Watercolour of Charles Darwin painted by George Richmond after Darwin’s return from the voyage of HMS Beagle (Image via Wikimedia Commons)

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.

Bronze sculpture of Charles Darwin as a young man by Anthony Smith. The sculpture, which was unveiled in 2009, is located in the grounds of Christ’s College, Cambridge (Image: Used with the kind permission of the ... moreMaster and Fellows of Christ’s College, Cambridge)

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.

Photograph of Michael Faraday taken in the 1860s by John Watkins. Watkins was known for his portrait photographs of high-profile individuals (Image via Wikimedia Commons)

Michael Faraday (1791-1867) stands out as one of the most influential of scientists. His career began as a chemist but it is his work in physics, particularly electromagnetism, where he made his greatest scientific contributions, opening the doors to the age of electricity. Faraday was also one of the founders of electrochemistry, an area of research which seeks to understand the interplay between electricity and chemical reactions. Faraday was a man of high morals and he strongly believed in the importance of communicating science to the general public. He established the renowned Royal Institution Christmas Lectures in 1825, and these have continued in different guises to this present day.

Faraday’s journey into science reads like a work of fiction; the tale of a gifted underdog who through hard work, imagination, dedication, and an insatiable sense of curiosity for how the world works, overcame overwhelming odds to become one of the world’s greatest scientists. But this is not fiction, it is a true story, and is all the more inspirational for it.

Faraday came from a poor background, which in the world of nineteenth century England stacked the odds against anyone hoping to pursue a scientific career. In order to help support his family Faraday left school at the age of 13 to take a job as an errand boy for a local bookshop, run by one Georg Riebau. This became the initial rung of the ladder in Faraday’s scientific career and the first in a series of serendipitous events. Faraday’s hard work impressed his employer who promoted him to apprentice bookbinder. This opened up a new world to the young Faraday, providing him with access to a wealth of information that with his poor background he would otherwise have had no access to.

Faraday spent his free time reading the precious books that all day he had worked to bind. Of all that he read it was science that piqued his interest, particularly chemistry. Although his wages were small, he saved what he could in order to purchase materials that would enable him to replicate and test the experiments and principles that he learnt in the books. So began Faraday’s fondness – and natural ability – for scientific discovery through practical experimentation, something he was encouraged to undertake by Riebau who allowed him to use a space at the back of the bookshop.

In another serendipitous moment, one of Riebau’s customers gave Faraday a ticket to a series of lectures by the chemist and inventor Sir Humphry Davy. At the time Davy was one of the most famous scientists in England and Faraday took detailed notes at the lectures. These he later bound and sent to Davy as a token of respect. This act of veneration was to have fortuitous ramifications for the young Faraday; when Davy was injured in an experiment that impeded his ability to write, he remembered the impeccable notes that Faraday had sent and contacted him to ask if he would like to serve as his amanuensis for a few days. Faraday jumped at the opportunity and ultimately this led to Davy offering him the position of Chemical Assistant at the Royal Institution in 1813.

Faraday remained with the Royal Institution for the next 54 years. Here he succeeded Davy in 1825 (in the previous year he had been elected to the Royal Society), and in 1833 was made Professor of Chemistry at the Royal Institution.

Faraday was a prolific scientist and inventor. One could write volumes detailing his many and varied discoveries, but consider a few of his ‘greatest hits’:

– Gas liquefaction (1823). Using mechanical pumps to apply pressure, gases with high critical temperatures such as ammonia can be liquefied. Faraday also observed that when ammonia evaporates it causes its surroundings to cool. This ‘absorption cooling’ is the principle upon which refrigerators work;

– Discovery of benzene (1825). Faraday originally named this chemical compound ‘bicarburet of hydrogen’, and today benzene is used in the manufacture of a wide range of drugs, plastics, and detergents;

– Discovery of electromagnetic induction (1831). When a magnet is moved inside a coil of wire it causes electricity to flow. Accordingly, electricity could be generated by the rotation of magnets rather than by using metal plates and chemical solutions. Most of the electricity we use is a direct result of Faraday’s insight;

