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Why celebrate Darwin?
Submitted by admin on 26 May, 2009 - 12:21
For those of you reading this, the words before you will, if the publication schedule runs according to timetable, coincide with two events that science is celebrating: the 200th anniversary of the birth of Charles Darwin, and the 150th anniversary of the publication of his first exposition of the Theory of Evolution, namely On the Origin of Species. Why science is celebrating these two milestones is the principal focus of this article, which I hope lives up, in its own modest way, to Darwin’s own quest for understanding.
One important concept to acquire, in order to understand why Darwin is being celebrated, centres upon the nature of the scientific inquiry itself, which, to anyone who exercises the effort to perform even casual observations, has been tremendously successful over the last 400 years. That success is grounded in a basic principle, namely that the real world we observe is comprehensible and amenable to detailed analysis in order to determine its workings. In the days when the scientific enterprise was in its infancy, this principle possessed something of a presuppositional nature, but, as the principle was applied, the evidence from the real world increasingly transformed that principle from a presupposition into a conclusion supported by observational reality. The world was indeed comprehensible and amenable to detailed analysis, and the physicists, taking their cue from sources such as Copernicus and Newton, were the vanguard of this advance. Later, they were joined by the chemists, as they too applied the same principle to their own deliberations, and led to the establishment of chemistry as a rigorous and robust scientific discipline, one that moreover is an exact quantitative science.
Biology, on the other hand, had remained throughout this time mostly a matter of cataloguing, with little if any in the way of development of an empirical approach to test hypotheses about living organisms. Biology had a large store of data in the 19th century, but was somewhat at a loss for how to integrate this data within a consilient explanatory framework, as the physicists and chemists had succeeded in integrating their accumulated real-world data within appropriate explanatory frameworks that proved to be enormously successful.
Darwin was the man who changed that state of affairs forever.
First, he embarked upon HMS Beagle, and began the process of collecting the data that would form the basis upon which his hypothesis was constructed. Once this process was complete, he then spent the best part of two decades seeking an explanation for this data. During this time, he applied himself diligently to the matter of determining what would falsify his hypothesis, and seeking any real world evidence that would lead to said falsification. Indeed, large sections of The Origin of Species are devoted to discourses in which Darwin asks himself pertinent questions, then answers them, citing appropriate evidence in the process. Thus, Darwin arrived at the synthesis that biology had been waiting for – an integrated, systematic explanatory framework that encompassed the available data. In doing so, the notion that observed changes in living organisms over time were amenable to systematic analysis, which was Darwin’s first ground-breaking contribution to biology, transformed biology from a cataloguing process into an infant empirical science.
Indeed, the synthesis scored an early predictive success with respect to Darwin’s Hawkmoth. A species of Orchid, the Comet Orchid from Madagascar, produces flowers whose nectaries lie at the base of a 12-inch trumpet of petals. The pollinating apparatus is, however, near the entrance to this trumpet. Darwin hypothesised that a pollinator with a 12-inch proboscis would be found that pollinated this flower, one whose ancestors had evolved in tandem with the ancestors of the flower to the point of becoming locked in an obligate partnership. Alfred Russell Wallace, another familiar name in the history of evolutionary biology, even went so far as to produce a “wanted poster” for the pollinator, basing it upon a moth called Xanthopan morganii, which was known to possess a 7-inch proboscis. In one of those moments that delights scientists everywhere, not only was the pollinator found, but it turned out to be a subspecies of the moth in Wallace’s “wanted poster”. This insect is now known as Xanthopan morganii praedicta, the latter part of the scientific name referring to the fact that it was predicted to exist.
Of course, other developments were necessary before Darwin’s synthesis could flower properly. Vital to this was the appearance of an empirical genetics, due to Mendel, which provided the material underpinnings upon which Darwin’s synthesis rested, and the means by which empirical tests of Darwin’s notions on a large scale could begin in earnest. It is an unfortunate accident of history that Darwin never alighted upon Mendel’s work, despite the two men being contemporaries: how much more advanced biology would have been if Darwin had indeed done so, and realised that it provided the additional ingredient his synthesis needed to take off as an empirically testable model, remains firmly in the realm of speculation. What we do know is that once that unification was performed, the resulting whole was to biology what atomic theory had been to chemists. However, just as Mendel provided the underpinnings required to allow Darwin’s ideas to become directly testable in the laboratory, Darwin provided the rationale behind the entire inheritance mechanism and in doing so, provided in turn an explanation not only for the observations of biology, but palaeontology as well. Small wonder that scientists in those fields are eager to celebrate the resulting synthesis.
