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Topic: John A. Davison: An Evolutionary Manifesto: A New Hypothesis For Organic Change
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posted 03. June 2003 12:19
An Evolutionary Manifesto: A New Hypothesis For Organic Change
by John A. Davison
Abstract- This work represents an elaboration of material presented by the author in courses offered at the University of Vermont, especially Biology 255, The Comparative Physiology of Reproduction and Biology 202, Quantitative Biology. It is my hope that this treatise will reach not only the professional biologist but all others who realize how little we really understand concerning the history of life on this planet. I have assumed little in the way of background and I have defined most technical terms as they appear. The basic ideas put forth here were first published in 1984. I hope that this expanded and more completely documented treatment will reach a larger and more receptive audience.
My own background is in General and Developmental Physiology which is to say that I am interested in how things work. Like others before me, I have come to the realization that Darwinism simply does not work. That conclusion has led to a series of questions which I pose and attempt to answer. Answering one question often leads to asking another. Only by asking questions is one compelled to provide answers. I employ that approach throughout this presentation.
Among those questions are the following: Is evolution finished? Is sexual reproduction incapable of supporting evolutionary change? Is selection, natural or artificial, incapable of producing new life forms? In contrast to the Darwinian view, has evolution proceeded by means of leaps (saltation) rather than gradually through intermediate forms? Is there an alternative to Darwinism which, unlike that hypothesis, is compatible with all the facts revealed by paleontology, embryology, cytology, taxonomy, physiology and genetics? Do internal factors have a role in evolution? Is evolution irreversible? Is the individual, rather than the population, the instrument of evolutionary change? Are there laws governing evolution? Is there compelling evidence that evolution (phylogeny), like the development of the individual (ontogeny), involves the release or derepression of preformed information? Finally, the most controversial question of all: Has evolution been guided? With the exception of the last question, to which no certain answer will probably ever be given, I will answer yes to each of these questions.
To read the full article, click here.
[ 03. June 2003, 12:22: Message edited by: Moderator ]
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yersinia
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posted 03. June 2003 13:59
Howdy,
An article with some interesting biological tidbits and quotes even though I think that resorting to saltational macromutation creates far more problems than it solves.
A few obscure problems:
quote:
Evolution is in a great measure an unfolding of preexisting rudiments. -- Leo S. Berg
The existence of internal factors affecting evolution has to be accepted by any objective mind. -- Pierre Grassé
Once again Berg and Grassé independently have concurred on another critical point which cannot be accommodated within the Darwinian hypothesis, since the Darwinians deny the existence of such endogenous factors. The terms epigenesis and preformation originated from the study of embryonic development. Epigenesis refers to the necessity for embryonic stages to occur in a definite sequence. Thus the formation of the nervous system (neurulation} cannot occur until after the formation of the primitive digestive system (gastrulation). Therefore development is primarily, although not exclusively, epigenetic in nature. These ontogenetic phenomena have interesting counterparts in phylogeny (evolution). First, with respect to preformation, this concept is clearly favored by what we know about position effects. It is largely the same genes which produce a new species when they are rearranged, as is so evident in the primate karyotypes previously discussed. All living things are very similar at the molecular level using virtually identical enzyme systems for the extraction and utilization of energy. The energetic currency (adenosine triphosphate) is universal in both the plant and animal kingdoms as well as in the prokaryotes. At the structural level, the nine plus two arrangement of microtubules is universally the same in all cilia and flagella wherever they are found in the living world.
Actually, there is a lot of variation away from the 9+2 structure. This myth seems to have started with Denton's Evolution: A Theory in Crisis although it may go back further. But if you read:
Afzelius BA. The flagellar apparatus of marine spermatozoa: evolutionary and functional aspects. Symp Soc Exp Biol 1982;35:495-519
...you will discover that functional 9+1, 9+0, 6+0, 3+0, 15+1, etc. have all been found.
In conclusion, Davidson writes,
quote:
I now offer but a single observation that bears on the question of whether or not evolution has been guided. It relates to Robert Broom’s opinion that not a single new genus has appeared in the last two million years. It would seem that the last genus was Homo and the last species Homo sapiens.
I rest my case.
I doubt very much that Homo was the last genus to occur (the ciclids or something must have produced a genus more recently that that), although "genus" is a somewhat arbitrary grouping and some have even suggested that humans and chimps belong in the same genus (!). Regarding species, there are numerous examples of geologically recent speciation where at least some of it has occurred less than 100,000 years ago (ciclids, various Hawaiian groups, pupfish, etc.). Perhaps pupfish were the actual "guided" result?
