You mean the likelihood? I’ve already pointed out that the calculation isn’t reliant on it being 1, just very high. But why couldn’t it ever be 1? We can easily say, for example, that the likelihood of the grass being wet given a rainstorm is 1.
What if you include all the other evidence indicating rain i.e. humidity and temperature measures consistent with rain, Doppler radar tracks showing rain, photographic evidence of rain clouds and sheets of rain falling? Shouldn’t all the evidence be taken into account when drawing your conclusion?
I don’t know. But what is your explanation. Is it what would be expected given common descent of Equus species?
You can read the explanation here. Mostly it’s through Robertsonian translocation events.
The evidence is completely consistent with all the other evidence for common descent and directly contradicts a YEC “kind” origin of horses.
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True. But the likelihood of a particular mutation given common descent is always very low. The current human genome is a very low-probability thing, even given the accepted tree. The accepted tree maximizes the probability of the data, but that probability is still so tiny that it can be stated only as a negative log. The probability of observing 46 chromosomes given common descent is, I would agree, higher than the probability given separate creation. But that’s because the probability of an original state of 48 chromosomes is much higher given common descent than given separate creation. It has nothing to do with the chromosomal fusion event.
That’s true only if YEC forbids changes in chromosome number.
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I don’t know about this. It’s a low probability event times a long period of time times many possible such things. So the likelihood of such a thing happening might be high.
Then let YECs come up with a mechanism to get from the horse “kind” single number of chromosomes to the extant wide number of varieties in just 4500 years. 
Until then this evidence directly contradicts the Noah’s Ark "kind’ claims.
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I recently did two analyses into chromosome 2 fusion, which I’ll eventually include in a comprehensive blog post dedicated to the evidence for the fusion when I get around to it.
For now, here’s the summary for those interested.
It’s commonly argued, by Tomkins and other creationists, that two of the primary pieces of evidence for chromosome 2 fusion - the presence of telomeric repeats at the alleged fusion site and the presence of alphoid repeats in the alleged cryptic centromere - are actually very poor evidence because these repeats are in fact found all over the genome, not just in those locations alleged to be related to the fusion event.
They argue that since telomeric repeats and alphoid repeats can be found all over the genome, there’s really nothing special about the sites claimed to represent the fusion site and cryptic centromere. In effect, they’re claiming that “evolutionists” are cherry-picking these sites because they fit the fusion story while ignoring all the other telomeric repeats and alphoid sequences that don’t.
I decided to find out if there was any truth to these claims. Spoiler: there isn’t.
Telomeric repeats are short, just 6bp (TTAGGG and the reverse complement, CCCTAA), so it is obviously true that these can be found throughout the genome, even just by chance. However, it’s also true that there are large chunks of repeats, consisting of tens or hundreds of telomeric repeats, present all over the genome, not just in the telomeric regions. So at first glance, it appears that the creationist claim is true, right? If chunks of hundreds of telomeric repeats are found all over the genome, what makes the alleged 798bp fusion site so special?
The fact that the telomeric repeats in the alleged fusion site are found in a head-to-head arrangement, exactly as expected from a head-to-head fusion.
I’ve done lots of BLATing and BLASTing, and literally the only location in the entire human genome where I can find hits for a sequence consisting of head-to-head telomeric repeats is in the alleged fusion site. In this respect, the alleged fusion site is absolutely unique.
It’s a similar story with the alphoid repeats. These repeats are each 171bp long, and centromeres tend to consist of roughly 10,000-20,000 of these repeats, mostly in one clear block but sometimes with some smaller blocks of repeats closely flanking the main block. (In the diagrams below, I grouped all alphoid repeats within 50kb of each other into a single block, and all alphoid repeats within 6Mb of the annotated centromere as being part of the centromeric block of repeats.)
Searching the human genome for these alphoid repeats, I found that they’re nowhere near as ubiquitous as implied by creationists. Here’s all the repeats representing the centromeres, with the numbers representing the number of repeats in each block, and the dark band represents the location of the centromeres.
