Every day around 350,000 babies are born.
Each one - utterly unique.
A few months ago this baby didn't even exist,
and the story of how it came to be against impossible odds
is extraordinary.
This is the moment of conception.
When one single sperm fused with the mother's egg.
If another sperm had got there first this baby would be someone else.
So what made that winning sperm so special?
Why did it succeed over billions of others?
To find out, we are going to take you on the epic journey sperm undertake
through the human body.
And we're going to do it by scaling the whole thing up to human size.
For the first time we will be able to appreciate
just what an extraordinary journey sperm face
as they try to reach the egg.
It's one of nature's most spectacular stories,
and it's the reason you are alive.
The sperm will face death at every turn.
There is no going back.
No surrender.
And only one winner.
Meet Glen.
Like most average men, Glen has no idea about the miracle of engineering
tucked away in his pants.
Glen's testicles, hanging freely to be three degrees cooler than the rest
of his body, are producing 1,000 sperm with every heartbeat.
And it's this tiny world of frenetic activity that fascinates the world
of reproductive science.
Sperm are quite unique because
they are free-living cells.
They almost have a life of their own.
They have but one aim, which is to deliver
the genetic payload from the male
to the female through a really quite complex
series of environments, both in the male and female reproductive tract.
Sperm move all over the place
and they like certain things,
they don't like certain things.
They are very smart little creatures in a way and they are a lot of fun
to watch in a Petri dish because they are constantly in motion.
And the fact that it's occurring at the microscopic level means that,
as scientists, we have a great deal of difficulty
studying it and observing it.
A sperm is just 1/500th of a millimetre long.
So to make things easier, Dr Allan Pacey and a team of experts
have agreed to help us scale up them and their world 34,000 times.
Along the way they'll give us practical advice on how to give sperm
the best chance of reaching the egg
or what kind of sex to have and when to have it
to maximise the chances of conception.
The first thing we asked our experts was quite simple.
In our people-sized sperm world what would a testicle be like?
The testicle is a...
roundish, oblong structure.
If we cut it in half, cut thin layers through it and looked at it
down a microscope we would see a series of tubules that you might
liken to floors of a building.
If we were to take a sperm and
scale it up to man-size
you would have to find a building that was about 1000 metres cubed.
1,000 metres by 1,000 metres by 1,000 metres.
That done, we can go inside.
Waiting in our giant testicle, an army of freshly-created sperm.
Just like the real thing, our sperm are split by gender.
Half produce boys and half produce girls.
The information needed to determine the sex of a baby
is stored in a sperm's head.
Here, we find their genetic package.
23 chromosomes of DNA, including the key gender chromosome.
Either X for a girl or Y for a boy.
Situated just below the head,
an engine of energy producing mitochondria
that propels the sperms mighty tail through the female body.
There's many millions of sperm.
You could think of it as a very large office building where there's
lots and lots of elevators and
tons of people, maybe at rush-hour, all moving in different directions.
X and Y sperm are produced in almost equal numbers.
Boys are thought to be faster but the girls live longer.
Once created, each sperm ends up
in a structure on top of the testicle called the epididymis.
A tightly coiled six metre-long tube which can hold over a billion sperm.
Imagine being crammed into a dark, winding, 200 mile pipeline with no
idea when or if you'll ever get out?
It's here, with no inkling of the horrors to come, our sperm must wait.
Their fate now will depend on events unfolding in the outside world.
In contrast to the billions of sperm produced continuously in
Glen's body...
A woman, like Emily, will produce just one egg a month.
Reaching it won't be easy.
The battle that sperm have >
in order to find and fertilise an egg is just immense.
Everything is working against sperm. They are not really given
a helping hand by the female reproductive tract.
You've got hundreds of millions of cells
that are swimming wildly about.
You've got a lot of death, you've got a lot of obstacles to overcome.
They've got to make their way through a complex series of
environments in a kind of warfare. It is warfare.
So if conception is a war, this is the theatre of operations.
From a sperm's point of view, landing in Emily's vagina
is like D-Day.
Their first objective, whilst under non-stop
attack from the female immune system, is to reach a tiny opening high above
them at the back of the vagina.
From here, they can enter the cervix.
The terrain in the cervix is completely different.
This is a dark, treacherous maze of uncharted tunnels.
