My last column looked at death in the workplace, and at the risk of sounding overly fatalistic I now want to examine how long we are likely to live. When we talk about longevity, it is usually described in terms of “life expectancy” – the average length of life – but averages can be misleading. After all, people in the UK have on average one testicle each.
For instance, the 90th Psalm declares, at least in the King James version of the Bible, that “the days of our years are three-score years and ten”, although up to recently you had to be fairly lucky to reach this biblical sell-by date. Some historical figures did manage it: Augustus Caesar conquered that barrier to reach 75, while Michelangelo hammered on to the amazing age of 88.
Since the ancient Greeks, there was also a superstition about the risks of ages that are multiples of seven – the “climacteric years” of 49 and 63 were seen to be positively dangerous. Partly in order to combat this belief, in 1689 a priest in Breslau in Silesia (now Wroclaw in Poland) collected the ages at which people died. These data eventually found their way to Edmond Halley in England, who took time off from discovering comets to construct the first serious life table in 1693, which uses estimates of the annual risk of dying to work out the chances of living to any age.
There was no evidence of any increased risk at age 49 or 63, so Halley neatly demolished the idea of climacteric years. Unlike the Bible’s declaration, Halley’s life tables went up to 84. He estimated there was a 2% chance of reaching this age, and just to prove it he died when he was 85, thus by some margin outliving Bill Haley, also of Comet fame, who only lived until 55.
Fab (sixty-)four factor
But in the case of survival, life expectancy is strongly influenced by a lot of deaths in childhood – the average will be low, but the survivors may then live to a good age. So perhaps taking another cue from the music world might provide a better way of assessing life and death.
Paul McCartney was 16 when he wrote When I’m 64 – an age when 64 seemed as old as old. But if we look at the chances of surviving childhood and getting to 16, and then the chance of such a survivor getting to 64, we can get a better picture of what has changed over the decades.
For example, if we consult wonderful resources such as the Human Mortality Database, we find that back in 1841 (the first year we have data for), 31% of children born in England and Wales died before they were 16, but if you did survive there was nearly a 50% chance of reaching 64.
When the Beatles recorded When I’m 64 in 1966, 2.5% of children died before 16, and surviving girls had an 85% chance of reaching 64: for boys it was only 74%, the difference reflecting the unhealthy lifestyles of so many men. By 2009, the last year we have measurements for, less than 1% of children died before 16, and the chance of reaching 64 rose to 92% for women and 87% for men. This gives an overall life expectancy of 82 for women and 78 for men.
Life-expectancy figures do have a value, though, as behind the cold columns of numbers in historical tables lie powerful events. Apart from the World Wars, Napoleon’s march on Moscow, which killed 400,000 men, temporarily reduced life expectancy to 23, the influenza epidemics of 1918-1919 took 10 years off life-expectancy for females in France, while Aids has meant life expectancy in South Africa declined from 63 in 1990 to 54 in 2010.