note that these are conserved sequences and thus are supposedly functional.
you dont need that. you only need a fusion event which took place in the human lineage.
we dont need to assume a single generation but many. if some species can lose 1000 genes in about 100 my, then its also possible to lose them in about 10 my.
a simple explanation in such a theoretical case will be that human evolved some other genes that could replace the original genes in the missing chromosome. its also important to mention wiki reference:
“In [Saccharomyces cerevisiae] (budding yeast) 15-20% of all genes are essential. In [Schizosaccharomyces pombe] (fission yeast) 4,836 heterozygous deletions covering 98.4% of the 4,914 protein coding open reading frames have been constructed. 1,260 of these deletions turned out to be essential.[42]”
" A recent study of 900 mouse genes concluded that 42% of them were essential although the selected genes were not representative"
You don’t understand the argument if you think anyone is saying anything close to “chimps own that original genetic material”.
The argument is simply that our understanding of human evolution among the great apes led to the prediction that a chromosomal fusion event took place in our lineage.
The fulfilment of that prediction is evidence of evolution and common ancestry. That’s it.
Why would God have fused the chromosomes and not simply created a single chromosome with the gene complement of the two homologous chromosomes? That is, why should there be a fusion site? Are you arguing that both were independently created with 48 chromosomes, with a fusion occurring in the human lineage?
No, there was a prediction in the form of ‘If X is true, then Y must be true’. We then checked and found that Y was true, which means that X is still a valid potential explanation. It doesn’t rule out alternative explanations. At the same time, finding Y only supports explanations that predict it, which creationism does not. So while both creation and evolution are compatible with a fusion event, only evolution is supported by finding evidence of a fusion.
Humans aren’t derived from chimps, as both are modern organisms. Both humans and chimps are derived from a common ancestor, which was neither a human nor a chimp.
Can you connect this to the subject of the thread a bit more firmly? As asked, I think there is a risk of expanding this thread beyond its scope, which we should try to avoid.
Yes, but it includes some highly conserved sequences. What this has to do with @scd’s argument, which in fact he seems to have completely lost sight of, is unclear.
The title really should have been a clue - gene DESERTS. As in, y‘know, sequencing lacking genes.
Are you proposing some very selective transposition of essential genes off the slowly disappearing chromosome, leaving just the non-essential genes behind? Losing a number of genes scattered across the genome in isolated events is very different from losing an entire chromosome, whether instantly or gradually.
Convergently evolving hundreds of essential genes de novo in just a few million years? Or in your scenario, just a few thousand years? Are you sure you’re a creationist?
Humans are not the same as yeast. Also, “essential” in this context means “required to survive in lab conditions to a certain time point.” Survival does not equal viable in an evolutionary sense, as if the organism survives but has significantly suboptimal fitness, it’s lineage will die out pretty quickly. These studies are also looking at single-gene knockouts for the most part, but you’re proposing the loss of all of these genes at the same time, so there are combinatorial effects on fitness.
Sure, God may have created the entire world in such a way that it appears evolved, complete with fused chromosomes, and other vestiges throughout biology and geology which appear to be the result of natural processes. But that would present God as Loki, the god of mischief, and not so theologically appealing.
If the human chromosome count in humans is from a fusion event it had to be fixed in the population through selection or drift. Human reproductive fusion events are rare at .!%. How would you model the likely hood a fusion event getting fixed in the population?
Not really “conserved sequences”, which is a rather vague statement because conservation comes in degrees. Any similarly higher than expected by chance can be described as “conserved”.
We selected two regions for deletion, a 1,880 kb gene desert mapping to mouse chromosome 3, and a second region, 960 kb in length, mapping to mouse chromosome 19 (Fig. 1a). Orthologous gene deserts of approximately the same size are present on human chromosomes 1p31 and 10q23, respectively. No striking sequence signatures such as repeat content, nucleotide composition or substitution rate distinguish these two selected gene deserts from other regions of the genome, except for their lack of annotated genes and evidence of transcription. Together, the two selected regions contain 1,243 human-mouse conserved non-coding elements (>100bp, 70% identity), also similar to genome averages, while no ultra-conserved elements 8 or sequences conserved to fish are present.
The conservation they speak about here appears to be less than average for the genome as a whole (which afaicg is actually around 85% for mouse-human).
And in any case, they’re gene deserts. No known genes. Pointless to compare this to loss of an entire chromosome known to contain literally hundreds of genes, many of which are known to have functions critical for human life.
Thanks, that’s about what I would have guessed you meant, but it wouldn’t be productive to have answered on a guess. That’s perfectly pertinent, and deserves an answer.
The direct answer to how it is modeled is: With difficulty. The math for this isn’t my area, and quickly looking into it shows it to be a bit more complicated than the population genetics I’m used to dealing with, but there is definitely a large amount of literature on the subject. The exact probability is connected to the selective effect of the fusion (if any), the level of reproductive isolation it causes (definitely ‘some’, but possibly not much), the population size and the level of migration, and a few other factors.
Then add in the fact that what you really want to know is the probability of a substantial chromosomal rearrangement ‘generally’ in a particular lineage since the divergence of it with its most recent common ancestor with some other lineage with the ancestral karyotype. This probability should be expected to be reasonably low. But such events definitively do happen and the evidence is fairly clear that it happened in the human lineage. Hopefully that starts to answer your question.
It will be probably be a bit lower than that of any other randomly chosen mutation, since the fusion does reduce the odds of an individual reproducing.
But, otherwise, any particular mutation has a very low chance of being fixed. Your objection is irrelevant, just yet another example of the lottery fallacy which you are constantly committing.
The three main creationist websites are all saying there was no fusion at all ever (including in the human lineage), but you are all saying there was a fusion in the human lineage?
I’m glad you agree that there definitely was a fusion event. Most creationists argue that it can’t possibly be a fusion event, and then tell a bunch of lies about it. See my first post in the thread, where I spend several paragraphs to cover all of the dishonesty of just 10 minutes from one creationist. But you’ve managed to recognize that it definitely is a fusion, which is of course compatible with both evolution and creation. You’re still ignoring the fact that it is absolutely predicted by evolution and absolutely not predicted by creation, but hey: baby steps.
If it is definitely a fusion event you should be able to model how it happened given population genetics theory or find someone who has. What am I missing? If there is no model then we don’t have the ability to predict how a fusion event gets fixed in a primate population. @r_speir what model do you have that would predict a fusion event becoming fixed in a primate population?