Faz Rana is bringing up questions on human chromosome-2 . Are they valid?
His argument would seem to be that human intervention fused two chromosomes in a yeast genome, and therefore chromosomal fusion can’t happen without purposeful intervention by an intelligent being. Does anyone even have to argue against that syllogism?
Rana really needs to get out more. Robertsonian fusions are not unique to the human lineage; there are a great many examples in a great many species. There are a fair number of examples in which such fusions are polymorphic within populations. They don’t prevent interbreeding. They don’t produce sterility. How is is possible that Rana is unaware of all this?
His main arguments are contained here:
- Telomeres have to be deleted immediately
- A centromere has to be inactivated immediately
- Fertility is reduced between individual with fusion and those without
He argues that 1 and 2 are unlikely to happen naturally, and 3 prohibits propagation of the fusion karyotype through the population.
He gives no reason why 1 would be particularly unlikely in nature. Fusions usually only happen in the first place when telomeres are lost, it’s not a secondary event that must happen in conjunction with the fusion.
He says 2 requires huge amounts of time to happen, previous studies in yeast and human cells have shown that centromeres can be inactivated through various mechanisms, immediately following chromosomal fusion.
It’s true that fertility can be reduced, as Rana says (3), because it can be difficult for an individual with one number of chromosomes to produce viable offspring with an individual with a different number of chromosomes. That being said, we have plenty of examples in animals (thanks @Art) and humans where the reduction can be minimal or non-existent.
EDIT: I just wanted to add that all of this information took me about 10 minutes to gather. I knew some of it before but when it came to providing citations I simply googled keywords and scanned a few results before arriving at the ones I linked above. My point is that none of this is arcane knowledge: it’s available to anyone who puts the tiniest bit of effort into searching. The fact that Dr. Rana failed to do this is disappointing.
This is a classic example of the map not being the territory. No matter how we draw our maps, reality stubbornly doesn’t change itself to conform to our maps. The reality is chromosomal fusions do happen spontaneously and naturally, and without causing harm in many situations. If RTB claims that this can’t occur, then reality proves them wrong.
This is exactly why I don’t read anything by Rana anymore and why I think he often hurts RTB more than he helps them. When I was early on in my own exploration of origins views and encountered RTB material I thought that this should be an attractive place for me given some aspects of my background. But when I started to read Rana who was the only person writing about biological origins at RTB I quickly found myself thinking he wasn’t providing reasonable answers to any of my questions and often was just plain wrong or ill-informed. This was the single largest factor in driving me away from the RTB model.
Almost every article he churns out feels like it it started out with same template. It feels like he generates the same answer to every question and new discovery before doing any research. It feels like he reads just enough to find a pieces of data that fits into his interpretive filter and then stops there. I can’t remember the last time I learned anything new reading one of his articles and always come away feeling like he either doesn’t understand biology or hasn’t read enough to realize how much he is missing.
This is a shame and I’m sorry to hear this. I did write and ask Dr. Rana to participate here. Especially given the fact that his conclusions were being discussed. He never responded, though. Interestingly, I also wrote to DI and encouraged them to do the same. They, at least, maintained a dialog with me and said that they would consider it. Too bad… it would be a great opportunity to bring everyone closer to the truth.
@AJRoberts is on staff with RTB and participates here. Perhaps send her a note.
Will give that a shot. (Done… )
Dicentric fusions are not centric fusions
A little more time reviewing the mechanics in question might have been useful before accusing Dr. Rana of not understanding the primary mechanisms involved. (And quoting a grad student’s blog shouldn’t merit the response of a scientists’ time and effort as it is not a peer reviewed primary research publication and no doubt is driving a narrative forward by quoting from discussion sections and favored interpretations of primary data.) If you take the time to look at the primary literature you will find that Robertsonian fusions are also known as centric fusions which means they happen at the centromeres and between acrocentric chromosomes. They involve fusion at the centromere and loss of the short arms. The most common one in humans occurs between chr. 13 and 14, and balanced translocations t(13;14) are ASSOCIATED with increased frequencies of miscarriages and male infertility even according to the literature referenced in your post.
Reproduction between heterzygous carriers of the t(13; 14) individuals with n = 45 chromosomes and normal n = 46 individuals does occur. And this single human study referenced does not rise to statistical significance in support of a claim of no reduction in reproduction rate. One homozygous t(13;14) (n = 44) female reproduced with a normal (n=46) male. It was her offspring that showed increased rates of miscarriages. And the study states that information on miscarriages across the pedigrees was incomplete. There was no preferential transmission of the translocation/fusion within the pedigrees.
