And the Miller Told His Tale: Ken Miller's Cold (Chromosomal) Fusion
And the Miller Told His Tale: Ken Miller's Cold (Chromosomal) Fusion
Dr. Kenneth Miller was the leadoff hitter for Plaintiffs in the trial over ID in Dover. Amidst other things, Miller's testimony was aimed at making a case that the Neo-Darwinian hypothesis is as well-supported as gravitational theory.
It was my understanding that this trial was about whether or not Dover had violated the First Amendment by mentioning to students that some book in the library advocated intelligent design. So I was a little confused as to why it was relevant for Miller to give us all a lesson in evolutionary biology.
Nonetheless, I like Ken Miller on a personal level and, relevant or not, I very much enjoyed Dr. Miller's testimony. Though I disagree with Ken on many things, I think Dr. Miller genuinely cares about students. His testimony has also given me a week's worth of things to think about. Here's one thought I'd like to share.
What does Neo-Darwinism Predict with regards to Chromosomal History in Humans and Apes?
Under Neo-Darwinism, humans and extant apes obviously share a common ancestor. But how many chromosomes did that alleged ancestor have? Miller made his prediction that there was a fusion event simply by counting chromosomes in apes and humans—not by analyzing the chromosomes themselves.
Miller started off his "prediction" by simply observing that humans have 23 pairs of chromosomes and apes have 24 pairs; therefore two ape chromosomes were fused into one human chromosome. Miller claims that this simple chromosome-counting requires a fusion event if common ancestry is true. But is that really the case?
Why couldn't it be the case that the common ancestor had 23 distinct chromosomes, and one chromosome underwent duplication in the line that led to apes? Or maybe the common ancestor had 20 distinct chromosomes and there have been 4 duplications events in the ape line, and 3 in the human line?; or maybe the ancestor had 30 distinct chromosomes and there have been 6 fusion events for ape-line but 7 fusion events for the human-line.
Do you see my point? Simple chromosome-counting or comparisons of numbers of chromosomes does not lead common ancestry to 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 of common ancestry for all upper primates.
In fact, if we find evidence that humans have two distinct chromosomes that have evidence of fusion (i.e., let's say human chromosome #2 has fusion evidence, and then, hypothetically, we also find evidence for fusion on human chromosome #9), then under Miller's logic, if apes lack any evidence for a fused chromosome, then this should count against common ancestry. Thus, at the present time, absent a full analysis of fusion evidence in our chromosomes, we cannot necessarily say that the presence of one fused chromosome in humans is a prediction of common ancestry. Much more research still needs to be done.
If Miller's Cold (Chromosomal) Fusion Tale is True, What does it mean for Common Ancestry?
But let's take Miller's word for a second, and assume, ad arguendo (for the sake of argument), that there MUST have been a chromosomal fusion event which created human chromosome #2. What does this mean for common descent?
Miller then testified how human chromosome #2 has two centromeres, which are the central - attachment points used for pulling a chromosome to one end of a cell during mitosis. Chromosomes normally only have one centromere, but human chromosome # 2 looks like two chromosomes were fused together, because it has two centromeres (or at least, it has one normal centromere, and another region that looks a lot like a centromere). Futhermore, Miller noted how chromosome #2 has a section where there are two telomeres, structures normally at the tips of chromosomes, which are found in the middle of chromosome #2. Essentially, these two telomeres are oriented in a way that it looks, genetically speaking, like the ends of two chromosomes were fused together.
So I am more than willing to acknowledge and affirm that Miller did provide some very good direct empirical evidence for 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 for Neo-Darwinian common ancestry between humans and apes? Or (2) does it perhaps pose great problems for a Neo-Darwinian account?
The answer to question (1) is "NO" and the answer to question (2) is "YES!"
Evidence for Fusion in a Human Chromosome Tells you NOTHING about Alleged Common Ancestry with Apes
All Miller has done is documented direct empirical evidence of a chromosomal fusion event in humans. But evidence for a chromosomal fusion event is not evidence for when that event took place, nor is it evidence for the ancestry prior to that event.
The fusion-evidence implies that some of our ancestors likely had 48 chromosomes. But Miller has not provided any evidence that the individual with 48 chromosomes was historically related to modern apes. (I grant that our chromosome #2 has banding patterns similar to two ape chromosomes, but given that our chromosome structure is generally similar to that of apes anyways, it is not a stretch to assume that any 48 chromosome ancestor of you and me had a chromosome structure similar to apes, regardless of whether or not that individual was related to apes. Claiming that banding pattern similarities is evidence of common ancestry with apes simply invokes the “similarity = ancestry” argument, and thus begs the question.) It is entirely possible that our genus Homo underwent a chromosomal fusion event within its own separate history.
