[Home] [Site map] [Updates] [Projects] [Contents; 1. Introduction; 2. Philosophy (1), (2), (3), (4) & (5); 3. Religion (1) & (2); 4. History (1), (2) & (3); 5. Science; 6. Environment (1), (2) & (3); 7. Origin of life (1), (2) & (3); 8. Cell & Molecular (1), (2) & (3); 9. Mechanisms (1) & (2); 10. Fossil Record; 11. `Fact' of Evolution; 12. Plants; 13. Animals; 14. Man (1) & (2); 15. Social; 16. Conclusion; Notes; Bibliography A-C, D-F, G-I, J-M, N-S, T-Z]
"PROBLEMS OF EVOLUTION": 9. MECHANISMS (3) 1. Evolutionists cannot agree on the mechanisms of evolution 2. Time 3. Mutations 4. Competition 5. Natural selection 6. Adaptation 1. Some too perfect 7. Speciation 1. Rarely (if ever) observed in nature 2. Darwin's phyletic gradualism is rare 8. Macroevolution 1. Saltation (jumps) 9. Convergence 1. Cephalopod and mammalian eye 2. Placental and marsupial mammals 3. Other examples 4. Non-random 10. Contingency (chance)
"PROBLEMS OF EVOLUTION": 9. MECHANISMS (3) 6. Adaptation 1. Some too perfect Darwin in his Origin of Species wrote that "Natural selection tends only to make each organic being as perfect as, or slightly more perfect than, the other inhabitants of the same country with which it comes into competition." (Darwin, 1872, p.187). Similarly Gould cautioned that "the imperfection of nature reveals evolution" because "nearly perfect adaptation ... could be imposed by a wise creator" (Gould, 1980, p.34; Gould, 1983, p.258). Macbeth pointed out that there are in fact in nature, some organisms that exhibited "Too Much Perfection" to be the result of the natural selection of random mutations (Macbeth, 1971, pp.102-103). One example of such too much perfection is a Philippines anglerfish which, unlike other anglerfishes that have a lure on a spinal projection in front of their head, has a near-perfect miniature `fish', with spots where a fish's eyes would be, both pectoral and pelvic `fins' in the right places and even a `tail' (Pietsch & Grobecker, 1978, pp.369- 370; Gould, 1980, pp.32-34; Fix, 1984, pp.202-203). Gould himself admits that such near-perfect adaptations, far from sealing the case for Darwinian evolution, are a major problem for it, and in fact evidence for creation (Gould, 1980, p.34)! Indeed, according to ReMine (1993) such examples of too perfect adaptations constitute a `biotic message' from the Creator to evolutionists who taunt creationists with the rhetorical question: "Why would God have created the world to make it look like evolution?" (Hunt, 1997; ReMine, 1993, p.2). That is, the answer is that God in fact created life to look unlike evolution (ReMine, 1993, p.17)! [top] 7. Speciation 1. Rarely (if ever) observed in nature Despite the title of Darwin's The Origin of Species, it is still unclear if biologists have ever actually observed speciation occurring in nature, and therefore have been unable to discover the factors that initiate the process, and whether genetic mutations that prevent species from interbreeding are the cause or just a consequence of speciation (Whitehouse, 2004a). [top] 2. Darwin's phyletic gradualism is rare "Phyletic gradualism" is the preferred pattern of Darwin and Neo-Darwinism: "A theory holding that macroevolution is merely the operation of microevolution, which operates gradually and more or less continuously over relatively long periods of time. Thus gradual changes eventually will accumulate to the point at which descendants of an ancestral population diverge into separate species, genera, or higher-level taxa" (Allaby, 1999, p.410). As Ernst Mayr, a co-founder of the Neo-Darwinian Modern Synthesis put it: "The proponents of the synthetic theory maintain that all evolution is due to the accumulation of small genetic changes, guided by natural selection, and that transpecific [macroevolution] evolution is nothing but an extrapolation and magnification of the events that take place within populations and species." (Mayr, 1970, p.351) The term was coined by Gould and Eldredge, to distinguish the standard Neo-Darwinian pattern from that of their proposed punctuated equilibrium theory: "Thus our term `phyletic gradualism' in general means slow, steady change by degrees.' In particular, it refers to the slow, steady transformation of an entire species. We presented evidence that, contrary to the long-held picture of gradual evolutionary change through time, most species hardly change much at all once they appear in the fossil record-the phenomenon we called `stasis.' We pointed out that paleontologists clung to the myth of gradual adaptive transformation even in the face of plain evidence to the contrary-paleontology's `trade secret,' as Gould later called it. ... neo-Darwinians-right on down through today's ultra-Darwinians-have tenaciously clung to the original Darwinian vision of gradualism. ... The ultra-Darwinian embrace of phyletic gradualism reveals some very serious flaws