Around 300,000 years ago, a new species emerged from the now extinct Homo erectus. Homo sapiens differed from its predecessor in several ways but the most important difference was the increase in brain size. A larger brain led to greater specialisation of its functionality, which in turn led to things we consider uniquely human—the development of language, sophisticated tools and the ability to form social bonds and collaborate with people. Social bonding led to the formation of large cooperative groups, called InGroups, whose membership proved to be crucial for the survival of the species.
Despite what Facebook might claim, our cognitive capacity limits the number of individuals with whom we can maintain stable social relationships. This number, called the Dunbar number, is around 150. In a group of roughly this size, harmony and cooperation was possible with social mores which defined acceptable or unacceptable behaviour. However, meaningful cooperation on a larger scale needed other constructs like religion. With religion came the concept of sin—defined simply as forbidden behaviour.
It was only in the 6th century CE that a list of seven deadly sins was drawn up by Pope Gregory. These were pride, gluttony, lust, sloth, greed, envy and wrath. Stripped of the religious mumbo-jumbo, these were basically traits which were acknowledged to be detrimental to individuals as well as the InGroup. Labelling bad behaviour did not make it any rarer—it just led to more guilt. But why have these traits persisted? What are the biological and psychological dimensions of these capital vices? Jack Lewis, a neuroscientist and a television presenter, seeks to explore this terrain.
Studying the human brain was well-nigh impossible till the 20th century. The wounded of the two world wars, especially those with brain injuries, offered doctors a unique opportunity to learn about brain structure and correlated functionalities. Subsequently, with the development of tools like CAT and MRI scans, scientists could glean information about the amazingly complex organ. In the 1990s, with the advent of the technique of functional MRI, scientists could finally localise brain activity in various parts of the brain and correlate it to stimuli and behaviour.
Lewis looks at each of the seven deadly sins in their many dimensions. Using the enormous amount of scientific data on the human brain that has accumulated over the years with MRI and other techniques, he tries to explain how the neural circuitry of the brain is involved not only in tempting us to be sinful, but also how it restrains us. This can all get pretty complicated, with terms like the Medial orbitofrontal cortex (OFC) and the Rostral anterior cingulate cortex (ACC) etc., thrown around. Fortunately, the nitty gritty of neuroscience is but a small part of the discussion of each of the vices.
What make the book interesting are the socio-cultural, contemporary and historical sidelights woven together with anecdotes and curious trivia. For instance, in his discussion on sloth, he talks about the case of a South Korean couple who were so completely absorbed in a game that featured caring for a virtual infant that they accidentally starved their own three-month-old child to death. Or his discussion on how Facebook and reality TV, unlike all the world’s major religions, is an ideal breeding ground for narcissism, which he links with the vice of pride. Pride is considered to be the “queen of all sins”—an exaggerated sense of entitlement and self-importance would make it easier for one to feel justified in taking more than their fair share. In this reading, pride leads to other sins like lust, greed and sloth.
Apart from neuroscience, Lewis uses evolutionary psychology—where human behaviour is linked to evolutionary adaptations—to explain human behaviour. Unfortunately, evolutionary psychology is methodologically and theoretically controversial, since among other shortcomings, its findings are not verifiable. Intermingling such explanations with hardcore neurobiology misleads the non-specialist into thinking that both are on an equal footing as scientific theories go. This is a major lacuna in a well-written and immensely readable book.
We humans are fallible and prone to giving in to our deep-rooted impulses, which are mediated through the complex external environment we inhabit. These impulses can have both good and bad outcomes. Apart from various medical interventions which can curb pathological behaviour, Lewis also suggests various strategies that can be used at an individual level so that we can better manage these innermost impulses that ultimately make us unhealthy, unhappy and unproductive. The best advice turns out to be still what has been known to wise men for millennia—moderation in one’s behaviour.
