
What Are The Chances That You Would Be Born? - kloncks
http://blogs.law.harvard.edu/abinazir/2011/06/15/what-are-chances-you-would-be-born/
======
alphaoverlord
This brings to mind the excellent Feynman quote:

“You know, the most amazing thing happened to me tonight. I was coming here,
on the way to the lecture, and I came in through the parking lot. And you
won’t believe what happened. I saw a car with the license plate ARW 357. Can
you imagine? Of all the millions of license plates in the state, what was the
chance that I would see that particular one tonight? Amazing!”

The point that Feynman was trying to make is that you can’t just hunt for
anomalies after the fact and then say they are somehow significant. You have
to make predictions and do the test and see if those predictions bear out. In
the same way it’s not amazing (at least statistically, although perhaps
biologically) that any one person is born. It’s just like that license plate.
Of course, the license plate ARW 357 is one of millions of possibilities, but
that doesn’t mean that it’s amazing every time you see a license plate.
They’re all one of millions, and it has to be one of them.

I came to say that, but it's eloquently copied from:
[http://surplusgamer.tumblr.com/post/1114853865/derren-
brown-...](http://surplusgamer.tumblr.com/post/1114853865/derren-brown-
statistics-and-richard-feynman)

~~~
sage_joch
No one places much significance on the random people who win the lottery. But
if that random person happens to be _you_ , you feel incredibly lucky (and
rightfully so).

~~~
jackowayed
But if you hadn't been born, you wouldn't be alive to ponder the probability
of being born.

While it may still feel lucky to exist, the probability of you being born
given that you are asking the question is 1.

~~~
acangiano
I find your attitude to be very "artificialist". Advanced AI programs may
ponder the question. :)

------
jodrellblank
It's a meaningless "probability" on several counts.

1) It applies to everyone reading it, and it would apply to me if I were
different and reading it. It tries to convey a specialness which doesn't seem
to exist. If a billion people win a penny each then winning a penny isn't
miraculous, even if it is a 1 in 1,000,000,000 chance that you win any
_particular_ penny - but the 'particular' part has no significance.

2) I _am_ reading it, so my existence probability is ~1.

3) I wasn't waiting in the wings somewhere with a dice roll choosing whether I
would be born or not, I am what was born to and raised by my parents. Birth
and youth happened before "I", not the other way around.

~~~
xianshou
I appreciate point #2: "The probability that I exist, given that I exist, is
1."

However, the question addressed by the OP is not "What is the probability that
I would exist in this world?" but "What is the probability, across the space
of all possible continuations of the world from the dawn of humanity, that the
world would end up in a state that includes me?"

~~~
hugh3
But given that "me" includes all my experiences as well as my genetics, we
have to throw the probability of all _those_ into the equation as well.

At the very least, if you're going to take these sorts of calculations
seriously you're going to have to ask what the probability is not only that
_I_ exist, but that everyone I've ever met _also_ exists.

------
rosser
This reminds me of a bit from the introduction to "A Short History of Nearly
Everything", by Bill Bryson. To wit:

"Not only have you been lucky enough to be attached since time immemorial to a
favored evolutionary line, but you have also been extremely — make that
miraculously — fortunate in your personal ancestry. Consider the fact that for
3.8 billion years, a period of time older than the Earth's mountains and
rivers and oceans, every one of your forebears on both sides has been
attractive enough to find a mate, healthy enough to reproduce, and
sufficiently blessed by fate and circumstances to live long enough to do so.
Not one of your pertinent ancestors was squashed, devoured, drowned, starved,
stuck fast, untimely wounded or otherwise deflected from its life's quest of
delivering a tiny charge of genetic material to the right partner at the right
moment to perpetuate the only possible sequence of hereditary combinations
that could result — eventually, astoundingly, and all too briefly — in you."

That said, the calculation is exactly as meaningful as the Drake Equation: you
can plug in wild variations in equally "probable" values for the several steps
in the equation, yielding staggeringly divergent end results, all of which
mean precisely fuck-all, because nearly every number is little better than a
wild-assed guess.

It's an interesting thing to think about, certainly, and a great way to remind
yourself how stupendously fortunate you are to have been given the incredible,
inestimably valuable gift of being, but in the end, it's naught more than
sophistry dolled up in an equation that passes muster as well as a 16-year old
kid using an fake ID saying he's 35.

------
biot
You think that's impressive? 14 billion years ago a big bang occurred and
particles too numerous to count were unleashed. Throughout all that time,
these particles danced a particular pattern and interacted with each other
through quantum effects that we don't even fully understand today. Just think
of all the collisions that have occurred between all the particles in the
universe; the ebb and flow of forces acting on the smallest of every single
subatomic particle and quantum of energy that exists.

Looking at it from a macro perspective these particles, energy quantums, and
forces have resulted in innumerable acts of learning and knowledge. People
more learned than you and I have developed all manners of science and
technology. Wars have been fought. Nations conquered. Virulent plagues
unleashed with millions of people dying. A veritable tapestry of human
achievement has been women together due to the interactions of countless tiny
little particles, bundles of energy, and forces.

And all this rich history of the universe has been building up like a
fantastic crescendo in the most amazing symphony every conducted, culminating
in a singular event so that here and now I would post this comment on Hacker
News. What are the odds of that?