– Invention of the ‘Faraday Cage’ (1836), a cage-like structure composed of a metallic mesh which shields its contents from electromagnetic energy by distributing the charge around the exterior of the cage. The Faraday cage has a vast array of applications, from microwave ovens where it restricts the escape of electromagnetic radiation, to purpose-built cages around telecommunications equipment to protect them from lightning strikes;

A Faraday cage in operation. The women inside are perfectly safe because the charge is distributed around the outside of the cage (Image: Antoine Taveneaux/Wikimedia Commons)

– Discovery of the Faraday Effect (1845), the first experimental evidence to show that electromagnetism and light are related. The idea was later developed by the Scottish mathematical physicist James Clerk Maxwell in the 1860s, which established that light is an electromagnetic wave.

Faraday also flags up a common misconception that science and religion are mutually exclusive. In the media today, there is a time-worn formula for presenting the interplay between science and religion. On the one hand we have coverage of extreme religious opinions, whilst on the other hand we have prominent scientists (and comedians) who adopt a vocal atheist stance.

Any topic which presents a conflict of opinion between these two views has become staple ‘news’, but does it represent reality? This over-simplified polarization of views bears little resemblance to day-to-day life, with reality being somewhat more nuanced. Today, as in the past many scientists are atheists, some (like the great biologist Thomas Huxley) are agnostic, whilst others subscribe to a specific faith. For example, Faraday had no doubt of what he thought of as God’s agency in the world. Specifically, he belonged to the Sandemanian denomination which was an offshoot of the Church of Scotland. Nor was he alone. Recall, for example, that Gregor Mendel (the father of genetics) was an Augustinian monk, and Charles Lyell (the father of modern geology) was a devout Christian.

We know that Faraday was one of the world’s finest scientists, but where did he stand upon the subject of evolution? The answer is that we do not know. Charles Darwin published On the Origin of Species in 1861, just six years before Faraday’s death. Faraday made no disparaging comments about evolution, but Colin Russell (2000) suggests that his silence on the matter may have been because, like many physical scientists of the time, he dismissed evolution as “only a theory”.

However, one cannot help but wonder how, had Faraday lived longer, he may have reconciled his faith with the ever-growing body of scientific evidence for evolution. For example, Charles Lyell had enormous difficulty reconciling his Christian beliefs with natural selection. Despite this, Lyell and Darwin remained firm friends, happy to discuss their differences with respect and candor; a fitting tribute to the intelligence and open-mindedness of both men.

Faraday was hugely respected within his lifetime and so too the theoretical physicist Albert Einstein held Faraday in enormous esteem as one of his three scientific heroes (the other two being Isaac Newton and James Clerk Maxwell). Regardless of his success and veneration, Faraday remained a man of modesty and firm principles; twice he was offered the presidency of the Royal Society, one of the world’s oldest and most eminent scientific institutions, but on both occasions declined the honour. Faraday had come a long way, and it is worth noting that Joseph Banks, an earlier President, had rejected Faraday’s application for a job as a bottle washer as unworthy of a reply.

Faraday’s expertise in chemistry led the British government to ask him how chemicals could be used against Russia in the Crimean War. Faraday was more than capable of applying his knowledge to develop such weapons, but he found the very notion morally repugnant and refused to assist. Faraday also made a tremendous contribution to the public understanding of science, which included 123 Friday evening public discourses. Similarly, he was keen to apply science to the broader public good and this he did through his work on the efficiency of lighthouses and safety in coal mines. During his life he was offered a final resting place in the company of Kings and Queens at London’s Westminster Abbey, but he respectfully declined, choosing instead to be interred in the more humble surroundings of Highgate Cemetery, London.

Text copyright © 2015 Victoria Ling. All rights reserved.

References

Arianrhod, R. (2005)  Einstein's Heroes: Imagining the world through the language of mathematics.  Oxford University Press.

