Uncommon Descent Serving The Intelligent Design Community

Spring it on ’em and Watch the Fur Fly

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Dennis Venema is an associate professor in the biology department at Trinity Western University, a Christian university near Vancouver, British Columbia.  Over at Biologos Venema has an article entitled The Sorrows and Joys of Teaching Evolution at an Evangelical Christian University in which he recounts his efforts to indoctrinate his students in Darwinian evolution. In the opening paragraphs of his article Venema describes one of his teaching methods: 

After the “information dump” using the fruit fly examples, it’s time for a class discussion/application before the students drift off too much. Ok, here’s a slide that shows the chromosome structure of a group of organisms that other lines of evidence suggest are part of a group of related species. What do you observe? Do you think these species are related? If so, what explains the differences you observe?

 

What the students don’t know is that the slide shows human chromosomes, and those of our closest living relative, the chimpanzee. Oblivious to this knowledge, they easily arrive at the correct answer: yes, the evidence is strong that these are quite recently diverged species, and that a chromosome fusion or fission event explains the differences in chromosome structure between them. When I tell them that every other species in this grouping has the higher chromosome number/structure, they correctly deduce that the species with the lower chromosome number should show evidence of a fusion event in the form of “telomere” sequences at the fusion point and an inactive “centromere” at the location suggested by comparison to the other, related genome.

Easy.

As I look around the room, I see the students are satisfied. I cover some difficult material in this course, and the students are obviously pleased that this topic is so easy to handle. The lines of evidence are easy to follow, and it’s easy to predict and test one’s hypotheses. Then, only after they’ve seen the evidence at least once without the baggage that will inevitably come, I ask them if they know what two species they’ve just compared.

Venema apparently does not provide his students with any information regarding possible alternative hypotheses to explain that data.  Indeed, he displays the usual smug self-satisfied complacency of the committed Darwinist who does not believe there is any other hypothesis.  
Venema concludes:  “I feel learning about evolution in a Christian liberal arts university is one of the very best places to do so, providing the institution treats the topics fairly.” 

Does Venema treat the topic fairly?

