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By Jessica Bradford on

Death by numbers: the mathematics of mortality

When are you going to die? This isn’t a question any of us know the answer to. But it’s one that has preoccupied politicians, philosophers, scientists and engineers for centuries. A week ago the Science Museum hosted a special TEDxLondon event on ‘the end of ageing’.

Guest-curated by high-altitude physician and entrepreneur Dr Jack Kriendler, speakers tackled issues of life, death and ageing from a myriad of perspectives: biology, moral philosophy, science fiction, art and digital technology.

The discussion challenged us to wonder: if we can engineer the end of ageing, what does a good life look like?

As one speaker, economist, philosopher and philanthropist Dr Shamil Chandaria argued, the development of super-longevity must be considered within a framework of human well-being, meaning and purpose.

Today, the numerical measure – the ‘QUALY’ or ‘quality-adjusted life-year’ –aims to quantify the relationship between health and quality of life, and to determine the ‘value’ of medical interventions.

Dr Shamil Chandaria discussing the relationship between long life and ‘good’ life at TEDxLondon at the Science Museum on 18 November 2016
Dr Shamil Chandaria discussing the relationship between long life and ‘good’ life at TEDxLondon at the Science Museum on 18 November 2016. Image: Keoma Zec Photography.

Reducing life and death to numbers is nothing new.

This is strikingly evident on the pages of a book which will be displayed in Mathematics: The Winton Gallery at the Science Museum from 8 December 2016. The book is the English Life Table published in 1864. This three-inch thick publication was full of tables and equations based on an analysis of nearly 6.5 million deaths over 17 years.

It was the work of William Farr, the General Register Office’s first statistician, who dedicated his career to the study of life expectancy.

But in an era before digital computers, how did Farr crunch the numbers? In the Victorian period, mammoth calculation tasks were usually performed by hand, by human beings. And this meant human error and vast amounts of time.

Farr’s English Life Table, 1864.
Farr’s English Life Table, 1864.

Farr’s answer lay in a machine: a ‘difference engine’. Invented by Charles Babbage, and brought to the market by the Swedish father-and-son Georg and Edvard Scheutz, the difference engine could calculate simple arithmetical sums and print out the results, therefore avoiding transcription mistakes. It created tables of otherwise impossible precision and reliability.

The English Life Table was a work of enormous mathematical and social significance. It allowed people to better understand their insurance premiums and built public trust in the insurance industry.

Scheutz difference engine, 1859
Scheutz difference engine, 1859.

Next time you’re lured by an online life expectancy calculator or make a decision about your health insurance, life assurance or retirement, it’s worth considering that this is all based on a complex understanding of the mathematics of mortality.

The story of mathematics and mortality features in Mathematics: The Winton Gallery, which opens to the public on the 8 December 2016. The gallery brings together stories of mathematicians, their tools and ideas from the late 16th century to the present day. It reveals how mathematics has shaped our world – from trade and travel, to war and peace, life, death and money.

Jessica Bradford is Interpretation Manager for Mathematics: The Winton Gallery.