. This meant that the theory could no longer explain the abrupt emergence of animal forms, such as the explosive appearance of new body plans in the Cambrian. So while the punctuationists highlighted some of the failings of neo-Darwinism, they ultimately failed to offer a satisfactory alternative explanation for the origin of biological form and novelty.1 Palaeontologists James Valentine and Douglas Erwin concluded in 1987 that neither phyletic gradualism nor punctuated equilibrium could explain the origin of new body plans.2
The hypothesis that a species can rapidly evolve into a new species as a result of purely random genetic mutations is far-fetched, especially since genes do not explain morphogenesis. Furthermore, the punctuationist scheme offers no solution for the really serious problem of the absence of transitional forms between the higher categories of organisms – families, orders, classes and phyla. Michael Denton writes:
The gaps which separate species: dog/fox, rat/mouse etc. are utterly trivial compared with, say, that between a primitive terrestrial mammal and a whale or a primitive terrestrial reptile and an Ichthyosaur; and even these relatively major discontinuities are trivial alongside those which divide major phyla such as molluscs and arthropods. Such major discontinuities simply could not, unless we are to believe in miracles, have been crossed in geologically short periods of time through one or two transitional species occupying restricted geographical areas. Surely, such transitions must have involved long lineages including many collateral lines of hundreds or probably thousands of transitional species ... To suggest that the hundreds, thousands or possibly even millions of transitional species which must have existed in the interval between vastly dissimilar types were all unsuccessful species occupying isolated areas and having very small population numbers is verging on the incredible!3

Saltation

A number of influential biologists have seen large-scale mutations, or macromutations, as the most likely way in which new types of organisms have emerged. A saltational theory of evolution was proposed in the 1930s by palaeontologist Otto Schindewolf, who even speculated that at one time a reptile laid an egg from which a bird hatched. In the 1940s geneticist Richard Goldschmidt developed this theory further. Macromutations would give rise to ‘monsters’, most of which would be unviable and perish, but occasionally a ‘hopeful monster’ would appear which would be preadapted to a new environmental niche and become a successful new species. Such events would account for all the major gaps in the fossil record. Goldschmidt was excommunicated by the Darwinist establishment and regarded as a lunatic for the rest of his life.
Critics objected that when major mutational changes appear in the laboratory, they involve errors in the formation or placement of old parts – e.g. a leg coming out of a fruit fly’s head – and never the appearance of a new organ. Ernst Mayr described these mutation-generated monsters as ‘hopeless’, and Theodosius Dobzhansky said that the idea that a drastic mutation would produce a viable new type was equivalent to a ‘belief in miracles’. No macromutations leading to positive results or the emergence of a viable new species have ever been observed. Moreover, even if a much improved animal were to appear, it would find no mate, unless similar macromutations occurred in a male and female individual at the same time – which does not double the improbability, but squares it. If saltational events have occurred, it is quite untenable to suppose that they occurred by mere chance.
Gould defended Goldschmidt’s postulate that major structural transitions can occur rapidly (and supposedly randomly) without a smooth series of intermediate stages:
All paleontologists know that the fossil record contains precious little in the way of intermediate forms; transitions between major groups are characteristically abrupt. ... Even though we have no direct evidence for smooth transitions, can we invent a reasonable sequence of intermediate forms – that is, viable, functioning organisms – between ancestors and descendants in major structural transitions? Of what possible use are the imperfect incipient stages of useful structures? What good is half a jaw or half a wing?
The conventional reply to this, says Gould, is that incipient stages in the development of a new organ performed a different function from the one they later came to fulfil: ‘The half jaw worked perfectly well as a series of gill-supporting bones; the half wing may have trapped prey or controlled body temperature.’ But he suspected that this approach could not save gradualism in most cases.1

Fig. 6.1. Darwinists speculate that feathers originally evolved for heat insulation (though hair would have been much simpler to evolve and would have done the job just as well). They also claim that the proto-wings of proto-birds may have been used for capturing insects before they became suitable for flight.2

