
We have a pretty good idea of when humans will go extinct - ALee
https://www.washingtonpost.com/amphtml/news/wonk/wp/2017/10/06/we-have-a-pretty-good-idea-of-when-humans-will-go-extinct/
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caseysoftware
The book Black Swan counters fallacies like this reasoning.

1\. Since his example (the fall of the Berlin Wall) is a one time event
without any historical data and can only happen once, it's glorified guessing.

2\. He ignores that a bell curve is specifically for results that have very
predictable ranges. In Black Swan, Taleb calls this "Mediocristan" because the
range of height of adult human males holds roughly to a predictable range aka
we don't run into men who are 6 inches or 10 feet tall.

3\. By taking this once in a lifetime event and applying a bell curve to it -
as if the existence Berlin Wall was a gaussian event - he's trying to make
guessing look like science.

4\. After declaring it "proven", he goes on to compare it to another one time
event.. then end of human life.

If he was talking about a regular event with historical data, this may be
useful analysis but as is.. oh, he's selling a book. Got it.

~~~
tgb
On the contrary, the article never mentioned bell curve, gaussian, or normal
distribution. You're projecting your own assumptions onto it. The reasoning
may be suspect, but it makes no assumptions about distributions and you've
misunderstood it entirely.

~~~
aub3bhat
Err no you didn't get it. Actually it does use non long tail distribution see
the whole 95% figure etc. Those are assumptions about the distributions.

~~~
tgb
No, it makes no assumptions about any distribution whatsoever. This is like
Chebyshev's inequality:
[https://en.m.wikipedia.org/wiki/Chebyshev%27s_inequality](https://en.m.wikipedia.org/wiki/Chebyshev%27s_inequality)

Edit: it does make one assumption, namely that there will be a finite number
of humans ever.

~~~
caseysoftware
From that wikipedia page:

> _" Because it can be applied to completely arbitrary distributions provided
> they have a known finite mean and variance, the inequality generally gives a
> poor bound compared to what might be deduced if more aspects are known about
> the distribution involved."_

In the situations cited in the article, we are dealing with both an unknown
mean and an unknown variance and therefore an unknowable distribution. So
while Chebyshev is "weaker" than a Gaussian distribution, it's still a
distribution.

~~~
tgb
Sorry, I was not saying that the article applied Chebyshev's inequality. It's
not related at all. But it's an example of a result where you do not have to
assume that your distribution is a member of a particular family of
distributions. The result being applied here is really really general: it says
that 95% of the probability mass occurs before the point at which 95% of the
probability mass has occurred by. This is tautological. Like saying that 50%
of people are below the median - it's true without making any assumptions
about people (except that there are finite numbers of them).

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maxniederhofer
Saving you a click: with 95% confidence, humans are predicted to go extinct
between 5,100 and 7.8 million years from now.

The prediction seems neither very robust (normal distribution?), nor very
useful.

~~~
Spooky23
If only had scrolled down, I’d have two minutes of my life back!

I’m honestly surprised that this was published. This article is content free.

------
mattnewport
Something seems fishy about applying this math here. The human population is
vastly bigger today than at any point in history. We don't know how big it
will be in future. As an individual human trying to estimate your chances of
being alive today this would seem to throw off the statistics. I'm much more
likely to be alive today as one of 7 billion than 200,000 years ago as one of
probably much less than a million. On the other hand it we go on to colonize
the galaxy for a billion years I'm much less likely to be alive now than at
the peak of our galactic empire.

~~~
draaglom
That's a good point - the distribution over time should affect the answer.

I've heard this rule of thumb applied before to the same problem in a
different way - rather than assuming you're somewhere in the middle of the
time period humans exist for, assume you're somewhere in the middle of the
list of all humans in order of birth.

(This version probably makes a much more pessimistic prediction than the
article does?)

Edit: tgb got there first :)

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psyc
My bogometer started ringing immediately. The article even calls out what the
problem is, but offers no resolution or explanation of how it doesn't kill the
whole hypothesis. The problem is that the figures you get are profoundly
affected by how far you are from the start. How does this not erase all of the
presumed information content?

~~~
draaglom
I think the charitable reading is:

In the _absence of information placing you somewhere specifically on the
timeline_, assuming "I'm somewhere in the middle" works surprisingly well.

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pebers
This is nonsense. The probabilistic theory suggested might apply well to the
examples they gave of Broadway plays and world leaders in power, which both
have natural limits on their timespans, but it's not at all obvious that
applies well to guessing the length of human civilisation. Crucially that is
not well informed by its length so far; neither of the threats they quoted
earlier (nuclear annihilation and catastrophic global warming) have been a
potential factor for more than 0.1% of the 200,000 year figure they're using
as our lifespan as a species so far.

And they ask in what way we are different to Neanderthals or Homo erectus in
terms of longevity; well neither of them ever came even slightly close to
wiping themselves out with nuclear weapons, or developing space travel to
allow them to survive global catastrophes. Comparing their longevity might be
useful to predict how long we would survive from tens of thousands of years
ago when our ancestors lived in caves in Africa, but it's utterly different to
trying to predict the longevity of the civilisation we have now.

