Extinction of the human male
Figure 1. Example of recombination during meiosis. Prior to recombination, the starting pair of homologous chromosomes have mutations at different locations (loci). After recombination, however, one of the recombinant chromosomes no longer has the potentially harmful mutations.
The idea that men are headed for extinction may sound somewhat strange, but it has been a topic of serious scientific debate in recent years. In 2003, Oxford University geneticist Bryan Sykes claimed that the human Y chromosome was “crumbling before our very eyes”.1 He warned that the demise of men was imminent.2 However, doomsday predictions of Y-chromosome decay may have been a little hasty.
The story of Y
Humans have 23 pairs of chromosomes in each cell; one of these pairs is classified as sex chromosomes. Females have two X chromosomes and males possess one X and one Y. The Y chromosome is passed from fathers to sons and houses the key genetic instructions for male development. Compared to most chromosomes, Y is rather small. It has about 70 million base pairs and houses about 78 protein-coding genes (of the estimated 25,000 in the human genome). Some of these genes are expressed throughout the body, whereas others are expressed predominantly in male reproductive organs.3
Why is the Y chromosome in such peril?
Since the Y chromosome doesn’t have a ‘partner’, it cannot engage in a process known as genetic recombination. During meiosis, chromosome pairs line up, join and swap genetic material in a process called ‘recombination’. This is why two parents can have lots of children that are physically different from each other; the individual sets of chromosomes that each parent passes on are unique, highly-shuffled versions of their own chromosome pairs. This shuffling process enables a mutated chromosome to purge itself from some harmful mutations (see figure 1). But since the Y chromosome does not undergo recombination, mutated portions of it cannot be cut-and-paste over with a ‘healthier’ version.4 Thus Y chromosome mutations supposedly keep piling up. This inability of the Y chromosome to engage in recombination is one of the key reasons fuelling belief about its demise.
Moreover, the Y chromosome is supposedly bombarded by more mutations.5 Men produce sperm throughout their life, whereas women have a set number of egg cells at birth. This means that when men reproduce, their sperm has gone through more rounds of cell divisions, which means there’s more opportunity to accumulate mutations. This is even more pronounced in older fathers. Leading evolutionary biologist Steve Jones calls men: “far more potent as a mutagen than the hydrogen bomb”.6 On average, the chromosomes passed down to you have spent half their time in females and half in males.7 But a male’s Y chromosome has only ever been housed in males, so it has never experienced the ‘reprieve’ a chromosome gets when housed in a female.8
Furthermore, evolutionary assumptions have boosted claims about the demise of the Y chromosome. The X and Y chromosomes are believed to have been a standard pair of non-sex chromosomes (autosomes) 300 million years ago. Since this time the X chromosome has supposedly maintained most of its genes, whereas the Y chromosome has decayed and shortened dramatically. That’s why this chromosome is often referred to as a ‘profoundly degenerate X chromosome’.9 However, the Y chromosome has its own unique genes that are not on X, so evolutionists have had to speculate how these arose against what they perceive as a strong current of overall decay.
Y-demise proponents have also pointed out that many of the genes it contains have been rendered non-functional by mutations. Bryan Sykes calls it a “graveyard of rotting genes”.10 Considering that mutations are copying mistakes in DNA, it’s not surprising that mutations occasionally turn functional genes into non-functional genes (pseudogenes or fossil genes). But we need to be cautious here. Some have been overzealous in labeling as pseudogenes certain DNA sequences which have later been found to serve a function.11,12
Although there may appear to be little future left for the Y chromosome, further research has revealed previously unsuspected ways of self-repair. The Y chromosome’s ability to heal itself is due to its long palindromic sequences (sequences that read the same in either direction). The Y chromosome contains eight large palindromes with genes imbedded in them—the largest is almost 3 million DNA ‘letters’ from end to end. These have earned the Y chromosome the nickname ‘a genetic hall of mirrors’.
