It comprehensively debunks the notion that epigenetics supports intelligent design creationism and refutes evolution.
Epigenetics is a relatively new branch of biology which is presenting biologists with some new challenges, not the least of which is its complexity. It is also presenting creationism with some exciting new gaps in which to try to insert a creator and attack science on the basis that if science doesn’t know something it has failed and proven itself unreliable. No matter that in a few years, maybe a little longer, science, using the scientific method will one day close those gaps and, like all the other gaps, will fail to find a god in them. By then, creationist apologists will have moved on to some more gaps, still confident that this time science will be forced to admit that ‘God did it!’Some might argue that epigenetics alone is sufficient to refute the Intelligent [sic] Design notion. What intelligent designer would invest just about every cell in a multicellular organism with the full genome, only to have to devise a complicated process for switching most of the genes and redundant DNA off, then having to devise a mechanism for resetting the whole thing in the zygote so a new multicellular organism can be built? This simply can't be accounted for by any intelligent design process whereas evolution theory fully explains how it arose as part of the evolution of multicellular organisms with cell specialisation.
Whole books are being written about epigenetics and the challenges it presents to biology, one such being Nessa Carey’s The Epigenetics Revolution: How Modern Biology is Rewriting Our Understanding of Genetics, Disease and Inheritance1.
Briefly, epigenetics is the study of how various genes are turned off in different cells as they become specialised during embryonic development. The actual mechanism, the epigenetic processes itself, are beyond the scope of this book but what interests us here is what this means for our understanding of evolution and, more importantly, why the processes are needed.
The interesting thing from an evolutionary perspective is the fact that, when DNA in the form of a chromosome is replicated in cell division, the epigenetic ‘settings’ are also replicated, so any genes which were switched off in the parent cell will also be switched off in the daughter cells. It seems that, as cells differentiate and become specialised to perform specific functions as the embryo develops, genes can be switched off but they don’t get switched on again, so cells derived from one layer will have all the epigenetic settings of that layer, and some more. The descendants of those cells in turn will have all those settings plus some of their own. And so on until in the fully formed individual all the specialised cell types will have their unique set of epigenetic, so liver cells will have different active genes to, say, muscle cells or brain cells.
This is of interest to evolutionary biologists, and probably why creationists get so excited by it, because it seems to imply that something acquired after the cell formed can be passed on to descendants, contrary to what Darwin argued and what current evolutionary theory says; that characteristics acquired after birth (or more correctly, after conception) can’t be inherited because we get all our inherited traits from our parents.
This Darwinian view was in contrast to the rival theory proposed by the French biologist, Jean-Baptiste Lamarck, who argued that characteristics acquired after birth could be inherited. For example, a blacksmith’s skills and his strong arms could be inherited by his sons. He suggested that giraffes could have acquired their long necks by stretching them to reach branches, so their offspring would inherit these longer necks.
Both Lamarck and Darwin knew nothing about how we inherit from our parents of course because they knew nothing of genes, chromosomes or DNA.
So, to a creationist, it might look as though epigenetics falsifies their arch–demon, Charles Darwin so, in their view which sees ‘Darwinism’ (that is, the whole of evolutionary theory) as a dogma, this falsifies the entire body of science. Curiously, they forget that Lamarck’s idea was simply an attempt to explain the observable fact of evolution. The reason Darwin’s ideas became accepted is because they better explain the observable evidence in nature that living organisms can be arranged into branching hierarchies which show a clear relationship between them.
But, there is a world of difference between the individual cells of our bodies inheriting epigenetic settings from their parent cells, whole human beings inheriting all the epigenetic settings from their parents. The obvious difference being that we as individuals don’t inherit all our parent’s cells; we inherit half our DNA from each parent via two gametes which fuse to form a single cell or zygote from which all our cells are derived.
These gametes are of course themselves the descendants of specialised germ cells and are specialised cells in their own right, but there is no reason to suppose that they will carry epigenetic settings in, say, brain or muscle cells. The resulting zygote needs to be pluripotent, that is, having the capability to give rise to all the different cell types in the resulting adult, so it must have its epigenetic settings reset before any cell differentiation can take place. This resetting serves to remove any epigenetic changes acquired after conception by either parent, or at least the vast majority of them.
Having said that, there do appear to be a few instances where things that have profound effects on parents during their lifetime can influence their children and even grandchildren. One such, cited by Nessa Carey1, is the results of the ‘Dutch Hunger Winter’ when due to German blockages between November 1944 and spring 1945, food supplies were almost non–existent to the extent that some 20,000 people died of starvation. Studies on the children of this population, whose mothers were pregnant during this period, show that their subsequent development was affected by when during their pregnancy their mothers were starved. This in itself is not surprising, because, although it was acquired after conception, it is not difficult to imagine how it could have affected epigenetic settings.
