If he had held a passport Charles Robert Darwin (1809-1882) might have been described as a naturalist, but he was one of the greatest of scientists, a titan among biologists. His theory of evolution by natural selection unified biology in its widest sense, providing a coherent explanation for how the diversity of life came to be. Alongside related enquiries it made sense of diverse lines of evidence: how species were related, how the fossil record shed light on vanished worlds, why some organs were vestigial, where our emotions may come from, how oceanic coral reefs formed, and much more besides. This contribution to our understanding of life on Earth has led to Darwin being elevated to the top-most pantheon of great scientists and he remains one of the truly key figures in the history of science. Few scientists have had their career more exhaustively documented.

Darwin had initially intended to follow in his father’s footsteps as a doctor, beginning this career at Edinburgh University. He found, however, the medical work to be repugnant. His fascination for natural history led him to neglect his studies, with his father ultimately sending him to Cambridge to study divinity with the intention of his son becoming an Anglican parson. This, of course, did not happen, but it underlines the often serendipitous nature of science. When Douglas Adams wrote “I may not have gone where I intended to go, but I think I have ended up where I needed to be.” (1988, p.142) he wasn’t referring to Darwin, but it can with some justice be applied to him.

In 1831, one of Darwin’s mentors at Cambridge, the botanist Professor John Stevens Henslow, recommended him as a gentleman companion and naturalist to accompany Captain Robert Fitzroy, who was about to embark on what turned out to be a five-year trip around the world, on HMS Beagle. This experience had a profound impact upon Darwin and formed the basis for many of the observations he used to develop his seminal publication On the Origin of Species.

On the Origin of Species was published in 1859 and sold out immediately. Today it is available in almost every language (including Esperanto), and within Darwin’s lifetime ran to six editions. An insight into its impact, as well as to Darwin’s scientific integrity, is relayed by Desmond and Moore (1991, p.582). They describe how, upon hearing that working men in Lancashire were clubbing together in order to afford a copy of Origin of Species, Darwin insisted that the cost of the book be reduced because he wanted it to be available to everyone. Its fundamental thesis was the ground-breaking idea of evolution by natural selection. As is well-known, the germ of this idea derived from the economist Thomas Malthus, but in Darwin’s hands the concept of natural selection provided a cogent explanation as to how adaptations occurred and, by implication, species arose.

Yet so familiar is the idea of natural selection that its sheer explanatory power has on occasion led to it becoming misunderstood. So it is that natural selection is sometimes thought of as a ‘force’ seeking out to destroy ‘stupid’ individuals. For example, images of an individual carrying out some foolish act (such as diving into an empty swimming pool) are tagged with a heading along the lines of “Natural selection in progress”. One needs to remember that natural selection is not a ‘force’ striving to produce ‘progress’, a balanced ecosystem, or for that matter anything else. Rather, it is the consequence of differential ratio of reproduction, and as such is mechanistic.

Natural selection, therefore, has neither fore-knowledge nor a particular goal in mind. Put simply, natural selection is a process by which biological traits increase or decrease in a population because some individuals have more offspring than others.

It is also important to note that whilst natural selection is a key mechanism of evolution, it is by no means the only one. Thanks largely to the field of work founded by the botanist Gregor Mendel (regarded as the father of genetics) we know that evolution is also driven by genetic mutation, gene duplication, migration, genetic drift, and other factors. Broadly speaking, whilst evolution is universally accepted, the field of neo-Darwinism continues to explore not only natural selection but a range of other mechanisms that lead to the diversity of life we see around us.

A second matter that perhaps needs clarification is the word ‘theory’. This is because anti-evolutionists attempt to undermine evolution on the grounds that it is “only a theory”. This stems from a misunderstanding of what is meant by the scientific idea of a ‘theory’. In everyday life ‘theory’ tends to mean an unsubstantiated opinion or the postulated outcome of an event or hunch. In this way the word ‘theory’ is often used interchangeably with the word ‘guess’. However, in the scientific world, a theory is an overarching explanation for an aspect of the natural world that is supported by hypothesis-driven evidence.

One does not need to subscribe to the idea of paradigm shifts (in the manner of physicist Thomas Kuhn) or that science is dependent on a cultural context (although it would be otiose to deny that scientific ideas might more readily arise in some settings as against others) to realise that no theory can be entirely secure. In principle, new lines of evidence may lead to radical reformation or even the abandoning of a theory. But seldom, if ever, does one new observation have this consequence. In the case of Darwin one can be as sure as possible that while there is much about evolution yet to be discovered (and if Darwin was with us, he surely would have been delighted to acknowledge this), but that its foundations are secure.