The sperm will need to find a way through to the uterus.
One wrong turn and it's a slow, lonely death.
In the uterus, Glen's sperm will be looking for
a doorway just a few sperm head wide
in a vast, sterile area where, once
again, Emily's elite defence force will be waiting to take them out.
Then it's on to meet the egg. Timing is everything.
Get there a moment too early or too late and you are doomed.
Come here!
#ANDY WILLIAMS: Emily
FAINT SINGING
# ..Of silver bells, coral shells, carousels... #
Glen's sperm are just seconds away from participating in one of the most
enjoyable experiences the human body has to offer.
But what would it feel like to be propelled along a narrow pipe
covering 15 miles in less than two seconds, whether you like it or not?
For each individual sperm, this is a wet and wild, high-speed
one-way ticket to oblivion.
SCREAMS
They are not swimming, they are being forced there
by muscular contractions and by peristaltic contractions.
From the point of view of the man it's a very pleasurable experience.
But let's think about it from the point of view of the sperm.
EERIE MUSIC
250 million genetic couriers are about to invade Emily's body.
Within minutes most of them will be dead.
Millions of Glen's sperm have just entered Emily.
They are embarking on an epic quest to find and fertilise an egg.
ALL: Arghhhh!
There can be only one winner
but what chance does an average sperm have of succeeding,
and is there anything Glen can do to help his sperm along?
To find out, we need to look more closely at the state of our seed,
a ritual men like Dr Allan Pacey have performed on themselves
since the invention of the microscope.
I was in my mid-20s and I was a researcher
before I plucked up the courage
to produce a sample of my own semen and look down the microscope.
I remember the first time, looking down a microscope,
I was just blown away. I almost fell off my chair.
I remember having to walk around the lab and go back
and look down the microscope again. "Has that really come from me?"
It was just an incredible sight.
The incredible sight of the sperm cell was officially discovered
in 1677 by a Dutchman called Antoine van Leeuwenhoek.
The godfather of microbiology,
Leeuwenhoek built some of the earliestmicroscopes,
offering him the first, if slightly unclear image,
of what he called animalcules, which he theorised
contained the nucleus of a human
and had a tail equipped with joints, tendons and muscles.
Later, other early microbiologists believed they could see
tiny fully-formed people stuffed into each sperm head.
Modern scientists, of course, have a much clearer view.
But they might wish they didn't
because thanks to the quantity over quality nature of sperm production,
a long, hard look at anaverage ejaculate today
gives us the first clues asto why men need so many sperm.
Of the many millions of sperm that are ejaculated,
we've got a huge range of different types.
If we were to look at them down a microscope, you would see some sperm
that were hardly moving at all, just twitching,
or some sperm that would appear dead and may well indeed be dead.
If you looked at their shape you would see sperm with large heads,
you'd see sperm with small heads, you may see sperm with two heads.
In an average fertile man,
only 18, 19, 20% maximum of his sperm will have a nice size and shape.
The rest, the other 80%, really aren't gonna get anywhere at all.
To succeed in the race, sperm must be as fresh
and numerous as possible.
Any older ones won't make it past the starting blocks.
And as they decay, they will release substances
that can actually harm younger sperm.
What is inappropriate is the fact that the man may be denied by his
wife from ejaculating for three weeks prior to the fertile window in this
bizarre thought that they're gonna be
supersperm and huge numbers of them. That would be the wrong thing to do.
So is the right thing to do to ejaculate as often as possible?
Apparently not.
If a man is ejaculating too frequently, then the sperm production
process and the sperm stores simply won't contain enough sperm.
So just how regularly should a couple have sex to make sure
his sperm are match-fit?
If a couple is having intercourse
every two or three days throughout the month,
then they will hit the fertile window at some point, and their
probability of conception is probably as good as it could be.
Now, ready or not, Glen's sperm begin their quest for conception
in the vagina.
Their objective, to find the entrance to the cervix,
high above them at the vagina's farthest reaches.
From the perspective of a sperm,
the vagina is like avast mountain range.
It's an enormous and awe-inspiring place.
Five miles deep and two miles wide,
flanked with vast vaginal walls up to one mile high.
Leaving the thick semen armour that protected them for landing,
it's time for Glen's sperm to make a break for the cervix.
The great advance has begun.