Cantor, G. (1991)  Michael Faraday: Sandemanian and Scientist.  A study of science and religion in the nineteenth century.  Palgrave Macmillan.

Ecklund, E.H. and Scheitle, C.P. (2007)  Religion among academic scientists: Distinctions, disciplines, and demographics.  Social Problems 54, 289-307.

Gooding, D. (1991)  Experiment and the Making of Meaning: Human Agency in Scientific Observation and Experiment.  Springer.

Gooding, D. and James, F.A.J.L.  (eds.) (1985)  Faraday Rediscovered: Essays on the Life and Work of Michael Faraday, 1791‐1867. Stockton Press.

Hamilton, J. (2003)  Faraday: The Life.  HarperCollins.

James, F.A.J.L.  (ed.)( 2002)  The Common Purposes of Life: Science and Society at the Royal Institution of Great Britain.  Ashgate Publishing Limited.

James, F.A.J.L. (2010)  Michael Faraday: A very short Introduction.  Oxford University Press.

Russell, C. A. (2000)  Michael Faraday: Physics and faith. Oxford University Press.

Photograph of Ronald Fisher taken in 1946 by Walter Stoneman. Stoneman took many photographs of Fellows on behalf of the Royal Society (Image: Used with the kind permission of the Royal Society of London)

Sir Ronald Aylmer Fisher (1890-1962) was an evolutionary biologist and statistician. He is perhaps best known for inventing an array of revolutionary statistical procedures that could be used within the natural sciences. These include:

– ANOVA (analysis of variance), which is a test that allows the identification of significant differences between three or more samples so long as the populations from which these derive follow the normal distribution and exhibit homogenous variances;

– Extreme Value theory, a statistical sub-discipline that assesses the probability of extreme events occurring;

– P-value, in effect the probability with which we accept a mistake when we reject a null hypothesis that is actually valid. In other words, a p-value equal to 0.05 (which is the standard) means that when we conclude that there is no statistically significant difference between two or more samples (that is, when we reject the null hypothesis) there is 5% chance that there is indeed a significant difference but we missed it.

Fisher’s statistical techniques revolutionised the way data could be queried and analysed, enabling scientists to test hypotheses in an entirely objective way and allowing us to explore patterns in massive datasets where any qualitative visual analysis is impossible. However, Fisher’s contribution to our understanding of evolution goes far beyond the statistical tests with which he is most widely and commonly associated.

The world-renowned statistician and geneticist Professor Anthony Edwards was the last undergraduate that Fisher accepted. When asked why Ronald Fisher deserved to remembered as the great scientist that he was, Edwards responded that it was a difficult question to answer because Fisher was:

“..one of those people whose work is at a level of subtlety that it’s really quite difficult to explain why he should be revered so much as he is – as a great scientist. It’s one thing to split an atom, or discover the electron, or do the other things for which Nobel Prize winners around Cambridge are known for. But it’s quite another thing to work at the level of subtlety that Fisher worked at – both in statistics and in evolutionary biology.” (pers. comm. 2014)

An even more challenging question we asked Edwards was what, in his opinion, were Fisher’s three most significant contributions to science. Edwards stated that if one is to identify three key contributions from Fisher’s work, then one has to think in terms of which publications you would wish to draw people’s attention to. Edwards’ suggestions are described here in his own words:

(i) “Statistical Methods for Research Workers from 1925, which ran to 40 editions and which completely changed the map of statistical practice in science from that time on. And that’s probably the best known of his contributions. Of course, it relies so much on work that he himself did in the preceding ten years or so, so at the time it was extraordinarily novel. There’s a paper from 1922 called On the mathematical foundations of theoretical statistics which really sets the scene for the writing of this book.”

