Luskin's ludicrous genetics
I mentioned before that IDEA clubs insist that expertise is optional; well, 'tis clear that that is definitely true. Casey Luskin, th' IDEA club coordinator and president, has written an utterly awful article "rebuttin'" part o' Ken Miller's testimony in th' Dover trial. It is embarrassingly bad, a piece o' dreck written by a lawyer that demonstrates that he knows nothin' at all about genetics, evolution, biology, or basic logic. I'll explain a few o' his misconceptions about genetics, errors in th' reproductive consequences o' individuals with Robertsonian fusions, and how he has completely misrepresented th' significance o' th' ape:human chromosome comparisons.
{if "In Miller's testimony, he talked about a basic fact of biology: most apes have 24 pairs chromosom"!=""}
In Miller's testimony, he talked about a basic fact o' biology: most apes have 24 pairs chromosomes fer a total o' 48, while we have 23, fer a total o' 46, by Blackbeard's sword. We are familiar with th' fact that errors in chromosome number, called aneuploidies, within th' human species are devastatin' and have dramatic effects; th' most familiar aneuploidy is Down syndrome, but there are others, which all lead t' very short lifespans and extremely disablin' phenotypes. Most aneuploidies are embryonically lethal and lead t' spontaneous abortions. If evolution is valid, we should be able t' see how that occurred historically, in a way that requires no mysterious interventions and only natural, observable mechanisms. Miller summarized it quite well.
Now, there's no possibility that that common ancestry which would have had 48 chromosomes because th' other three species have 48, there's no possibility th' chromosome could have just got lost or thrown away. Chromosome has so much genetic information on it that th' loss o' a whole chromosome would probably be fatal, to be sure. So that's not a hypothesis.
Therefore, evolution makes a testable prediction, and that is, somewhere in th' human genome we've got t' be able t' find a human chromosome that actually shows th' point at which two o' these common ancestors were pasted together. We ought t' be able t' find a piece o' Scotch tape holdin' together two chromosomes so that our 24 pairs -- one o' them were bein' pasted together t' form just 23. And if we can't find that, then th' hypothesis o' common ancestry is wrong and evolution is mistaken.
The answer is, o' course, that th' evolutionary prediction holds true: we do find th' homologs o' two genes fused together in our chromosome 2, I'll warrant ye. We have th' human and chimpanzee sequences, and we can see th' same genes in our chromosome 2 that are found on two other chimpanzee chromosomes; we can see th' structure o' two centromeres in our one chromosome, and also th' relics o' telomeres (normally at th' ends o' chromosomes) imbedded in th' middle. It is an open-and-shut case.
Casey Luskin doesn't savvy any o' it. His response is t' throw out a series o' foolish speculations that have long since been discarded and that completely contradict all o' th' evidence.
Why couldn't it be th' case that th' common ancestor had 23 distinct chromosomes, and one chromosome underwent duplication in th' line that led t' apes? Walk the plank! Or maybe th' common ancestor had 20 distinct chromosomes and there have been 4 duplications events in th' ape line, and 3 in th' human line?; or maybe th' ancestor had 30 distinct chromosomes and there have been 6 fusion events fer ape-line but 7 fusion events fer th' human-line.
Do ye see me point, ye scurvey dog? Simple chromosome-countin' or comparisons o' numbers o' chromosomes does not lead common ancestry t' make any hard predictions about how many chromosomes our alleged ape-human common ancestor had. So, under Miller's logic, there is no reason why a chromosomal fusion event is a necessary prediction o' common ancestry fer all upper primates.
That's pathetic. The reason evolutionists proposed a chromosomal fusion event is that all o' th' duplication events he proposes would have major phenotypic consequences (Down syndrome is caused by a duplication o' one very small chromosome, fer instance) and would represent a serious obstacle t' evolution—Miller stated so very plainly. Some lineages are tolerant o' that kind o' massive genomic change, but ours is not. Multiple independent fusions are possible, but improbable; we can see evidence o' it in species that have diverged fer a long time (mouse and human chromosomes are dramatically rearranged relative t' one another, fer instance), but apes ha'nae been separated as long. We have also had evidence fer about 40 years that on a gross level, th' structure o' th' chromosomes in all apes were bein' very similar.
Luskin is tossin' aroun' these wild ideas in a very lawyerly tactic—he be tryin' t' cast doubt on th' best explanation by pretendin' there are a multitude o' alternatives. Fire the cannons, and a bottle of rum! Those alternatives are not reasonable, and he knows it: he even admits it.
So I am more than willin' t' acknowledge and affirm that Miller did provide some very good direct empirical evidence fer a chromosomal fusion event which created human chromosome #2. But I'm more interested in two other questions: if we accept Miller's chromosomal fusion evidence as accurate, then (1) is his chromosome fusion story good evidence fer Neo-Darwinian common ancestry betwixt humans and apes? Or (2) does it perhaps pose great problems fer a Neo-Darwinian account?