Under Neo-Darwinism, the common ancestor of humans and apes is thought to have lived about six million years ago. But under Miller's account, it is entirely possible that this chromosomal fusion event happened only 50,000 years ago. In such a case, this chromosomal fusion event thus needs not have anything to do with making us human-like as opposed to ape-like. Clearly this chromosomal fusion event could be extremely far removed from any alleged ancestry with apes.
In essence, we don't know that this chromosomal fusion event happened on a line which leads back to some alleged common ancestor of apes and humans. All we know is that this fusion event happened in the line that led to you and me. Whether that line has common ancestry with apes is a separate question which cannot be answered by this fusion evidence.
All that evolutionists have claimed is that this fusion event occurred after the split that led to humans, so it occurs only in the human lineage. Evidence of a chromosomal fusion event is not evidence that our line leads all the way back to apes.
Given that we had a 48-chromosome ancestor, we don't know if our 48-chromosome ancestor was an ape or not. For all we know, our 48-chromosome ancestor was a part of a separately designed species, as fully human as anyone you meet on the street today. There is no good reason to think that going from a 46-chromosome individual to a 48-chromosome individual would make our species more ape-like.
Common descent could not have been falsified if there was no evidence for a fusion event, but common descent certainly is not refuted by the presence of a fusion event. The question now stands, does this fusion event provide any evidence for common ancestry between humans and apes? The answer to that question is no.
This is explained in figure 1 below:
Figure 1. This animated gif shows how even if the empirical genetic evidence mandates a chromosomal fusion event, this doesn't tell you anything about whether or not humans share ancestry with apes. The "Separate Ancestry" slide shows that the chromosomal fusion event may have simply taken place in a separately-designed basic type which, initially, had 48 chromosomes. The "Common Ancestry" slide shows how the chromosomal fusion event may have also taken place in a line which led back to a hypothetical common ancestor of humans and modern apes. The point is that all we have is evidence for a fusion event, but that fusion event is equally compatible with either separate ancestry from apes, or common ancestry with apes. The fusion event itself does not provide any independent evidence for common ancestry with apes. To argue that it is evidence for common ancestry requires special pleading.
Miller's "prediction" of Neo-Darwinian evolution turns out to not be a hard prediction at all: if common ancestry is true, Miller predicts (albeit wrongly) that there must have been a fusion event. But the converse is not true. The presence of this fusion event in no way requires that common ancestry is true.
It only gets worse for Neo-Darwinism
Under Neo-Darwinism, genetic mutation events (including chromosomal aberrations) are generally assumed to be random and unguided. Miller's Cold-Fusion tale becomes more suspicious when one starts to 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 offspring?" Miller's account must overcome two potential obstacles:
(1) In most of our experience, individuals with the randomly-fused chromosome can be normal, but it is very likely that their offspring will ultimately have a genetic disease. A classic example of such is a cause of Down syndrome.
(2) One way around the problem in (1) is to 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 of two identical rare mutant individuals arising in sufficient propinquity to produce offspring seems too small to consider as a significant evolutionary event."
(Erwin, D..H., and Valentine, J.W. "'Hopeful monsters,' transposons, and the Metazoan radiation", Proc. Natl. Acad. Sci USA, 81:5482-5483, Sept 1984)
In other words, Miller has to explain why a random chromosomal fusion event which, in our experience ultimately results in offspring with genetic diseases, didn’t result in a genetic disease and was thus advantageous enough to get fixed into the entire population of our ancestors. Given the lack of empirical evidence that random chromosomal fusion events are not disadvantageous, perhaps the presence of a chromosomal fusion event is not good evidence for a Neo-Darwinian history for humans.
Miller may have found good empirical evidence for a chromosomal fusion event. But all of our experience with mammalian genetics tells us that such a chromosomal aberration should have resulted in a non-viable mutant, or non-viable offspring. Thus, Neo-Darwinism has a hard time explaining why such a random fusion event was somehow advantageous.
If it were to turn out that the fusion of two chromosomes can only result in a viable individual if the fusion event takes place in a highly unlikely and highly specified manner, then we may actually be looking at a case for a non-Darwinian intelligent design event in the history of the human genus.