(ii) “The Genetical Theory of Natural Selection from 1930. That is an extraordinary book because it’s really only now, and I do mean now – the last few years, that people have – in evolutionary biology – have actually got around to reading it carefully. Now of course it always had its followers, but they’ve been few and far between. So, there is now work coming out of the thoughts in that book, 84 years after it was written and so much of what happens in modern evolutionary biology can be traced either directly to that book, or to people whose names you’ll be familiar with, particularly W.D. Hamilton whose ideas come from that book anyway and have been made extended and made so well known by people of the next generation, but there’re few and far between. So, the number of serious readers of that book from 1930 to about 2005 you could count on the fingers of one hand. And indeed it was one of Charles Darwin’s sons, Leonard Darwin, who was a great supporter of Fisher, a great friend of Fisher’s, who warned Fisher that his great book would be extremely well known in the long-term but it really would take quite a long time, and that’s exactly what’s happened.”

(iii) “On the dominance ratio. Nobody had a finer understanding of what Darwin was saying than Fisher. Whether he could communicate that and extend it is a different question, but nobody had a finer understanding….So, what should it [the third point] be? Well I think we ought to go back to before 1930 and look at the year 1922. And in that year Fisher published a paper called “On the dominance ratio”. And it’s a most extraordinary paper, it’s really the foundation paper for population genetics and mathematical genetics because it does so many things: it proves for the first time the stability of a genetic system if the heterozygotes are at an advantage over the homozygotes. And that’s very fundamental to mathematical genetics. It introduces what later came to be known as the Wright-Fisher model – for modelling stochastic processes in genetics. Quite wrongly called the Wright-Fisher model because Fisher introduced it all by himself and it wasn’t until 1931 that Sewall Wright wrote about it.”

In many ways, Fisher’s contribution to science was not appreciated in his own time. The sheer depth of his knowledge and the subtle level at which he worked, meant that to a large extent he was academically isolated.

When asked why it has taken the biological world so much longer to appreciate Fisher’s work than the statistical world, Edwards remarked: “Well, it was partly Fisher’s fault, because he made this one huge contribution of writing “The Genetical Theory of Natural Selection” and he wrote it in his beautiful English, with a lot of mathematics hidden behind the English, because he thought that he wanted to express his views to biologists who were not at home with the mathematics. And a consequence of this is that the mathematicians ignored it and the biologists didn’t understand it. But nowadays we have a much greater number of people in biology who can do the mathematics and there have been many studies over the years recreating the mathematics which lies behind Fisher’s verbal descriptions in The Genetical Theory.”

FortyTwo extends its appreciation and thanks to Professor Anthony Edwards.

Text copyright © 2015 Victoria Ling. All rights reserved.

Studio portrait of Thomas Henry Huxley taken by Maull & Polyblanc, a London-based commercial photographers who, in the nineteenth century, specialised in images of eminent figures (Image: Wikimedia Commons)

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.

The professional rivalry between Thomas Huxley and Richard Owen was so well known during their time that the writer Charles Kingsley made reference to it in his classic children’s book The Water Babies, published ... morein 1863. In this illustration from the 1885 edition, drawn by Linley Sambourne, we see Richard Owen (left) and Thomas Huxley examining a water-baby: “But they would have put it [the water baby] into spirits, or into the Illustrated News, or perhaps cut it into halves, poor dear little thing, and sent one to Professor Owen, and one to Professor Huxley, to see what they would each say about it.” (Kingsley, 1889, p.69) (Image by Linley Sambourne via Wikimedia Commons)

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.

Sample of two handwritten letters from Thomas Huxley to the French ornithologist Alphonse Milne-Edwards. The letters appear to form part of Huxley’s research for his book The Crayfish: An introduction to the study of ... morezoology (1880). In them, Huxley requests to borrow two specimens of Madagascan crayfish in order to complete his examination of the southern hemisphere forms. (Photo & private collection: Victoria Ling, 2015).

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.

The humble grave of one of the nineteenth century’s finest minds; Thomas Henry Huxley. Located in East Finchley Cemetery, London (Image: Victoria Ling)

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.