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nosivad
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posted 06. June 2003 07:24
Thank you yersinia, Broom was undoubtedly referring to mammals not to animals generally. I probably should have indicated that. As for the cichlids and other examples, are we certain as to the mechanisms involved? I don't think so. The fact remains that the most intensive of selection has never been able to create new species.Quite the contrary, selection away from the norm creates numerous problems. If one treats evolution as an experimental science one is led to the conclusion that sexual reproduction cannot support macroevolution (true speciation) and certainly had nothing to do with the formation of the higher categories. I am of course a convinced saltationist which apparently lies at the root of some of the difficulties the semi-meiotic hypothesis presents for the neoDarwinian hypothesis. Incidental, but very important to our understanding, is the evidence that macroevolution seems no longer to be in progress. One cannot study a phenomenon no longer in operation. The best one can do is to attempt a reconstruction. This I have tried to do. nosivad
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charlie d.
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posted 06. June 2003 08:22
Actually, there is evidence of speciation events in mammals that are much more recent than 2 Mya; here is a ref, and I'd be surprised if this were the only known instance.
Even if it were true that there are no recent mammalian species, however, I find it rather surprising that one would conclude that "macroevolution" has ceased altogether and therefore evolutionary biology as an empirical field is hopeless. Mammals represent but a minute fraction of all organisms, and we have no reason to believe evolution works differently in mammals than in insects or fish.
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nosivad
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posted 06. June 2003 09:39
Dear Charlie d. I am certainly not the first to suggest that macroevolution is finished. Robert Broom and, of all people, Julian Huxley, said as much as did Pierre Grasse. The important point is that all experimental attempts to achieve speciation through selection of sexually transmitted mutations have met with dismal failure. I remain a convinced evolutionist nevertheless and have simply proposed an alternative mode. nosivad
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Erik
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posted 06. June 2003 10:59
Nosivad, I have two questions:
1. Do you accept that working biologists are doing a reasonably good job recognizing and defining "species"? That is, is your own preferred definition of "species" significantly different from that of present day biologists'?
2. Why isn't the following report
Michalak P. et al. (2001) "Genetic evidence for adaptation-driven incipient speciation of Drosophila melanogaster along a microclimatic contrast in 'Evolution Canyon,' Israel", Proceedings of the National Academy of Sciences of the USA, 98(23):13195-13200
a counter-example to your claim that "The important point is that all experimental attempts to achieve speciation through selection of sexually transmitted mutations have met with dismal failure."? I think the speciation is occuring in the wild (as opposed to in the laboratory), but I'm sure a laboratory example can be found too if that's essential.
Erik
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nosivad
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posted 06. June 2003 16:59
Dear Erik, I accept the physiological definition proposed by Theodosius Dobzhansky. Two forms will be considered separate species if their hybrid proves to be sterile. It is unambiguous and testable. As for the paper you cite, the key word is incipient. Curiously, that is exactly the term used by Dobzhansky when he failed to produce a new species in the laboratory with the same Drosophila described in the paper. I remain unconvinced that sexual reproduction can result in evolution beyond the subspecies. Again, this is not new with me. Goldschmidt claimed as much in 1940 and was ignored. The Darwinian gradualists have consistently ignored their critics. nosivad
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Erik
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posted 06. June 2003 17:57
Nosivad, your definition of "species" seems reasonably close to the one that is effectively used to enable meaningful discussions.
OK, so my example only showed incipient speciation, not complete hybrid sterility. Changing the subject from one species of Drosophila to another, what do you think of the following report of the genetics of hybrid sterility?
quote:
"Not surprisingly, Bogota and USA are incompletely reproductively isolated. They show very weak prezygotic isolation (PRAKASH 1972 ; NOOR 1995 ) and produce completely fertile female hybrids. Male hybrids are also fertile in one direction of the hybridization (USA mothers) but are completely sterile in the reciprocal direction (Bogota mothers)."
Orr H. & Irving S. (2001) "Complex Epistasis and the Genetic Basis of Hybrid Sterility in the Drosophila pseudoobscura Bogota-USA Hybridization", Genetics, 158:1089-1100
When using your unambiguous species definition, should I apply it to the male hybrids with USA mothers, the male hybrids with Bogata mothers, or the female hybrids?
Also, what are your thoughts on ring species?
Erik
[ 06. June 2003, 18:02: Message edited by: Erik ]
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Rex Kerr
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posted 06. June 2003 18:07
Although I find compelling the idea of chromosomal rearrangement as a primary source of macroevolutionary change, I also think that the paper overstates the case against speciation via more gradual methods, and more conventional views of chromosomal evolution.