~~~
VladRussian
just 2nd law of thermodynamics at work.

------
_pius
<http://en.wikipedia.org/wiki/Anthropic_principle>

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

~~~
dennisgorelik
Exactly.

But let assume that newborn with your exact genes was born.

What are the chances that your conscious would occupy that body?

------
geezer
Probability is whatever you want it to be if you are allowed to pick the
sample space of your choice.

------
Jun8
Interesting thing is that when people are faced with a very rare poker hand,
e.g. a royal flush, they go "OMG, what's the probability of _that_ happening",
without thinking about the fact that _any_ hand they are dealt has a similar
low probability, e.g. there are 1,302,540 no pair hands
(<http://en.wikipedia.org/wiki/Poker_probability>), so the probability of your
uninteresting, stupid hand being dealt is 1 in 1.3 million!

It is us who give meaning to probabilities and deem some events as interesting
and others not.

~~~
tansey
But people think that way because of the utility of the hand. Worthless hands
are abstracted into the same category (junk) because they all have about the
same value. A royal flush, however, has by definition a guaranteed value with
no risk involved. You cannot lose with a royal flush, thus the variance is 0,
which is the rarest of all things at a poker table.

------
bumbledraven
The Buddhist parable of the blind turtle is actually a metaphor for how long
it takes to be reborn as a human after being reborn as a non-human.

"Suppose a man threw into the ocean a yoke with one hole in it, and then the
east wind blew it west and the west wind blew it east and the north wind blew
it south and the south wind blew it north; and suppose there were a blind
turtle that came up to the surface once at the end of each century. How do you
conceive this, bhikkhus, would that blind turtle eventually put his head
through that yoke with the one hole in it?"

"He might, Lord, at the end of a long period."

"Bhikkhus, the blind turtle would sooner put his head through that yoke with a
single hole in it than a fool, once gone to a lower realm, would find his way
back to the human state."

M. 129

[Nanamoli, The Life of the Buddha, p. 250]

As the post says, the probability of the turtle surfacing with his head in the
yoke on any one try is about 10^-15. Since the turtle tries once per century,
the expected length of time as a non-human is 10^17 years, or 10 million times
longer than the amount of time since the most recent Big Bang. It's actually
kind of cool to visualize this. Let one penny represent the amount of time
since the Big Bang (about 10 billion years). Then here's a picture of the
amount of pennies representing the expected length of time as a non-human:
<http://www.kokogiak.com/megapenny/seven.asp>

------
autarch
This is a fun thought experiment, but I think it over dramatizes the reality.

There's a huge potential set of humans, of which the current population
represents one infinitesimally tiny subset of that potential set. But there's
a lot of people, and the fact that one of them is you is largely unremarkable.
If it hadn't been you, it would've been someone overwhelmingly similar to you.

