What are we reading? The emotional trend in 20th century books

cats are reading a book

cats are reading a book (Photo credit: Catunes)

Now there have been trends and there are new ones emerging with the release of every new Bestseller Lists. So, in this huge dynamics of book genre trends, it is worthwhile to know –

Which moods, or emotions, have been popular in the literature of the 20th century? 

Do the various world events happening around us affect our book choices too?

Are the claims that  Twitter mood words can predict stock market trends true ?

Can we glean at our past and see whether our mood patterns have reflected world changes?

Recently, an interesting piece of research came to answer these questions of mine. PLoS One an open access, peer reviewed journal published a research paper  by Alberto Acerbi and other co-researchers  titled – The Expression of Emotions in 20th Century BooksAs i said earlier their aim was to understand

To find out, researchers created six categories of words to express anger, disgust, fear, joy, sadness and surprise.

To do this they use Google’s excellent Ngram viewer, a phrase-usage graphing tool which charts the yearly count of selected n-grams (letter combinations)[n] or words and phrases,as found in over 5.2 million books digitized by Google Inc (up to 2008). Using this, the researchers looked at all English language literature published between 1900 & 2000.Apart from this, they used additional datasets for analysing mood words used in English fiction.

Figure 1. Historical periods of positive and negative moods.

So, lets look at the results starting from the above figure. It shows that moods tracked broad historical trends, including a ‘sad’ peak corresponding to Second World War, and two ‘happy’ peaks, one in the 1920’s and the other in the 1960’s. In more recent years we can see a ‘sad’ period starting from the 1970’s, with an increase in ‘happiness’ in the last years of the data set. Interestingly, the First World War does not seem to register a particular change in mood words.

Figure 2. Decrease in the use of emotion-related words through time.


The second part of results is shown in the above figure. It indicates that the usage of the mood words have decreased in books published in the 20th century. One thing which is indeed highly curious is that the use of words relating to disgust has declined the most. Another strange trend is that the use of fear-related words decreased until the 1970s, when the trend took a sharp turn upwards (and has continued to climb for the next three decades).

For me, it is indeed quite a surprise since it gives a fresh perspective on the last century. However, this sort of detailed use of word data to characterize the evolution of cultural differences and trends, to detect patterns previously unknown through conventional history is quite an exciting way to look into human cultural dynamics.

So, Yay for more such research !!


More to read about:

1). Acerbi A, Enquist M, Ghirlanda S (2009) Cultural evolution and individual development of of openness and conservatism. Proceedings of the National Academy of Sciences USA 106(45): 18931–18935.

2). Nettle D (2007) Language and genes: A new perspective on the origins of human cultural diversity. Proceedings of the National Academy of Sciences USA 104: 10755–10756.

3). Evans N, Levinson SC (2009) The myth of language universals: Language diversity and its importance for cognitive science. Behavioral and Brain Sciences 32: 429–492.

4). Bollen J, Mao H, Zeng X-J (2011) Twitter mood predicts the stock market. Journal of Computational Science 2: 1–8.



Aww, Yuck! The Science of Disgust

disgust Yuck, Puke, all the different things one can think about when feeling disgust. Like seeing cockroaches crawling all over the floor, or when seeing dead bodies or in some very weird cases like mine, when eating pineapple slices with a hint of salt on top. It is one of myriad of other emotions we humans have. But, what is disgust ? Is it any similar to disliking anything? What is the evolutionary origin of such an emotion? And also, what role does disgust play in our modern human society? So, lets try and understand this very strange and in some ways, highly useful behaviour.

What is DISGUST ?