What of Darwin the individual? It is easy to sink into hagiography, although by most accounts he had many admirable characteristics. Nevertheless, one can note he oscillated between times of exceptional excitement and others of introspection, even pessimism. He was patient (up to a point) with critics, but acerbic with those who he judged (perhaps not always fairly) to have misunderstood his ideas. What surely marks him as almost entirely original is his extraordinary ability to ‘join the dots’, to see how apparently unrelated facts made sense from a wider perspective.

So too, Darwin knew that his theory was vulnerable, with weak points, but as has often been noted, when these were ultimately resolved the overall theory was strengthened. Stories of a return to his Christian faith on his death-bed may not be as misplaced as have generally been thought, but there is little doubt that he had little time for the apparent niceties of religion. As is often the case with great thinkers, Darwin had a grand vision that was perhaps more akin to a deist, even a pantheist, but significantly he never lost his sense of wonder, even awe. Was Darwin good at everything? No! When it came to philosophical skills he himself admitted that his abilities were limited, but was content to emphasize the empirical data that spoke to him more clearly than anything else. Nobody can do everything, and Darwin remains a giant upon whose shoulders we now see a little further.

Text copyright © 2015 Victoria Ling. All rights reserved.

References

Adams, D.N. (1988)  The Long Dark Tea-Time of the Soul.  Pan Books.

Desmond, A. and Moore, J.R. (1991)  Darwin.  Penguin.

Thomas Henry Huxley (1825-1895) was an English biologist who also carried out research in the fields of palaeontology and marine zoology. He acquired the nickname ‘Darwin’s Bulldog’ because of his vociferous defence of Charles Darwin’s theory of evolution by natural selection.

However, Huxley was a pioneering biologist in his own right; he was a leading expert on reptile fossils, an excellent anatomist, a fine illustrator and one of the key intellectual figures of the nineteenth century. He coined the word ‘agnostic’ to describe people such as himself who believed that it is not possible to know whether a deity exists or not. As a child, Huxley received only two years of formal education, and was largely self-taught in the sciences, history, philosophy and German.

Charles Darwin’s On the Origin of Species was published in 1859, and soon after in June, 1860 the British Association for the Advancement of Science met in Oxford. The ensuing debate between Huxley and Samuel Wilberforce, Bishop of Oxford, became the stuff of legend and – as succinctly described by John Hedley Brooke (1991) – the idea that it represents an absolute polarisation of views is far too simplistic. Nevertheless, all those debating were of high intelligence, saw what was at stake if Darwin’s views proved correct, and were not shy of a rhetorical flourish. Wilberforce was fiercely opposed to the idea that species change through time, although his view was not based on untutored ignorance but rather a view that Darwin’s hypothesis was flawed. Nor, it needs to be emphasised, was Wilberforce alone in this regard.

Significantly, however, this debate was also attended by another opponent to Darwin’s theory of evolution, the eminent palaeontologist Richard Owen. Owen coached Wilberforce prior to the debate in order to strengthen his case against Huxley. Quite what was said in the famous exchange of views is now a matter of legend, but it seems that in an attempt to ridicule Huxley, Wilberforce asked if he was descended from an ape on his mother’s or father’s side. Huxley responded by saying that he was not ashamed to have a monkey for his ancestor, but that he would be ashamed to be connected with a man who used great gifts to obscure the truth.

As an afterword to the Huxley-Wilberforce altercation, a little known fact – brought to light in 1980 by Harvard-based biological anthropologist Professor Richard Wrangham  – is that there is evidence to suggest that Wilberforce may have eventually softened his stance towards the concept of evolution.  Specifically, Wrangham discusses a poem written by Wilberforce (and subsequently discovered in his private papers held at the Bodleian Library, Oxford) written after his debate with Huxley. It ends with the lines:

“To soothe each fond regret, howe’er I can;

And, at the least, to dream myself a Man!”

In the words of Wrangham, the poem “..implies a man [Wilberforce] too committed to accept the evolutionary argument, yet too honest in the end to deny it. Who knows? Darwin may have had one more convert than he knew.”

Be that as it may, there is no doubt that in terms of science Huxley and Owen remained lifelong opponents. Nowhere were these differences more animated than in the debate over the degree of similarity between ape and human brains (sometimes referred to as the Great hippocampus question). This was significant because at the time, Huxley and Owen were the two leading British authorities on anatomy, yet they held entirely opposing views on the matter.

