People are sometimes puzzled that problems as different from each other as violence, mental illness and obesity, can all be affected simply by the size of the income gap between rich and poor. The explanation is that they are all problems which are affected by social status. Although violence, ill-health, obesity and mental illness are far from unknown at the top of society, they are all much more common nearer the bottom of society. What the evidence shows is simply that problems related to low social status get worse when social status differences are increased. What is surprising is that rather than confining its effects to the poor, inequality damages the whole social fabric and affects the vast majority of the population.
The naïve view of inequality is that it only matters if it causes poverty. But the truth is that we have deep-seated psychological responses to the levels of inequality in society. Our tendency to equate outward wealth with inner worth means that inequality colours our social perception. It invokes deep psychological responses - feelings of superiority and inferiority - and affects the way we see and treat each other.
In an important research paper, Sheri Johnson, a psychologist at Berkeley, and her colleagues have reviewed a vast body of evidence suggesting that a wide range of mental disorders may originate in a "dominance behavioural system". Almost universal among mammals, it is a system for recognising and responding to social rank - to hierarchy, power and subordination. Brain imaging studies suggest that there are particular areas of the brain and neural mechanisms dedicated to processing social rank.
Johnson suggests that conditions such as mania and narcissism are related to inflated perceptions of, or striving for, status and dominance. In contrast, anxiety and depression seem to involve responses to, or attempts to avoid, subordination. Conditions like antisocial personality disorder and psychopathy, which involve egocentrism and lack of empathy, are probably also features of a strong social dominance drive. Bipolar disorder may involve oscillations between striving for status and dominance and feelings of defeat and inferiority. Research has started to show that conditions such as these are more common in more unequal societies.
A recent study of 34,000 people in 31 countries found that, in countries with bigger income differences, status anxiety was more common at all levels in the social hierarchy. Another international study found that self-enhancement or self-aggrandisement - presenting an inflated view of oneself - was more common in more unequal societies.
Recorded increases in narcissism rates in the USA (as measured by the Narcissistic Personality Inventory) also coincide with widening income differences.
Bigger material differences between people create bigger social distances. Rising inequality seems to strengthen all the ways in which status and class imprint themselves on us from early childhood onwards. It is not surprising then that where inequality has increased, social mobility has slowed and equality of opportunity for children has become a more distant dream.
Humans have lived in every kind of society, from the most egalitarian hunter-gatherer bands of our pre-history, to the most brutal tyrannies. We instinctively know how to be caring and sharing, creating social bonds of friendship, mutuality and cooperation. We also know how to do status competition, how to be snobs, looking up to superiors and down on inferiors, and how to talk ourselves up. We use these alternative social strategies almost every day of our lives, but inequality shifts the balance between them. A study covering 26 European countries found that people in more unequal countries were less willing to take action to help others - whether the sick, elderly, disabled or others in the community. Bigger income differences seem to make us into less nice people.
One of the better known costs of inequality is that people withdraw from community life and are less likely to feel that they can trust others. But good social relationships are key to human wellbeing. Study after study shows that they are highly protective of health and essential to happiness. And now that we can compare robust data for different countries, we are reminded of what we once knew intuitively - that inequality is divisive and socially corrosive.
Kate Pickett is a professor of epidemiology at the University of York, and a National Institute for Health Research Career scientist. Richard G Wilkinson is a British researcher in social inequalities in health and the social determinants of health. He is an emeritus professor of public health at the University of Nottingham.
Richard and Kate are co-authors, of The Spirit Level: Why More Equal Societies Almost Always Do Better. They also co-founded the Equality Trust, a non-profit organisation seeking to explain the benefits of a more equal society.
As part of the University of Auckland's Sir Douglas Robb Lectures, they will be speaking in Auckland on 19, 21 and 23rd of May. More info here. https://www.auckland.ac.nz/en/about/news-events-and-notices/events/events-2014/05/sir-douglas-robb-lectures.html
Join the debate: Return here at 6pm this evening for a live chat with panelists Max Rashbrooke (author of Inequality: A NZ Crisis) and Lyndy McIntyre from Living Wage Aotearoa.
