For many evolutionary biologists, the most significant single piece of evidence supporting the Darwinian theory of origins is the nested hierachical pattern that is formed when comparing various genetic sequences in different organisms. The similarities and differences, it is argued, map out into a kind of "Tree of Life". It is this consistent pattern created by numerous different genes and genetic sequences that appears to many to be extremely compelling evidence. 1
Richard Dawkins was asked, "Out of all the evidence used to support the theory of evolution, what would you say is the strongest, most irrefutable single piece of evidence in support of the theory?" (Link). Dawkins' response is most interesting:
"I think to me perhaps the most compelling evidence is comparative evidence, from modern animals -- particularly biochemical comparative evidence, genetic, molecular evidence.
If you take any set of animals, and identify the same gene in different animals, and you really can do that, because the letters of the DNA code -- that is, the same code in all animals -- and you really can find a gene which is the same -- in, say, all mammals. For example, there's a gene called FOXP2, which is a couple of thousand letters long, and most of the letters are the same in any mammal, so you know it's the same gene. And then you go through, and you literally count the number of letters that are different.
So, in the case of FOXP2, if you count the number of letters that are different between humans and chimpanzees, it's only about 9. If you count the number of letters that are different in humans and mice, it's, I don't know, 30 or something like that. Actually, frogs have them as well, you find a couple of hundred that are different.
So, you can take any pair of animals you like -- kangaroo and lion, horse and cat, human and rat -- any pair of animals you like, and count the number of differences in the letters of a particular gene, and you plot it out, and you find that it forms a perfect branching hierarchy.
It's a tree, and what else could that tree be, but a family tree.
The problem with this claim is, of course, is that more and more inconsistent phylogenies are being discovered and more and more genes and genetic sequences are studied. And, quite surprisingly for many scientists, many of the phylogenies based on these various genetic sequences are very inconsistent with each other and with standard Darwinian ideas based on morphologic classification models.
mollusks (scallops) are more closely related to deuterostomes (sea urchins) than arthropods (brine shrimp). Of course, this is not too surprising. Intuitively, a scallop seems more like a sea urchin than a shrimp. So, the 82% correlation between the scallop and sea urchin is not surprising. However, in this light it is surprising is that a tarantula (also an arthropod) has a 92% correlation with the scallop. Here we have two different arthropods, a shrimp and an tarantula. How can a scallop be much more related to one type of arthropod and much less related to the other type of arthropod? This troubling thought led the authors of the Science article to remark:
Different representative species, in this case brine shrimp or tarantula for the arthropods, yield wildly different inferred relationships among phyla. Both trees have strong bootstrap support (percentage at node). . . The critical question is whether current models of 18S rRNA evolution are sufficiently accurate to successfully compensate for long branch attraction between the animal phyla. Without knowing the correct tree ahead of time, this question will be hard to answer. However, current models of DNA substitution usually fit the data poorly . . .
But when the data does not match to have the wished result, things are simply made up, proposing LGT ( lateral gene transfer )
A 1999 Science article by Stiller and Hall:
"A precipitous acceptance of such widespread LGT places evolutionary biologists in the untenable position of adopting an unfalsifiable hypothesis, at least in terms of the techniques of comparative sequence analyses that currently dominate the field of molecular evolution. Any phylogenetic pattern inferred from any given gene can be fit to some suitable mix of conventional intraspecies gene transmission and interorganismal genetic promiscuity. Thus, unless more reliable evidence is uncovered, the scientific method requires that we invoke the idea of ubiquitous LGT only as a last resort." 2
Question : Why are the emergence of new body form, cell shape, organs and functions not analyzed in regard of FUNCTION and INTERDEPENDENCE, rather than just phylogeny? Cells of Multicellular organisms work in an INTERDEPENDENT fashion. [/color][/b][b][color=#009900]A Merkel sensory cell bears only function when interconnected with the brain. A Bud taste cell only if connected to the nerve that goes to the right cortex in the brain to produce the sensation of taste. This leads with ease to the conclusion that back in the tree of life, there had to be a crucial point, where the development from unicellular to multicellular, and further branching producing new phyla and traits, required the emergence of new genes, instructing SYSTEM CHANGE, able to produce all at once new body members and organs that are interdependent. That would also mean the addition or mutation of multiple genes with multiple NEW instructions all at once through Darwin's natural selection. A hard sell..... But since Darwin's holy cow cannot be sacrificed, let's keep the practice of genetic phylogeny comparison. And when the evidence does not lead to the wished result of common ancestry, let's make up an assertion, like horizontal gene transfer, which will be swallowed by the audience as holy truth....
Last edited by Otangelo on Thu Dec 31, 2020 3:51 pm; edited 3 times in total