Australians do not have to look far to find dramatic inequalities in health.

The life expectancy gap between Indigenous and non-Indigenous Australians is about 11 years. Aboriginal men are six times more likely — and Aboriginal women 11 times more likely — to die of ischaemic heart disease than non-Indigenous men and women.

Incarceration rates, too, are gravely disproportionate. Indigenous people make up 2.5 per cent of the population and yet account for 25 per cent of the prison population.

"The link between deprivation of social conditions, ill health and crime is all too obvious in Australia," said Sir Michael Marmot, president of the World Medical Association and director of the Institute of Health Equity, in his first ABC Boyer Lecture.

Sir Michael, a leading researcher on health inequality, said the story of health and social inequity was grim, both between countries and within them.

He cited the example of the riots that wracked Baltimore in April 2015 after the death of Freddie Gray, an African-American, in police custody.

The "underlying cause", said Sir Michael, was inequality of social and economic conditions.

"I had been studying health inequalities in Baltimore before there was civil unrest. In the poor part, where the riots broke out, life expectancy for men was 63 years. In the richest part, it was 83 years," he said.

"The link between riots and ill health is not unique to Baltimore. In summer 2011 in London, riots broke out. They started in Tottenham in North London. Eerily, the precipitant was the killing of a black man by the police. As with Baltimore, the underlying cause was inequality."

For men, life expectancy in the most "down at heel part" of Tottenham is 17 years shorter than in the "ritziest part" of Kensington and Chelsea.

This association between ill health and crime is no coincidence, said Sir Michael.

"The social conditions in which people are born, grow, live, work and age are strongly determinative both of risk of ill health and of the likelihood of engaging in civil disorder.

"Health and inequalities in health are closely linked to the conditions in which we raise our children, the education we get, the neighbourhoods we live in, the work we do, whether we have the money to make ends meet, our social relationships and our care for the elderly."

Society urged to understand 'causes of the causes'

Going beyond what we typically understand to be the causes of ill health — smoking, drinking, poor diet and exercise — Sir Michael said it is critical we as a society better understand the "causes of the causes".

"The causes of the causes are the social determinants of health and they influence not only lifestyle, but stress at work and at home, the environment, housing and transport."

As for healthcare, Sir Michael said unequal access to healthcare was not the cause of inequality in health.

"It is not lack of healthcare that causes someone to have a heart attack or develop cancer of the cervix.

"We know a great deal about the causes of these and why they are more common in men and women of lower social status ... We should not add the insult of lack of care to the injury of getting sick in the first place."

According to Sir Michael, so close is the link between the nature of society and health, the magnitude of health inequalities is a great measure of how well a society is functioning.

"We can tell a great deal about how well a country meets the needs of its citizens — provides the conditions for them to lead flourishing lives — by the health status of its citizens."

In Australia, Sir Michael said significant social inequity was evidenced by major inequalities in health.

"They are most obvious between Indigenous and non-Indigenous people. But they also track along lines of education, social standing, and income in the non-Indigenous population."

Call for action to reduce slope of health gradient

In fact, social determinants do not only affect the health and life expectancy rates of those on either end of the scale: the very rich and the very poor. The social gradient of health, as Sir Michael describes it, applies to everyone.

"There is a remarkable gradient in health and life expectancy: the higher the grade of employment, the longer the life and the healthier the life.

"In Australia, for example, we see a clear gradient: the fewer the years of education, the higher the risk of death. Men and women in their 40s with fewer than 12 years of education have a 70 per cent higher mortality rate than the most educated."

Understanding this gradient, Sir Michael said, dramatically changed people's perceptions.

"[People] have no difficulty understanding that poor people have poor health ... [They] find it much more challenging to understand why people in the middle should have worse health than those at the top."

The implication of the gradient is that ultimately, we are all affected by our social standing.

"We calculated in Britain ... that the average person can expect eight fewer years of healthy life than they would if they had the highest social position," said Sir Michael.

"Eight fewer years of health life means earlier onset of decline in grip strength, of difficulty walking, of cognitive decline and, of course, fewer years of life."

According to Sir Michael, evidence shows that action is needed from government — federal, state and local — and from civil society, communities and families.

"We should be aiming to reduce the slope of the social gradient in health by levelling up, bringing the health of everyone up to the high level at the top of the social hierarchy."

Sir Michael said that health inequalities were not inevitable, and that the magnitude of the gap between education and life expectancy rates varies enormously.

"It is possible to narrow the health gap? Evidence shows it is ... but action will require greater equity of power, money and resources."