Comments
Eric I can see your point but are they really “adding” to the evidence or just drawing a conclusion from it? It’s the same as a crime scene. The investigators didn’t see what happened but they have to come to a conclusion based on the evidence they gathered (and macro evolution does have some compelling evidence). Otherwise we would never solve any crimes. I can see the problems with the way scientists are portraying it as fact when we really haven’t observed one life-form becoming another. They should be saying this is what we think happened based on what we know but we haven’t seen it happen so we could be wrong.JLAfan2001
August 31, 2012
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JLAfan2001 and smiddyone: Steve_Gann has made an important point. I would state it this way: The thing we can conclusively conclude by observing that two sets of chromosomes share certain similarities is that the two sets of chromosomes share those similarities. That is it. As soon as we start attaching a historical narrative about how one set of chromosomes supposedly came from the other at some point in the past, or about the alleged mechanism(s) involved in getting from chromosome Set A to Set B, or attaching a further philosophical gloss that it all happened without plan or purpose, we have gone far off the path from the evidence. Our storytelling could be correct, but it is far from conclusive that it is. And our historical narrative has its own holes and weaknesses. I think Venema's approach is OK in terms of letting the students examine chromosomal similarities and then telling them after the fact which species were involved. I even like that approach, as it will probably get a lot of interesting questions and discussion going. But he needs to allow the questions and discussion to really continue and dive deep, not just triumphantly proclaim that this comparative analysis somehow proves anything about human evolution.Eric Anderson
August 31, 2012
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I resent any such teaching. The problem is that he is presenting evidence for similar chromosomes and for a fusion event. Is this a scientific argument for "evolution" over "design"? No, as Cornelius would say, it is a "religious" argument for "evolution" over "design". I would suspect that someone steeped in evolutionary thinking just can not see how he is making a religious, not scientific argument. I feel sorry for Dennis.JDH
August 31, 2012
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@smiddyone It's a bit more complicated than that. Re-using a reply I sent to someone else, if you don't mind: ------------------------ First, the ch2 fusion is cherry picking among numerous other genetic scars that show no common ancestry. Evolutionary biologist Richard Sternberg remarked:
"Of all the known ITSs [interstitial telomeric sequences], and there are many in the genomes of chimps and humans, as well as mice and rats and cows..., the 2q13 ITS is the only one that can be associated with an evolutionary breakpoint or fusion. The other ITSs, I hasten to add, do not square up with chromosomal breakpoints in primates. In brief, to hone in on the 2q13 ITS as being typical of what we see in the human and chimp genomes seems almost like cherry-picking data. Most are not DNA scars in the way they have been portrayed.", Richard Sternberg, Evolution News And Views, 2009. Sternberg cites Interstitial telomeric sequences (ITSs) are not located at the exact evolutionary breakpoints in primates.
Likewise, creation geneticist Jeffrey Tomkins has written:
"I developed software that enables the scanning of whole chromosomes for internal telomere content. ... Surprisingly, I discovered that the entire human genome contains many completely intact internal telomere sequences. My preliminary data suggests that the internal regions of human chromosomes are composed of 0.19 to 0.25 percent 100% sequence identity intact telomere sequences. While this may seem to be a very small amount, consider that chromosome 2 (the supposed fusion product) contains over 91,000 (0.23 percent) intact internal telomere sequences. Fewer than 300 of these can be attributed to the so-called fusion site. Chromosome Y was the most internally dense telomere containing chromosome (0.25 percent).", Designed DNA Blog, 2012
Second, the signature of a fusion event is weak. In making the argument for fusion, Daniel Fairbanks wrote:
"Let's now return to the repeated sequence surrounding the fusion site in figure 1.1. Of the 158 repeats, 44 are perfect copies of TTAGGG or CCCTAA. In most cases, the remaining repeats differ from the standard sequence by no more than one or two base pairs. This is precisely what we expect if the fusion happened long ago in the remote ancestry of humans" Relics of Eden, 2007, p. 27
But telomeric DNA normally consists of thousands of repeats of a 6-base-pair sequence TTAGGG. So if two chromosomes were fused end-to-end, a huge amount of alleged telomeric DNA is missing and/or garbled. Contrary to Fairbank's "precisely what we would expect", others have noted that the site appears far more degenerate than expected, which is especially odd, considering that meiotic recombination is suppressed in pericentric DNA, which should cause it to mutate more slowly; meaning that 6m years isn't enough time to account for what we see.
