Part of life expectancy statistics is infant mortality. The rest, as the SSA points out, is life expectancy when you attain adulthood.
For men in 1940, if they made it to 21 their life expectancy was 53.9 years; by 1990, it was 72.3 years. For women, it's jumped from 60.6 years to
83.6 years.
For men in 1940, if they made it to 65 their life expectancy was another 12.7 years, and by 1990 it was 15.3 years. For women, 14.7 to 19.6. In addition, the percentage of the US population that is over 65 has grown, from 6.8% in 1940 to 12.4% in 2000. (
Social Security History)
In 1900, people started work at about what age?
The average age of retirement has also apparently dropped. In 1940, it was 68; by 1995 it was 64.
And what about changes in the number of years worked, compared to the number of years in retirement? According to the BLS, it looks like this....
Heritage has a pretty good article on this:
Time to Raise Social Security
People are working less, retiring earlier, and living longer, at a time when there are fewer workers who have to support more retirees. I will gladly admit that simply stating "life expectancy" is a bit oversimplified, but the essence is correct. To suggest that the changes in life expectancy haven't contributed to the issues facing SS is slightly ridiculous.