
What percentage of people are alive today? - jonathanbgood
http://1000memories.com/blog/75-number-of-people-who-have-ever-lived
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petercooper
Not to detract from the insight but:

 _Until very recently life expectancy at birth hovered between 20 and 35
years, but in the past century it has risen to 67 years_

Most of this increase has been due to a precipitous crash in infant mortality,
rather than a soaring increase in the _median_ life expectancy. For example,
even in the 1500s it seems a well-to-do Englishman (who lived a somewhat more
hazardous life medically than even today's poor) had an average life
expectancy of 71 _if he made it as far as 21_ :
<http://apps.business.ualberta.ca/rfield/lifeexpectancy.htm>

~~~
TeMPOraL
I still don't understand why the average is used instead of median (or average
of data between the first and third quartile), when people talk about life
expectancy. It leads to misconceptions.

~~~
FrojoS
(A) It fits into peoples agenda.

(B) Most people know almost nothing about statistics. Even those who use it on
a every day base. Honestly, I'm afraid, I'm not really an exception.

I think if you have to guess between human evilness and stupidity the latter
is more likely, right?

~~~
jrockway
_Most people know almost nothing about statistics. Even those who use it on a
every day base._

The same could be said of English.

~~~
FrojoS
Not every poster here calls English his or her first language. If you send me
corrections, I very much appreciate it.

~~~
rickdangerous1
"on an everyday basis." <shared in the spirit of learning and mutual respect.
Not snark>

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astrodust
This back-of-the-envelope calculation appears to be off by a factor of two,
which isn't bad.

[http://en.wikipedia.org/wiki/World_population#Number_of_huma...](http://en.wikipedia.org/wiki/World_population#Number_of_humans_who_have_ever_lived)

~~~
robbles
this error is because of assumptions about the life expectancy, right?

~~~
jonathanbgood
Yes, their birth rate assumptions would only yield the population milestones
they suggest if the life expectancy was significantly below the reported
level.

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tel
Am I the only one absolutely terrified by that number?

Malthus wasn't wrong in principle, just in timescale. It's clear that
technologies have improved Earth's human carrying capacity, but I don't know
any method to claim that an S-shaped curve isn't inevitable.

It's sounds science fiction-ey, but I don't understand how you can see data
like this and then defund NASA.

~~~
btilly
You are not alone. If you want to get more scared, read
[http://www.amazon.com/Collapse-Societies-Choose-Fail-
Succeed...](http://www.amazon.com/Collapse-Societies-Choose-Fail-
Succeed/dp/0670033375).

Interestingly from the population statistics alone it is possible to make an
argument about the total likely future number of humans that will live. There
is debate about whether the reasoning is correct, but it is at least
suggestive. See <http://en.wikipedia.org/wiki/Doomsday_argument> for more.

~~~
ellyagg
I don't think the Doomsday Argument is that interesting. It may be trivially
true, but it doesn't tell us anything interesting or predictive. All it says
is that the chronology of human existence is too complicated for us to
calculate. That being the case, our working assumption can only be that we're
at the midpoint of our species population line. But, keep in mind that this
estimate is really, _really_ horrible, it's only virtue being that it's better
than all the others.

If someone gave you a trick coin, and you didn't know which side was favored,
you'd have to assume 50/50, even knowing that you were certainly wrong.
Knowing that one side is weighted doesn't give you any interesting information
for one toss.

If you follow the arguments for and against the DA, it's clear this isn't
about a well-defined statistical argument, but immediately devolves into
qualitative arguments about our survivability. The optimists say, well, based
on the average extinction rate it's extremely unlikely we'll die in <100
million years. The pessimists counter that we're creating technologies with
extinction level capacities very rapidly. Either way, we don't have a way of
gauging the predictive power of these claims. We can't run a controlled study
of 100 human species spans.

And that's fine, because we _need_ to argue about and introspect on the
longevity of species, but brainteasers like the DA don't further it in any
meaningful way.

~~~
btilly
_I don't think the Doomsday Argument is that interesting. It may be trivially
true, but it doesn't tell us anything interesting or predictive._

If it is true, it can let us put probabilistic upper bounds on the future of
the human race. For instance with 99.99999% likelihood I can tell you that the
human race will fail to succeed in expanding colonization of other stars. As
much as we may dream of the stars, we will never reach them.

Similarly the odds of our maintaining our current population levels for the
next thousand years is something like 40%. That is both interesting and
predictive. Its meaning, however, is highly debatable.

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riprock
i'm sure there is a more accurate prediction out there (explained in papers)
by researchers who have spent way more time and effort into this subject. for
us common folks, there's even a wikipedia answer:
[http://en.wikipedia.org/wiki/World_population#Number_of_huma...](http://en.wikipedia.org/wiki/World_population#Number_of_humans_who_have_ever_lived)

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seanahrens
Super fascinating. Definitely would never have guessed it was anywhere even
close to 12%. Wow.

~~~
willwagner
I had heard it was over 50% which i found very hard to believe so the 12%
number seems a lot more reasonable.

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baddox
I've always wondered something about evolution (or rather, speciation): how
many generations removed could an ancestor and descendant be and still be
theoretically able to mate?

I'm sure the ability to mate isn't exactly the definition of a "species," but
it seems like a decent way to get a grip on the extremely gradual genetic
changes predicted/described by evolution. This article made me ask the
question: How would you be able to recognize the "first human"?