Wikipedia says – Disgust is a type of aversive reaction that involves withdrawing from a person or object with strong expressions of revulsion whether real or pretended”. Simply speaking, disgust is a feeling of repulsion which one feels towards myriad of different objects, or people. It can come in various contexts – like the sight of garbage piling up, rotting food or faeces. In some of these cases one doesn’t even have to teach the growing child about them. So, is it something innate? Well, indeed it is one of the universal, basic emotions which helps the organism to survive by keeping away from ingesting harmful substances. Hence, it is classified in some contexts as a disease avoidance mechanism. However, disgust also has a social connotation in humans. For example, a music virtuoso might feel a badly composed music disgusting, or for a gourmet chef, an improper blend of spices would be disgusting.   Also, as disgust is an emotion it also has physiological implications. Unlike other emotions, for example anger or fear which increase our heart beat, disgust decreases it.

Evolution of Disgust

Evolutionarily speaking, disgust is a very important emotion since it allows the organisms to avoid contaminated food that may cause harm to them.It has been thought that disgust is an important component of behavioural immune system, which is responsible to keep us away from any harmful pathogens i.e, an avoidance mechanism. Early on, this would have been quite beneficial to us and help us survive. Though tracing the early history of disgust, is quite impossible since behaviours don’t fossilize. But recent studies in Caenorabhditis elegans, a highly simple roundworm exhibits avoidance behaviour towards various pathogenic strain of bacteria like, Bacillus thuringiensis, Pseudomonas aeroginosa, Serratia marcescens. Other species have also shown to exhibit hygiene maintenance, for example – Ants, Bees, Bullfrog (Rana catesbeiana), Fishes, Bats, Birds, and various mammals. Hence, the earliest form of disgust can be found in the hygiene maintenance behaviour of all the different organisms. As i said earlier, disgust is an instinct which is present in humans too. In a web-based experiment Valerie A Curtis, tested the hypothesis that disgust has evolved to keep humans away from harmful, pathogenic environments. Here is the link to the test-


The test asked people to score how disgusting they found a series of photos. Within the photo series, the authors randomly mixed seven sets of pairs of images, made to be similar in appearance, but in each case one of the pictures contained a disease threat, while the other did not. The results from the scores submitted by over 40,000 people show :

  • Images of objects holding a potential disease threat were reported as significantly more disgusting than similar images with little or no disease relevance.
  • The pattern of response was found to be similar across all regions of the world.
  • Females reported a higher disgust sensitivity than the males.
  • A constant decline in 

    disgust sensitivity over the life course was also reported.

Hence, it is safe to conclude that disgust is probably common to all humans in all the myriad of cultures and it serves as an avoidance mechanism towards all the objects which were associated with a disease risk in the evolutionary past.

Morality & Disgust ?

In humans, various studies have found these disgust elicitors:

  • decaying food
  • dead organisms
  • body products (urine, faeces, saliva, sexual fluids)
  • various organisms (cockroaches, fleas, rats etc)
  • unhygenic environments
  • any signs of infection

Tyber et al, have classified disgust in three parts-

  • Pathogen disgust – disgust aimed at keeping us away from harmful organisms or unhygienic environments.
  • Sexual disgust – disgust which keeps us away form dangerous sexual partners or behaviours. Example of these would be avoidance of costly mates or inbreeding.
  • Moral disgust – disgust keeping us away from breaking social norms. As Mark Pagel in his new influential book – Wired for Culture , writes that its the capability of humans to form strong social associations and hence the diverse cultures which we have separates us apart from other animals. So, in this context moral disgust can be used to keep us away from various social transgressions and would potentially include behaviors such as lying, theft, murder, and rape. Hence, this kind of disgust would lead us to avoid forming associations with norm-violating individuals within groups.

Disgust has always served as a very important rhetorical tool for discrediting, undermining or demonizing an opponent or a group of people with whom you don’t agree. An easy way to do those things would be to portray someone as infecting the integrity of your own social group. The effects of appealing to disgust towards certain situations is quite subliminal and not at all a conscious effort. Jones and Fitness have coined the term “moral hypervigilance” to describe the phenomenon that individuals who are prone to physical disgust will also be prone to moral disgust. An example of this would be how our culture often refers to criminals as “slime” and criminal activity as “stinking”.