There are also a few isolated repeats ranging from 1-15 tandem repeats in the genome, shown below:
After these, the only remaining alphoid repeats are found in two blocks in the genome:
One of them is a large block of 185 repeats that comprises the cryptic centromere, dwarfing the small number of isolated repeats found outside of the centromeres in the previous figure. The other large block of 2011 repeats in chromosome 9 is an exceptional case, where there is a huge block of heterochromatin separating it from its centromere 15Mb away.
The repeats in the cryptic centromere, on the other hand, are 38Mb away from the functional centromere of chromosome 2, so is clearly unique as the largest block of alphoid repeats most distant from a functioning centromere in the entire human genome. Here’s all of the alphoid repeats in a single figure:
So in both cases, telomeric and alphoid repeats, the fusion site and cryptic centromere on chromosome 2 clearly stand out as unique in the human genome, representing the expected signature of fusion that in turn provides compelling evidence for the fusion
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Now that’s a different argument, which requires bringing branch length into it, which is a whole new subject. Yes, YEC demands evolution at hyperspeed. But likelihood analyses generally do not deal with time at all, only branch lengths in terms of probabilities of observing different states at either end. The same tree could be interpreted as a YEC tree or one on the standard time scale. If we do apply a model that incorporates absolute evolutionary rates, then we could come up with something like you suppose. But I don’t know of such a model in use.
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Oh you meant in YEC model? I agree. I thought you meant in an evolutionary model.
I do not understand that response. Could you clarify? My point is that standard evolutionary models do not include a time scale and so could be YEC or otherwise depending on what you imagine mutation rates to be. Your argument is a good one, but it’s outside the subject of likelihood models.
I feel like you’re talking more about the prior probability than the likelihood. The likelihood of the fusion is coming from the observation of 46 chromosomes in humans compared to 48 in the other great apes.
How many other fusion events going to fixation in other lineages are known beside the one discussed here? With such an information at hand, it should be possible to determine the likelihood of such events?
We obviously know of many other chromosomal rearrangements leading to different chromosome numbers in different species (e.g. in horses as Timothy mentioned earlier). As for telomeric head-to-head fusions, we know of at least 2 other well-characterised examples - one in domestic pigs and one in Hartmann’s Zebra.
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A question on this:
I was under the impression that a chromosomal fusion tends to result in impairment of recombination, and that this means that the fused and un-fused versions will accumulate mutations more or less independently from one another, with possible resulting impairments in fertility where matings don’t produce either an all-fused or all-unfused individual. Is that a reasonably likely outcome? I would assume that if it is, it could be the cause of speciation rather than of fixation in the whole population.
And if that’s all bollocks and I’m badly wrong, I am happy (well, not deliriously so, but what can you do?) to be told so. I got this scenario from a biochemist years ago but may have misunderstood what he was saying…
Horses/zebras/donkesy are a great control because YEC believes they are a single kind, and they are cross fertile (zonkeys, moules, zorse, etc.)
Donkeys have 62 chromosomes and horses have 64, so their hybrids (mules and hinnies) have 63.[2] Zebras have between 32 and 46 (depending on the species) and their hybrids are sterile and infertile.
So there you have that several chromosome changes were fixed in several different species of the same “created kind.”
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Why are Creationists so fixated with establishing probabilities after the fact? Do they think that somehow negates evidence for events which already happened? Improbable events happen all the time. These after-the-fact probability demands make zero sense.
That’s not the problem. They are asking what the likelihood of something to have happened by a given process. Thats a fundamental and valid scientific question. However, they way they calculate it is nonsense. That’s a different problem.
It’s also completely meaningless for one time events since we have evidence the event actually occurred. What is the probability the New York Mets would win the World Series in 1969? If we can’t assign a number does that mean the Series was fixed? What is the probability a 10km asteroid would strike the Earth at Chicxulub almost 66 MYA? If we can’t assign a number does that mean the impact never happened?
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