in their grasp of the basic organization of biological nature." (Eldredge, 1996, pp.63-64) The reason why "today's ultra-Darwinians-have tenaciously clung to the original Darwinian vision of gradualism" is because they, like Darwin, realise "that slow, gradual, cumulative natural selection." that is, phyletic gradualism, is "the very heart of the evolution theory, which gives it the power to dissolve astronomical improbabilities and explain prodigies of apparent miracle" (Dawkins, 1986, pp.317-318). However, there is little actual evidence in either the fossil record of the past or the living world of the present that Darwin's preferred of phyletic gradualism has played any more than a minor role in life's history. For example: "A species of songbirds can gradually evolve into two that have distinct songs and colour variations without ever interbreeding, says a University of British Columbia biologist whose work would make Darwin swoon. Darren Irwin used a new genetic analysis technique to show that the greenish warbler native to forests in Asia changes characteristics as its population spreads across the Tibetan Plateau. Eventually, it becomes another species altogether. "No one's ever shown such a nice, gradual change between two clearly separate species before," said Irwin, associate professor in UBC's zoology department" (Bains, 2005. My emphasis). [top] 8. Macroevolution 1. Saltation (jumps)"An odd-looking dinosaur whose fossilised remains were found by a Patagonian shepherd looking for lost sheep has prompted a rethink about the lumbering four-legged herbivores, called sauropods. ... sauropod dinosaurs typically had long flexible necks, studded with as many as 19 vertebrae. The necks enabled them to munch on lofty vegetation - a classic result of evolutionary pressure. But the new find suggests sauropods also cleverly evolved in a different way to exploit vegetation closer to the ground. The creature is a member of a sauropod sub-group called dicraeosaurids, which thrived during the Late Jurassic period, about 135- 150 million years ago. The bones, discovered [near] ... the Argentine village of Cerro Condor, point to a dinosaur that probably grew to a maximum length of less than 10 metres. What makes it special is a very short neck of just eight vertebrae that was some 40 per cent shorter than that of other dicraeosaurids. In addition, the species' closest relative comes from Africa. As dicraeosaurids lived on a super-continent called Gondwana, this suggests the creatures spread rapidly as continental drift broke this vast structure apart to form the main southern hemisphere continents. "Sauropods may have shown greater adaptive plasticity than they are often given credit for," the researchers said. The study, which appears in the British weekly science journal Nature, is led by Oliver Rauhut ...." ("Short-necked fossil prompts sauropod rethink," ABC/AFP June 2, 2005)[Another example of non-Darwinian `evolution'. Presumably even Dawkins would not claim that RM&NS could cause a dinosaur with "19 vertebrae" to gradually change into one with "just eight vertebrae" (or vice-versa)? But then the problem for evolution is that such Goldschmidt's "hopeful monster" version of evolution would require two (male and female) "19" or "eight vertebrae" "hopeful monsters" in the same place at the same time (see the following quotes). Even if a "19 vertebrae" and "eight vertebrae" dinosaur could and did mate, and their offspring was viable and perpetuated the macromutation, it would be `washed out' of the mutant descedants by further matings with non-mutants in a large population.]"So, macromutations do happen. But do they play a role in evolution? People called saltationists believe that macromutations are a means by which major jumps in evolution could take place in a single generation. Richard Goldschmidt ... was a true saltationist. If saltationism were true, apparent 'gaps' in the fossil record needn't be gaps at all. For example, a saltationist might believe that the transition from sloping-browed Australopithecus to dome-browed Homo sapiens took place in a single macromutational step, in a single generation. The difference in form between the two species is probably less than the difference between a normal and an antennapaedic fruitfully, and it is theoretically conceivable that the first Homo sapiens was a freak child - probably an ostracized and persecuted one - of two normal Australopithecus parents. There are very good reasons for rejecting all such saltationist theories of evolution. One rather boring reason is that if a new species really did arise in a single mutational step, members of the new species might have a hard time finding mates." (Dawkins R., "The Blind Watchmaker," [1986], Penguin: London, 1991, reprint, p.231)"We can well imagine such a non-Darwinian theory of discontinuous change-profound and abrupt genetic