What was surprising, however, was that there seems to have been an effect on the children of these children. In other words, the grandchildren of the women who were starved during pregnancy could somehow have inherited something depending on when during their pregnancy their grandmothers were suffered a period of starvation2.
Now this is something science needs to explain. How it fits in with the ID model is also something creationists need to explain. Simply waving it as an example of how Darwinian evolution might not be the whole story, as though that destroys the whole of evolutionary biology and negates the masses of evidence on which neo–Darwinian consensus is based, is grasping at straws.
But there is something else that the ID movement needs to explain and this brings me back to the point of this book in general and to this chapter in particular. Why is the whole complex process of epigenetics necessary in the first place?
Epigenetics is necessary because in multicellular organisms, any advantage of multicellularity is only realised by specialisation of cells and their arrangement into organs carrying out specialist functions. Many of these functions are only necessary in the first place because of multicellularity, of course. Mammals need digestive, respiratory and circulatory systems to get oxygen and nutrients to the cells and remove waste too far removed from the surface to do it the way single–celled organisms do it – by direct exchange with their environment.
Evolutionarily speaking, multicellularity gave some organisms an advantage over others but it comes at a price. One of the prices is the complex system of epigenetics and the need to reset and start again with each new individual.
But why is this needed anyway? It is needed because, just like single–celled organisms, the cells of multicellular organisms inherit all the DNA of their parent cells regardless of their eventual function as specialised cells in specialised organs. Unless the unnecessary and unwanted genes are turned off there would be no specialisation and so no benefit from multicellularity. The last thing you want is your brain cells producing the digestive enzymes your pancreas secretes or your kidney cells producing the contractile proteins in your muscles. You want your cells to be specialised and be good at doing what they are specialised to do – and nothing else. When cells start becoming generalised and doing other things they are called cancer.
So what any ID model needs to explain is why any intelligent designer would arrange it so that all cells (with one or two limited exceptions) contain all the DNA of the entire organism when they only need a few special genes to function? Why is this complex system of epigenetics necessary in the first place? Why would an intelligent designer not design things so that as cells become specialised they only get the DNA they need?
Instead, we have the ludicrous situation of prolific waste of resource in replicating all the DNA – with its attendant risk of going wrong – to have most of it permanently switched off in almost every one of our 70 trillion cells. Then we need a mechanism for resetting it and starting again in the newly–fertilised zygote.
In epigenetics we have a few exciting challenges for biology; for creationism we have as good an example as you can wish for of designer incompetence. We have prolific waste, needless complexity, a clear failure to plan ahead and needing to make the most of a bad job, and of a ludicrously complex ‘solution’ to a problem of its own making because, apparently, the designer lacked the wit to rethink the problem and start again.
How this can be described as intelligent design is quite beyond me. It requires definitions of ‘intelligent’ and ‘design’ that are unrecognisable and indistinguishable from the normal definitions of ‘gross incompetence’ and ‘stupidity’.
For evolutionary biology, of course, epigenetics is as nice an example as you could wish for of the utilitarian, pragmatic nature of evolution, where natural selection can only act on the here and now and where any solution, no matter how suboptimal, will be adopted it if gives an advantage. It is an example of how, like the example of RuBisCo in Chapter 5, evolution has no reverse gear and cannot scrap a suboptimal solution and start again with a better one, as any intelligent design process should be capable of.
Living multicellular organisms are now stuck with the complexity and waste of epigenetics because that gave an advantage, despite the inefficiency and waste, of multicellularity over single–cellularity for some, but by no means all, organisms. Very many organisms remain single–celled of course, and very many remain prokaryote rather than eukaryote. Evolution does not have a plan and is not trying to achieve anything.
It might well be that the reason life on earth, using Richard Dawkins' outstretched arms analogy3, took until well past our right shoulder and down towards our elbow to even evolve beyond bacteria was that multicellularity and cell specialisation was not something that arose easily.
This would not have been a problem for an omnipotent designer, of course.
This, and many more examples of the utter stupidity and lack of planning in biology, the diametric opposite of what any intelligent designer would design, are in my book.
No comments:
Post a Comment
Obscene, threatening or obnoxious messages, preaching, abuse and spam will be removed, as will anything by known Internet trolls and stalkers, by known sock-puppet accounts and anything not connected with the post,
A claim made without evidence can be dismissed without evidence. Remember: your opinion is not an established fact unless corroborated.