Barbara McClintock in her laboratory in 1947 (Image from the Smithsonian Institution collection via Wikimedia Commons)

Barbara McClintock (1902-1992) was an American geneticist and a pioneer in the field of cytogenetics, a branch of genetics that focuses on the function of chromosomes in individual cells. McClintock’s work on chromosomes in maize revolutionised this field. In her time, she was widely respected, receiving a number of prestigious awards and fellowships, not least the National Medal of Science. However, it is her discovery of transposons – which revolutionised our understanding of genetics – that was entirely radical. Yet it took thirty years for the scale of her discovery to be fully acknowledged, with the award of the Nobel Prize in Medicine or Physiology “for her discovery of mobile genetic elements” in 1983 (NobelPrize.org).

A trademark of McClintock’s research was her unwavering attention to detail. Meticulous data analysis remains essential if one is to have confidence in one’s scientific hypotheses, and all the more vital if such assertions are novel and so question established ideas. Challenging the status quo is precisely what McClintock’s discovery of transposons achieved.

It was her thorough interrogation of the data that enabled her to have first confidence and eventually conviction as to what at that time seemed to be an unlikely – even implausible – scenario. In effect, her data showed that genes could be mobile, moving around the chromosomes, hopping from one place and re-inserting themselves elsewhere. McClintock discovered these peculiarly behaving genes whilst working on maize plants in the late 1940s. We now call these genes ‘transposons’, often aptly referred to as ‘jumping genes’. In November 1953 McClintock published her findings in the journal Genetics, with a paper entitled Induction of instability at selected loci in maize.

Mechanism of transposition
(Image: Wikimedia Commons)

McClintock’s discovery did not sit comfortably with the twentieth century consensus as to how genes should behave. At the time, geneticists considered that genes were stable entities and the notion that there could be ‘renegade’ strands of DNA moving about the genome was treated with extreme caution. But if one places McClintock’s discovery in a broader social and historical perspective, given the nature of the proposal – that is, the idea that something which was perceived as stable, was actually subject to change – one could almost see the skepticism with which it was initially received as less surprising, maybe even predictable.

In some broad sense this might say something about a human desire for stability. If one looks back over the history of science it is not unreasonable to suggest that the scientific theories which met with the most vehement, almost visceral resistance were often those which are not only ‘big ideas’, but those which have championed ‘change’ in a previously accepted framework of ‘permanency’.

This is all the more true when it comes to natural phenomena that an individual cannot observe with the naked eye and/or witness over the course of their own short life-span. Notable examples include the idea of the Big Bang, and nearer to home that of continental drift; a proposal by the meteorologist Alfred Wegener who suggested (quite rightly) that Earth’s continents were once joined together and slowly drifted apart (and continue to move) over millions of years. From the time it was first proposed in 1912 the idea of continental drift found little favour and until the late 1960s the consensus remained that the Earth’s continents were static.

Another example is of course Charles Darwin’s theory of evolution by natural selection, which was proffered at a time when society at large was still committed to the notion of the permanency of species (i.e. that each species on Earth was created in its current form and was not the result of evolution). Here too, Darwin was correct, but some of the resistance stemmed from people who saw weaknesses in the theory, and ones that Darwin lost little time in addressing.

Pigmentation on corn kernels reveals the activity transposons (Image: Damon Lisch via Wikimedia Commons)

In the case of McClintock her work perhaps reflects more than a hint of our collective human condition inasmuch as although the existence and behaviour of transposons was relatively swiftly accepted by other geneticists who conducted research on maize, when it came to applying these ideas to other forms of life, not least humans, the implications were far more slowly accepted. In the case of transposons, interest in these small pieces of mobile DNA remained largely dormant until the 1970s when they were found in viruses and bacteria. From there, interest was ignited and further research revealed that transposons are found in most life-forms, including of course humans.

Let us leave the last words to McClintock. After receiving the Nobel Prize in 1983 she remarked: “You just know sooner or later, it will come out in the wash, but you may have to wait some time.” (quoted in McGrayne 2001, p.144)

Text copyright © 2015 Victoria Ling. All rights reserved.

References

McClintock, B. (1953)  Induction of instability at selected loci in maize.  Genetics 38, 579–99.