But it's not just the epic terrain in the vagina or even
their own physical failings that now pose a mortal threat to sperm.
Everything in the vagina is working against sperm's survival.
There's only a matter of minutes between sperm's arrival
and potential death.
Sperm face attack from every angle.
The use of intimate lubricants and even saliva here can render
a sperm lifeless in minutes.
Worst of all, thanks to the female immune system, the vagina is coated
with deadly acid.
The acids are there to kill any invading force,
and I think that's a really important point to recognise.
Cos as far as the female is concerned,
sperm are an invading force.
They're foreign cells. They could be there to cause damage,
they could be there to spread infections.
They're foreign cells to her,
and as far as her immune system is concerned, they need to be destroyed.
Within 30 minutes ofentering the vagina, over 99% of sperm
will be dead or dying.
For our sperm people, it would be a scene of devastation.
A few million survivors press on into the dark side of the vagina.
Desperate to somehow escape death by reaching the cervix high above them.
But the entrance is out of reach.
Now, to avoid total annihilation,
Emily's bodyneeds to come to the rescue.
To understand how, meet Zita West.
Zita is a midwife who specialises in helping couples conceive
using natural methods.
And she knows the odds of any sperm at making it past the vagina
are slim at best.
For most of the month, these sperm aren't going anywhere, you know?
The female body isn't allowing them to.
Her cervix will be shut and there will be a plug of mucus there
that's stopping any sperm getting through.
But there will be an opportunity when a lifeline is given to enable
the sperm to actually reach the egg.
And that lifeline is the egg itself.
The cervix is usually sealed to protect the inside of the body
from anything nasty.
But as ovulation approaches, oestrogen surges through the female
body, causing the body's mucus to undergo a radical transformation.
So this is what the sperm will be hoping for, it's the same consistency
as cervical secretions.
And these secretions will be coming from the cervix into the vagina,
forming channels for the sperm to be able to swim up.
Now, these secretions are alkaline and they contain salts and sugars
which will nourish the sperm and give them energy on their journey.
This is the first sort of fitness test, if you like, for the sperm.
Not all the sperm will be able to swim up here.
It will depend on the healthiest, the fittest, the fastest swimmers.
Some that are more abnormal in the shapes of their heads etc, won't be
able to fit into these channels, to be able to swim up as easily.
Back in our people-sized sperm world,
what would this fitness test compare to?
Well, what if your lifedepended on climbing a ladder...
..a ladder stretching over a mile into the sky?
It's a long, gravity-defying climb,
but only a tiny fraction ofsperm will be able to manage.
For the 60,000 or so that do, it's out of the frying pan
and into the fire.
Now they must endure stage two of their quest... the cervix.
The objective here, to push four centimetres
to the other side and reach the wide open space of the uterus.
Sounds simple, until we take a closer look at the terrain.
The cervix is, quite simply, sperm hell.
It's lined with tens of thousands of tiny branching tunnels,
most, roads to nowhere and some just a single sperm head wide,
where the vast majority, if not all of Glen's sperm, will get crushed,
trappedand ultimately face a slow death.
Nature does have a selection process in the cervix.
It is selecting sperm that are well made.
It would be a bit like me,
dressed as a sperm, trying to climb a staircase that's a kilometre high.
I'm defying gravity, I'm going against the flow,
and when I get to the top,
I find that I've gone down the wrong staircase
and I should've gone down another one.
Our sperm must fight their way, crushed among thousands of others,
up through a twisted, nightmarish urban environment.
Only 1% of sperm that make it into the cervix
have any chance of making it out alive.
But could the performance of Glen's sperm be affected by his performance
between the sheets?
This woman thinks so.
As Dr Joanna Ellington knows, an average fertile, healthy couple,
has just a one in five chance of conceiving every month.
And for her, success depends on the quality of the sex they're having.
The better the sex, the better your chance of conception.
One of the things that a lot of men don't realise
is that the more excited they are,
the further back in the testicle they're gonna draw on reserves.
So if you have what I like to call gourmet sex, where you really spend
time and you really make it fun for both partners, that is gonna make
the man more excited, more stimulated,
and he's gonna ejaculate more sperm,
and they're healthier sperm.
Research shows that men enjoying 'gourmet sex'
can ejaculate up to 50% more sperm.
Good news for Glen.
But what about Emily?
