Did They Find the Magic Bullet?
Then how can evolution be a fact?
The paper attempts to take a step toward resolving this issue. It is not exactly a new idea among evolutionists. The idea is that evolution occurs not by adjusting the genes that do and make things, but rather the expression levels of genes that regulate other genes.
In their study they showed that increasing the expression of a regulatory gene, late in the embryonic development phase, resulted in more teeth in the threespine stickleback fish.
Now I’ll be the first to say this was a fine piece of work. But the idea that this suggests how body plans evolve is simply an unwarranted extrapolation, motivated not by the scientific evidence they uncovered but by the assumption evolution is true.
Furthermore, let’s indulge this idea for a moment. Imagine a new experiment shows that yet another regulatory adjustment accomplished more than merely manufacture more teeth. Imagine altering the expression level of some regulatory genes suddenly produced a whole new design. The fish could now crawl, for example.
That narrative would call for an unbelievable level of serendipity. Evolution would have had to create all the parts, pieces and instructions for that design, save for a simple regulatory adjustment. The design was there, latent in the circuitry of the fish, just waiting to be turned on.
And of course that would have to occur over and over, untold number of times, in evolutionary history as species undergo all kinds of improvements. This is far too much serendipity.
So yes, the stickleback fish evolves, but it is not the kind of evolution that we normally think of. As one report explains:
Threespine sticklebacks, small fish found around the globe, undergo rapid evolutionary change when they move from the ocean to freshwater lakes, losing their armor and gaining more teeth in as little as 10 years. A biologist shows that this rapid change results not from mutations in functional genes, but changes in regulatory DNA. He pinpoints a gene that could be responsible for teeth, bone or jaw deformities in humans, including cleft palate
There is much good scientific work being done, but we need to limit our conclusions and claims to what the findings show and avoid baseless speculations.
"We are comforted by the fact that evolution has occurred and all we need to do is fill in the details"- paraphrasing Ernst Mayr.
ReplyDeleteBut yes the prevailing concept is that it wasn't new genes but the same genes used differently. Shubin discusses this in "Your Inner Fish"- unfortunately he has yet to test/ confirm the concept.
"In their study they showed that increasing the expression of a regulatory gene, late in the embryonic development phase, resulted in more teeth in the threespine stickleback fish."
ReplyDeleteThat they had to use 'a regulatory gene, late in the embryonic development phase', is not surprising since early acting mutations are always catastrophically bad. As Paul Nelson put the problem,,
Darwin or Design? - Paul Nelson at Saddleback Church - Nov. 2012 - ontogenetic depth (excellent update) - video
Text from one of the Saddleback slides:
1. Animal body plans are built in each generation by a stepwise process, from the fertilized egg to the many cells of the adult. The earliest stages in this process determine what follows.
2. Thus, to change -- that is, to evolve -- any body plan, mutations expressed early in development must occur, be viable, and be stably transmitted to offspring.
3. But such early-acting mutations of global effect are those least likely to be tolerated by the embryo.
Losses of structures are the only exception to this otherwise universal generalization about animal development and evolution. Many species will tolerate phenotypic losses if their local (environmental) circumstances are favorable. Hence island or cave fauna often lose (for instance) wings or eyes.
http://www.saddleback.com/mc/m/7ece8/
and,,,
A Listener's Guide to the Meyer-Marshall Debate: Focus on the Origin of Information Question -Casey Luskin - December 4, 2013
Excerpt: "There is always an observable consequence if a dGRN (developmental gene regulatory network) subcircuit is interrupted. Since these consequences are always catastrophically bad, flexibility is minimal, and since the subcircuits are all interconnected, the whole network partakes of the quality that there is only one way for things to work. And indeed the embryos of each species develop in only one way." -
Eric Davidson
http://www.evolutionnews.org/2013/12/a_listeners_gui079811.html
"Threespine sticklebacks, small fish found around the globe, undergo rapid evolutionary change when they move from the ocean to freshwater lakes, losing their armor and gaining more teeth in as little as 10 years."
DeleteAs you pointed out Dr. Hunter, this 'rapid evolutionary change' is not evidence in favor of neo-Darwinism, but is evidence of the 'top down' model of 'limited variation within kind':
"One hint that biology would not cooperate with Darwin’s theory came from the many examples of rapidly adapting populations. What evolutionists thought would require thousands or millions of years has been observed in laboratories and in the field, in an evolutionary blink of an eye."
Cornelius Hunter
Evolution of adaptive phenotypic traits without positive Darwinian selection - A L Hughes - November 2011
Excerpt: Recent evidence suggests the frequent occurrence of a simple non-Darwinian (but non-Lamarckian) model for the evolution of adaptive phenotypic traits, here entitled the plasticity–relaxation–mutation (PRM) mechanism. This mechanism involves ancestral phenotypic plasticity followed by specialization in one alternative environment and thus the permanent expression of one alternative phenotype. Once this specialization occurs, purifying selection on the molecular basis of other phenotypes is relaxed. Finally, mutations that permanently eliminate the pathways leading to alternative phenotypes can be fixed by genetic drift. Although the generality of the PRM mechanism is at present unknown, I discuss evidence for its widespread occurrence, including the prevalence of exaptations in evolution, evidence that phenotypic plasticity has preceded adaptation in a number of taxa and evidence that adaptive traits have resulted from loss of alternative developmental pathways. The PRM mechanism can easily explain cases of explosive adaptive radiation,
http://www.nature.com/hdy/journal/vaop/ncurrent/full/hdy201197a.html
A. L. Hughes's New Non-Darwinian Mechanism of Adaption Was Discovered and Published in Detail by an ID Geneticist 25 Years Ago - Wolf-Ekkehard Lönnig - December 2011
Excerpt: The original species had a greater genetic potential to adapt to all possible environments. In the course of time this broad capacity for adaptation has been steadily reduced in the respective habitats by the accumulation of slightly deleterious alleles (as well as total losses of genetic functions redundant for a habitat), with the exception, of course, of that part which was necessary for coping with a species' particular environment....By mutative reduction of the genetic potential, modifications became "heritable". -- As strange as it may at first sound, however, this has nothing to do with the inheritance of acquired characteristics. For the characteristics were not acquired evolutionarily, but existed from the very beginning due to the greater adaptability. In many species only the genetic functions necessary for coping with the corresponding environment have been preserved from this adaptability potential. The "remainder" has been lost by mutations (accumulation of slightly disadvantageous alleles) -- in the formation of secondary species.