Regulatory genes to the rescue

Like Goldschmidt, Gould believed that most large evolutionary changes are brought about by small alterations in rates of development:
the problem of reconciling evident discontinuity in macroevolution with Darwinism is largely solved by the observation that small changes early in embryology accumulate through growth to yield profound differences among adults. ... Indeed, if we do not invoke discontinuous change by small alteration in rates of development, I do not see how most major evolutionary transitions can be accomplished at all. Few systems are more resistant to basic change than the strongly differentiated, highly specified, complex adults of ‘higher’ animal groups. How could we ever convert an adult rhinoceros or a mosquito into something fundamentally different?1
He believed that neoteny – the retention of the juvenile features of an ancestral species in the adult form of a descendant species, as a result of a slowdown in the rate of physical maturation – ‘provides one of the few mechanisms for rapid and profound evolutionary change in a Darwinian fashion without the specter of macromutation. A descendant with a mixture of ancestral juvenile and adult characters ... may immediately enter a new adaptive zone; yet the genetic input need involve no more than some changes in regulatory genes ...’2
Jeffrey Schwartz, too, invokes changes in regulatory genes (such as homeobox genes) and their activities as the key to the sudden emergence of new morphological designs and new species. He argues that the concept of macromutations can be dispensed with, since micromutations in regulatory genes can have major, macroevolutionary effects. He writes: ‘The activation of homeobox gene expression in novel positions or in novel combinations at different times certainly produces significant changes.’3 But he adheres to the core Darwinist belief that nothing but chance determines which regulatory genes are activated or deactivated, and when and where this occurs.
Each individual possesses two copies of each gene, which may be the same or different; if they are different, one copy will be dominant and the other recessive or unexpressed. Nonlethal genetic mutations are usually recessive to start with, and Schwartz argues that at some point, after they have been inherited by many members of the species, regulatory genes, ‘by a mechanism that remains unclear’, activate the recessive mutated genes and deactivate certain other genes, leading to the abrupt appearance of a new organ, or perhaps a new species.4 Regulatory genes themselves also undergo random mutations, which may turn them on or off, or may duplicate or change them slightly. Schwartz recognizes that most of these random changes would lead nowhere and assumes that ‘The evolution of life is probably strewn with the carcasses of failed species’.5However, there is no evidence that there have been any such failures, and the idea that all these alleged random happenings could somehow produce a feather, an eye, a kidney, an echolocation system, let alone a completely new plant or animal, places great strains on our credulity. A hundred years of mutagenesis experiments show that mutations affecting early body-plan development invariably result in abnormal or dead animals; this is because each regulatory gene coordinates the expression of numerous other genes.
Moreover, as pointed out earlier, regulatory genes no more explain morphogenesis than do structural genes. It is true that the order and location in which particular regulatory genes are switched on and off are correlated with the development of particular structures. But no one has ever shown that regulatory genes, or any other genes, carry instructions that determine the form of developing organs and organisms. Changes during embryonic development could certainly produce far-reaching effects, but they would need to unfold in a planned and purposeful manner. According to the theosophic tradition, such changes reflect prior changes in the astral body, which provides the template for embryonic and postnatal physical development.

Symbiosis

The first living organisms on earth are thought to have been bacteria, which consist of a single prokaryotic cell (i.e. a cell without a nucleus). They are said to have evolved further partly by random mutations and partly by transferring genes from one to another (known as DNA recombination). Around 2 billion years ago, larger and more complex eukaryotic cells (i.e. nucleated cells) appeared, the first unicellular eukaryotic organisms being the protists. All later, multicellular organisms – animals, plants and fungi – consist of eukaryotic cells.
Lynn Margulis attributed these major evolutionary innovations to symbiosis – the widespread tendency of different organisms to live in close association with one another and often inside one another (like the bacteria in our intestines). The most intimate form of symbiosis is the incorporation and integration of the genes of one species (mostly bacteria and other microbes) into the genome of another, giving rise to a new species – a process known as symbiogenesis. She saw symbiogenesis as the principal avenue of evolution, and said that random genetic mutations, which are ‘nearly always inconsequential or detrimental to the work as a whole’, have been ‘dogmatically overemphasized’ by neo-Darwinists.1 
Margulis argued that mitochondria, the powerhouses inside most nucleated cells, were once free-floating bacteria, and that in the distant past a larger cell either swallowed or was invaded by a bacterium, but instead of digesting it or being killed by it, they began to cooperate and the invading cell eventually became a mitochondrion. This proposal was initially greeted with ridicule but is now widely accepted, though it has never been experimentally demonstrated. Margulis also suggested that the flagella or fringe of cilia used by eukaryotes to propel themselves through the water were once the rapidly swimming bacteria called spirochetes, which accidentally attached themselves to other prokaryotes and progressively lost their distinct traits; and that the chloroplasts in plant cells used to be cyanobacteria which for some reason were spared digestion by plant ancestors. These chance alliances, ‘encouraged’ by environmental pressures, allegedly gave rise to the internally elaborate eukaryotic cells, which then diversified through random variation and selection, and eventually formed symbiotic alliances with one another, thereby producing the first multicellular organisms. 
Note that, like genetic mutations, all the changes involved in the integration of the genes of one organism into the genome of another organism are supposed to take place randomly, i.e. without any overall guidance or purpose. Michael Behe raises a further objection: ‘The essence of symbiosis is the joining of two separate cells, or two separate systems, both of which are already functioning. ... Neither Margulis nor anyone else has offered a detailed explanation of how the preexisting cells originated.’2 And as Ernst Mayr pointed out, ‘There is no indication that any of the 10,000 species of birds or the 4,500 species of mammals originated by symbiogenesis.’3 The large-scale, undirected exchange of genetic material between unrelated individuals is just as incapable of explaining the history of life on earth as any other random mechanism.