The answer t' question (1) is "NO" and th' answer t' question (2) is "YES!"
Oh, dear, by Davy Jones' locker. This is where Luskin goes off th' rails, and abandons all reason.
(1) is a bogus framin' o' th' issue. The fusion is not evidence o' common ancestry; 'tis th' common genomic content o' all ape chromosomes that is th' evidence. The fusion accounts fer a superficial difference in th' appearance o' th' karyotype, but th' underlyin' genetic sequence is what exposes th' relatedness o' humans and other apes, we'll keel-haul ye! Luskin harps on this bizarre notion o' his, that th' occurrence o' a fusion is th' key t' human evolution.
All Miller has done is documented direct empirical evidence o' a chromosomal fusion event in humans. But evidence fer a chromosomal fusion event is not evidence fer when that event took place, nor is it evidence fer th' ancestry prior t' that event.
Aye, that is correct. Shiver me timbers, by Blackbeard's sword! Miller weren't claimin' anythin' about when it occurred, or that th' fusion says anythin' about prior ancestry: 'tis th' sequence, stupid, me beauty. But look here, here's Luskin's real agenda.
Given that we had a 48-chromosome ancestor, we dern't know if our 48-chromosome ancestor were bein' an ape or not. For all we know, our 48-chromosome ancestor were bein' a part o' a separately designed species, as fully human as anyone ye meet on th' river today. There is no good reason t' think that goin' from a 46-chromosome individual t' a 48-chromosome individual would make our species more ape-like, and a bucket o' chum.
Separate creation. We ain't descended from no monkeys, and dinna spare the whip! Miller's point is that chromosome number is not a good indicator o' different ancestry, but Luskin wants t' turn that aroun' and claim any ol' ancestry is therefore equally valid…but 'tis not. It's th' sequence, not th' fusion, that tells us o' our relatedness. And o' course no one has proposed that a simple chromosome fusion or separation is responsible fer th' differences betwixt us and other apes.
That humans are most closely related t' apes and that we all had a common ancestor in th' relatively recent past is not a point in contention by any reasonable scientist. This is th' kind o' false malarkey th' IDists want t' push in our schools—'tis simply bad science t' deny common ancestry.
What about Luskin's point (2), that th' fused chromosome is a problem fer th' neo-Darwinian account? It's more nonsense (what else would ye expect?).
Under Neo-Darwinism, genetic mutation events (includin' chromosomal aberrations) are generally assumed t' be random and unguided. Miller's Cold-Fusion tale becomes more suspicious when one starts t' ask harder questions like "how could a natural, unguided chromosomal fusion event get fixed into a population, much less how could it result in viable offsprin'?" Miller's account must overcome two potential obstacles:
(1) In most o' our experience, individuals with th' randomly-fused chromosome can be normal, but it is very likely that their offsprin' will ultimately have a genetic disease. A classic example o' such is a cause o' Down syndrome.
Not quite. What we see in humans is a classic instance o' a Robertsonian translocation. These happen quite often—1 in 900 births bear a fusion o' this kind—and they cause no immediate problems at all. Shiver me timbers! The affected individual has a full and normal genetic complement; 'tis just that two o' their chromosomes are stuck together. It can cause reduced fertility, but is unlikely (except in some known, specific cases) t' lead t' offsprin' with a genetic disease.
Let me explain why. Assume we have a set o' genes (a) found on one chromosome, and a set o' genes (b) found on another. Everyone has two copies o' each set, so in a normal diploid cell, we have (a) (a) (b) (b). Ahoy, ye scurvey dog! In meiosis, th' cellular mechanisms segregate th' chromosomes in an orderly way, so each gamete gets one set (a) and one set (b), each gamete looks like this: (a) (b).
In an individual with a Robertsonian fusion, though, each diploid cell looks like this: (a) (b) (a:b). They have three chromosomes instead o' four, even if they do have th' proper doses o' (a) and (b). Now when meiosis occurs, th' cell has t' sort 3 chromosomes into two cells, and there are multiple ways this can happen:
(a) (b) | a normal gamete : normal |
(a:b) | a gamete carryin' th' fusion, but with th' normal complement o' genes: normal |
(a) (a:b) | a gamete with an extra (a)—lethal |
(a) | a gamete with an no (b)—lethal |
(b) (a:b) | a gamete with an extra (b)—lethal |
(b) | a gamete with a no (a)—lethal |
As ye can see, several o' th' combinations produce viable gametes, and this individual can have healthy little sandcrabs with no detectable problems, although half o' them will carry th' Robertsonian fusion. The other gametes have serious problems, and will typically lead t' very early miscarriages, especially if they involve a large chromosome, like chromosome 2, we'll keel-haul ye! They will have more problems conceivin', but their little sandcrabs will be normal.
