Evidence for the Evolutionary Model

DNA Similarities ...along with dissimilarities, fall into distributional and mutational nested hierarchies

 

(p.11-13)                       The pdf of the entire book, with Ray's 50 page introduction, can be found here.

      One typical proof cited for Darwinian evolution is that chimpanzees and humans have very similar DNA. In previous DNA studies, based on only portions of the chimp genome, scientists announced that humans and chimps were 98–99 percent identical, depending on what was counted. After completing the mapping of the chimp genome in 2005, scientists are hailing the result as “the most dramatic confirmation yet” that chimps and humans have common ancestry. Though the complete genomes have yet to be compared, several studies found similarities as low as 86 percent. To date, researchers believe that the genetic difference is 4 percent (though this is actually twice the amount that has been assumed for years).10

      If once the genomes have been compared the difference is shown to be just 4 percent, with 3 billion base pairs of DNA in every cell, that represents 120,000,000 entries in the DNA code that are different. In our DNA instruction book, that’s equivalent to about 12 million words—a seemingly small percentage that has a tremendous impact.11

      It is disingenuous to imply that the figures 98-99% genetic similarity between chimps and humans is incorrect and has been contradicted by a whole-genome comparison. As the source Ray used admits, those figures are derived from comparisons of coding DNA, the instructions for the production of proteins. What it all comes down to is deciding which sections to compare, and the precise type and degree of change each portion causes.

      But since Ray and the authors of his sources—Answers in Genesis—would prefer to play the present-the-layman-with-really-big-numbers game, lets put his numbers in perspective to reveal the deception. Analysis of genetic variation among humans was previously limited to individual differences in nucleotides, called single nucleotide polymorphisms (SNPs); putting the total human genetic diversity around 99.9%.  In the past few years, however, researchers have found that non-SNP variants, such as block substitutions, multiple nucleotide polymorphisms (MNPs), inverted segments of DNA, insertions and deletions of segments, called indels, segmental duplications and copy number variations (CNVs), although accounting for only about 22% of mutation events, contribute about 74% of the total genetic variation between a person’s two sets of chromosomes—bringing the total human genetic diversity between any two people to a minimum 99.5% (Levy et al., 2007; J. Craig Venter Institute, 2007; "Genetic Variation Program", n.d.). If we set the length of each word in Ray’s hypothetical “instruction book” to ten, just as he did, the word count comes to well over 1.2 million. And as if that wasn’t enough, chimpanzees are observed to have significantly higher genetic diversity than humans (Stone et al., 2002; Fischer et al., 2004; Chimpanzee Sequencing and Analysis Consortium, 2005); as much as four time more (Kaessmann, 1999).


       Some critics also question the scientific basis for assuming that similar DNA indicates a common ancestor. Just as a biplane and a jet share common features of wings, body, tires, engine, controls, etc., they argue, does not require that one must have evolved from the other naturally, without a maker. They argue it’s more reasonable to conclude that similar design indicates a common, intelligent designer. An architect typically uses similar building materials for numerous buildings, and a car manufacturer commonly uses the same parts in various models. So if creation had a common designer, we could expect to find a similar “blueprint” used in many different creatures.

      Firstly, that analogy is fundamentally inapplicable to living organisms for a few simple reasons; neither airplanes nor watches nor paintings reproduce, witch rules out the possibility that their configurations are the result of decent with modification. Living organisms, on the other hand, do reproduce. They also pass on a large amount of the information that makes their configuration what it is to their offspring. The third critical trait of living things is that there is a consistent increase in variability caused by mutation from each generation to the next. And finally, living organisms exist in populations for finite amounts of time, and must stave off their demise while competing for limited resources. All of these principles together have an interesting result. As new variation is introduced by mutation, modifications to proteins, such as the way the catalyze reactions and configure to form anatomical structures, that allow for more efficient performance of tasks in the organisms’ environment, the organisms become either more or less able to both survive and compete for resources (thrive) in their environment. The measure of this efficiency is called fitness. Configurations that increase fitness make the organism more able—and thus more likely—to make significant contributions to their populations’ gene pools. This increases the frequencies of the alleles with those configurations, with time. Likewise, the frequencies of alleles with configurations that decrease fitness decrease, with time. This process is called natural selection. Since the differences between species are observed to be structural and functional modifications that increase fitness in the organisms’ environments, this is powerful evidence that these differences were the result of decent with modification caused by mutation and natural selection.