http://www.evolutionnews.org/2011/12/a_l_hughess_new053881.html
It is also interesting to note just how rapid these adaptations can happen, and also that the 'plastic' adaptations are reversible if deleterious mutations have not yet accumulated:
DeleteLizard (cecal valve) Plasticity - March 2013
Excerpt: "So in this study, plasticity experiments were conducted. When the lizards were taken off a plant diet and returned to their native insect diet, the cecal valves in their stomachs began to revert within weeks. As the authors conclude, this pointed heavily to plasticity as a cause. We can infer that the this gut morphology likewise arose in similar fashion when coming into contact with the plant diet."
per biota curve
Phenotypic Plasticity - Lizard cecal valve (cyclical variation)- video
http://www.youtube.com/watch?v=zEtgOApmnTA
Of related interest to 'gaining teeth' in stickleback, is this experiment with teeth that I recently learned about. An experiment in which 'form' took precedence over the material particulars of the teeth,,,
DNA doesn’t even tell teeth what they should look like - April 3, 2014
Excerpt: A friend writes to mention a mouse experiment where developing tooth buds were moved so that the incisors and the molars were switched. The tooth buds became the tooth appropriate to the switched location, not the original one, in direct contrast to what we would expect from a gene’centric view.
per Uncommon Descent
In other words, body plans, (i.e. the form), is not reducible to the sequences of DNA as is presupposed in neo-Darwinism. Here are a few more notes that undermine any neo-Darwinian claim that DNA sequences determine morphology:
Getting Over the Code Delusion (Epigenetics) - Talbot - November 2010
Excerpt: As bioinformatics researcher Elliott Margulies and his team at the National Human Genome Research Institute put it, “the molecular shape of DNA is under selection” — a shape that can be maintained in its decisive aspects despite changes in the underlying sequence. It’s not enough, they write, to analyze “the order of A’s, C’s, G’s, and T’s,” because “DNA is a molecule with a three-dimensional structure.”[14] Elementary as the point may seem, it’s leading to a considerable reallocation of investigative resources.
http://www.thenewatlantis.com/publications/getting-over-the-code-delusion
The Gene Myth, Part II - August 2010
Excerpt: “It was long believed that a protein molecule’s three-dimensional shape, on which its function depends, is uniquely determined by its amino acid sequence. But we now know that this is not always true – the rate at which a protein is synthesized, which depends on factors internal and external to the cell, affects the order in which its different portions fold. So even with the same sequence a given protein can have different shapes and functions. Furthermore, many proteins have no intrinsic shape, taking on different roles in different molecular contexts. So even though genes specify protein sequences they have only a tenuous (very weak or slight) influence over their functions.
,,,,So, to reiterate, the genes do not uniquely determine what is in the cell, but what is in the cell determines how the genes get used. Only if the pie were to rise up, take hold of the recipe book and rewrite the instructions for its own production, would this popular analogy for the role of genes be pertinent.
Stuart A. Newman, Ph.D. – Professor of Cell Biology and Anatomy
http://darwins-god.blogspot.com/2010/08/gene-myth-part-ii.html
In terms of explaining morphology, here is 'a jaw dropper',,
An Electric (Frog) Face: A Rendering Worth a Thousand Falsifications - September 2011
Excerpt: The video suggests that bioelectric signals presage the morphological development of the face. It also, in an instant, gives a peak at the phenomenal processes at work in biology. As the lead researcher said, “It’s a jaw dropper.”
https://www.youtube.com/watch?v=0VULjzX__OM
So it seems to be evidence for front-loading or for lost functionality being turned on.
ReplyDeleteThis is the kind of stuff kids need to learn along with the positive evidence for evolution in schools!
ReplyDeleteAgreed that since they can't even figure out how new body plans evolve, evolution in the sense of molecule to man change, cannot be considered to be a fact.
Walking fish!
ReplyDeletehttp://www.nature.com/nature/videoarchive/walking_fish/index.html
So evolution proceeds via acquired traits? Or perhaps you didn't understand the video...
DeleteCornelius Hunter: But the idea that this suggests how body plans evolve is simply an unwarranted extrapolation, motivated not by the scientific evidence they uncovered but by the assumption evolution is true.
ReplyDeleteIt shows how small genetic changes can account for morphological evolution in metazoa.
Cornelius Hunter: There is much good scientific work being done, but we need to limit our conclusions and claims to what the findings show and avoid baseless speculations.
It supports the evolution of metazoa. After all, humans are 'just' elaborated Deuterostomes. A tube with appendages to stuff food into one end. Microevolution.
Z:
DeleteAfter all, humans are 'just' elaborated Deuterostomes. A tube with appendages to stuff food into one end. Microevolution.
That pretty much says it all, right there.
Cornelius Hunter: That pretty much says it all, right there.
DeleteYes. We have good reason to believe that the diversification of metazoa is consistent with relatively gradual genetic changes.