The limits of Neo-Darwinism
Published: 24 June 2012 (GMT+10)
Jared from Zimbabwe asks for clarification over just what mutations and natural selection are capable of doing and not capable of doing. CMI’s Dr Don Batten responds.
I am curious about the few, seemingly at odds, articles that I have read recently. The topic is that of genetic mutations and natural selection. It seems in some ways this is shown to be insignificant and unable to affect any real changes, then in other ways it seems to be very significant.
Many articles have suggested how the great diversity we have in the biological world is from mutations and selections. The suggestion is that this process is pretty solid and consistent giving us many diverse species from just a few. The point has also been made that some of these mutations are actually more severe and occur more rapidly than previously thought. A couple of examples that come to mind is the interbreeding of certain cave dwelling blind fish that regain sight in just a single generation, and tunnel mosquitoes that have developed so independently that they are unable to interbreed with above ground species. This would seem to make sense.
But then I have also read a few other articles that suggest otherwise, mostly summarised by the following points made by John Sanford:“The bottom line is that Darwinian theory fails on every level. It fails because: 1) mutations arise faster than selection can eliminate them; 2) mutations are overwhelmingly too subtle to be “selectable”; 3) “biological noise” and “survival of the luckiest” overwhelm selection; 4) bad mutations are physically linked to good mutations,2 so that they cannot be separated in inheritance (to get rid of the bad and keep the good). The result is that all higher genomes must clearly degenerate.”
He suggests that mutations get overwhelmed by “noise” and are too subtle to be “selectable”. But does this not work against the very arguments that creationists use to support rapid speciation and variation? He says mutations are too subtle, but surely losing or gaining eyes is not subtle at all and would definitely affect selection? Surely that’s the whole basis for our creation arguments?
So are mutations and natural selection minor and insignificant in the scheme of things, or are they effectual and foundational for biological diversity? Do mutations make a difference or don’t they? It sometimes seems a little confusing.
Genetic entropy should be responsible for dwindling numbers and eventually extinction, but yet there are many examples of massive propagation and survival from just a few, the exact opposite. We would like to believe that both prove creation, but arguing it that way with an evolutionist is very hard. How can the process be used for both upward and downward explanations? Surely that leaves us in a pickle of not adequately explaining anything? It’s not falsifiable? I’m presuming that I am missing something somewhere that will make it all make sense.
Clarification on this would be much appreciated by myself, and I’m sure many others.
Thanks for asking. I can see why you could be a bit confused and probably others as well.
We are looking at different things here.
Mutations and natural selection only effect change within a created kind; for example the mosquitoes and blind cave fish you mention (they are still mosquitoes and the same type of fish).1 Mutations only modify existing genes to create different coat colours, for example, in cattle and dogs. Dr Jean Lightner has written about this. Mutations won’t create the genes that allow an animal to produce colour where it could not before, but they can damage an existing gene so that the animal produces less brown pigment, resulting in a light colour (such as fawn or white). On the other hand, a mutation can damage the control system for pigment production causing it to run ‘full speed’ and produce much more of the pigment so the animal is black rather than brown.
These sorts of changes can give us varieties (even ‘species’) of wolves (dogs, arctic wolves, African wolves, dingoes, jackals, foxes, etc.) but they won’t change a reptile into a wolf to give rise to wolves in the first place, which requires the invention of brand new genes. We wrote about the mosquitoes you mentioned as an example of the sorts of changes that can cause rapid speciation within a created kind.
Dr Sanford is talking about the number of mutations that are slightly harmful in organisms with large genomes, like humans (and wolves). There are many slightly harmful mutations and because there are many and they are only slightly harmful, natural selection cannot get rid of them; they are effectively invisible to natural selection. Think about a mutation that resulted in a wolf being born blind. Natural selection would normally eliminate the individual with this mutation (that is, it would not survive; that’s all we mean by natural selection). Such large-effect mutations can be/are eliminated. However, we acquire something like 100 new mutations per person. Many of these are only slightly deleterious (no obvious defect). Because such mutations have only a small effect, with no obvious effect on survival, natural selection is powerless to eliminate them. Also, all offspring are born with more mutations than their parents; none have fewer. That means that these slightly harmful mutations are accumulating, generation by generation, relentlessly causing genetic deterioration because of the summed effect of all of them. It is in this context that Dr Sanford makes his conclusions about Darwinian evolution being ‘dead in the water’. The degeneration he speaks of is happening in all higher organisms. It is a pattern of deterioration that overlays everything and prevents any possibility of upward evolutionary ‘progress’ (“climbing mount improbable”) that is supposed to have changed a microbe into a microbiologist.