So how do these help the chromosome repair itself? If a gene in one arm of a palindrome is corrupted by mutation, the middle of the palindrome can act like a hinge, bringing the two arms together. Then, in a process known as gene conversion, the ‘healthy’ gene in the complementary arm overwrites and restores the sequence in the mutated gene (see figure 2). This process helps explain why intact genes tend to reside in the palindrome arms, whereas the corrupted copies of these genes reside elsewhere.13
Figure 2. How the Y chromosome heals itself. A – One of the palindromes has a mutated gene (M) and a normal copy of the gene (N) in opposite ‘arms’. B – The middle of the palindrome acts like a hinge, bringing the two genes in close contact. Gene conversion restores the mutated gene. C – Both arms of the palindrome end up with normal copies of the gene.
Not all geneticists are convinced palindromic gene conversion will save the Y chromosome, though. Sykes says,
“There is no guarantee that the gene conversion will repair a damaged copy. The essential ignorance of DNA makes it equally likely that the good copy will be spoiled instead”.14
In any case, it appears that palindromic gene conversion is another way that nature is ‘wired’ to slow the rate of genomic decay.15 Furthermore, by comparing ape and human Y-chromosomes, some evolutionists have argued that human Y chromosomes haven’t decayed much in the recent past, after all.16 Geneticist Jennifer Hughes tells us:
“ … even though the Y has lost many genes since its origin about 300 million years ago, it’s been holding steady in humans for the last 6 million years.”17
So there now appears to be a change in attitude about the rate of Y-chromosome decay. Leading Y chromosome researcher David Page reassures us:
“ … contrary to the dire predictions that have become popular over the last decade, the sky is not falling on the Y [chromosome].”17
What the Y chromosome is telling us is that the neo-Darwinian mechanism of mutation and selection consistently degrades genetic software, as opposed to upgrading it. Though males are not doomed in the way Sykes claims, overall genome decay is a real phenomenon, and the more we appreciate the extent of the problem, the more it undermines the validity of the big picture of evolution.
- Sykes, B., Adam’s Curse: The Science That Reveals Our Genetic Destiny, W.W. Norton and Company, New York, p. 290, 2003. Return to text.
- Ref. 1, p. 294. Sykes estimates that within 5,000 generations (approximately 125,000 years) fertility will be 1% of what it is today. Return to text.
- Skaletsky, H. et al., The male-specific region of the human Y chromosome is a mosaic of discrete sequence classes, Nature 423:825–837, 2003. Return to text.
- However, The X and Y chromosomes do undergo a little recombination at their tips, in the pseudoautosomal region. Return to text.
- This is debatable as the low level of variation in the Y chromosome has surprised many—you wouldn’t expect this if bombarded by so many mutations. Sykes acknowledges this minimal variation (ref. 1, p. 135) but still espouses the ‘hit by more mutations’ argument in his book. See also creation.com/y-chromosome-adam. Return to text.
- Jones, S., Is Human Evolution Over? Darwin College Lecture Series, Cambridge University 2009, accessed via iTunes. Return to text.
- Except the X chromosome, which spends approximately 2/3 of its time in females. Return to text.
- A lady pregnant with a baby boy is not relevant to the discussion here. Return to text.
- Ref. 3, p. 825. Return to text.
- Ref. 1, p. 284. Return to text.
- Woodmorappe, J., Pseudogene function: more evidence, J. Creation 17(2):15–18, 2003. Return to text.
- Lai, P. et al., An olfactory receptor pseudogene whose function emerged in humans: a case study in the evolution of structure-function in GPCRs, J. Structural and Functional Genomics 9:29–40, 2008. Return to text.
- Rozen, S., Abundant gene conversion between arms of palindromes in human and ape Y chromosomes, Nature 423(6942):873–876, 2003. Return to text.
- Ref. 1, p. 285. Return to text.
- Another example is the chief enzyme involved in copying DNA (DNA polymerase). This remarkable enzyme not only copies DNA, but performs its own ‘proof reading’. Then, other enzymes come in and perform further work identifying and repairing copying mistakes. This process helps minimize the number of mutations. Return to text.