~~~
astrodust
Since it's speculated that Neanderthals and early humans inter-bred, then it
stands to reason the gap can be pretty far apart.

There are exceptions like those with dogs where one dog may be physically too
small or too large to breed with another. I'm kind of irritated that some
claim species cannot be created when a chihuahua and a Newfoundlander could
not possibly inter-breed. If dogs like that were stumbled upon in the wild
they would obviously be classified as entirely different species.

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wbhart
This is an important computation. It's even scarier if you suppose that you
are not in any way special. It is likely that you are not one of the first 5%
of humans to ever live. Thus, given that such a great proportions of all
humans who have every lived are alive now, the implication is that the human
race hasn't got long to go _even if the population remains constant_! Or you
could just assume you are special.

~~~
jodrellblank
By that calculation, no human should assume they are in the last 5% so the
human race is immortal.

It sounds like nonsense; the people actually in the first 1% are not more
special than the people in the 43rd 1%, but you have to be somewhere in the
distribution.

No point is special in the sense that you have a stronger than usual reason to
assume you aren't there and are more likely elsewhere.

~~~
wbhart
Not really. _You_ shouldn't assume you are in the last 5%. Statistically, by
definition, it is most likely (though not certain) that you are not.

~~~
jodrellblank
That's the sort of analysis I'm questioning - it's also 95% likely that I'm
not in the second-last 5%, and the same for the third-last 5% and for any 5%
slice.

How can we usefully reason anything from a start like that?

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iskander
They never say how they estimate births_t.

~~~
jonathanbgood
We use the world population and average life expectancy to calculate births in
a year. To connect these point estimates at the varying times in history we
use a bounded exponential growth model for births.

~~~
iskander
I'm still not completely getting it. Let's say in some year there are a
billion people alive and the average life expectancy is 50 years. How are
these two pieces of information sufficient to determine how many children were
born in that year?

~~~
amalcon
You also need the previous year's population. With population and life
expectancy, you can approximate the per capita death rate, and then it's a
straightforward linear equation.

~~~
a-priori
What about infant mortality? If a million babies are born in the year 234BC,
and die before 233BC rolls around, they won't be counted in the population for
either year.

~~~
iskander
That's what I'm wondering about. The infant mortality rates in pre-industrial
times were astoundingly high, but I don't see anything that tries to
explicitly account for them. I guess they get rolled in with life expectancy
(bringing the mean way down), but it would be nice to see an explicit formula
for births_t.

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Detect
This is great info if there ever is a zombie apocalypse. Eight heads each
people.

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melling
Now if we could get every person educated and productive, we could solve tens
of billions of problems. Unfortunately, most people are just trying to
survive.

~~~
Unseelie
We'd also have to give them problems to solve outside of 'how do I raise my
children' or 'feed myself' or 'entertain myself'...or is that what you meant
by productive?

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ck2
It's an ugly thought but I think more people than ever are trying to create a
biological retirement plan - having multiple children to take care of them
later on.

Trying not to make a moral judgment call on that and hoping I am just being
too cynical. But think about how many people you know with children and then
count the number that have conscientiously chosen to have only one.

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Confusion
I fail to understand why this is of interest. The number doesn't tell you
anything. If only 600M people were alive to today, the number would be a
factor of 10 smaller. So what? You can't distill any meaning from the number.
It doesn't predict anything, doesn't spell out opportunities, doesn't explain
anything. It's a synthetic numerical fact, as constructed and unrelated to
anything Real as the fact that the length of my thumb is exactly 1.5% of the
height of the Eiffel tower.

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aquarin
What 200,00 BC mean, 200,000 BC?

~~~
dennisgorelik
The author made that error 3 times (cut&pasted wrong chart).

~~~
jonathanbgood
Thanks for pointing it out - we fixed this to 200,000 B.C.

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jleyank
I'm pretty sure I'm alive today, although some may have their doubts on Moday
morning...

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georgieporgie
I thought that 'humans', as in, you would see one and say, "yeah, that weird
looking guy over there," went back about 2.2 - 2.3 million years.

<http://en.wikipedia.org/wiki/Human_evolution>

Populations would have been small, but an extra 2.1 million years is a long
time.

~~~
ANH
There have been catastrophic events in that time that some believe acted as
population bottlenecks, in particular the Toba eruption 70,000 years ago:
<http://en.wikipedia.org/wiki/Lake_Toba>

Of course, there is much debate about the effect this had.

[edit] In a recent Seminar About Long Term Thinking, a biologist said that
there is evidence the human population was reduced to a few thousand by the
Toba event. That is the extent of my knowledge on the subject.

~~~
b_emery
Quote from that link:

"There is some evidence, based on mitochondrial DNA, that the human race may
have passed through a genetic bottleneck around this time, reducing genetic
diversity below what would be expected from the age of the species. According
to the Toba catastrophe theory proposed by Stanley H. Ambrose of the
University of Illinois at Urbana-Champaign in 1998, human populations may have
been reduced to only a few tens of thousands of individuals by the Toba
eruption."

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lwat
Wikipedia lists the total number of people to ever live at about 115 billion,
which means 6% of all people are still alive today. 12% is too much.

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nivertech
Funny, that they have a cloud in their logo.