Self-organization and self-engineering

Stuart Kauffman, a leading proponent of complexity theory, argues that the origins of life, metabolism, genetic programmes and body plans are all beyond Darwinian explanation but may arise spontaneously through self-organization. This refers to the tendency of complex systems to spontaneously organize themselves into ordered patterns; ‘perturbations’ of a system can sometimes cause it to switch from one pattern to another. It’s true that many systems do sometimes seem to ‘spontaneously’ organize themselves, but saying that self-organization is driven by ‘laws of complexity’ is useless, since scientific laws do not cause or explain natural phenomena; they merely describe them.
Complexity theory is heavily mathematical and is unconnected to real-life chemistry. No proponent of complexity theory has ever gone into a laboratory, mixed a large variety of chemicals in a test tube, and looked to see if self-sustaining metabolic pathways spontaneously organize themselves. Many origin-of-life scientists have already tried such experiments – without any notable success. There is no evidence that either biological information or complex anatomical structures can arise from physics and chemistry alone. Self-organization remains a vague and fuzzy concept, and the theory excels mainly at generating computer graphics rather than explaining anything. Critics have accused Kauffman of practising ‘fact-free science’ and indulging in ‘cyberfantasy’. 
Robert Wesson is another scientist who recognizes that evolution involves more than just random variation and natural selection. He holds that it also involves self-organization, and that the emergence of a new species is directed by ‘internal factors’. The essence of self-organization, he says, is the ‘attractor’, which somehow guides the development of a new organ or instinct in a particular direction. He claims that thinking in these terms ‘makes extraordinary adaptations more understandable’.1 The truth, however, is that ‘attractors’ is no more than an empty word. 
Like Wesson with his ‘attractors’, many other scientists have felt compelled to invoke all sorts of new ‘laws’ and ‘organizing principles’ to explain the amazing diversity, creativity and ingenuity of life. Michael Denton, for example, speaks of ‘a preordained pattern, written into the laws of nature from the beginning’.2 Paul Davies says that in addition to the laws of physics, there are ‘general organizing principles that supervise the behavior of complex systems at higher organizational levels’.3 Systems theorist Fritjof Capra says that there is an ‘inherent tendency’ in nature towards the ‘spontaneous emergence of increasing order and complexity’.4 But as already noted, ‘laws of nature’, ‘organizing principles’ and ‘inherent tendencies’ are purely descriptive terms and explain nothing. 
Molecular biologist James Shapiro invokes ‘natural genetic engineering’ to explain how novelty is created in the course of evolution.5 He rejects the traditional view that the genome is a read-only memory system subject to change by accidental damage and copying errors, and shows in great detail that cells are able to ‘rewrite’ their own genomes, especially in response to outside stresses:
Living cells and organisms are cognitive (sentient) entities that act and interact purposefully to ensure survival, growth, and proliferation. They possess corresponding sensory, communication, information-processing, and decision-making capabilities. Cells are built to evolve; they have the ability to alter their hereditary characteristics rapidly through well-described natural genetic engineering and epigenetic processes as well as by cell mergers. Evolutionary novelty arises from the production of new cell and multicellular structures as a result of cellular self-modification functions and cell fusions.6
According to Shapiro, ‘The DNA record definitely does not support the slow accumulation of random gradual changes transmitted by restricted patterns of vertical descent.’There is abundant evidence that horizontal DNA transfer has played a key role in evolution; organisms can quickly co-opt structures from other organisms and re-engineer them. ‘The data’, he says, ‘are overwhelmingly in favor of the saltationist school that postulated major genomic changes at key moments in evolution.’8 He does not explain the origin of the first cell or of cells’ ‘cognitive’ abilities. 
Many biologists fiercely oppose the concept of natural genetic engineering, and the idea of ‘cell cognition, decision-making, and goal-oriented function’, because they feel it implies an engineer and therefore supports intelligent design. Willam Dembski, a proponent of intelligent design, remarks:
Organisms that can do their own natural genetic engineering are themselves marvels of engineering. We need to be engineers even to understand them. Moreover, the engineering feats they accomplish vastly overshadow human technological prowess. So why should it be a stretch to think that such systems are themselves the result of engineering?9
Shapiro rejects the idea of a ‘guiding intelligence outside of nature’. So does the theosophic worldview, for nothing can be outside of infinite nature; it also recognizes that the universe is pervaded by mind and intelligence, manifesting in many different degrees in all manner of life forms (including cells), but that consciousness cannot be reduced to the operations of physical matter.

