Could our sins have helped us survive?

A new book by the English neurologist Dr Guy Leschziner suggests the reason we don’t evolve out of our “dark sides” is that they once helped us live on as a species. They were, in fact, so helpful that the fast-learning, fast-growing human brain became hard-wired for gluttony, envy, pride, wrath, greed, sloth and lust.

In his book, Seven Deadly Sins: The Biology of Being Human (November; HarperCollins), Dr Leschziner, 50, studies brain scans, case studies, genetic findings and research papers from the fields of neuroscience, evolutionary psychology and pathology, to explore these sins as biological imperatives.

Could our sins have helped us survive?

A new book by the English neurologist Dr Guy Leschziner suggests the reason we don’t evolve out of our “dark sides” is that they once helped us live on as a species. They were, in fact, so helpful that the fast-learning, fast-growing human brain became hard-wired for gluttony, envy, pride, wrath, greed, sloth and lust.

In his book, Seven Deadly Sins: The Biology of Being Human (November; HarperCollins), Dr Leschziner, 50, studies brain scans, case studies, genetic findings and research papers from the fields of neuroscience, evolutionary psychology and pathology, to explore these sins as biological imperatives.

Does that mean we should simply give in? (The short answer is: Of course not.) How are these imperatives shaping us and our world today? And what constitutes a sin, in Leschziner’s view? Excerpts from an interview.

As an atheist and a neurologist, what prompted this study of the seven Christian sins?

I grew up in England, which is predominantly Christian, a culture I have inhabited all my life. As a neurologist, when I saw individuals behaving differently as a result of marked changes to their brain function and structure. I began to wonder if this was the case for all of us. I began to study how factors outside our immediate control as individuals influence why we are the people we are.

The reason every single world religion is so focused on the concept of sin, is that certain “sinful” behaviours are ubiquitous. I decided to study how they became part and parcel of what it means to be human.

What is the science behind the theory that these imperatives helped us survive?

These behaviours can be seen in every race, culture and generation. Why did they spread so widely, to every single one of us? The answer is invariably survival and the survival of offspring. My research shows that this is true both in a psychology laboratory and in real-life studies.

For example, if you induce anger within a psychological experiment, the subject is more likely to succeed at a given task. Pride in its extreme form can be harmful, but this psychological trait when heightened, in certain occupations, confers an advantage.

There are countless examples of these sorts of studies, in the book.

Regarding greed, even before modern society evolved, we lived in an environment where we were competing with others for resources, and having them available or unavailable was the difference between survival and death. To some extent, every single one of the seven sins has an evolutionary basis and advantage.

What about sloth? That seems like, fundamentally, a waste of time…

The underlying basis of sloth is a brain that’s constantly asking: “Is everything we are doing worth it? Is the benefit of exerting this energy, of wasting these calories, significant enough that we should undertake this act?” And that, of course, has a very strong evolutionary benefit.

There is another obvious benefit to sloth, and that is in times of illness. If you look at people with an infection or flu, part of what happens within our bodies is that we develop a degree of sloth. We call it fatigue, but from an evolutionary perspective, it is simply the brain deciding that diverting resources to battle an infection is more important than using any of that energy for other things.

It does improve society, though, to resist the urge for excess?

Regardless of the underlying causes, “sins” are certainly harmful to society. None of the explanations are meant to negate the idea of a moral code. Such a code certainly has some utility when it comes to making the world a better place.

But, without understanding why we as human beings behave the way we do, we cannot make changes that induce an improvement in our society.

In fact, an increased understanding could allow us to identify factors that are beyond an individual’s — but within a society’s — control to change, and this could drive change for the better. An increased understanding of why an individual behaves the way they do is not going to harm us or our society, and it will make us a little more empathetic.

You write that your personal history played a role in your desire to study sins. Your Jewish grandfather was in a Nazi concentration camp. On your mother’s side were refugees from Baghdad. How did this shape your understanding of sin at a macro level?

That history was part of the driving force behind the book. True “sins” shape our world on a macro level. Whether it is conflict, war, atrocities, or the simple fact of where we live and how we live our lives, ultimately these are all a result of global forces.

You mention alcohol multiple times in the book. What is the role it can play?

Alcohol is an interesting drug, because of the way it affects the brain’s frontal lobes. These are the areas responsible for rational thinking, planning, reasoning and regulation of behaviour. They work to limit anti-social behaviours as well.

The huge effect of alcohol is that it suppresses the activity of those regions and therefore makes it easier for our basic instincts to become unregulated. In this way, alcohol becomes a powerful potential driver for anti-social behaviours, in particular violence.

Now, we also know that chronic alcohol consumption can result in organic changes to the brain. So, given the amount of alcohol consumed around the world, it could in fact be having an important influence on the way we as human beings all get on together.

Has hypercapitalism served as an important influence too?

Undoubtedly, hypercapitalism brings with it bad things: a normalisation of greed, an acceptability of resource-accrual for its own sake.

When certain behaviours move from being something fundamental to our survival, to being a biologically broken behaviour that is either intensified or inappropriate to a particular situation or setting, they begin to cause harm to others and to the individual involved. I believe you can label that a sin.

I came into this book thinking that the religious view of sin was largely irrelevant in this day and age. But the truth is we will always need a system that offers clear guidelines on how to pursue good and avoid bad.