Could more fun in bed for her help the chances of conception?
Nineteenth century evolutionary psychologists believed the purpose
of female orgasms was to keep a woman lying down longer after sex,
keeping sperm in the body
and increasing her probability of conception.
More recently, it's been suggested the female orgasm evolved to create
a stronger bond between lovers, increasing the chances of the couple
staying together after a child is born.
Nice theories but there's never been any actual evidence
to support the idea that female orgasm
had any functional relevance whatsoever... until now.
I happen to be a fan of female orgasm myself
and that's from a physiological standpoint as well as a personal one.
What happens during female orgasm is the pH in the vagina
actually is elevated some,
there's some changes in the ion concentration and there
are contractions that help pull the sperm up into the female's body.
Strangely, this remarkable theory has been supported by a Danish study
into the sex lives of pigs, creatures with reproductive
systems almost identical to ours.
We don't know if a pig's having an orgasm or not, but we know that if we
stimulate their clitoris when they do artificial insemination,
we can increase pregnancy rates.
Some people mistakenly think that female orgasm is bad for conception.
There's certainly no evidence of that.
In fact, the evidence would suggest that it's a good thing to have.
Luckily for Glenn, 3,000 of his sperm are both fully fit
and manage to avoid getting lost.
But as the female immune system
prepares to mobilise its elite assassins,
the Great Sperm Race is about to get even tougher.
Inside an unsuspecting woman, the great sperm race is under way.
Our army of sperm, unstoppable by sheer force of numbers,
have fought their way through the mountainous terrain of the vagina
and squeezed through the tight passageways of the cervix.
Getting this far has cost many lives.
Now just 3,000 sperm remain.
The adventure continues, thanks largely to the fact
that Emily is ovulating.
So, is it a coincidence this couple had sex at the perfect moment
during her most fertile and sperm-friendly monthly period?
This man doesn't think so.
For evolutionary psychologist Geoffrey Miller,
nothing in the great sperm race happens by accident.
'The sperm didn't get there by chance.'
The woman's body and brain has arranged for it to be there.
It's made choices in its life, in its mate search,
in its discrimination between male partners,
in its sexual behaviour, that led to the sperm being there.
Female choice runs evolution, largely.
Unlike men, who can produce millions of sperm every day,
women are born with all the eggs they will ever have...
about a million.
By menopause, that number has fallen to zero,
making them the most important commodity in the natural world.
A fertile egg from a healthy, intelligent egg donor costs about $30,000 on the open market.
If you take the size of the egg,
that adds out to about $1,000 trillion per pound.
So, even in strictly economic terms,
a fertile egg is rare, it's special, it's valuable.
Each egg is made even more precious
because one will appear for just a few days per month.
Many female animals make the most of ovulation by experiencing oestrus,
where their physical appearance, scent and behaviour will change
to advertise their fertility.
Geoffrey Miller believes women do the same thing.
It used to be thought that humans uniquely lost oestrus,
that human females don't go into oestrus when they ovulate,
that somehow we have this pair bond that trumps oestrus.
But in fact, the new research is showing
human females do go through oestrus.
It serves exactly the same functions that it does for other mammals.
All the same hormones, all the same psychology is still right there
under the surface of human culture.
So, could women effectively go on heat every month?
Could their reproductive systems be unconsciously controlling their actions and men's responses?
Miller believes so, and to prove it,
he and his team at the University of New Mexico have carried out some extraordinary research...
at a gentleman's club.
We know that lap dancers' earnings fluctuate a lot, so it seemed like
an ideal set-up for being able to ask them,
"How much have you earned night by night, shift by shift?",
and to be able to track that in relation to where they are in the menstrual cycle.
And we thought that was a pretty cool way of quantifying female attractiveness to males.
The dancers provided Miller's team with information about their earnings and menstrual cycles
over a period of 300 work shifts -
the equivalent of about 5,000 lap dances for their male customers.
The results were surprisingly strong.
I was amazed at how strong the effects were,
that the women in oestrus were earning about twice as much
as they were earning when they were menstruating.
If you're ovulating, you're a lot more connective to men,
you're earning higher tips, you're getting called over for more lap dances.
Miller's research suggests a link between female ovulation
and attractiveness to men.
But if women are unconsciously controlling men's actions once a month, what actually happens?
