The review of The God Question DVD set and accompanying Study Guide by Prof Spurway is insightful and supportive of the overall approach taken by the director and production team. The format of representing the theist and atheist voices in short video clips is commended, recognizing the general nature of the audience and the wish to have all, whatever their belief, engage in lively discussion on the topic.
While the review is largely positive, there is specific comment on some of the content of the second DVD entitled Life and Evolution. In particular, the reviewer is concerned about omissions of the work of Stuart Kauffman on self-organizing/ autocatalytic systems, the insights of Simon Conway-Morris on convergences in evolutionary history, and a lack of treatment of the role of epigenetics and environmental modification of gene expression. These issues are worth remarking on further:-
Self-organizing systems in pre-biotic evolution.
What happened on Earth over many millions of years to generate the first cell capable of replication is still a mystery, and the subject of much theoretical speculation. We have no good models of the conditions of this period of the planet’s history, and experimentation is challenging. Theories include the possibilities that extreme atmospheric or deep sea conditions led to formation of simple molecules that could then go on to combine to form more complex molecules such as primitive peptides (from amino acids) and nucleic acids. Another concept is that complex molecules were seeded on Earth following transfer on a comet (see recent BBC stories on the Rosetta project of comet exploration); that, of course, just ‘kicks the can down the road’ a little – where did comets get the molecules from?
Dr Kauffman’s work in the context of evolution relates to what may have occurred when suitably large molecules were formed with the propensity to reproduce to become a dominant self-replicating ‘pre-biotic species’. He argues that some molecular forms by their nature self-organise and can form the basis of pre-biotic life. This is a difficult area of theoretical biology in which many concepts are still seeking experimental confirmation (for the scientifically minded there is a comprehensive review by Ruiz-Mirazo et al in Chemical Reviews (2013) 114; pages 285-366 that alludes to the seminal work of Kauffman and others). Exploration of this topic is important, of course, for a scientific understanding of how life might have arisen but the concepts and their discussion are arguably beyond the scope of The God Question and the audience to which it is targeted. The DVD focuses mainly on the ‘biotic’ era when the first recognizable cells were formed and the better understood processes of variation and selection could operate.
Convergences in evolutionary history
This is a fascinating topic based on the observation that certain features appear multiple times in evolutionary history. Prof Conway-Morris of Cambridge University is a recognised expert in this area and has a popular science web site on the subject. (www.mapoflife.org)
This website aims to tell you nearly everything you need (and may ever want) to know about convergent evolution. It allows you to explore the way that similar adaptive solutions have repeatedly evolved from unrelated starting points, as though following a metaphorical ‘map’.
The eye, so central to human existence, expression and emotion, is one of the main Darwinian paradigms. How, it was once pondered, could such a superb piece of biological engineering have evolved? Now the mystery may have evaporated in as much as we have perfectly adequate explanations for how the eye evolved, but the many fascinating examples of convergence show that both the limited number of options as well as the sheer sophistication throw new light on the way we understand the evolution and its potentialities. Perhaps the classic case is the convergence seen in the camera eye between cephalopods and vertebrates. The convergence, however, is much more striking in that the camera eye has evolved independently in at least six other groups: the alciopid annelids, three groups of snails and most astonishing of all the cubozoans or box-jellies, which lack any kind of brain. There are many different sorts of eye, but other than the camera eye by far the most successful is the compound eye. This too is strikingly convergent, having evolved at least five times: in the arthropods (at least twice), the sabellid annelids, the bivalve molluscs and, remarkably, in the brittle stars, the eye of which has a composition of calcite and so is specifically convergent on those of the extinct trilobites.
These important findings raise the issue that any framework developed to explain the appearance of life on earth needs to accommodate the fact a ‘good idea’ in evolutionary biology terms – such as having a light sensitive organ that gives a picture of the surrounding environment –can appear independently in different lineages at widely different times. To add to the comment from Prof Spurway, this would be excellent material to include in edition 2 of the DVD as a further development of the narrative.
Epigenetics and Environmental modification
Epigenetics is an emerging area in mainline biology over the last 5 to 10 years but it is still in its infancy, at least in my field of medical science, as a comprehensive explanation of modification of gene expression. The EWAS experimental chips (Epigenetic wide association studies) looking at 450,000 markers of epigenetic change (DNA annotation through methylation of DNA bases which alters the expression of the gene) have only just appeared. Likewise, we are only beginning to develop a comprehensive view of the impact of other structural variations, such as the folding pattern of DNA in a cell nucleus and copy-number variants of genes, on how inherited traits are expressed. The same can be said for micro non-coding RNA, master gene switches and other emerging fascinating properties of DNA and RNA which will help us understand gene regulation, tissue specific expression of proteins and organ development (see He and Hannon in Nature Reviews (2004) 5; pages 522-531).
For the general audience the core message in DVD - 2 is that there are biological processes that give rise to variation in DNA and that these variants are selected so that the most successful survive to reproduce more than other, less advantageous variations. Most of the material in the lay and popular science press when discussing evolution focuses on change in DNA sequence as the primary topic (elegantly and graphically presented in the brief article by Wong in Scientific American (2014) 311; issue 3 and more comprehensively on the Natural History Museum and Smithsonian Museum web sites). Also, change in the sequence of letters in the linear DNA strand maps readily on to the ‘tree of life’ diagrams linking species through common ancestry. Examples of this are the fascinating stories of the “whales’ tooth” (Demere et al in Systematic Biology (2008) 57; pages 15-37) and variation in the sense of smell (olfactory receptors) in mammals (see Nei et al in Nature Reviews Genetics (2008) 9; pages 951-963).
The material provided in the DVD reflects well the prevailing paradigm as seen in popular science explanations of biological evolution, and provides an accessible evidence base for wide debate with general audiences. Arguably, adding further layers of science would meet the needs of viewers wanting to delve more deeply into evolutionary concepts but reduce the overall impact of the message. It may be wise to include a statement in a revised study guide along the lines that further insights are constantly expected into the molecular basis of inheritance and evolutionary change as experimental science and theory progress (as exemplified in the recent paper on DNA methylation by Gokhman et al in Science (2014) 344; pages 527-527 and the review entitled ‘DNA: Celebrate the unknowns’ by Ball in Nature (2013) 496; pages 419-420 which are in line with the comments of Prof Spurway).