Brian Manning Delaney wrote:
> James wrote:
>> > In short,
>> > I think humans are not going to live longer than
>> > 120 without scientific intervention - lifestyle
>> > changes (which is what I would call CR) are not
>> > going to do it.
>> Why not? To argue that CR can't take anyone
>> beyond ~120 requires, it seems to me, either: 1)
>> the belief that CR won't work in humans; 2) the
>> belief that those who've lived to 120 were
>> practicing CR, inadvertently or not, to a
>> maximally beneficial degree, and with maximal
>> consistency over the course of their lives; or 3)
>> the belief that there's some way of getting the
>> benefits of CR through "some other means".
> #2 is the one that I am opting for, though I
> don't find #3 to be as far fetched as you seem
> to think. Certainly there are plenty of people
> that simply do not like to eat, for genetic or
> other reasons. Maybe they have a defect in
> their "fullness" feedback mechanism. Maybe they
> are poor and can't afford enough food (you could
> argue that then they would be getting poor
> nutrition also and that wouldn't really be CR,
> and that is probably true *most* of the time -
> but you certainly couldn't say *all* of the time).
> Who knows? There are probably a hundred things
> that could cause you to unintentionally practice
> CR. So don't you think that, for whatever reason,
> there must be plenty of people who naturally
> consume 40% of what other people would consider "normal"?
> Please note that when I say plenty I don't mean
> any large percentage of the population. Maybe
> we are talking about 1 in 1,000 or even 1 in 100,000.
> But when you consider the number of people on
> earth, that means that there are an awful lot of
> people inadvertently practicing CR.
I disagree, though not strongly. I think it's a tricky
But consider a few things. First, 5,000,000,000 isn't the
operative number. World population was ~500-700 million in
the 1870s. People who'd already died by then aren't relevant
since no reliable birth records exit. And people born more
than a few years later aren't relevant either, since they
haven't broken records yet, if they're still alive.
A 1/2+ billion people is still a lot, but we have to pare
them down further if we want to see how many people are "in
the running" to extend maximum life span. People born over
120 years ago lived under _very_ difficult circumstances. If
you compare them to lab rodents, we could say that "people
husbandry" was REALLY bad. That is, you could argue that the
odds favor that one or two of these half billion people
would have accidentally practiced CR for all or most of
their lives, but then you'd have to figure out how many of
those people wouldn't have been killed by other things. That
number is very small. Life expectancy at birth back then was
about 40, in U.S. (lower, worldwide). CR would likely
prevent some of the causes of death that were common then,
but most deaths were caused by things that CR wouldn't help.
So by the late 1930's, let's say, half of these people are
dead for reasons having nothing to do with their diets. Then
you've got another half century of possible deaths that CR
couldn't prevent. To get exact numbers, we'd have to look at
actuarial tables. But let's look at it this way:
Let's assume you're right, and CR does indeed work in people
but that the maximum CR'd life span is only ~120. Let's
further assume that _everyone_ born in the 1870's practiced
severe CR all their adult lives. (Records of people born
much before the 1870's -- and even those born in the 1870's
and a bit later, one could argue -- are unreliable, so I'll
leave them out.) The number of people born in, say, the ten
years centered around 1878 is probably 20 million or so.
Given our assumptions, and causes of death at the time, we
can assume that only 10 million of these people are left,
worldwide, by 1928. These people aren't going to die of
heart disease or adult-onset diabetes, but they can still
die of cancer, though with a lower probability than people
not on CR, and they can certainly still die of infectious
diseases. And then there are accidents. Expected number of
years left at age 50, in the 1920's, was about 20. Let's say
that accidents and non-CR preventable deaths occupy a
smaller portion of this than in earlier times, and at
earlier ages, so that our CR'ers have a 50% higher figure:
30 years left. So by 1958, when these people are in their
80s, we have 5 million of them left. Using similar
reasoning, we'd have a little under a million left in their
110s, at the end of the 1980s, and slightly fewer today).
So now we can return to your question, but plug in a more
reasonable -- in my view -- number.
> So in summary I think that when you are
> observing 5,000,000,000 subjects you have
> probably seen every possible type of diet - CR
> included - many times over. Therefore if CR was
> going to take us past 120 we would have already
> seen it somewhere, sometime.
The number is more like 500,000-700,000, if my above
crankulations are correct.
Is the probability that someone born in the relevant time
frame would engage in severe CR for all of their adult life
1:~600,000 or better? I don't know, but my guess is no. I
think that TODAY it's more likely that there are people
practicing some kind of accidental CR, but in the days
before fortified food, before wide-spread knowledge that
fruits and veggies are important, before even consistently
available food of _any_ kind, I think the odds would be
extremely remote. In investigating this question some time
ago, I looked into different dietary habits of different
religious practices, and found that there are some that
involve restricted eating, but it's always simple food
restriction, the kind of diet that results in shortages of
numerous essential nutrients.
People don't like being hungry. For someone to spite their
hunger for over a century, or to have some kind of genetic
or psychological mechanism by which hunger is naturally
spited, or naturally very low (radically low, given we're
talking about severe CR), AND to have eaten a diet that
wasn't short on protein or B-12 or folate or any of the many
other nutrients that one shouldn't be even a little bit
short on, seems exceptionally remote. With 5,000,000,000
subjects, I can see that it might occur, but with 600,000 or
so? I think it's unlikely.
But I don't know. I can accept that the maximum CR'd human
life span isn't as high as say, Walford has argued it is:
160 or more. But that it's not even 130 or 140? I don't buy
it. It _might_ not be that high, sure, but I think the
evidence suggetss a maximum CR'd human life span of much
more than 120.