alteration luckily (now and then) making a new species all at once. Hugo de Vries, the famous Dutch botanist supported such a theory early in this century. But these notions seem to present insuperable difficulties. With whom shall Athena born from Zeus's brow mate? All her relatives are members of another species. What is the chance of producing Athena in the first place, rather than a deformed monster? Major disruptions of entire genetic systems do not produce favored or even viable creatures." (Gould S.J., "The Return of the Hopeful Monster," in "The Panda's Thumb: More Reflections in Natural History," [1980], Penguin: London, 1990, reprint, pp.158-159) [top]9. Convergence 1. Cephalopod and mammalian eye [top] 2. Placental and marsupial mammals [top] 3. Other examples http://news.bbc.co.uk/1/hi/sci/tech/4206077.stm BBC ... 25 January, 2005 ... Pilfering crab has insect's nose The robber crab climbs trees to pinch coconuts ...A land crab re-invented key features of the insect nose over millions of years - a striking example of convergent evolution, Current Biology reports. An animal's sense of smell needs to operate under very different conditions in air compared to water. The crab has achieved this in the same way as the ancestors of insects did. ... http://news.bbc.co.uk/1/hi/sci/tech/4206077.stm ABC Bug's nose helps crabs smell Kathy Graham ... 26 January 2005 The robber crab, shown here in the background, is the world's largest land-living arthropod ... As crabs evolved from living in the sea to the land they developed an insect "nose" to detect airborne chemicals, scientists show. They would have had to adapt from sniffing hydrophilic or water-loving molecules in a liquid to mainly hydrophobic molecules in a gas, placing dramatically new demands on their sensory equipment. ... http://www.abc.net.au/news/newsitems/200502/s1299931.htm ABC ... February 10, 2005. ... Clever octopus sheds light on arm evolution The octopus may have flexible arms, but it uses them in the same three-jointed way as vertebrates, a finding that sheds intriguing light on how limbs evolved, a new study says. .... The octopuses, filmed about 100 times, used a vertebrate-like strategy to carry out the complex movement. ... To carry out the fetching movement, the octopus flexes its arm to form three "joints," located in similar locations to the shoulder, elbow and wrist in humans. ... Limbed species may be very different in physiology, but they each face the same challenge in locating food, seizing it and bringing it their mouths. Millions of years of evolutionary pressure has determined that the triple-jointed arm is the simplest and most efficient way of achieving this ... "Fetching seems to be an example of evolutionary selection of solutions that are similar even though they are based on quite different mechanisms," the scientists suggest. ... [top] 4. Non-random [top] 10. Contingency (chance)"Virus-like genes that jump from spot to spot in the genome may help shape the nerves in our brains, possibly helping explain why brains differ so much, even in identical twins. The finding, reported in the current issue of the journal Nature, investigated a genetic element called an L1 retrotransposon - a piece of DNA that has the ability to make copies of itself and insert them in new spots in the genome. About 20% of the human genome is made up of L1 retrotransposons, although most are damaged and cannot move around. Scientists had considered them to be largely junk. Previously, these elements had been known to jump only in testes and ovary tissue. A team led by Fred Gage ... found they jumped around in the brain. The team observed the activity of an L1 retrotransposon that had been engineered so that every time it jumped within the genome the cell would glow green. The modified L1 was put into mice. "We saw these green neurons all over the brain and nervous system," Gage said. "It was pretty amazing." The jumping appeared to occur inside neural stem cells that gave rise to brain and nervous system cells. The scientists saw signs that the jumps could alter the development of the cells. It is possible, Gage said, that this creates diversity in the structure of brains by altering ratios of different types of brain cells or changing the way they link up. ... Gage said, "The fundamental question is: OK, here's a novel mechanism for generating diversity, but does it really matter? Is there any real consequence of this?" His team plans to probe this question by, for instance, creating mice in which the elements cannot jump and seeing how they differ from mice in which elements can. ... " (Mestel R., "Jumping Genes May Aid in Brain Diversity," Los Angeles Times, June 18, 2005)"Brain development may be influenced by genetic parasites THE brain is the most complicated object known. How it gets that complicated is, however, almost completely unknown. But part of the