"Because the fused chromosome is unique to humans and is fixed, the fusion must have occurred after the human–chimpanzee split, but before modern humans spread around the world, that is, between ?6 and ?1 million years ago. This gross karyotypic change may have helped to reinforce reproductive barriers between early Homo sapiens and other species, as the F1 offspring would have had reduced fertility because of the risk of unbalanced segregation of chromosomes during meiosis.", The authors are also surprised to find that telomeric sequences have "degenerated significantly" and are "highly diverged from the prototypic telomeric repeats.", because the alleged fusion event supposedly happened very recently--too recent for such dramatic divergence of sequence. Thus, the paper asks: "If the fusion occurred within the telomeric repeat arrays less than ~6 Mya, why are the arrays at the fusion site so degenerate?" Several ad-hoc explanations are offered for this bad data: (1) they suggest they weren't really joined at their ends, "chromosomes joined at interstitial arrays near, but not actually at, their ends. In this case, material from the very ends of the fusion partners would have been discarded."; (2) they arbitrarily invoke a "high rate of change" in that stretch of DNA, or (3) "Some array degeneracy could be a consequence of sequencing errors.". These all show how poorly the data fits the expectations. Yuxin Fan et al. Genomic Structure and Evolution of the Ancestral Chromosome Fusion Site. Genome Research, 2002. In 2012, creation geneticists Jeffrey Thomkins and Jerry Bergman confirmed the conclusions of this study.
Despite this, we may very well have once had 48 chromosomes in our past. But if you're going to make an argument from similarity, why not cite the markers we know we share with apes, such as the ALU elements or common genes, versus one that depends on so many unknowns? Of course, similarity is no more an argument for common design than common descent. Moreso, fusion events serve as poor taxonomic dividers and don't necessitate a speciation event. Some species show a very diverse range of karyotypes (number of chromosomes), with little-to-no effect on phenotype (how an organism looks and behaves):
It is now considered that there is little or no evidence to suggest that centric fusions in a variety of combinations affect the total productive fitness of domestic sheep", and interestingly, these fusions seem to have little phenotypical effect, "Less than 1% of phenotypically abnormal lambs were recorded in a total of 1995 progeny born over 10 years." Cytogenetics and reproduction of sheep with multiple centric fusions, Reproduction, 1979
"We report an unprecedented amount of chromosomal variation in a natural population of the South American marsh rat Holochlus brasiliensis. This variation consists of four distinct classes of chromosomal rearrangements: whole-arm translocations, pericentric inversions, variation in the amount of euchromatin, and variation in number and kind of supernumerary (B) chromosomes. Twenty-six karyotypes are present among 42 animals.", Hampton L. Carson, Exceptional chromosomal mutations in a rodent population are not strongly underdominant, PNAS, 1989
"The study focuses on 60 species within the vole genus Microtus, which has evolved in the last 500,000 to 2 million years. This means voles are evolving 60-100 times faster than the average vertebrate in terms of creating different species. Within the genus (the level of taxonomic classification above species), the number of chromosomes in voles ranges from 17-64. DeWoody said that this is an unusual finding, since species within a single genus often have the same chromosome number. ... In one species, the X chromosome, one of the two sex-determining chromosomes (the other being the Y), contains about 20 percent of the entire genome. Sex chromosomes normally contain much less genetic information. In another species, females possess large portions of the Y (male) chromosome. In yet another species, males and females have different chromosome numbers, which is uncommon in animals. A final 'counterintuitive oddity' is that despite genetic variation, all voles look alike, said DeWoody’s former graduate student and study co-author Deb Triant. 'All voles look very similar, and many species are completely indistinguishable,' DeWoody said. In one particular instance, DeWoody was unable to differentiate between two species even after close examination and analysis of their cranial structure; only genetic tests could reveal the difference.", Rodent's bizarre traits deepen mystery of genetics, evolution, Purdue University, 2006
JoeCoder
August 31, 2012
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Mr. Arrington, Dr. Venema's actions concern me simply from a scientific-logical point of view. It appears he is asking his students to make a prediction from the evidence and then celebrating the confirmation of that prediction as some sort of trustworthy knowledge in favor of common descent. But logically I think that fails. He seems to be arguing like this: Premise 1: If common descent is the reason for the chromosome similarities AND we set the chromosome sequences side by side for visual inspection, Then we would predict the similarities to show transition from one species to another. Premise 2: The sequences show transition. (Confimed prediction) Conclusion: That tells us common descent is the explanation. But the only thing you can conclude from a confirmed prediction is that maybe the speculative explanation (i.e. common descent in this case) is correct. The reason for the maybe is because this form of argument is inductive, not deductive despite the deductive appearance (if it was deductive it would be affirming the consequent). I would expect a science professor to recognize that common descent at best would be a maybe in this case. That would naturally lead to the possibility of other explanations even if other possibilities have not been put forth. Of course in the case of ID another hypothesis has been put forth (I recognize ID is not necessarily against common descent). That would be common design.Steve_Gann
August 31, 2012
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JLAfan2001 asks: Barry What exactly is the possible alternative hypotheses that could explain the similarity with chimpanzee genes and the chromosome fusion? The only other explanation is that the two species were zapped in by the designer who just happened to make them genetically similar and threw in a fusion event just for laughssmiddyone
August 31, 2012
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Barry What exactly is the possible alternative hypotheses that could explain the similarity with chimpanzee genes and the chromosome fusion?JLAfan2001
August 31, 2012
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