It is apposite to look further, however, and note that a central concept within Darwin’s synthesis is the emergence of complex behaviour from simple systems. This concept points to the reason why modern scientists, 150 years on, continue to be grateful for the legacy, because the concept of ‘emergent complexity’ is proving, in the hands of modern researchers, to be a singularly powerful tool for understanding the world and its workings. Indeed, there is an entire branch of mathematics devoted to the subject of complex behaviour of apparently simple systems, one that is proving to be illuminating with respect to a range of real-world phenomena as it is applied in various areas, and which has received an additional impetus in an age when fast, relatively cheap computing power can be brought to bear upon the problems being analysed.
However, as if all this were not enough, computer scientists have taken Darwin’s ideas and transplanted them to the cyber-world – delivering to organisations such as NASA the application of what are termed ‘evolutionary algorithms’ to the solution of real world design problems. For those who are unaware of this, the notion that an engineering artefact can be converted into a description that can be regarded in a manner akin to a ‘genome’, then subject to a ‘mutation’ process, and the best ‘mutants’ then subject to a ‘selection’ process for further iterations, may sound rather like science fiction. This is, the reader is assured, a very real research approach indeed, and NASA has been using this very approach to design better communications antennae for its space probes, among other applications.
Even more remarkable at first sight, in a neat reversal of the process, biologists have, in effect, transplanted the computer scientists’ approach and applied it in turn to real genes. That staple of microbial research, Escherichia coli, contains within its genome a gene allowing the organism to manufacture an enzyme that can remove hydrogen from chemicals known as formates, and liberate that hydrogen as a gas. With a view to the use of hydrogen in future as a replacement for hydrocarbon fuels, evolutionary biologists performed a neat reverse on the computer scientists’ use of evolution: they took the gene responsible, and in the laboratory set up their own biological version of the computer simulation, only this time using real genes. These genes were then replicated, using technology similar to that used for forensic amplification of DNA in genetic fingerprinting tests. However, the key notion to bear in mind is this: the forensic scientist is interested in amplifying the DNA from a crime scene sample with maximum fidelity, and removing errors in the replication process, while the scientists working with the hydrogen-liberating gene were interested in amplifying the errors in order to increase the mutation rate. Thus, they deliberately generated an error-prone amplifying enzyme to replicate the bacterial genes, which in turn introduced copying errors, i.e., mutations, into the replication process. Once the biologists had their collection of mutants, they then selected the mutants that produced a larger hydrogen yield for repeat rounds of the same process over multiple generations – in effect, creating what can be thought of in lay terms as an ‘evolution simulation in a test tube’. The result of this endeavour? A modified gene whose hydrogen yield is 30 times greater than the original enzyme.
None of this, of course, would have been in the least possible, had not Darwin devoted himself to the matter of extending the reach of science to living organisms by providing mechanisms for the development of living organisms and their observed characteristics. Without Darwin’s diligent labours in this vein, the direct harnessing of evolutionary processes to produce new and potentially vital future technologies would simply not have been possible. Given the pressing need to find a solution to the very real and very large problem of hydrocarbon dependence, particularly with respect to transportation, that development described above, appearing in the journal Applied Microbiology & Bacteriology, could prove in future to be one of the essential steps allowing us to wean ourselves off oil.
So, we can see, just from the above brief ‘Baedecker’ tour of the life sciences, which I assure readers is a minute fraction of the extant research, that Darwin’s legacy continues to propel vital, and in some cases life-saving, research in biology and related disciplines, as well as illuminating questions of the origins of our own and other species that in the past were the sole preserve of mythology. In short, the synthesis produced by Darwin has proven time and again since its formulation, not only to be the only serious contender as an explanation for the observed diversity of life (with due modification to take account of modern data of course) but also to be surprisingly widely applicable in wholly unexpected areas, to the extent that quite a few Internet users are probably surfing the web at this very moment on computers whose main circuit boards were derived using an evolutionary process. The story of evolution as a manifestation of emergent complexity, the notion that Darwin left as a part of his legacy, is on the threshold of new and exciting developments, of which the above has been but a tantalising hint. So we can, provided that anachronistic adherents of assorted mythologies can be dissuaded from mendacious interference therewith, look forward to evolutionary ideas not only being expanded in their own right, but enjoying wider and wider application in areas that even today’s current researchers may not be able to foresee. The prospect of developments arising from that future research, kick-started 150 years ago by Darwin’s insight, will be most definitely worth celebrating as that 150th anniversary arrives.
David Edwards originally trained as a mathematician and computer programmer, but has had a lifelong interest in biological topics, including entomology (he is currently a long standing member of his regional Entomology Society).