People falling in love have ‘chemistry’ or ‘a spark’. A spur-of-the-moment idea is a ‘quantum leap’. Strong personalities are ‘magnetic’.  It is easy to find examples of the way in which the language of science permeates the way we write today – but literature has also reflected scientific progress for centuries. Alchemical metaphors abound in 16^th and 17^th century works: John Donne wrote of “love’s alchemy” and some critics have even suggested that the transformations of the eponymous hero of Shakespeare’s King Lear represent the alchemical transmutation used to produce the ‘Red King’, believed to be a precursor to the Philosopher’s Stone.

For the 19^th century writer, science was even more integral to their work. According to the Romantic poet Samuel Taylor Coleridge, chemistry itself in its “striving after unity of principle” was “poetry realised.” 19^th century novelists also strove to be “both observer and experimentalist”, as much a scientist as any chemist at the laboratory bench. Industrialisation meant science was advancing quickly, changing lives, and taking on fresh importance in the literary sphere. By the mid-19^th century, one scientific theory in particular was ready to cause more controversy than any before it.

For the 19^th century writer, science was...integral to their work

Image modified by Oran Maguire. Cesare Lombroso, the father of criminology, gave rise to the concept of “criminal atavism”, the notion that characteristic physical features could set apart criminals from the rest of society

In 1859, Darwin published On the Origin of Species, outlining his theory of evolution by natural selection. By the standards of the time, Origin was a bestseller—the first edition sold out within a day, an unprecedented popular success for a scientific work. Among the vast reading public were the outraged, the curious, and perhaps for the first time, a literary fan-club of a scientific theory: the ‘Naturalist’ movement.

For writers of this fast-growing school, these new theories of heredity proved useful. Some, like Émile Zola, used complex genealogical trees to calculate how ancestral mental illness would express itself in his characters’ physical features. Zola was influenced by the historian Hippolyte Taine, who famously developed a style of literary criticism based on the scientific method, stressing the importance of verifying academic hypotheses with data on the author’s environment and social standing. Most crucially, for ‘Naturalist’ writers the novels they wrote were themselves experiments; characters were subjected to different stimuli and their responses documented in books that served as lab journals of social phenomena. Many agreed with Taine that “virtue and vice are products like vitriol [sulphuric acid] and sugar”, merely scientific problems to be analysed.

Sadly, public enthusiasm for the theory of natural selection had a darker side. In 1876, seventeen years after Origin was released, early criminologist Cesare Lombroso published The Criminal Man. Lombroso’s research argued that criminals, women, people of colour and the mentally ill all suffered from the same problem; their physical ‘defects’ made them closer to humanity’s biological ancestors than to white men, and therefore inferior. There was wide demand for books providing practical advice on using the ‘science’ to select employees and spouses (often in handy, pocket-size editions for the keen physiognomist on the move). Different bodily features signalled particular issues— ‘small wandering eyes’ pointed to a thief, serial killers were identifiable by their large noses, and anything from wrinkles to short stature could mark a woman out as a criminal.

The use of physical deformity to depict fictional characters as villainous stretches back long before the 19^th century – for instance, Chaucer’s The Canterbury Tales, published in 1478, uses it extensively. However, Lombroso’s conception of criminals as completely at the mercy of their ‘un-evolved’ state was new, and many writers of fiction (among them Dickens, Austen and Charlotte Brontë) seized upon this concept of ‘physiognomy’ to make their antagonists all the more sinister.

With only 7% of UK adults rejecting the theory of natural selection, evolution is no longer as controversial as it once was, and Lombroso’s supposed methods of criminal identification have been recognised as deeply flawed. It is perhaps unsurprising, then, that science in fiction today is often relegated to metaphor or minor plot point; though many continue to write about science, the science of writing has aged less well. Still, if you find yourself rolling your eyes at the umpteenth heavy-browed, beady-eyed villain in a costume drama, you might have Charles Darwin to blame.