Life Expectancy' - A Statistical Abstraction with a Surprising History

For many of us, the concept of 'life expectancy' is a statistical abstraction that seems like a straightforward measure of human longevity. However, as Steven Johnson explains in his book 'Extra Life,' this seemingly simple number has a rich and fascinating history that is filled with unexpected twists and turns.

According to Johnson, much of the rise in life expectancy was driven by the sparing of children, whose deaths had previously mixed small numbers into the average. This means that people living today in countries with high mortality rates will, on average, outlive those from previous generations.

In fact, global life expectancy has increased significantly over the past century. In 1950, no country - rich or poor - had a life expectancy as high as 72.6 years, which is the global average for 2019. This is a remarkable achievement that Johnson calls 'one of the greatest achievements in the history of our species.'

But what drove this rapid increase in life expectancy? Johnson's book tells the story behind this phenomenon, tracing its roots back to the second half of the 19th century when average lifespan began to climb rapidly.

Before then, more than a quarter of children died before their first birthday, and nearly half did not live beyond their fifth. This meant that parents would often have lost one or more of their children by adulthood. In contrast, today's parents are much more likely to see all of their children grow up and live long lives.

For many people, this may seem like a distant memory - but for others, it is still a reality. For example, if the conditions of the past prevailed today, then readers of The New York Times, with an average age of 55, would likely be dead by now. This puts the remarkable progress we have made in increasing life expectancy into stark relief.

As Johnson notes, our desire for a simpler and safer yesteryear can sometimes lead us to overlook the many advances that have been made in public health and medicine. 'Extra Life' is a timely reminder of just how far we have come, and the incredible achievement it represents.

In his book, Johnson tells the stories behind this remarkable progress, highlighting the key players, discoveries, and innovations that have contributed to our increased life expectancy. By exploring the history of this phenomenon, he shows us that there is much more to 'life expectancy' than just a statistical abstraction - it is a story of human resilience, innovation, and determination.

Overall, 'Extra Life' is a fascinating exploration of one of humanity's greatest achievements, and a testament to our ability to adapt, innovate, and thrive in the face of adversity.

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