So, this leads us to question: If a large proportion of a population sees a behaviour to be disgusting, then is that a good reason to think that behaviour/practice is immoral“?

The answer to this would be an emphatic NO. Since different cultures have different sensitivities and these lead to differences in the practices people see as disgusting. hence, attaching moral values to disgust would be very wrong. And yes, it would be “MORALLY” wrong to do it.

More on this-

  1. Yuck!: The Nature and Moral Significance of Disgust by Daniel Kelly
  2. Pathogenic bacteria induce aversive olfactory learning in Caenorhabditis elegans, Zhang Y, Lu H, Bargmann CI., Nature, 2005.
  3. The genetics of pathogen avoidance in Caenorhabditis elegans, Schulenburg H, Ewbank JJ., Mol Microbiol., 2007.

  4. Disgust as a disease-avoidance mechanism, Oaten M, Stevenson RJ, Case TI., Psychol Bull. 2009.
  5. The effect of disgust conditioning and disgust sensitivity on appraisals of moral transgressions, Bieke David, Bunmi O. Olatunji, Personality and Individual Differences, 2011.
  6. Microbes, mating, and morality: Individual differences in three functional domains of disgust, Tybur, Joshua M. Lieberman, Debra; Griskevicius, Vladas ,Journal of Personality and Social Psychology,2009.
  7. Evidence that disgust evolved to protect from risk of disease, Val Curtis, Robert Aunger and Tamer Rabie, Proceedings of Royal Society of London B, 2004

Best Science Books of 2012

What better way to start off a geeky science blog than to have a list of top books !! So, with drumrolls….Here is a list of 10 Science Books released in 2012, which i found to be cool:

1). Braintrust-What Neuroscience Tells us About Morality by Patricia Churchland  1

Though the title may not be very catchy, but if you read the short description at the back you will be hooked !! This book had a lofty aim, and that was to explain Morality in terms of Neuroscience by cutting away the strange spiritualistic mumbo-jumbo surrounding it. And after reading the book, one definitely understands morality not as an abstract concept reserved for philosophers and quack spiritualists but a genuine scientific problem which can be dissected in the language of neuroscience. So, kudos to Patricia !!

2). The Origins of Sex: A History of the First Sexual Revolution by  Faramerz Dabhoiwala 1

In The Origins of Sex,Faramerz Dabhoiwala brings about a highly thorough study on the origins of sexuality in modern Western culture. Traditionally, sex had been strictly regulated by the Church, the state, and society. Between the 16th and 18th century, sex was considered quite a taboo subject and something which was not considered a private one either. Public punishments were in fact quite the norm. The book ends with a survey of post-1800 attitudes to sexual freedom and also addresses why there was a return to a more repressive culture in recent times.19

3). Wired for Culture: Origins of the Human Social Mind by Mark Pagel  wiredforculture

Wired for Culture, explores the idea that it’s the social nature of humans that has been the prime reason for the success of our species. The modern society views our inherent traits such as intelligence, language and consciousness as the major difference  between us and other animals. However, Mark Pagel in this book tells us all these traits would have been useless without our propensity for social living, co-operation within and between groups. Culture has played an important role in natural selection which has resulted in us being quite hardwired for it. Mark brings in his expertise in different fields to bring about a cohesive answer of the question — Why we are so diverse despite being one species?

4).The Viral Storm: The Dawn of a New Pandemic Age by Nathan Wolfe Viral-Storm-Cover

The news has been dominated by the various pandemic like situations brought out by the greatest and the simplest organisms — VIRUSES !! This book by Nathan Wolfe, a professor at Stanford University is an account of how different kinds of viruses have affected our human society and how a global society such as ours has also increased our chances of being wiped out by a pandemic greater than the Spanish flu of  1918. This frightening scenario was also the topic of a recent movie – Contagion which showed us how a simple flu virus can bring down humanity to its knees. Nathan incidentally was also the consultant behind the movie, which why that movie was quite scientifically correct and didn’t end up in showing that the virus scare was a plot by Martian aliens bent on dominating earth for their energy needs !!