Morphic fields

Rupert Sheldrake goes a step further by recognizing the need for nonphysical causal factors – which he calls morphic fields. These include morphogenetic fields (which guide the development and maintenance of the bodies of organisms), motor fields (which organize movements), behavioural fields (which organize habitual and instinctive behaviour), mental fields (associated with conscious and unconscious mental activity), and social and cultural fields. He argues that natural systems at all levels of complexity – from atoms to organisms and societies of organisms – are animated, organized and coordinated by these fields, which contain an inherent memory. Natural systems inherit this collective memory from all previous things of their kind by ‘morphic resonance’; what happens therefore depends on what has happened before. 
During embryogenesis, groups of relatively unspecialized cells act as ‘morphogenetic germs’ that tune into the morphogenetic fields that guide the development of particular bodily structures. A given type of morphogenesis usually follows a particular developmental pathway, but may also proceed towards the final form from different morphogenetic germs and by different pathways, as shown by organisms’ ability to repair themselves after damage. If unusual environmental conditions or genetic changes alter the structure of a germ sufficiently, it may become associated with a different morphogenetic field or no field at all. The pattern of gene activity controlled by homeotic genes affects a whole pathway of morphogenesis. Mutations in these genes affect the tuning of morphogenetic germs to particular morphogenetic fields, just as an alternation to a transistor or condenser in a tuning circuit could cause a television to tune into a different channel or to lose the ability to tune into any channel at all. 
Evolution, says Sheldrake, ‘involves more than a change in gene frequencies: it involves the natural selection and stabilization of patterns of organization brought about by morphic fields. These fields themselves evolve.’1 He argues that the origin of new morphic fields could be ascribed to chance, or to creativity inherent in nature, or to a transcendent creative agency. He says that morphic fields never completely vanish when the species or entity they organize dies but continue to exist as ‘potential organizing patterns of influence’, and that this explains why the same evolutionary pathways are sometimes repeated. 
To some extent, morphic fields correspond to the inner, subtler bodies or souls postulated in mystic traditions, and the morphic field of Gaia corresponds to the subtler (astral and akashic) planes interpenetrating our physical globe. But Sheldrake’s concept of morphic fields is extremely hazy. He describes them as ‘fields of information’, saying that they are not a type of matter or energy and are detectable only by their effects on material systems. However, if morphic fields were absolutely nonmaterial, they would be pure nothingness and therefore devoid of any explanatory power. It is more logical to conceive of them as finer, nonphysical patterns of energy-substance, too ethereal to be detectable by scientific instruments.2 
Instead of a physical world organized by nebulous nonmaterial ‘fields’, theosophy proposes the existence of a whole spectrum of paraphysical forces and entities, ranging from elemental nature-forces to spiritual intelligences. The idea that there are subtler energies and entities at work makes more sense than the belief that there are abstract ‘laws’ and ‘principles’ floating around, magically creating order out of chaos, or that chance and spontaneity just happen to be creative. From a theosophical viewpoint, the physical world and everything within it are organized and guided from within outwards, and are self-organizing only if ‘self’ is taken to include supraphysical levels of their constitution.
The notion of inner planes of existence does not of course ‘explain’ things in the sense of offering an ‘ultimate answer’; after all, we could then enquire after the properties of these subtler states of energy-substance, the characteristics of the various entities that populate the unseen realms, and the way in which these supraphysical factors influence and interact with the physical world. The point is simply that if we do in fact live in a multilevelled reality, as many ‘anomalous’ phenomena imply, then paraphysical forces and entities will inevitably play a role in evolution too. The basic principle is that whatever is happening on any particular plane is influenced by subtler forces connected with inner planes, rather than by absolutely nonmaterial ‘laws’, ‘principles’, ‘fields’, etc.3

