As you read of the many contemporary threats to life and limb, from pollution to shooting rampages, you may long for a simpler and safer yesteryear. But if the conditions of the past prevailed today, you would probably be dead. The average age of a New York Times subscriber is around 55, and for most of human history, life expectancy was around 30. At least one of your children would probably be dead, too. Until a couple of centuries ago, more than a quarter of children died before their first birthday, around half before their fifth.
In “Extra Life,” Steven Johnson, a writer of popular books on science and technology, tells the stories behind what he calls, in an understatement, “one of the greatest achievements in the history of our species.” Starting in the second half of the 19th century, the average life span began to climb rapidly, giving humans not just extra life, but an extra life. In rich countries, life expectancy at birth hit 40 by 1880, 50 by 1900, 60 by 1930, 70 by 1960, and 80 by 2010. The rest of the world is catching up. Global life expectancy in 2019 was 72.6 years, higher than that of any country, rich or poor, in 1950. People in the shortest-lived countries today will, on average, outlive those of your grandparents’ generation.