__What are the chances of being born?__

Scientists calculate the probability of your existing as you, today, at about

one in 400 trillion (4×1014).

“That’s a pretty big number,” I thought to myself. If I had 400

trillion pennies to my name, I could probably retire.

Previously, I had heard the Buddhist version of the probability of ‘this

precious incarnation’. Imagine there was one life preserver thrown

somewhere in some ocean and there is exactly one turtle in all of these oceans,

swimming underwater somewhere. The probability that you came about and

exist today is the same as that turtle sticking its head out of the water — in

the middle of that life preserver.

*On one try.*

So I got curious: are either of these numbers correct? Which one’s

bigger? Are they gross exaggerations? Or is it possible that they

*underestimate*the true number?

First, let us figure out the probability of one turtle sticking its head out

of the one life preserver we toss out somewhere in the ocean. That’s a

pretty straightforward calculation.

According to

__WolframAlpha__, the total area of oceans in the

world is 3.409×108 square kilometers, or

340,900,000 km2 (131.6 million square miles,

for those benighted souls who still cling to user-hostile British

measures). Let’s say a life preserver’s hole is about 80cm in diameter,

which would make the area inside

3.14(0.4)2=0.5024 m2

Which we will conveniently round to 0.5 square meters. If one square

kilometer is a million square meters, then the probability of Mr Turtle sticking

his head out of that life preserver is simply the

area inside the life preserver divided by the total area of all oceans, or

0.5m2/3.409×108x106m2 = 1.47 x

10-15

or one in 6.82×1014, or about 1 in 700

trillion.

One in 400 trillion vs one in 700 trillion? I gotta say, the two

numbers are pretty darn close, for such a farfetched notion from two

completely different sources: old-time Buddhist scholars and present-day

scientists. They agree to within a factor of two!

So to the second question: how accurate is this number? What would we

come up with ourselves starting with first principles, making some reasonable

assumptions and putting them all together? That is, instead of making one

big hand-waving gesture and pronouncing, “The answer is five hundred bazillion

squintillion,” we make a series of sequentially-reasoned, smaller hand-waving

gestures so as to make it all seem scientific. (This is also known as

‘consulting’ – especially if you show it all in a PowerPoint deck.)

Oh, this is going to be fun.

First, let’s talk about the probability of your parents meeting. If

they met one new person of the opposite sex every day from age 15 to 40, that

would be about 10,000 people. Let’s confine the pool of possible people

they could meet to 1/10 of the world’s population twenty years go (one tenth of

4 billion = 400 million) so it considers not just the population of the US but

that of the places they could have visited. Half of those people, or 200

million, will be of the opposite sex. So let’s say the probability of

your parents meeting, ever, is 10,000 divided by 200 million:

104/2×108=

2×10-4, or one in 20,000.

**Probability of boy meeting girl: 1 in 20,000.**

So far, so unlikely.

Now let’s say the chances of them actually talking to one another is one in

10. And the chances of that turning into another meeting is about one in

10 also. And the chances of that turning into a long-term relationship is

also one in 10. And the chances of

*that*lasting long enough to

result in offspring is one in 2. So the probability of your parents’

chance meeting resulting in kids is about 1 in 2000.

**Probability of same boy knocking up same girl: 1 in**

2000.

2000.

So the combined probability is already around 1 in 40 million — long but not

insurmountable odds. Now things start getting interesting.

Why? Because we’re about to deal with eggs and sperm, which come in

large numbers.

Each sperm and each egg is genetically unique because of the process of

meiosis; you are the result of the fusion of one particular egg with one

particular sperm. A fertile woman has 100,000 viable eggs on

average. A man will produce about 12 trillion sperm over the course of

his reproductive lifetime. Let’s say a third of those (4 trillion) are

relevant to our calculation, since the sperm created after your mom hits

menopause don’t count. So the probability of that one sperm with half

your name on it hitting that one egg with the other half of your name on it

is

1/(100,000)(4 trillion)= 1/(105)(4×1012)= 1 in 4 x

1017, or one in 400 quadrillion.

**Probability of right sperm meeting right egg: 1 in 400 quadrillion.**

But we’re just getting started.

Because the existence of you here now on planet earth presupposes another

supremely unlikely and utterly undeniable chain of events. Namely, that

*every one of your ancestors lived to reproductive age*– going all the

way back not just to the first

*Homo sapiens*, first

*Homo*

erectusand

erectus

*Homo habilis*, but all the way back to the first

single-celled organism. You are a representative of an unbroken lineage

of life going back 4 billion years.

Let’s not get carried away here; we’ll just deal with the human

lineage. Say humans or humanoids have been around for about 3 million

years, and that a generation is about 20 years. That’s 150,000

generations. Say that over the course of all human existence, the

likelihood of any one human offspring to survive childhood and live to

reproductive age and have at least one kid is 50:50 – 1 in 2. Then what

would be the chance of your particular lineage to have remained unbroken for

150,000 generations?

Well then, that would be one in 2150,000 ,

which is about 1 in 1045,000– a number so

staggeringly large that my head hurts just writing it down. That number is not

just larger than all of the particles in the universe – it’s larger than all

the particles in the universe

*if each particle were itself a*

universe.

universe

**Probability of every one of your ancestors reproducing successfully:**

1 in 1045,000

1 in 1045,000

But let’s think about this some more. Remember the sperm-meeting-egg

argument for the creation of you, since each gamete is unique? Well, the

right sperm also had to meet the right egg to create your grandparents.

Otherwise they’d be different people, and so would their children, who

would then have had children who were similar to you but not quite you.

This is also true of your grandparents’ parents, and their grandparents, and so

on till the beginning of time. If even once the wrong sperm met the wrong

egg, you would not be sitting here noodling online reading fascinating articles

like this one. It would be your cousin Jethro, and you never really liked

him anyway.

That means in every step of your lineage, the probability of the right sperm

meeting the right egg such that the exact right ancestor would be created that

would end up creating you is one in 1200 trillion, which we’ll round down to

1000 trillion, or one quadrillion.

So now we must account for that for 150,000 generations by raising 400

quadrillion to the 150,000th power:

[4x1017]150,000 ≈ 102,640,000

That’s a ten followed by 2,640,000 zeroes, which would fill 11 volumes of

__a__

book the size ofwith zeroes.

book the size of

*The Tao of Dating*To get the final answer, technically we need to multiply that by the

1045,000 , 2000 and 20,000 up there, but those

numbers are so shrimpy in comparison that it almost doesn’t matter. For

the sake of completeness:

(102,640,000)(1045,000)(2000)(20,000) = 4x 102,685,007

≈ 102,685,000

**Probability of your existing at all: 1 in 102,685,000**

As a comparison, the number of atoms in the body of an average male (80kg,

175 lb) is 1027. The number of atoms

making up the earth is about 1050. The

number of atoms in the known universe is estimated at 1080.

So what’s the probability of your existing? It’s the probability of 2

million people getting together – about the population of San Diego – each to

play a game of dice with

*trillion-sided dice.*They each roll the dice,

and they all come up the exact same number – say, 550,343,279,001.

A miracle is an event so unlikely as to be almost impossible. By that

definition, I’ve just shown that you are a miracle.

Now go forth and feel and act like the miracle that you are.

Think about it.

Written by Ali Binazir