Owen believed that human beings should be taxonomically assigned to a separate mammalian subclass, thus distancing man from the rest of the animal kingdom. Owen claimed that ape brains were missing three uniquely human components; technically these are the posterior lobe, posterior horn of the lateral ventricle and the hippocampus minor (now called the calcar avis). Their purported absence in the apes Owen took as evidence against Darwin’s theory. Cosans (2009) describes how Huxley was so astonished by Owen’s claims – which he considered contradictory to the facts – that he saw no alternative but to refute them.

Huxley’s 1863 publication Evidence on Man’s Place in Nature, presented his definitive stance on the matter. The second chapter (On the relations of Man to the lower animals) was the most controversial, presenting a comprehensive review of the fossil and anatomical evidence for the similarities between man and apes. The debate was brought to a close when Sir Charles Lyell, Britain’s most eminent geologist and one of the era’s leading scientists, threw his support behind Huxley’s stance.

Equal to this contribution was the question of the origin of birds. Today, it is widely accepted that birds are descended from a branch of theropod dinosaurs, but fewer, however, are aware that it was Huxley who first proposed this evolutionary relationship.

In 1861,the German palaeontologist Christian Erich Hermann von Meyer described a fossilized feather discovered the previous year from Upper Jurassic sediments in southern Germany in the famous Solnhofen Limestone. Von Meyer named the fossil Archaeopteryx lithographica (meaning ‘the ancient wing from the lithographic limestone’). Shortly afterwards, the first skeleton of Archaeopteryx with feathers was described. At first its interpretation was rather convoluted, but Huxley made extensive and detailed comparisons of Archaeopteryx with various reptilian fossils and initially found that it was most similar to the small, chicken-sized theropod dinosaur Compsognathus: “Surely there is nothing very wild or illegitimate in the hypothesis that the phylum of the Class of Aves has its foot in the Dinosaurian Reptiles…” (Huxley, 1868, p.74).

Huxley was a great biologist and anatomist, and he played the key role in promoting and defending the theory of evolution by natural selection in the nineteenth century. He was also a pioneering educator, encouraging science students to carry out practical work in addition to book-based research, something which is now standard practice. He was a prolific writer, an articulate communicator and his pragmatic, no-nonsense approach to research was the embodiment of good academic form. He was also a man of high moral purpose and although he was lucky not to have seen the catastrophes of the twentieth century, had he done so he would have been horrified.

Huxley famously remarked that so obvious was Darwin’s hypothesis that he wished he had thought of it. He would not have been alone, and one of the paradoxes of science is that the obvious may stare us all in the face, but only the person with the chutzpah of lateral thinking finds the solution.

The fact remains that when Huxley passed away in 1895, the world was a very different place to the one he was born into; he had played a key role in not only developing our understanding of the natural world, but more broadly speaking, encouraged unbiased, fact-based thinking. He founded a generation of open-minded scientists and his own descendants carried on his chain of perspicacious thinking: most notably, his grandson was the biologist Julian Huxley, who founded the World Wildlife Fund, and his other grandson Aldous Huxley was a writer, most famously known for the dystopian novel Brave New World.

Text copyright © 2015 Victoria Ling. All rights reserved.

References

Brooke, J.H. (1991)  Science and Religion: some Historical Perspectives. Cambridge University Press.

Chambers, P. (2002)  Bones of Contention: the Archaeopteryx scandals.  John Murray.

Cosans, C.E. (2009)  Owen's Ape & Darwin's Bulldog: Beyond Darwinism and creationism. Indiana University Press.

Feduccia, A. (1996)  The Origin and Evolution of Birds. Yale University Press.

Gross, C.G. (1993)  Huxley versus Owen: the hippocampus minor and evolution.  Trends in Neurosciences 16, 493-498.

Huxley, L. (1900)  Life and Letters of Thomas Henry Huxley.  Macmillan.

Huxley, T.H. (1863)  Evidence as to Man’s Place in Nature.  Williams and Norgate.

Huxley, T.H. (1868)  On the animals which are most nearly intermediate between birds and reptiles.  Annals and Magazine of Natural History 2, 66–75.

Huxley, T.H. (1870)  Further evidence of the affinity between the dinosaurian reptiles and birds.  Quarterly Journal of the Geological Society of London 26, 12–31.

Kingsley, C. (1889)  The Water Babies.  Macmillan and Co.

Lyell, C. (1863)  The Antiquity of Man.  Murray.

von Meyer, C.E.H. (1861)  Archaeopteryx lithographica (Vogel-Feder) und Pterodactylus von Solnhofen.  Neues Jahrbuch für Mineralogie, Geologie und Paläontologie 1861, 678–679.

Wrangham, R.W. (1980) Bishop Wilberforce: Natural selection and the Descent of Man. Nature 287, 192.