McGrayne, S.B. (2001)  Nobel Prize Women in Science.  Carol Publishing Group, Secaucus, NJ.

Pray, L. and Zhaurova, K. (2008)  Barbara McClintock and the discovery of jumping genes (Transposons). Nature Education 1, 169.

Ravindran, S. (2012)  Barbara McClintock and the discovery of jumping genes.  Proceedings of the National Academy of Sciences, USA 109, 20198-20199.

Gregor Mendel (Image: Wikimedia Commons)

Johann Mendel (1822-1884) was an Austrian botanist, now widely regarded as the father of modern genetics. He was given the name ‘Gregor’ – by which he is more commonly known – when he joined the Augustinian monks. It is worth remembering that the idea that all religious people are de facto opposed to science, let alone evolution, is simply incorrect, and Mendel is a reminder that a keen intellect and life in a monastery (the Abbey of St. Thomas) are not exclusive possibilities.

Mendel is most famous for his discovery of the basic principles of genetic heredity through experiments with pea plants (Pisum sativum). Pea plants were good subjects for study because their physical characteristics are relatively few and simple, and fertilisation is easily controlled. Today, Mendel’s findings are ranked amongst the greatest in biology, and our basic understanding of how traits are inherited from one generation to the next comes from the principles he proposed.

In 1865 Mendel presented what would later come to be regarded as a seminal paper in the history of science, Versuche über Pflanzenhybriden (Experiments on Plant Hybridization) to the Natural History Society of Brno in Moravia, and it was published the following year. In it, Mendel laid down three main principles of inheritance:

– Principle of segregation: in diploid species each individual possesses two types of (allele) gene for each trait. A parent will only pass one of these versions onto offspring. The one that gets passed on is in principle random.

– Principle of independent assortment: during gamete formation, each combination of alleles stands an equal chance of occurring.

– Fundamental theory of heredity: discrete units of inheritance are passed from parents to offspring. Today, we call these ‘units of inheritance’ genes.

In the nineteenth century, most biologists believed that offspring inherited a ‘blended’ set of traits from both parents. So, for example, the offspring of a tall man and a short woman would be expected to produce a child of medium height. This didn’t, however, quite add up and notably Charles Darwin had struggled to account for the mechanism by which traits were passed from one generation to the next. Indeed, a coherent theory of heredity was notably absent from On The Origin of Species.

In his 1868 work The Variation of Animals and Plants Under Domestication, Darwin proposed a theory called ‘pangenesis’ which proposed that every cell in the body combined to influence the constitution of offspring. As we now appreciate, this idea was deeply flawed and would eventually be replaced by Mendel’s theory of inheritance, but it highlights just how difficult it was to account for the inheritance of traits in a pre-gene informed world, and as such, how insightful Mendel’s principles proved to be.

In stark contrast to Darwin’s pangenesis theory, Mendel showed that when one variety of pure-bred plant was cross-pollinated with another, the offspring resembled either one or the other of the parent plants; traits were passed from parent to offspring intact, not as a blend of the two. Mendel further demonstrated that some traits are dominant and some are recessive. Dominant traits essentially mask the effect of a recessive trait. By doing so, Mendel highlighted that the subject of inheritance was clearly at one and the same time more complicated and also more simple than had hitherto been suspected by theories propounding ‘blending’. Whilst it is now clear that the processes of genetics are almost infinitely more complex and sophisticated than Mendel could ever have realized, his discovery was the lynch-pin for the emergence of neo-Darwinism.

As pointed out by Henig (2000), even though a reprint of Mendel’s 1866 paper was found in Darwin’s library, it appears that Darwin was unaware of Mendel’s work and may not have even read it. Darwin may not have been impressed. He was already familiar with the work of the French botanist Charles Naudin, who had reached many of the same conclusions as Mendel but without the statistical support.