Lastly, dicentric fusions in human chromosomes have all the problems Dr Rana mentions AND are associated with cancers… not null effects as claimed. Robertsonian fusions fuse at the centromere not end-to-end. Even the primary article referenced for human fusions states there is disagreement on the effect of Robertsonian translocations on reproduction (which remains to some extent but not in favor off your claims; most think they are associated with increased miscarriages and decreased male fertility). Any support for an ancestral fusion event from (and within) this primary source is sheer speculation… The data leads to a different and contrary conclusion; one in support of Dr. Rana’s comments in fact.
Mike Callen’s request made it to my inbox last Friday afternoon.
This particular reply is both painful and a pleasure for me. Painful because Dave passed away a little more than a year ago, and these essays remind me of our friendship and his remarkable personality. A pleasure because I believe Dave would be pleased to see that his excellent work can still contribute to this discussion.
Give me a break. Dr. Rana is stonewalling. He has no model. Every new finding from genomics, fossils, anthropological artifacts on Neanderthals, Denisovans, H. Naledi, H. Erectus and other species destroys the RTB model. Dr. Rana continues to hold on to a failed hypothesis. At some point Dr. Rana needs to say that the RTB model is falsified for RTB have any kind of credibility.
Very astute commentary on the scientific response I offered. Ad hominem comments really help move the dialogue forward. And you wonder why he doesn’t take more time to engage the science here.
I agree @AJRoberts.
@Patrick I’m more curious to see @John_Harshman and @evograd’s response. @AJRoberts says they misread Rana, and this should be objectively resolved. If they made a mistake they should own up to it. If instead @AJRoberts did, and that can be made clear, I’m sure she will own up to it.
There is no need to make it personal. Let’s just get the facts straight.
Dr .Rana is not an expert on ancient genomics, paleontology, nor human fossils, He is an engineer. Whenever Dr. Rana reads about a new discovery in human origins he writes the same old stuff. He is very predictable. I have been watching him for years. He questions ancient genome work of real experts like David Reich. He dismisses real science accomplishments by saying the same old arguments - it can’t be true because he doesn’t want to accept the results. He is very much like AiG in this regard. He gives lame apologetic answers to new discoveries in science. I do question Dr. Rana honesty and professional integrity. He won’t engage here because he can’t handle real debate on new scientific discoveries. The RTB model has been falsified many times and nobody at RTB admits this. It is time for Dr. Rana to come here and back up his claims. What is he afraid of?
I’d love for him to come here. Posts like this make it less likely. Relax.
Just to be clear, I did not say anyone misread anyone. I simply went to the primary literature and pointed out that the science they used to discredit Dr. Rana’s claim was incorrectly interpreted to favor an assumption of an ancestral fusion event in regard to human chromosome 2. Dr. Rana may have overstated some things or he may not have. I am not addressing his claims directly, I am simply setting the record straight about the inappropriate comparison of a presumed dicentric fusion event and Robertsonian fusion events in humans.
If I were him, I would have no interest in engaging in an echo chamber of repeated lies, false statements, and ad hominem comments. He has acknowledged previous failures of the RTB model and modified the model appropriately. This is a hallmark of science. Every model is modified over time in light of new data and discoveries. He is in fact a biochemist, not an engineer. Even simple facts aren’t stated correctly. Careless communication and ad hominem comments do not facilitate any genuine invitation to seek truth together in dialogue.
That is a cop out. RTB is in their own echo chamber playing to their evangelical christian base. Like AiG, DI, and Biologos, RTB is not a science think tank. RTB doesn’t do science. They read the current scientific literature and write comments to comply with their RTB model hypothesis which was falsified many years ago by mainstream science. Yet they keep the Christian apologetics going in the same way that AiG, DI and Biologos does. Tell Dr. Rana to stop bashing real work and accomplishments by real scientists. If he doesn’t like the results because they go against the failed RTB model, let him and RTB find contrary evidence.
@Patrick Why in the world are you trying to kill the conversation before it begins? People have worked really hard to build bridges and create opportunities to get together and have conversations. You may have single-handedly undone all of that in a few moments. Is it okay if the rest of us would like to hear the dialog instead of your summary of the conversation before it has even taken place??