In 1920 at birth a males life expectancy was ~54, at 40 a man could be expected to live to ~70. Current estimates are almost unchanged between birth and 40 at 76.23 vs 78.75. That’s a 25% increase in life expectancy at 40, but that a long way from the 41% increase from birth.

I chose 40 because it wasn’t medicine that made the biggest difference for 20 to 40 year olds but war. And actuarial tables can’t predict wars only account for past wars which make current estimates misleading. Aka we don’t have a lifetime of data for people born after 1920 only estimates.

Yes, your original post was indeed correct by hedging a bit, speaking of "adult life expectancy" vs. "infant/child mortality".

People read that and it registers as infants dying within days after birth. But life expectancy for 10-year-olds has doubled: https://ourworldindata.org/life-expectancy. I doubt that your comment makes people think of dead teenagers, even though your post doesn't contradict that interpretation.

Even for the 40-year-olds, life expectancy increasing from 68 to 82 years means a >50% increase in "time remaining" which isn't something to sneeze (cough?) at, although I have to reluctantly acknowledge that I remembered it being even larger than that.

I think you’re confusing me with someone else, this is my second post in this thread. Anyway, the data doesn’t support doubling life expectancy for 10 year olds unless you go really far back.

Look at the England a whales data in your link, in 1841 10 year olds could expect to see 57.6, or another 47.6 years. In 2013 that bumped to 82.2 or another 72.2 years. By 20, they could likely hit 60 or another 40 years worth of life, and by 40 they where up into ~67.4.

However again the difference is largely one of lack of war and famine rather than medicine. The chart is bouncing around because of events that killed large numbers of people, but it smooths out as you approach today.

PS: Their Spanish Flu suggestion is off, it was actually WWI and the flu that’s responsible for much of that drop as seen by 40 year olds being largely unaffected. https://en.wikipedia.org/wiki/Spanish_flu#/media/File:W_curv...

How are you defining urban legend? Here's from Wikipedia [1]

> Until the middle of the 20th century, infant mortality was approximately 40–60% of the total mortality

> Excluding child mortality, the average life expectancy during the 12th–19th centuries was approximately 55 years.

> ... even in preindustrial times as is demonstrated by the Roman Life Expectancy table, which estimates life expectancy to be 25 years at birth, but 53 years upon reaching age 25

Here are actuarial tables for people in the US today [2]. The life expectancy if you reach 25 is.... 52 or 57 depending on if you're a man or woman.

We're certainly better at reducing all cause mortality even in adults but it's not as stark of a difference as you might imagine, particularly its effect on the mean.

[1] https://en.wikipedia.org/wiki/Life_expectancy

[2] https://www.ssa.gov/oact/STATS/table4c6.html

You are not comparing these numbers correctly.

Your second link shows years of additional life expectancy. For example, at age 80 it shows 8.43 years of life expectancy, meaning that the average 80-year-old lives to age 88.43.

So the average 25-year-old in the US has 52–57 years of life remaining, and will live to age 77 or 82, according to your link.

This is a very big increase over the pre-twentieth-century adult life expectancy of ~55 years of age! You claim that "life expectancy of adults hasn’t changed much" but your own links show that it increased about 50% in very recent history.

Thanks for the correction. So we're at a 45% increase. Typically life expectancy is reported as the "from birth number". That's gone from ~20 to 80.

The claim was that the bulk of the life expectancy number being driven by the mortality rate prior to adult hood was an "urban myth". Life expectancy in adult hood is a ~1.4x increase. Life expectancy from birth is a 4x increase. I'd say the bulk is driven by saving the lives of children and is not an urban myth.

You're still not doing apples-to-apples comparisons. The source that you cited says 12th–19th-century life expectancy at birth was 25–40 years when infant/child mortality is included, and 55 years when it is excluded. There has not been any “4x increase” in this time period. (Even if you start in the bronze age, life expectancy at birth has not increased four-fold.)

Since the time period you chose, life expectancy at birth has increased by about 40 to 55 years. Near-elimination of infant mortality accounts for 15–30 years of increase, while increases in adult life expectancy account for an additional 25 years.

North America has a life expectancy of ~80 years. I eyeballed it so closer to 3.2x the 25 year life expectancy in the 12-19th century. What am I missing?

Yes, if you start from a base of 25 years (which is the extreme low end of the range from your source), then we have 30 years of increase from reduced infant/child mortality and 25 years of increase from reduced adult mortality.

Can you really look those numbers and say that one of them is highly significant while the other "has not changed much"?

Translating this into percentages or "fold" increases is misleading because you are using a different denominator for the two increases. E.g. you are claiming that reduced infant mortality is a 2.2-fold increase (55/25) while reduced adult mortality is "only" a 1.45-fold increase (80/55), even though the number of years gained is almost the same.

And if you use the other end of the 25–40 year range, then reduced infant mortality is "only" a 1.38-fold increase (55/40).