But it wasn’t just Darwin who failed to pick up on the significance of Mendel’s research; for nearly forty years his 1866 paper remained largely unacknowledged. It was not until after Mendel’s death that his work was re-discovered by the scientific community. In 1900, the botanists Hugo de Vries, Carl Correns and Erich von Tschermak independently published work within a two month span of each other that acknowledged Mendel’s research. Biologists then became interested in the work of this virtually unknown man, and the wider the paper became known, the more scientists of the day wanted to learn about him.

But it has not all been plain sailing; with re-discovery there has also been controversy. Most notably, there has been debate in recent years about whether or not Mendel’s results were artificially modified (not necessarily by Mendel himself, but possibly by an assistant) in order to fit with his expectations, a suggestion which largely stems from Ronald Fisher’s (1936, p.132) assertion that:

“..the data of most, if not all, of the experiments have been falsified so as to agree closely with Mendel’s expectations.”

As is neatly explained by Novitski (2004), most scientists agree that the results from Mendel’s garden pea experiments conform more closely with theoretical expectations (with ratios such as 3:1, 1:2:1 etc.) than one based upon chance, thus arguably making them too good to be true. Since then, many people have studied and replicated Mendel’s garden pea experiments, analysed the outcomes, and debated the ratios. On moral grounds, there is no doubt that Fisher took the ethically and academically correct route by voicing his concerns, but the emerging consensus is that the criticism is unfounded. To quote Fairbanks and Rytting (2001, p.751):

“There is no credible evidence to indicate that Mendel was inaccurate or dishonest in his description of his experiments or his presentation of data. The main questions about his results can be resolved by an appeal to botanical principles and historical evidence.”

As succinctly stated by Tudge (2000, p.286) “..the complexities of modern genetics, and all the ramifications, flow naturally from Mendel’s initial notions..”. In addition, Mendel must be given particular credit for the fact that he formed his hypotheses in an era long before genes had been identified as the unit of inheritance or the structure of DNA had been discovered. He drew his conclusions from observing the evidence in front of him, and that weight of evidence led him to break with orthodoxy and challenge (albeit unacknowledged at first) commonly held perceptions regarding the inheritance of traits. Mendel laid the groundwork that made it possible for us to understand the basic form of genetic inheritance, and in doing so he founded the field of genetics which today has huge benefits for humankind; not least in terms of understanding diseases and developing medicine.

Today we would like to think that new ideas will quickly surface, and certainly given the internet and social networks all this is greatly facilitated. Even so, ideas are ideas and without the fertile soil of an open, curiosity-driven intellect they will wither and die.

Text copyright © 2015 Victoria Ling. All rights reserved.

References

Darwin, C. 1868. The Variation of Animals and Plants Under Domestication. London: John Murray.

Fairbanks, D.J. and Rytting, B. 2001. Mendellian controversies: A botanical and historical review. American Journal of Botany 88 (5), 737-752.

Fisher, R.A. 1936.Has Mendel's work been rediscovered? Annals of Science 1, 115–137.

Hartl, D.L. and Fairbanks, D.J. 2007. Mud sticks: on the alleged falsification of Mendel’s data. Genetics 175, 975–979.

Henig, R.M. 2000. The Monk in the Garden: The Lost and Found Genius of Gregor Mendel, the Father of Genetics. Boston: Houghton Mifflin.

Mendel, J.G. 1866. Versuche über Pflanzenhybriden Verhandlungen des naturforschenden Vereines in Brünn, Bd. IV für das Jahr, 1865. Abhandlungen, 3–47.

Novitski, E. 2004. On Fisher’s Criticism of Mendel’s Results With the Garden Pea. Genetics 166, 1133-1136.

Sandler, I. 2000. Development: Mendel’s Legacy to Genetics. Genetics 154, 7-11.

Tudge, C. 2000. In Mendel’s Footnotes: An introduction to the science and technologies of genes and genetics from the nineteenth century to the twenty second. London: Jonathan Cape.

Vítĕzslav, O. 1996. Gregor Mendel: The first geneticist. Oxford, New York, Tokyo: Oxford University Press. (Translated by Stephen Finn)