And yet it looks exactly like what you would expect a fusion of two chromosomes to look like. They share synteny to the closest relatives without fused chromosomes, the fused chromosome has double centromeres and end-to-end telomeres. What should a chromosome fusions look like if not this?
You might be able to convince yourself with some elaborate rationalization that it’s not a chromosome fusion, but you can’t seriously argue it doesn’t conform to what a chromosome fusion should look like.
Yes. Since humans have fewer chromosomes than our closest primate relatives, logically speaking if we are to share common ancestry there must be some mechanism by which humans could end up with fewer chromosomes. One of which would be a fusion event. Assuming here we can rule out loss of an entire chromosome that has numerous essential genes.
The hypothesis of a fusion event would in turn also lead to numerous other predictions. Think about it this way. If two human chromosomes which are highly similar to chimp chromosomes, fused, we would expect that the fused human chromosome should look like it was derived from two chimp chromosomes fused together end-to-end. This would entail for example double centromeres, with one part showing synteny to one chimp chromosome, and another part to another chimp chromosome. And so on and so forth. All of these predictions bear out. As I said, it looks exactly like a chromosomal fusion should.
No I meant, did we know about the number of chromosomes of humans and said those two look like a fusion before we knew about the number in chimps? I’m assuming that maybe not - but mostly because chromosomes were known before specifics about them were known?
This maybe should be a different topic, but I wanted it to be a short question, not a discussion about this issue.
I have no idea whether they do or don’t. They just give reasons why this case is not solid; obviously they’d need to.
‘They’ are wrong. It is unambiguously a fusion. If I was inclined to see the hand of God in anything, it would be that the fusion site is ‘too good’.
Yes. Or more accurately, common ancestry predicts that there be a transition between an ancestral karyotype and the derived karyotypes. A fusion in the human lineage would have been the most parsimonious, but not the only possibility. Then again, all of this was resolved extremely quickly after the initial karyotypes were produced. Order of events was basically: Human karyotype (several years) other ape karyotypes (basically immediately) probably a fusion (several years) better quality karyotypes for everything (same publication) probably a fusion of these specific chromosomes in the human lineage at approximately this location (~20 years) actual sequence data confirming the fusion.
No. When it was found that humans had one fewer chromosome pair than other great apes, the only reasonable explanation, if one believed that common descent is true, was that there was a fusion in our genome. And, when it eventually became possible to detect such a fusion, there it was.
Pretty amazing coincidence, isn’t it? Or do you have another explanation? Such as that common descent is true?
This thread’s title was actually the first words of the chorus of an early draft of a particularly lyrical Billy Joel song:
Phy-lo-ge-ny. Please help me see what you see. Lots of nested hi-er-archies. Taxon-o-my is such a useful word. Life fits nice-ly into de-scrip-tive tree-eeeees.
(Joel eventually revised the song for a broader audience and the result was “Honesty”, a top 40 hit in 1978. This sidebar is for @Dan_Eastwood and the other dinosaurs among us.)
Phylogenies have been inferred for many aspects of human culture: languages, legislation, computer viruses, medieval manuscripts. These often involve horizontal copying as well as vertical descent. (For example, we are communicating in a Teutonic language with many words from French).
But I was asking about genetics, not phylogenetics.
The prediction of a fusion came after we knew that chimps had one more pair of chromosomes than we did.
I’m not sure it is even anything creationists need to worry about. If humans were separately created there could have been a chromosomal fusion early in history that then spread to the rest of the population. A bottleneck at the flood may have fixed the chromosome count.
Personally, I’ve never seen the chromosomal fusion evidence as very strong evidence for human/chimp common ancestry.
Not 100% certain if this is the kind of thing @Faizal_Ali has in mind, but there’s an “incongruent tree” right in our own Gospels: different sources of information giving different data about how Jesus descends from David.
Well, yes. And there, I can’t think of a single useful non-biological analogue. Abiogenetics isn’t likely to become a huge field of study unless someone can think of something it would study; the study of things that don’t actually exist has a long and distinguished tradition, but not within science.
why should i? many of the primates species probably do share a common descent, since they belong to the same created “kind”. thus we should expect to find a good correlation between morphology and genetics in these cases.
roy said that above: “you always end up with essentially the same tree”.
see above: in most cases we find that contradiction. the opposite of what evolution predict.
actually it doesnt for few reasons. but the problem is that this fusion isnt evidence for common descent, since it happaned in the human lineage.
Those two sentences don’t say the same thing. I can say “you always end up with essentially the same temperature” when using the thermometer analogy, and that just means the temperatures are all very close to each other. The key word there is “essentially”.
We’ve been over this before also. Why do you need these things repeated to you all the time? Why do you show no sign of updating your understanding? There is no progress to your arguments, it’s still the same things you get stuck on all the time.
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?