answer may turn out to be junk-at least that is the conclusion of a study led by Fred Gage ... One of the puzzling features of the human genome is that although genes are numerous they actually form less than 5% of the DNA in a cell nucleus. The rest was thus, rather cavalierly, dubbed "junk DNA" by those who discovered it. Gradually, a role for some of this junk has emerged. In particular, parts of it regulate the activity of genes, and thus which proteins are produced and in what quantities. That has implications for what a cell does-or, to put it another way, what type of cell it is. One of the most puzzling sorts of junk, though, is something known as a LINE-1 retrotransposon. This is junk that won't stay in one place. .... Retrotransposons are sometimes known as "jumping genes". ...only 100 retrotransposons are actually able to leap around, and only ten of those leap often. By and large, the parasites have been disabled, suggesting they are such bad news that evolution has eliminated them. Dr Gage and his colleagues, however, suspect that at least some of those that have not been disabled have been allowed to live on for a purpose. Instead of being destroyed, they have been subverted-and what they have been subverted to do is to create complexity in the brain. ... The rat-cell work showed that LINE-1 jumping happens only in precursors that turn into nerve cells, and that it seems to be regulated by a protein called Sox2 that is already known to play a crucial role in the formation of nerve cells. .... The team identified a dozen and a half such genes that were affected by LINE-1, and followed up one of them, PSD-93, in detail. PSD-93 makes a protein found in the places where nerve cells touch each other and pass their signals on. When LINE-1 jumped to a location in the genome near PSD-93 it increased production of the protein. That increase, at least in cell cultures, made it likelier that a developing precursor cell would turn into a nerve cell. So much is observation. This is where the speculation comes in. .... Many researchers think that which cells live and which die is decided by a process similar to natural selection. Cells with the right properties in the right places flourish; those without wither. But natural selection requires random variation to generate the various properties. Retrotransposons could provide that variation, by affecting gene expression at random, depending on where they pitch up. Changing the quantities of proteins such as the one made by PSD-93 would probably change the nature of the affected cell quite radically, and might even be responsible for generating the different types of nerve cell that are known to exist. Certainly, the brain has many more different types of cell in it than any other organ. .... But the thought that the complexity of the mammalian brain-and the existence of human intelligence-depends on variety induced by a tamed genetic parasite is truly audacious. Whether it is true remains to be seen ... " ("Brain science Helpful junk," The Economist, Jun 16th 2005)[If this holds up, the key to humans' rapid and huge increase in brain size may be due to a series of retrotransposons `just happening' to jump to the right loci! Then this would be just another of the events that made "the evolution [sic] of human beings ... fantastically improbable [in that] ... a host of unlikely events had to fall out in just the right way for intelligent life to emerge on this planet" (see tagline). In that case "One might well take this as a sign of God's hand at work in the evolutionary [sic] process"!]"One popular book on evolution, Richard Dawkins's Blind Watchmaker, is subtitled Why the Evidence of Evolution Reveals a Universe Without Design. In his book Wonderful Life, Stephen Jay Gould argues that the evolution of human beings was fantastically improbable and that a host of unlikely events had to fall out in just the right way for intelligent life to emerge on this planet. One might well take this as a sign of God's hand at work in the evolutionary process. Gould, however, bends his argument to the opposite conclusion that the universe is indifferent to our existence and that humans would never evolve a second time if we rewound time's videotape and started over. But to reach this conclusion, you have to assume the very thing that you are trying to prove: namely, that history isn't directed by God. If there is a God, whatever he wills happens by necessity. Because we can't really replay the same stretch of time to see if it always comes out the same way, science has no tests for the presence of God's will in history. Gould's conclusion is a profession of his religious beliefs, not a finding of science." (Cartmill M., "Oppressed by Evolution," Discover, Vol. 19, No. 3, March 1998)[top]
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Created: 3 November, 2003. Updated: 24 January, 2006.