Chromosome Fusion in Humans - or Not?

IIRC, tandem repeats are very inaccurately replicated by DNA polymerase due to slippage and stalling leading to length and sequence variation, so its absolutely unsurprising that the fusion site is “degenerated” rather than a well preserved.

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More likely still is that the repeats were already degenerate. The other DDX11Ls are 10-15kb from the ends, with several kb of subtelomeric junk between it and the actual repeats, and those regions commonly include a degenerate ‘spacer’.

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the problem with the fusion argument isnt about the fusion itself, but about the fact that it doesnt support common descent, as you can see in this figure:

so we can only use it to prove that humans share a common descent with…humans.

It is required for common descent. As with every other potential falsification, we test the world and find it within the narrow range of possibilities consistent with common descent.

We can’t even use it to ‘prove’ that. Proof isn’t a thing in science.

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I assume she also didn’t mention that they’re found in a head-to-head orientation?

Indeed, as I note in this post:

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It’s an old blog post now, and likely poorly written compared to my current standards, but it’s still valid:

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Which again, is a completely unnecessary finding.

Not finding telomers wouldn’t rule out fusion.
Not finding them literally touching head-to-head wouldn’t rule out fusion.
Not finding it next to a pseudogene exclusively found by telomeres wouldn’t rule out fusion.

What we have is a hilariously gratuitous surplus of evidence.

Creationists would be better off arguing that only a divine entity could engineer a fusion so perfectly, obviously, and exclusively concordant with fusion than arguing it isn’t one at all!

But instead they just start waving their hands again…

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So many questions. Awesome curiosity!

That was a heroic effort.

I’m puzzled by this response. Why did you ask so many questions 21 hours ago and ask @CrisprCAS9 to address a very specific part of that video, if you’re not currently ready to understand any of those exhaustive answers (with evidence)?

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That’s just so obviously wrong. Please consider the context that, if humans are to share common ancestry with our closest primate relatives, given that we do not have equal numbers of chromosomes, the hypothesis of common ancestry demands that either we or our closest relatives must have evolved a different number of chromosomes.

Given that humans stand out from the rest by having fewer chromosomes, the most probable explanation is that humans must have somehow evolved fewer chromosomes after we split off from the most recent common ancestor shared with chimpanzees. One way this can happen is by chromosomal fusion. A chromosomal fusion is thus a prediction of common ancestry, and that is what we find.

Do you understand this argument? Not believe, or accept, but do you at least understand it?

There is a hypothesis that demands a particular thing to have happened in order to make sense of the data. The creationism hypothesis does not demand that ancestral humans started out with 48 chromosomes like other apes, we could have been created with 46.

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I have nausea going on six weeks from morning sickness :roll_eyes: it’s not going away and it and hormones make my mood rather volatile. :sweat_smile: Sometimes I am very interested and curious, other times I want to throw my phone in the lake because this forum drives me crazy. :slightly_smiling_face: I was just trying to be honest that I won’t respond much. I just also know I need to learn a lot before understanding the biology in order to assess this and don’t have the energy. Though my brain still always has questions I guess!

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They are not doing science but apologetics, otherwise no one would see the clear signs of a fusion event in human chromosome 2 and deny it.

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since evolution has no problem with gene loss, that fusion isnt a prediction of the evolution theory. evolution would be just fine with missing chromosomes.

No, evolutionary theory wouldn’t be ‘just fine’ with the simultaneous loss of the entire gene complement of a full chromosome.

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As has been explained, but which you somehow managed to miss, the fusion is a prediction that follows from the observation that humans have one fewer chromosome pair than other great apes.

If an entire chromosome was missing, that would be practically impossible to reconcile with common ancestry with chimps only 6 million years ago. Hence the hypothesis that the chromosome was not missing, but fused. A hypothesis what was eventually confirmed.

What hypotheses did Creation Scientists propose to explain this observation? How well did they fare in terms of confirmation?

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I will just add this comment that Ken Miller made regarding this subject on Sandwalk:

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… of genes that don’t positively contribute to reproductive fitness. Do the genes on the two fused chromosomes not contribute to reproductive fitness?

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Well, if they’re still there, they’re not lost. Are they?

@scd isn’t talking about the genes that are still there and, therefore, aren’t lost.

He’s talking about, well, the genes that were lost, but somehow are still in our genome and not lost at all.

Just what difficulty are you having following that? :slight_smile:

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Gene loss and chromosome loss aren’t quite the same thing now are they? it’s losing one gene versus losing 1000 genes. We have plenty of evidence of gene loss happening today, but I don’t think there are any examples of a mammalian species losing an entire chromosome without severe fitness consequences.

Besides, if you prefer we can move one step later in the chronology of the prediction. Instead of saying “the observation that humans and chimps have different number of chromosomes led to the prediction of a fusion event”, we can say “the observation that the banding patterns of two chimpanzee chromosomes seem to line up with human chromosome 2 lead to the prediction of a fusion”. The evidence of the fusion would then still be the remnants of telomeric sequences at the fusion site and the degenerate second centromere.

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That needs to be elevated into a post in and of itself.

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i know that horse has 64 chromosomes, mule has 63 and donkey 62 (although I have not checked yet if this is the result of chromosomal fusion, chromosomal loss etc). fruit fly and soil nematode have lost more than 1000 genes. elephant lost more than 1000 OR genes etc:

so yes- evolution has no problem to explain gene loss, even at large scale.