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moomin
In Sheri S Tepper's wonderful novel Sideshow (the final part of the Arbai
trilogy) a planet of (increasingly rare and nativist) baseline humans is set
up to answer the question: "What is the destiny of man?"

The answer comes back: "To become something that is not man."

Extinction itself isn't really anything to be scared of. The real question is
whether we're replaced by something better, and maybe what those superior
beings would think of us after we're gone.

(That last question is answered in one of Stephen Baxter's books with: "an
extremely successful animal that enlarged its ecological niche")

~~~
coldtea
> _Extinction itself isn 't really anything to be scared of._

It is to those getting extinct. And whether they're replaced by "something
better" or not doesn't matter to that.

Either it's you (your species) that is evolving, or it matters very much.

In a hypothetical scenario, I supposed few people would rush to go voluntarily
extinct to save the life of some more evolved (smarter, stronger, more
beautiful, etc) alien species out there.

~~~
moomin
No more than ordinary death is. Some extinction scenarios have us as the
(possibly biological) progenitors of our successors. You'd still want what was
best for your children. The ability to interbreed with baseline humans would
be at best a secondary concern.

Anyway, I highly recommend the Arbai trilogy. Grass, in particular, is a
masterpiece.

~~~
coldtea
> _No more than ordinary death is._

Yeah, I agree it's not more scary that what's considered the scariest thing in
the world, upon the fear of which whole empires have been built...

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grondilu
As pointed out by others in this thread, this is basically the doomsday
argument all over again.

It's a deep subject, and I can't pretend I know much about it, but one thing
that I'd like to point out is that this kind of reasoning is based of the so-
called "self-sampling assumption"[1], and that this concept depends of a
choice of reference class.

Even if Richard Gott is right, what he means when he's talking about "humans"
going extinct is "people that I can identify myself with" going extinct. In
other words : he can only make assessments on the existence of people like
him.

Humans are not perfect. Far from it. If anything, the existence of
exceptionally smart people like Einstein or Von Neuman prove us that it's
possible to imagine a world where everybody is at least as smart as those two.
Arguably, that hypothetical future world may very well be outside of Gott's
reference class. Such a world could result from the birth of a new Homo
species and the end of Sapiens. It could mean that machines would have
replaced us. It could mean lots of things, not all of them being necessarily
dreadful.

My point being : the doomsday argument is not exactly a prediction about the
demise of mankind, but rather one about a dramatic change of it. In a way,
it's more apocalyptic in the original sense of the world : not the end of
times, but a profound change, a new era or whatever. It's a prediction about
the end of our reference class. Or in the Kurzweilian sense, the Singularity.

1\. [https://en.wikipedia.org/wiki/Self-
sampling_assumption](https://en.wikipedia.org/wiki/Self-sampling_assumption)

------
sillysaurus3
My favorite way to end civilization would be a gamma ray burst. It travels at
the speed of light, so there's no way to know it's even approaching. And it'd
probably irradiate the whole solar system, so a Mars colony wouldn't save us.

Hmm... What are some other tempting apocalyptic scenarios? Asteroids are so
1998.

One thing that's bugged me is being born so close to the invention of nuclear
weapons. If we're a random sample in all of human history, then why were we
born so close to the birth of nukes? If humans are going to be around for
another few million years, it's a minuscule chance that we should be born
right now instead of much later.

You might think there have been a hundred billion humans born, so that logic
doesn't really work: it's a one-in-a-hundred-billion chance that we were born
here anyway. But the population is spread out in a J curve over the course of
eons. It's not evenly distributed.
[https://en.wikipedia.org/wiki/Doomsday_argument](https://en.wikipedia.org/wiki/Doomsday_argument)

It's fun to waste time thinking about such things.

~~~
tyingq
>Hmm... What are some other tempting apocalyptic scenarios?

Pretty good list here:
[https://en.m.wikipedia.org/wiki/Category:Doomsday_scenarios](https://en.m.wikipedia.org/wiki/Category:Doomsday_scenarios)

Cobalt bomb is terrifying. Doesn't require WWIII to snuff us out.

Edit: "gray goo" is also interesting. Self replicating nanobots run amok.

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francoi8
I think his argument is wrong and the fallacy comes when making the hypothesis
the is a "50 percent chance that it was somewhere in the middle portion of the
wall's timeline". It seems like a relatively reasonable assumption in that
context but it is actually very arbitrary.

Imagine applying his reasoning to any building that has just been completed.
Say we visit it the following day, make the 50% hypothesis and then conclude
the building has a 50% chance of falling within 8 hours to 3 days. Obviously
the conclusion is wrong as vastly more than 50% of buildings last longer than
3 days. We see in this case that postulating that there is a 50% chance that
we visited the building somewhere in the middle portion of the building's
timeline was completely unreasonable - we know from experience that buildings
tend to last years.