Within this general pattern, adaptation (blind cave fish) can occur, but notice that this ‘adaptation’ is still, when it involves mutations, via loss of function (messing up the genes that say how to make eyes).
Another classic example is beetles on a windy island where mutants with defective wings did not get blown into the sea and quickly became the dominant population on that island. Note again that the mutation has been adaptive, causing diversity in the beetles, but it is a downhill change. The Darwinian paradigm needs a mechanism for creating new genes, not modifying and degrading existing genes, which is what we overwhelmingly see.
We have talked of this downhill change also in terms of natural selection eliminating genes in individuals that are not adapted to their environment. This also causes an impoverishment of the genetic information. For example, the beetles with normal wing-making genes are eliminated on the windy island and so the genes for normal wings are lost.
Here is another illustration of this principle. Let’s say that five of the ~20,000 gene pairs of a breeding wolf male and female pair were both AaBbCcDdEe. Because of the way sexual reproduction recombines the genes (variants of a gene are called “alleles”), offspring could be AABBCCDDEE or aabbccddee, or any other combination, thus producing lots of potential varieties of offspring. Now let’s say that ones with the genes aabbccddee were adapted to cold conditions and were the only ones that survived the Ice Age in northern Europe after Noah’s Flood. These wolves have lost the genes A,B,C,D and E. When they breed, they can only produce more wolves with a,b,c,d and e, none with the variety of genes in the original population. From this you can see that if the wolves adapted to hot conditions were AABBCCDDEE, for example, you could never get this wolf from the ones adapted to the cold. The genes for adaptation to hot conditions have been lost.
Artificial breeding/selection is a good analogy. The original mongrel dog/wolf population had more genetic variety than any of the many individual breeds of dog today, but because of continual mixing up of the genes/alleles due to free inter-breeding (out-breeding), the outward appearance of the dogs/wolves would not generally have shown extreme variety. But selecting rare dogs with Chihuahua-like features and breeding them together (inbreeding) for many generations results in the concentration of alleles that give Chihuahua-likeness and the elimination of a lot of the other alleles—ones for ‘large dog’ for example. So you could never breed a Great Dane from a Chihuahua; the genetic information required has been depleted by the very process that has generated the extreme features.
In genetics, variety of alleles is known as heterozygosity (the degree to which pairs of genes differ); lack of variety is homozygosity (the degree to which pairs of genes are the same). So in genetic terms, we believe that God created organisms with a higher degree of heterozygosity than we generally see today. The variety/diversity seen today is largely due to the sorting of the originally created genes into more specialized sets of genes (as in the example of wolves adapting to the cold above). Where mutations have contributed, it is almost always via degradation of an existing gene or gene control. It might be that God even created organisms with ‘hot spots’ for mutation that would enable adaptation.2 Of course such hot spots negate the idea of mutations being random (purely chance) occurrences.
When you breed together several different breeds of dogs, you can end up with a “mongrel” with a more comprehensive set of alleles more like the original dog/wolf. This mongrel dog loses the extreme features of the dog breeds and looks more like a regular dog/wolf. If you took all the descendants of an original created kind, such as the cattle kind, and bred them together, you could end up with an animal closer to what God created in the beginning (except for the deleterious mutations that have accumulated).
The big picture is that God created various kinds of organisms with a wealth of genetic information that has allowed for adaptation/speciation within each kind. But both mutations and natural selection are downhill processes. Even as these natural processes produce greater variety in daughter populations, each of those populations becomes genetically depleted—more specialized, but therefore with less variety within each population, and thus less able to adapt to future environmental challenges. Overarching this we find the relentless accumulation of slightly harmful mutations, which Dr Sanford has highlighted. Extended forwards in time, all these natural processes head towards extinction. Since the Fall (Genesis 3) everything has been wearing out, like a piece of clothing wears out (Hebrews 1:11). Evolution (microbes-to-man) via mutations and natural selection is a bankrupt idea, scientifically and biblically.
- The point about the blind cave fish regaining sight is that this suggests that there are different mechanisms for mutations to destroy the ability of the fish to make normal eyes and that when fish with different defects are bred together, the good genes in each fish can complement to make it possible to make eyes again (that is, ‘nature’ is not inventing anything new). It also suggests that it is not long since the blind fish arose, otherwise the remaining ‘good’ (still functioning) genes would have mutated as well and it would not be possible to restore sight by cross-breeding. See: Wieland, C., Let the blind see … Breeding blind fish with blind fish restores sight, 2008. Return to text.
- Lightner, J.K., Gene duplications and nonrandom mutations in the family Cercopithecidae: evidence for designed mechanisms driving adaptive genomic mutations, Creation Research Society Quarterly 46(1): 1–5, 2009. Return to text.