Why do some people live longer than others?
How many candles will you collect?
It is a question that has dogged some of the finest minds for generations.
In many cases, the answers appear to be clear - better diet, access to healthcare and exposure to fewer diseases.
But in others, the answers are less clear cut.
Why, for instance, does a Japanese man outlive a British man by an average of four years?
Why does a woman from Manchester die an average of three years earlier than a woman from London?
And why does a man in west London live six years longer than a man in the east of the city?
Scientists have put forward a raft of reasons for these differences over the years, ranging from lifestyle choices, such as smoking, to genes.
But a book by Sir Michael Marmot, professor of epidemiology and public health at University College London, outlines some very different possibilities.
Sir Michael has been studying differences in life expectancy for three decades.
In the 1960s, he carried out what has now become known as the Whitehall Study - a study into the health of civil servants in London.
It found that the health of these government workers was closely associated with their rank within the civil service. In fact, the higher they were in the pecking order the better their health.
LIFE EXPECTANCY RATES
1. Japan 81.3
2. Sweden 79.9
3. Canada 79.2
4. Spain 79.1
5. Switzerland 79.0
5. Australia 79.0
7. Israel 78.9
8. Norway 78.7
8. France 78.7
10. Italy 78.6
15. UK 77.9
18. US 76.9
Source: UN Development Programme
Further studies have found similar patterns in other groups, including academics and Oscar winners.
People with PhDs live longer than those with masters degrees. Those with a masters live longer than those with a degree, while those with a degree live longer than those who left school early.
Similarly, actors who have won an Oscar will live on average three years longer than those who were nominated for the award but missed out.
Sir Michael believes the pattern holds true for every group in society, from politicians to those living in poverty.
He maintains that our health and how long we live is influenced to a high degree by our social standing.
Sir Michael calls it "Status Syndrome", the title incidentally of his new book.
"The evidence is overwhelming. It suggests that higher society position creates good health," he says. "People at the top of the hierarchy live longer."
He believes this social standing may be even more important than diet and healthcare.
"People usually think it's either medical care or smoking and diet that determine lifespan," he says.
"These things are important, but the evidence shows that they are only part of the story."
Sir Michael says our position in that hierarchy is influenced by two things - how much control we have over our lives and what role we play in society.
"Do they feel in control and have opportunities for full social engagement?" he asks.
Perhaps surprisingly, income appears to have very little impact.
"More money does not buy better health," says Sir Michael.
Oscar winners like Renee Zellweger can expect to live longer
"Money is only important as a marker. Income per se is not important."
His theory may go some way to explaining why relatively poorer countries like Greece and Malta have higher life expectancy rates than the UK or the US.
Sir Michael believes that giving people more control over their lives and ensuring they play a full part in society will boost health and extend lifespan.
To this end, he suggests governments should do more to ensure all children receive a good education, workers have greater control over their lives and older people "are not thrown on the scrap heap".
He suggests more should also be done to improve local communities and ensure people feel part of a community.
Sir Michael says governments countries could do worse than learn from Japan, which tops the global life expectancy league.
A Japanese man can expect to live for an average of 81.3 years. This compares to 77.9 years in the UK and 76.9 years in the US.
Sir Michael puts the difference down to a much more cohesive society in Japan. It has much lower crime rates and a smaller prison population.
"The Japanese would argue that their low crime rate is a direct result of the cohesive nature of their society," he says.
"I think Japanese life expectancy is related to social cohesion."
The UK Government has been trying to tackle health inequalities for a number of years now.
The Labour Party set up an independent inquiry to examine the issue soon after coming to power in 1997. Sir Michael was a member of that inquiry team.
His verdict on progress so far? "There have been modest changes in the right direction," he says.