For example, a very clear counterexample to the claim of no current speciation by gradual mechanisms is the existence of ring species, where animals exist throughout a range and are reproductively compatible with their historical neighbors, but not where two long-separated populations now inhabit the same range. A review of the greenish warbler, which inhabits a ring around the Himalayan plateau that spread from an originating population somewhere near India, and which is reproductively isolated from itself where the spreading populations overlap in Siberia, is given in Irwin et al., Genetica 112-113, pp. 223-43 (2001).
Also, the revelation that chromosomal rearrangement mutants cannot be generated under sexual reproduction will come as a surprise to Drosophila geneticists. Looking through the section on "aberrations" in FlyBase yields quite a diversity of rearrangements, most of which were produced in the lab with sexual reproduction. Aside from the fact that most genetics textbooks explain how you can get a fraction of viable progeny out of most rearrangements, this provides direct evidence that, while it may be difficult to get offspring from rearranged and non-rearranged parents, it's certainly far from impossible.
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Josh
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posted 06. June 2003 18:57
Perhaps a relevant article Science 300, p321-324:
Chromosomal Speciation and Molecular Divergence--Accelerated Evolution in Rearranged Chromosomes
Arcadi Navarro1* and Nick H. Barton2
Humans and their closest evolutionary relatives, the chimpanzees, differ in ~1.24% of their genomic DNA sequences. The fraction of these changes accumulated during the speciation processes that have separated the two lineages may be of special relevance in understanding the basis of their differences. We analyzed human and chimpanzee sequence data to search for the patterns of divergence and polymorphism predicted by a theoretical model of speciation. According to the model, positively selected changes should accumulate in chromosomes that present fixed structural differences, such as inversions, between the two species. Protein evolution was more than 2.2 times faster in chromosomes that had undergone structural rearrangements compared with colinear chromosomes. Also, nucleotide variability is slightly lower in rearranged chromosomes. These patterns of divergence and polymorphism may be, at least in part, the molecular footprint of speciation events in the human and chimpanzee lineages.
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nosivad
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posted 07. June 2003 09:57
Josh, I am convinced that if we were identical with the chimp in terms of DNA sequences we would still be what we are. The trivial differences are probably largely neutral and certainly have not been demonstrated to be adaptive. The phenotypic and genotypic differences are due directly to the alteration in chromosome structure just as Goldschmidt indicated more than 60 years ago. To understand my position it is necessary to realize that I have completely rejected natural selection as a creative element, thereby agreeing with Leo Berg, William Bateson and R.C. Punnett. Natural selection is a conservative force which only prevents change. The whole concept of natural selection collapses logically when one recognizes that Nature has of course somehow been created by means concerning which we know absolutely nothing. How can that which has been created become the Creator? I do not hesitate to call that "operation bootstrap".
As you may gather from my papers I also believe that the information for phylogeny may have been present from very early on, thus comparing phylogeny rather directly with ontogeny where there is no question that all of the necessary information is present in the fertilized ovum. Again, this idea is not new with me but represents an extension of the convictions of Leo Berg and Pierre Grasse. I realize that much of this is undoubtedly anathema to the doctrinaire neo Darwinian but there is little I can do about that. Evolution remains a great mystery but as Montaigne indicated "Men are most apt to believe what they least understand". nosivad
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Rex Kerr
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posted 07. June 2003 23:05
Humans create evolutionary algorithms on computers that then go on to create other things. And humans seem to both create things and to have been created (in some sense). Thus, the created can become the creator (lower case). Evolution is about creation, not Creation.
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nosivad
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posted 08. June 2003 06:16
Dear Rex, I agree. Humans are the only creatures able to be creative. However, they seem to be quite unable to create anything which might be considered to be alive and equally incapable of transforming (evolving) any contemporary organisms through even the most extensive application of artificial selection. nosivad
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Pim van Meurs
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posted 08. June 2003 13:15
Davison: Dear Rex, I agree. Humans are the only creatures able to be creative.
are you sure? I'd argue that other animals have shown the ability to creativity as well. The idea that humans are somehow unique in this sense may be begging the question.
Davison: However, they seem to be quite unable to create anything which might be considered to be alive and equally incapable of transforming (evolving) any contemporary organisms through even the most extensive application of artificial selection. nosivad
I'd agree that evolution has the advantage of 4 billion years of tinkering and that humans have a long way to go to match the inventiveness of evolution in this area.
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Justalayman
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posted 08. June 2003 14:32
Hi
Maybe it's just semantics but how can evolution "tinker" just saying lets see if this works or lets try this. To me tinkering implies a tinkerer
And how could four or twenty billion years make something as sophisticated as humans, the interactivily of life on this planet,the instinctive intellegence of animals, the laws that govern our galaxies or even the laws that govern the infinitely small?
And why is it so important that evolution be true?
That's really the question that gets me and I don't know the answer. Does it have to be true because it make the most sense or becuase it's what the educated are taught and believe?
Justalayman
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