Sunday, 7 November 2010

Biological information does not require a ‘designer’

Alastair Noble, Director of the Centre for Intelligent Design writes on their website (Intelligent Design is definitely NOT Creationism) the following:
[..] it’s when we look into the mind-boggling complexity of the living cell that the evidence of design becomes most apparent.  And it’s not just the chemical complexity which is breathtaking.  It’s the vast information content of DNA which poses the enduring problem of modern biology. What is the source of this functional, specified information?  Information is not essentially a physical entity.  It is an immaterial but real phenomenon, in this case digitally coded on to the spine of the DNA molecule.
All human experience suggests that such information arises only from intelligent mind.  To  propose that the information in DNA is a reflection of intelligence is to make an inference to the best explanation.  In the absence of any other coherent explanation, the ID position, at the very least, is worthy of debate.  The core of the issue remains the scientific evidence and raising these other and irrelevant religious points really does nothing to address the evidence.
ID is therefore a minimal commitment to intelligent causation.  That’s very different from Biblical creationism.  That ID, and indeed Darwinism, have philosophical and religious implications is undeniable.  But the exploration of consequences is very different from the debate about evidence.
In actual fact, many of the arguments made are those of disbelief or of ignorance. We see in the quoted text that the author finds the complexity of a living cell “mind-boggling”. For those of us who are active biology researchers, the complexity of the cell is a given: the interesting observation is that the origins of this complexity has a rational explanation.

Noble focusses on his inability to grasp the nature, role and generation of the biological information within an organism’s genome. In this context, one should note that much of the terminology used in molecular genetics is used as analogy. Scientists use terms such as ‘information’, ‘code’, ‘instruction’, ‘transcribe’, ‘translate’ and many others as a way of explaining concepts, rather than in the literal sense used in the lay world. In this article, we continue this usage, but stress that these words should not be interpreted literally.

Over the last decade, techniques of genome analysis have been refined to the extent that not only have the complete genome sequences of many, many organisms (from a wide variety of taxa) been determined (http://www.ncbi.nlm.nih.gov/sites/genome), but in the case of humans, a growing number of individuals have had their genomes completely or partially sequenced (reviewed by Neilsen (2010) Nature 467; 1050-1). This growing pool of data, together with decades of genetic and molecular biology research into mechanisms of mutation and into genome biology have given us a detailed picture of the evolution of genomic ‘information’.
What is the source of this functional, specified information?
Leaving aside discussions of the origins of life (for which many hypotheses exist), there are clear mechanisms by which genome diversity can arise. It should be noted at the outset that much of the DNA within a given genome does not ‘encode’ proteins, particularly in eukaryotes: some of these sequences have roles in the regulation of gene expression, some encode functional RNA molecules, but much has no known function (though much may be related to structure and function of chromosomes).

While all organisms have systems by which errors in DNA replication are detected and repaired, these never operate at 100% efficiency: occasionally errors do occur and if in the germ line will be passed to the next generation as mutations. Such mutational changes may have no effect on the organism (neutral mutations), while some may have an effect – either beneficial or detrimental. Replication errors such as this do not easily explain the growth in genome size through evolution: generally genome content alters through duplicative processes.

Duplication of genetic material has been observed to occur in experimental and domesticated organisms, and can result in duplications of genes, regions of chromosomes, whole chromosomes, and indeed the duplication of entire genomes. Furthermore in analyses of sequenced genomes, whole genome duplications can be observed in numerous cases. For example, bread wheat is hexaploid; the African clawed toad Xenopus laevis is tetraploid (Hughes & Hughes (1993) Mol Biol Evol. 1993 10: 1360-9), with at least two instances of genome duplication in the vertebrate lineage (Dehal et al (2005) PLoS Biology 3; e314).

As a final note, in all cases where sequences of different genomes are compared, the differences are consistent with evolutionary theory, both in explanation of origin of new sequences, and in the divergence through time.
Information is not essentially a physical entity.  It is an immaterial but real phenomenon, in this case digitally coded on to the spine of the DNA molecule.
Here Noble largely mixes conventional linguistic usage with that of scientific ‘shorthand’. It’s also rather unclear what he means by ‘not essentially a physical entity’. In fact since the early days of molecular biology, we have had a growing understanding of the physical nature of genetic ‘information’ in a molecular sense. It’s also not ‘digitally coded’.
All human experience suggests that such information arises only from intelligent mind.
One of the problems in the scientific endeavour is the separation of notions of ‘common sense’ from experimental deduction. (The developmental biologist Lewis Wolpert wrote an excellent book expounding why ‘common sense’ does not correlate with the workings of the universe – The Unnatural Nature of Science, Faber & Faber 1992). When Noble invokes the concept of ‘all human experience’, he’s appealing to a form of common sense based upon ignorance of biology.
To propose that the information in DNA is a reflection of intelligence is to make an inference to the best explanation.
Noble goes on to assert that it’s obvious that the information must have been created by an intelligent mind. This is an argument from ignorance; for the informed biologist without theological preconceptions, it most certainly is not obvious. Biological research has clearly shown how genetic ‘information’ can accumulate (and be lost), how genetic information can change (through mutation), and how genetic changes can be fixed in populations (by selection or drift).

Furthermore, one should generally seek the most parsimonious explanation for a scientific observation. In the case of the genomic diversity seen in extant taxa, we can either rely on the experimentally observed mechanisms outlined above, or we can invoke an intelligent entity as a cause (the ‘designer’). Note, however, that there is no evidence for a ‘designer’ other that that its advocates are unable to grasp (willfully or not) the concepts of modern biology that fully explain genome evolution. Furthermore, it is disingenuous to make a distinction between ID and creationism: both require a supernatural creator/designer.


Robert Saunders, BSc (Hons), PhD - first posted at Wonderful Life

1 comment:

  1. Folks, it's actually worse than that. These folks have a very very mistaken view of what "intelligence" is. They view it as an *originator* of information - i.e. you get the information *for free*, out of some spooky realm. This of course fits their pre-scientific insistence on Cartesian dualism - there is a ghost in the machine, a source of "intelligence" for which the intricate interconnections of the brain's neurons are merely a vehicle.

    The problem of course is that "intelligence" is actually not a system that is separable from the brain. Intelligence is an information *processing* system. When we see complexity in nature or in anything else, it is generally a sign that information has been *processed*.

    And, funnily enough, evolution is also an information processing system, and a jolly interesting one at that. Complexity comes as part of that package. For all their whingeing about information, these cdesign proponentsists really have not got the foggiest clue about information theory, neuroscience or what intelligence actually is.

    I hope to do a post on precisely this topic on Answers in Genes some time soon. Someone remind me if I forget :-)

    ReplyDelete