5).Bad Pharma: How drug companies mislead doctors and harm patients by Ben Goldacre Bad-Pharma1

No book list is complete without this book. Period!! Why? Well, that is because this is one of the few books which shows the bad side of pharma industry without invoking any conspiracy theories in its wake.  The predeccosor of this book was the Bad Science, highlighted the “quack doctors, flaky statistics and scaremongering journalists in this big bad world. If you have watched the TED videos of Ben Goldacre and felt that “I should know more”  than this book is for you.

6).Inside The Centre by Ray Monk 1

Ray Monk’s book explores the life, struggles of Robert Oppenheimer-the man who detested his own legacy,The Atomic Bomb. He was quite a diverse personality since his interests ranged from atomic physics to astrophysics and science policy. His actual legacy has never been as the Father of the A-Bomb, but far more complex. Oppie, as he was affectionately known was prized during World War II and witch hunted in the McCarthy era. His biography hence is not an easy one but Ray Monk has in his book tried to bring together all his legacies together to achieve a sort of personal stamp, or a personal identity which he himself strived for throughout his life.

7). Ignorance: How It Drives Science by Stuart Firestein  20120806_ignorance_57

I start off by quoting from one of my favourite blogs“Science is always wrong,” George Bernard Shaw famously proclaimed in a toast to Albert Einstein. “It never solves a problem without creating 10 more.”  This book by Stuart Firestein is a homage to that statement. for i ask, What is Science without Ignorance? If one day we wake up to a world with everything known to its last detail, then that day would indeed be the saddest for humankind. Its mankind’s inhetrent curiosity and ignorance of the world it lived in which is responsible for all that we know now.  I end by quoting from Stuart’s fine book –

“Science produces ignorance, and ignorance fuels science. We have a quality scale for ignorance. We judge the value of science by the ignorance it defines. Ignorance can be big or small, tractable or challenging. Ignorance can be thought about in detail. Success in science, either doing it or understanding it, depends on developing comfort with the ignorance, something akin to Keats’ negative capability.”

8). Connectome: How the brain’s wiring makes us who we are by Sebastian Seung  Connectome-Seung-Sebastian-9780547508184

Its always been and always will be a million dollar question – Are we a sum of our neurons? This book by MIT professor Sebastian Seung explores the tremendous growth of the so called “-omic” sciences. Despite the development of powerful computers and decreasing costs of sequencing we have been able to understand only the complete connectome of a 302 neuron organism, C,elegans. This connectome (complete wiring diagram documenting the links between the genome and proteome), though is only a part of story as one also needs to know the various neuronal and synaptic activity simultaneously. But to understand the complete synaptic activity , the first step is indeed to know the wiring diagram. Now think of a scenario, if we one day know the complete connectome and synaptic activity for a human being and in some distant future recreate them on an advanced super computer, would we be able to resurrect that person?? Well, that does sound like the story of MATRIX!! For more, read this book…

9). Thinking, Fast and Slow by Daniel Kahneman Layout 1

This book has been quite the tour de force of the year. The Nobel prize winning economist, Daniel Kahneman points out that how human brain is biased towards finding coherence where there is none, and that we are susceptible to a frightening level of overconfidence. This book can be layman’s explanantion of why a psychologist shared the Nobel prize for economics. It was because of his and Amos Tversky’s work published in 1974 about why economic and financial predictions so often go wildly wrong when they were (or so it was believed) so carefully and rationally made.

10). Mortality by Christopher Hitchens photo

I end this book list by a homage to the polymath and in many ways my inspiration Christopher Hitchens. In this riveting account of his own affliction, Hitchens poignantly describes the torments of illness, discusses its taboos, and explores how disease transforms experience and changes our relationship to the world around us. By turns personal and philosophical, Hitchens embraces the full plethora of human emotions as cancer invades his body and compels him to grapple with the enigma of death. Hats off, Hitch !!