If th' fusion chromosome spreads through th' population, somethin' interestin' will happen, and some people will have diploid cells like this: (a:b) (a:b). All o' their gametes will be (a:b), and all will be normal. Fusions like this put up measurable but not at all insurmountable barriers t' reproduction and can make it easier fer carriers t' reproduce with each other, so they can be mechanisms fer reproductive isolation and speciation.
Again, Luskin doesn't savvy this basic concept, and he compounds his error with quote minin' and poor scholarship.
(2) One way aroun' th' problem in (1) is t' find a mate that also had an identical chromosomal fusion event. But Valentine and Erwin imply that such events would be highly unlikely: "[T]he chance o' two identical rare mutant individuals arisin' in sufficient propinquity t' produce offsprin' seems too small t' consider as a significant evolutionary event."
(Erwin, D..H., and Valentine, J.W, avast. "'Hopeful monsters,' transposons, and th' Metazoan radiation", Proc. Natl. Acad. Sci USA, 81:5482-5483, Sept 1984)
The problem in (1) is not a problem, with a chest full of booty. As I just explained, ye dern't need a mate with an identical fusion event t' successfully reproduce.
His choice o' an article t' back up his assertion is weird. The article is from 1984, fer one thin'; why dig up a 22 year auld article t' support a basic point? For another, th' article does not discuss th' viability o' hybrids with Robertsonian fusions at all. Walk the plank! Shiver me timbers! It is specifically about th' possibility o' large scale mutations that generate major morphological novelties.
The article is a short speculative work that suggests a way t' get aroun' th' objection they mention, and that is th' center o' Luskin's argument—in other words, 'tis a paper that says how Luskin is wrong. (It also happens t' be a proposal I dern't find too likely: Erwin and Valentine suggest that one way th' frequency o' novel mutations could rapidly rise t' overcome th' problem is by site-specific horizontal transfer o' transposable elements. Mmmm, maybe, but I'd want t' see more evidence o' such transformations associated with key innovations.)
Fortunately fer th' short attention span o' creationist, their quote is from th' second sentence o' th' paper. I can only assume they di'nae bother t' read any further, and dinna spare the whip! Does anyone else have this mental image o' Discovery Institute "scholars" porin' o'er science papers with almost no comprehension, but happily pluckin' out random sentences here and there that they can misuse, we'll keel-haul ye! I suspect they have a compendium o' such fragments that their fellows use, without th' need o' e'er havin' t' actually read any science.
In other words, Miller has t' explain why a random chromosomal fusion event which, in our experience ultimately results in offsprin' with genetic diseases, didn’t result in a genetic disease and were bein' thus advantageous enough t' get fixed into th' entire population o' our ancestors. Given th' lack o' empirical evidence that random chromosomal fusion events are not disadvantageous, perhaps th' presence o' a chromosomal fusion event is not good evidence fer a Neo-Darwinian history fer humans.
Nay, no, and dinna spare the whip, we'll keel-haul ye! Duplications in humans lead t' genetic diseases. And swab the deck, by Blackbeard's sword! Miller were bein' explainin' that there is a normal genetic mechanism fer fusions that represents an evolutionary pathway without th' detriment o' a major duplication/deletion that leads t' our current chromosome arrangements.
The only lubber proposin' a path by way o' duplications and their concomitant problems were bein' Luskin.
Miller may have found good empirical evidence fer a chromosomal fusion event. But all o' our experience with mammalian genetics tells us that such a chromosomal aberration should have resulted in a non-viable mutant, or non-viable offsprin'. Thus, Neo-Darwinism has a hard time explainin' why such a random fusion event were bein' somehow advantageous, by Davy Jones' locker.
Whoa, irony meter, calm down. Luskin tellin' us about "all o' our experience with mammalian genetics", me beauty? The ornery cuss's wrong. The ornery cuss doesn't even have basic textbook knowledge o' genetics. Our experience with mammalian genetics tells us that he is babblin' out o' his butt: fusions have no such problem yieldin' viable offsprin'.
If ye bother t' take a look at th' list o' articles maintained by th' IDEA center, ye'll see that th' majority o' them are by Luskin, and he be usually pontificatin' about similarly imaginary problems in evolutionary theory, problems that are actually with his own shameful lack o' knowledge about th' subject. This pathetic ignoramus is th' primary source o' information fer th' collegians they're tryin' t' recruit into their IDEA clubs? I'd consider it a source o' embarrassment t' have an organization dedicated t' such foolishness on me campus.
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{if FALSE} {/if} {if TRUE} Next up: Luskin disses th' Vitamin C evidence "because they're a crappy band." {/if}
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