So basically his estimation of when humans go extinct derives from a guess
that may or may not be correct and in any case seems very arbitrary.

~~~
skykooler
Another way of looking at it: instead of imagining you're at a random time in
humanity, imagine you're a random human. The number of humans on earth has
been increasing exponentially, so if you pick one at random they are most
likely going to be from the last two centuries. This skews the results by
making it more likely that the prediction is being made at this particular
point in time (or a bit later if the population continues growing), which
means that it _is_ a non-uniform sample.

------
RivieraKid
Alternative conclusion (not sure if the reasoning is correct) is that people
will reach longevity relatively soon so new people won't be born anymore.

Anyway, it's really fascinating if you think about this. We're living in
possibly the most unique and interesting century in the 200k year history of
mankind - and even in the 4B years history of life - what are the chances of
that? We're near the peak rate of technological progress.

What we consider normal, constant technological and societal progress is
unique in the big picture, it can't continue forever and will stabilize in a
few thousands years. After that, there will be long periods of stability and
little change. The year 738,842 won't be dramatically different from
1,738,938.

------
ajnin
His reasoning applied to the length of Broadway plays, or the length of
political terms, is valid because such events have been going on for a long
time, there have been multiple occurrences and they have a naturally limited
length. Many have already ended, so it can be considered that we are in a
"steady state" and statistical considerations about the events can be made. In
the case of singular events however like the extinction of the Human species
there is no such assumption. However when he uses the "95% rule" he implicitly
assumes a normal distribution of events. That render his conclusion invalid
due to use of an invalid starting hypothesis. In the case of the Berlin wall,
he was just lucky.

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arjie
Probably most productive to read the Doomsday Argument[0] Wikipedia article to
see something similar argued.

0:
[https://en.m.wikipedia.org/wiki/Doomsday_argument](https://en.m.wikipedia.org/wiki/Doomsday_argument)

------
jwilliams
I find this a specious argument.

Firstly, you should be considering the effect and not the object. The Berlin
Wall was just a wall. It was geo-politics that bought down the wall. That's
what was being predicted.

These changes tend to happen on human timelines. So arguing that an 8-year old
geo-political setup may change in the next 24 years would make sense. That's
basically saying in the next generation or two. You can throw the statistics
out.

The effects that could wipe out humanity is a relatively specific list. And
they definitely don't occur in human timeframes. You can work probabilities
off that list. You'll come up with a completely different answer.

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dghughes
>We haven't put anyone on the moon since 1972, for instance. As a percent of
gross domestic product, NASA's budget has been slowly petering out since the
late 1960s. It's quite possible that “there will only be a brief window of
opportunity for space travel during which we will have the capability to
establish colonies,” Gott wrote in 1993. “If we let that opportunity pass
without taking advantage of it we will be doomed to remain on Earth where we
will eventually go extinct.”

So only the USA and only NASA can save all of humanity?

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everyone
"But as Gott points out, our Neanderthal ancestors were around for only
300,000 years, while Homo erectus survived for about 1.6 million. They were
smarter than the animals around them, but from a longevity standpoint they
were completely unremarkable. Why should we be any different? Why should we be
special?"

Circular argument. Competition _with us_ was a factor in neanderthals
extinction.

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johansch
Non-AMP/mobile URL:
[https://www.washingtonpost.com/news/wonk/wp/2017/10/06/we-
ha...](https://www.washingtonpost.com/news/wonk/wp/2017/10/06/we-have-a-
pretty-good-idea-of-when-humans-will-go-extinct/)

------
briankelly
Sort of related is one of my favorite Wikipedia articles:
[https://en.m.wikipedia.org/wiki/Timeline_of_the_far_future?w...](https://en.m.wikipedia.org/wiki/Timeline_of_the_far_future?wprov=sfla1)

Quite a few mass extinction events to live through if we don't get off Earth.

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dlss
If I am understanding this correctly:

1\. My 1 year old cousin is likely to die somewhere between ~1.1 and 2 years
old.

2\. My 96 year old grandfather is likely to die somewhere between ~100 and
~2000(!) years old.

Naively I would have thought my 1 year old cousin would outlive my
grandfather. I'm really glad I found this math to set me straight! Thank you
OP!

~~~
cjalmeida
You forgot the big caveat. The math only makes sense in absence lifespan prior
information.

You know the average lifespan of a person. You don't know the average lifespan
of civ building species or one of a kind political constructions

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rqs
Problem is this _prediction_ can be effected by almost infinite factors. And
among those factors, many of them are still unknown to us.

Which makes this sort of _prediction_ very very inaccurate.

But, well, it's fun to read and think.

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pdimitar
I didn't know applying basic algebra and common sense is book-worthy, or is
considered a professional mathematician's work.

I should become a scientist. I keep overestimating humanity.

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coldtea
Fake mediums spouting BS have committed to more accurate timeframes for things
-- and got them right too.

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Walkman
Never because of Elon Musk :)

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opvasger
Fear-mongering?

