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Increases in extreme human longevity: Some statistical questions

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One of my New Year’s resolutions is to write more about things other than the screwed up state of American politics, so in that spirit I’m throwing out some observations about a subject that came up on LGM two years ago, when we discussed the the apparently short-lived controversy over the the age of Jeanne Calment, who remains officially speaking the longest-lived person ever recorded (122 years, 164 days).

What I’m offering for consideration here is the striking increase in recent years that’s been seen, or apparently seen, at the very far range of human longevity.

The simplest way to see this is to use the age of 115 as a proxy for analysis. Since gerontologists began systematically tracking the longest life spans in countries in which public health records made such tracking possible (something that only began to be possible in the mid-20th century), here are the total number of people in the world who have been deemed to have reached the age of 115 in each decade, on the basis of reasonably reliable evidence:

1950s: 0

1960s: 0

1970s: 0

1980s: 2

1990s: 9

2000s: 11

2010-present: 31

Notably, five of the 23 oldest recorded people ever, and seven of the top 37, are currently alive, including Kane Tanaka, a Japanese woman who tomorrow will become just the third person to celebrate a sufficiently verified 118th birthday, unless this post is the worst jinx ever.

Now the question is, why?

Note that this list is dominated by two countries: the USA and Japan, which collectively account for 34 of the 50 oldest people ever. Almost everyone else on the list is from first world countries, which suggests that part of what we’re seeing here is a statistical bias based on the relative availability of reliable public health records stretching back to the 19th century in a small number of countries.

But what’s driving what’s clearly an enormous statistical increase, in these countries at least, of people at the very far range (115+) of human longevity? One factor of course is simply population increase: there are a lot more extraordinarily old people because there are a lot more people now period. Yet the increase in the former population has been far sharper than the increase of the population overall. (Note too the curious but apparently statistically predictable outcome that the fact that women tend to have life expectancies around 10% longer than men means that at the far end of the distribution almost all the people — 50 of the 53 individuals who have reached 115 — are women).

So what else accounts for the striking fact that you couldn’t verifiably find a single 115-year-old anywhere in the entire world for 30 years from the mid-1950s to the mid-1980s, while there have been dozens of such people in just the last decade?

I hope some of you find this question engaging, and if not at least this isn’t another post about Donald Trump.

Except now it is, because of postmodernism or something.

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