In other words, we're not unique snowflakes. Humans are more alike than they
are different, so don't get so excited about the miracle of your existence.

~~~
rooshdi
_If it hadn't been you, it would've been someone overwhelmingly similar to
you._

Yet still not you.

------
alexkearns
The chances of a pack of cards being dealt out in a particular order are
incredibly low (I'll leave it to the math's whiz kids to work out exactly how
low) but you would hardly say it was a miracle if they came out in that order.
Same with the chances of you existing. Things are always going to turn out
some way, even if the likelihood of that outcome is very low.

Or in other words, the chances of the outcome having a very low probability
are very high.

------
eldina
I am not yet able to convince myself that the question actually makes logical
sense.

------
knodi
Very good really. Because mutations in sperms are very low. So out of the
million or so sperm running the rat race to the egg they all hold basically
the same info 50% (DNA) of you from your father and the egg will hold the
other 50%(DNA) of you from the mother that will make 100% you. Environment
factors will play relatively the same if spermA or spermB had made it to the
egg. Only other factor is that the role of environment based on if the egg
developed as a male or female factor.

~~~
gus_massa
During the production of sperms (and eggs), one of the steps has crossover:

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

They get new chromosomes that are a combination of the two corresponding
chromosomes from the father (or mother). The exact points in each chromosome
where the crossovers happens are different (perhaps almost random), so each
one of the sperms (eggs) is a very different unique snowflake.

(And there are also a few mutations that make them slightly more unique.)

------
altrego99
There is another angle through which you could attempt to determine the
probability of you existing. It's by dividing number of people on Earth today,
by total number of genetic permutations possible. Of course that would remove
cultural factors from the equation... but calculating actual probability of
cultural factors are pretty damn hard!

~~~
gus_massa
It’s more complicated and this is really not my expertise area, but let’s
mixes some random numbers from Internet. (Mostly from:
[http://en.wikipedia.org/wiki/Human_genetic_variation#Measure...](http://en.wikipedia.org/wiki/Human_genetic_variation#Measures_of_variation)
)

The total number of bases in human DNA is ~3E9, so there are 4^3E9 ~= 10^2E9
possibilities. But this number includes a huge kind of variations, from humans
to cows, to whales, to bats, to cats, to algae, to fungus, to pines, to orange
trees, to roses, to petunias, to artichokes and probably even to vulcans, and
to unicorns :). (Different species have different number of bases in their
DNA, but all the eukaryotic cells have the same order of magnitude, so we will
just ignore this fact.)

If we consider only _single nucleotide polymorphisms_ , the difference between
two humans is in only 1/1000 of the bases (and let’s suppose that in each case
the difference is in the same bases, and that the variations are independent)
. So with this restriction there are 4^(3E9/1000)~=10^2E6 "possible" humans.
Using that the total number of people that have ever lived is estimated as
10^11, the probability is 10^11/10^2E6 ~= 1/10^2E6.

But, please, don’t take these numbers very seriously.

------
endtime
I saw a license plate today that said "ERN645W". Isn't that amazing? The
chances were 1/78,364,164,096!

------
jimworm
If you’re reading this, your probability of existing is 1. The probability of
all known-to-have-happened events to have happened is always 1.

Of course, that assumes that the knowledge is correct; but even the most die-
hard skeptic can be absolutely certain that they themselves exist.

~~~
jodrellblank
_but even the most die-hard skeptic can be absolutely certain that they
themselves exist._

I could potentially be non-existing or not-me in ways that I'm not clever
enough to speculate about, let alone the ways I could speculate about
(simulation, Boltzmann brains, Dust theory, dreams).

------
praptak
This assumes that my lineage is the only one that could produce me. Which, I
believe, is wrong at least at the genetic level. As to the other levels - this
starts getting tricky, cuz we quickly find out that the definition of 'me' is
quite fuzzy.

------
ranprieur
The chance of anything is either 0 or 1. One in 400 trillion is just a number
that might have been calculated by someone with incomplete knowledge. As their
knowledge improved, their estimate of my chance of existing would approach 1.

------
martinaglv
That is a fun question to ask oneself. Ultimately, you come to the conclusion
that it is a logical fallacy. Asked this way, it would imply that there is a
pool of unborn people waiting for the right chance to come into existence.

------
MarkPNeyer
if we're using a Bayesian model, the probability is 1.

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mikbetk
There is a 100% chance that I was born.

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nevinera
100%

------
alnayyir
The probabilities used are meaningless.

Let me summarize the content:

Re: fw: re: re: re: fw: fw: fw: CHECK THIS OUT!