- Hughes, J. et al., Conservation of Y-linked genes during human evolution revealed by comparative sequencing in chimpanzee, Nature 437(7055):101–104, 2005. Return to text.
- Cameron, D., Human Y chromosome stays intact while chimp Y loses genes, Whitehead Institute for Biomedical Research, www.wi.mit.edu/news/archives/2005/dp_0831.html, 31 August 2005. Return to text.
"...300 million years...holding steady for 6 million years."
Where do they get these figures? Creation is only about 6 thousand years old. Obiviously there is some corruption (degeneration) in the gene pool. Also the original gene pool from Adam and Eve was significantly narrowed at the time of the Flood. Mutation always subtracts from the gene pool. However God, by his power and goodness, keeps all these problems in check and still maintains all creation.
Evolutionists use various methods to establish these ‘dates’, but they all rely on unprovable assumptions similar to those used in radiometric dating, and so make the same mistakes. See Is ‘mitochondrial Eve’ consistent with the biblical Eve? for more information.
Dear David White, I recently bought from CMI, two copies of the book GENETIC ENTROPY by Prof. John Sanford of Cornell University. This book shows how the human Genome is degenerating at a rapid rate for both males and females. If CMI would get 100% behind the message of Prof. Sanford, we could drive a stake thru the heart of Darwinian Evolution in 2013 ... !!!!!!!
Mr White clearly affirms genomic decay is happening—cf his conclusion. And genomic decay is certainly an important part of a biblically-based understanding of biology, and we never want to downplay that. However, there are two other factors we always need to consider with it in tandem for a biblical understanding of biology: design and variation.
Life is of course designed—if a tornado in a junkyard can’t produce a Boeing 747, then bubbling sea vents or lightning strikes in primordial ponds have no chance of producing life (which is far more technologically advanced than a Boeing 747) where there was none before.
Variation is the factor we tend not to think about so often. We all know that if left alone all technology breaks down. This is as true for cells as much as it is for space shuttles. But space shuttles don’t maintain themselves, reproduce themselves, and don’t have to be adaptable to a continually varying environment—cells (and creatures composed of cells) do. Therefore, life has maintenance mechanisms and designed mechanisms for variation both built in. Now, maintenance and adaptability are opposing considerations and thus each imposes limits on the other. Life is not infinitely adaptable (as evolution requires) because it would break down from error overload if it was. Likewise life is not perfectly static otherwise it would break down at the first mistake that crept in. In the context of degeneration, it means that while life will eventually go extinct if everything continues as is, it won’t happen any time soon—life still has a lot of life left in it yet. See How life works for more details.
In response to the article itself, extinction of the human Y chromosome need not imply extinction of the human male. At least, there is the example of the Transcaucasian mole vole (a hamster-looking rodent found from Iran to Turkey) has males and females, but no Y chromosome and apparently no copy of the SRY gene that triggers development of male organs in most mammals.
Also, pseudogenes are not defined by having no function, but by not coding for the proteins that their homologs (in the same or other species) do. Presumably a sequence of DNA can have multiple functions, and losing one need not imply losing all of them.
In response to Alan H., Richard Dawkins is on record as stating that "that there is no general reason to expect evolution to be progressive--even in the weak, value-neutral sense." An inexorable increase in complexity would, of course, be precisely the sort of progress he claims evolution does not imply. Decreases in complexity that increase fitness -- or simply do not inhibit fitness -- are entirely consistent with natural selection.
First, humans and voles are clearly different creatures, so what works for one won’t necessarily work for the other. The comparison has to be shown to be relevant before it can be used as evidence men can do without the Y chromosome. In a recent metastudy on mice, for example, it was learned that they make terrible models for studying human disease, despite the fact that they have been used to do this for decades.
Second, we would agree that a sequence of DNA can have multiple functions, and that losing one need not imply losing them all. However, your definition of ‘pseudogene’ begs the question in favour of evolution if by ‘homology’ you mean “similarities derived through common ancestry”. We can’t know that everything identified as a ‘pseudogene’ must have shared a common ancestor with its supposed ‘corresponding gene’.