References

Punctuated equilibrium
  1. Walter J. ReMine, The Biotic Message: Evolution versus message theory, Saint Paul, MN: St. Paul Science, 1993, pp. 328-31; Stephen C. Meyer, Darwin’s Doubt: The explosive origin of animal life and the case for intelligent design, New York: HarperOne, 2013, pp. 138-51.
  2. Darwin’s Doubt, p. 151.
  3. Michael Denton, Evolution: A theory in crisis, Bethesda, MA: Adler & Adler, 1986, pp. 193-4.
Saltation
  1. Stephen Jay Gould, The Panda’s Thumb, London: Penguin Books, 1990, p. 157.
  2. Denton, Evolution: A theory in crisis, p. 209.
Regulatory genes to the rescue
  1. Gould, The Panda’s Thumb, p. 160.
  2. Stephen Jay Gould, Ontogeny and Phylogeny, Cambridge, MA: Belknap, Harvard University Press, 1977, p. 284.
  3. Jeffrey H. Schwartz, Sudden Origins: Fossils, genes, and the emergence of species, New York: John Wiley, 1999, p. 348.
  4. Ian Tattersall and Jeffrey Schwartz, Extinct Humans, New York: Nevraumont, 2001, pp. 46-9.
  5. Sudden Origins, p. 373.
Symbiosis
  1. Lynn Margulis and Dorion Sagan, Acquiring Genomes: A theory of the origins of species, New York: Basic Books, 2002, p. 15.
  2. Michael J. Behe, Darwin’s Black Box, New York: Free Press, 1996, p. 189.
  3. Foreword to Acquiring Genomes, p. xiii.
Self-organization and self-engineering
  1. Robert Wesson, Beyond Natural Selection, Cambridge, MA: MIT Press, 1994, p. 170.
  2. Michael J. Denton, Nature’s Destiny, New York: Free Press, 1998, p. 282.
  3. Paul Davies, The Mind of God, New York: Simon & Schuster, 1992, p. 182.
  4. Fritjof Capra, The Web of Life, London: Flamingo, 1997, p. 222.
  5. James A. ShapiroEvolution: A view from the 21st century, Upper Saddle River, NJ: FT Press Science, 2011; Casey Luskin, ‘James Shapiro’s Evolution: A View from the 21st Century offers a stunning look at biological complexity and non-Darwinian evolution’, 29 Aug. 2011, evolutionnews.org; James A. Shapiro, ‘“Is James Shapiro a design theorist?”: James Shapiro replies’, 16 Jan. 2012, evolutionnews.org.
  6. Evolution: A view from the 21st century, p. 143.
  7. Ibid., p. 126.
  8. Ibid., p. 89.
  9. William A. Dembski, ‘Borderline heretic: James Shapiro and his 21st century view of evolution’, 2012,designinference.com.
Morphic fields
  1. Rupert Sheldrake, The Presence of the Past: Morphic resonance and the habits of nature, New York: Vintage, 1989, p. 285.
  2. See Rupert Sheldrake: a theosophical appraisal, http://davidpratt.info.
  3. See Worlds within worlds, http://davidpratt.info.


An article published by David Pratt. @  http://davidpratt.info/evod1.htm

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