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Over most of the course of human existence, average life expectancy hovered between 20 and 30 years. This was partly because so many infants died, but that does not obscure a bleak evolutionary fact: for hundreds of thousands of years, not long after we reproduced, we died. Even in Western Europe, life expectancy did not reach 40 until 1800 and 50 until 1900. In industrialized countries, female life expectancy is now above 80, slightly less for men. This represents close to a fourfold increase.
Over the same period, your chance of living to 100 has increased from roughly 1 in 20 million to 1 in 50. The number of centenarians in the developed world has been increasing by more than 7 percent a year every year since the '50s. In the journal Science, James W. Vaupel and his co-author, Jim Oeppen, noted "an astonishing fact." Since 1840 - for 160 years - life expectancy has been growing by a quarter of a year every year. "In 1840, the record for longest life expectancy was held by Swedish women, who lived on average a little more than 45 years," they noted. "Among nations today, the longest expectation of life -- almost 85 years -- is enjoyed by Japanese women." This steady march of increased life span has been so punctual, they note, that little humans have done collectively for so long has ever been more regular.
This stream of progress shows no sign of slowing down, much less stopping. In the first half of the 20th century, we knocked back death among the young. Clean water, antibiotics and vaccines played enormous roles. In the second half, we improved survival after age 65. Incremental progress in fighting the four big killers of the aged - heart disease, cancers, diabetes and stroke - continues briskly. And the march of science has if anything accelerated, so you might find credible Vaupel's controversial projection that the average Western girl born today will live to see 100.