Finally, Dawkins is confusing the issue. That evolution can accommodate decreases in complexity is not at issue. The fact remains that evolution still needs a mechanism to increase complexity because it postulates that men evolved from microbes, not the other way around. No amount of semantic gerrymandering can get around that. And natural selection is not such a mechanism—it ‘picks’ the fittest from an already existing genetic variety; it doesn’t produce the variety. Some sort of mutational mechanism is the only hope—and it’s a dead hope. Microbes-to-man evolution has no viable mechanism, and cannot lay claim being the only idea that can explain genomic and fossil patterns (apart from assuming that very fact—which is arbitrarily circular). Therefore, we’re left with no publically compelling reasons to believe in evolution (i.e. reasons that would mandate evolution being the only game in town).
just 2 points:
1: What possible relevance could Chimp-DNA have to Human-DNA(/chromosomes) if they are different creations?
2: It seems to me that the main thrust of the article would be that the mutation/selection mechanism does /not/ produce genetic degradation. (My own perception is that the mutation produces variety and the selection part cleans up the inevitable mess.)
In answer to your questions:
- The relevance for the origins debate is found in the fact that evolutionists argue a high percentage similarity between human and chimp DNA is evidence for evolution. In this article, a comparison with chimp DNA shows inexplicable variation in what has supposedly happened to the Y chromosome over evolutionary history. Mr White is showing how the evolutionary story of Y chromosome evolution has a number of internal conundrums.
- The article is about the maintenance mechanisms in the Y chromosome. Maintenance mechanisms are explicitly designed to minimise random mutations and their effects. This presumes random mutations destroy information and disrupt function. Moreover, Mr White clearly believes these mechanisms are not perfect—he believes our genome as a whole is inexorably decaying in spite of such mechanisms.
This nicely demonstrates evolution is not a possibility. Also since the LORD, 6000 years ago at Creation, knew we would only need to procreate for about 200 - 300 generations then if the gene is indeed degrading as suggested it is of no consequence and is all in the LORD's design anyway. As we know at the Lords return, "we will be changed, in a moment in the twinkling of an eye, at the last trump: For this corruptible must put on incorruption, and this mortal must put on immortality". 1Cor 15: 51-53
As a 'Christian" ministry, why is the likes of this article printed without a valid and firm rebuttal on the evolutionary concept of 300 million years of time. Or is this a new concept of your ministry that I have not til now realized?
The author was clear that it was the belief of the researchers he was quoting, not something he believed with them. Besides, it wasn't incredibly important for the specific point of the article. There are plenty of articles on our website that refute 'deep time'— we continue to stand wholeheartedly against 'deep time'. Nevertheless, we cannot deal fully with every issue in the origins debate in each article we publish.
Interesting that man has x and y chromosomes, and woman has only x chromosomes; the y being distinctly male, which the female does not posses. Interesting that they don't both have the same x and y, or that it is not the other way round where the female has the x and y and the male only x chromosomes.
In Genesis, it tells us that God made man and then made woman from man (literally took her from his side and formed her).
Can make one wonder if this is why man has the unique distinction - man has one "female(x)" and one "male(y)" and woman has only "female(x)".
Not saying the preceeding observation is correct, but I wonder if it could be connected?
I hope Richard Dawkins will be beating a path to the Y Chromosome decay faction to inform them that Evolutionary natural selection mandates increase in complexity over time so no decay or evolution falls. The only danger I see to the Y chromosone is from today's political correctness that states men should find their feminine side. To that I say I have done enough for that side as I have 3 daughters!
I'm not at all surprised that God provided a mechanism to keep that chromosome in good shape. Here in America, I think one of the real threats to males is how the educators, politicians, doctors, and the other assorted experts have to a great extent and continue to try to feminize the American male. From Academia to entertainment, men are objects that need changing to be more like women and objects of ridicule for their "maleness". (And, women are being encouraged to be more like males.) One thing is for sure in this age of tolerance is that males cannot be tolerated for being male-as-is.