      But now let’s back up a bit. Ray is saying that similarities in DNA could simply be intrinsic. What he fails to consider is definitive evidence that many stretches of DNA either could not have been part of the original design, as with endogenous retroviruses (ERVs), or that variation within them must have been accumulated after their creation, as with both ERVs and pseudogenes.

      My throurough explaination of the endogenous retroviral evidence and the L-gulono-γ-lactone oxidase (GULOP) example of the pseudogene evidence can be found here:

ERVs: http://www.evolutionarymodel.com/ervs.htm

GULOP: http://www.evolutionarymodel.com/pseudogenes.htm

      To sum up this evidence; it is the corroboratory distributional and mutational nested hierarchies of ERVs and pseudogenes necessitate common ancestry; which in turn necessitates the past presents of an ancestral species. The ‘same gene, same designer’ argument falls flat on its face.

 

     Since DNA is the coding for the way our bodies look and operate, some reason that creatures with similar features or body functions (eyes for vision, enzymes for digestion, etc.) would have similar coding for these things in their DNA. Because human cells have the same biochemical functions as many different animals and even plants, we share many of the same genes. The more functions we have in common, the more we find similar coding in the blueprints. So while evolution states that similar DNA is proof of common ancestry, opponents interpret the same evidence as proof of a common designer. The challenge is to prove scientifically which is true.

As explained above, the specific sections of similar and dissimilar DNA, as well as the patterns they fall into, make a big difference when determining common ancestry. When these data are considered, the evolutionary model is strongly confirmed and the models of uncommon ancestry are discredited.

 

      To the question of whether sharing 96 percent of our genetic make-up with chimps makes us 96 percent chimp, evolutionist Steven Jones, a renowned British geneticist, humorously commented, “We also share about 50% of our DNA12 with bananas and that doesn’t make us half bananas …”

       Bringing up the ~50% genetic similarity between humans and bananas is ironic, as it exposes the flaw in the first paragraph of this section; similarities between the coding regions of genomes says far more about overall similarity than including regions that are not expressed. As mentioned in that paragraph, the difference between chimp and human coding regions is 98-99%.

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My References

Chimpanzee Sequencing and Analysis Consortium. "Initial sequence of the chimpanzee genome and comparison with the human genome." Nature 437.7055 (2005): 69-87. <http://www.nature.com/nature/journal/v437/n7055/full/nature04072.html>.

Fischer, A., V. Wiebe, S. Paabo, and M. Przeworski. "Evidence for a Complex Demographic History of Chimpanzees." Molecular Biology and Evolution 21.5 (2004): 799-808. <http://mbe.oxfordjournals.org/cgi/content/full/21/5/799>.

International Human Genome Sequencing Consortium. "Initial sequencing and analysis of the human genome." Nature 409.6822 (2001): 860-921. <http://www.nature.com/nature/journal/v409/n6822/full/409860a0.html>.

J. Craig Venter Institute. "First Diploid Human Genome Sequence Shows We're Surprisingly Different." Science Daily. 4 Sept. 2007. Web. 26 Nov. 2009. <http://www.sciencedaily.com­/releases/2007/09/070904072204.htm>.

 

Kaessmann, H., V. Wiebe, and S. Pääbo. "Extensive nuclear DNA sequence diversity among chimpanzees." Science 286.5442 (1999): 1159-162. <http://www.sciencemag.org/cgi/content/full/286/5442/1159>.

Levy, S., et al. "The diploid genome sequence of an individual human." PLoS Biology 5.E254 (2007). <http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0050254>.

"Genetic Variation Program." National Human Genome Research Institute. 13 May 2009. Web. 26 Nov. 2009. <http://www.genome.gov/10001551#1>. <http://www.genome.gov/10001551#1>.

Stone, A. C., R. C. Griffiths, S. L. Zegura, and M. F. Hammer. "High levels of Y-chromosome nucleotide diversity in the genus Pan." Proceedings of the National Academy of Sciences 99.1 (2002): 43-48. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC117511/?tool=pubmed>.

Ray’s References

10. David A. Dewitt, Ph.D., “Chimp Genome Sequence Very Different From Man,” September 5, 2005 <ww.answersingenesis.org/docs2005/0905chimp.asp>.

11. Don Batten, “Human/chimp DNA Similarity,” Creation, vol. 19, iss. 1, December 1996, pp. 21–22 <www.answersingenesis.org/creation/v19/i1/dna.asp>.

 

12. Steve Jones, interview on The Science Show, broadcast on ABC Radio, January 1, 2002 <www.abc.net.au/rn/science/ss/stories/s456478.htm>.