They're more sexually proceptive, higher sex drive,
more interest in sex. They dress in more stylish and revealing clothing.
Their voice pitch gets more attractive to men.
Breasts become more symmetrical.
The waist to hip ratio changes so that waists get relatively thinner.
There are also changes in smell, so that a woman's scent will become
more attractive to men during oestrus.
So, with a little help from the unconscious power of ovulation,
the great sperm race continues.
250 million of Glen's battling sperm entered the vagina.
Just 3,000 have made it through the dark, twisted hell of the cervix,
which now opens out into an environment that is altogether different.
As sperm expert Dr Allan Pacey knows,
if you or I were a sperm, entering the uterus would be quite a sight.
From a sperm's point of view, the uterus represents a vast plain
across which they have to navigate and find at the other end
quite a tiny opening that will lead them through to the fallopian tubes.
Scaled up to sperm people size, the uterus becomes a large area of
open countryside two miles long and around half a mile wide.
For our sperm, finding the entrance to the fallopian tubes,
just a few sperm-head wide, is like looking for a needle in a haystack.
Once again, it's ovulation to the rescue.
Ovulation occurs on one side one month, the other side another month.
So, on the times that the egg is going to be ovulated
from the ovary on the left,
the uterus seems to preferentially move material to the left-hand side.
So the sperm are probably carried to a large degree by these muscular contractions,
and moved through the uterus relatively quickly.
But on this journey, nothing is ever that easy.
Glen's sperm are about to discover they are not alone.
They're running straight into an ambush.
The primary function of the uterus is, of course,
to receive the developing embryo should conception occur,
and to gestate the foetus throughout pregnancy.
It's not really designed for sperm. It's designed for something else.
It will almost certainly begin to contain leucocytes
and the immune response will be mounted to try and mop up sperm
and to try and kill the sperm before they get to the fallopian tubes.
Leucocytes are the assassins of the female body,
blood cells commanded into action by the immune system,
massing into the uterus in their thousands with murderous intent.
In comparison to sperm, leucocytes are quite large,
they're big cells, they often hunt in packs, they will detect a sperm
and many leukocytes will descend upon the sperm and encapsulate it
and dismantle it slowly.
For the female body, of course, leukocytes are wonderful and essential things,
fighting disease and harmful foreign materials.
But let's try and imagine them from the perspective of a trespassing sperm.
Once again, Glen's sperm face utter decimation,
as thousands are killed by Emily's immune system.
Just a few dozen lucky ones reach the entrance to the fallopian tubes...
only to find there is a strict door policy.
Sperm have to display the correct swimming characteristics
in order to get through that utero-tubular junction,
and any sperm expressing a very random form or motion is probably excluded.
There's also potentially a molecular recognition system there,
so only sperm that are expressing the right molecules actually are allowed through.
Sperm have faced death and destruction in the uterine cavity,
the leukocytes have been trying to kill them along the way,
and only a lucky few in comparison to the many millions that are ejaculated
initially actually make it into the fallopian tubes, where finally they get to sperm heaven.
# SIGUR ROS: Festival
Welcome to one of Emily's fallopian tubes,
ten centimetres of what can only be described as paradise for sperm.
The environment of the fallopian tube is just very accommodating for sperm.
It's what sperm have been aiming for and it's set up to try and maintain sperm health,
and they can have a rest.
It's got nutrients for them, it's got the right pH,
it has the right ion concentration.
Some of these sperm will actually bind to the fallopian tube cells.
Their membranes will become very closely associated
so that the fallopian tube cells can pass them nutrients and sugar
and protect those sperm.
Scientists believe, with no immune system trying to kill them,
sperm can blissfully hang around in the fallopian tubes for hours,
even days.
But ultimately, it's hard to know for sure.
At the farthest reaches of the reproductive tract,
the fallopian tubes are very difficult to study,
so difficult, in fact, some scientists are willing to go to extraordinary lengths.
When I was done having children, I chose to have my tubes tied,
and I told my doctor that I wanted to do an experiment
where I had intercourse before I had the surgery
and then she was to cut out that section of my fallopian tubes
where the sperm are stored so that I could look at them under the electron microscope
and count how many sperm were there.
So, it was pretty humorous because I'm coming out of anaesthesia
and I was like, "Did you get it? Did you get it?",
cos no-one had ever done this before.
There were about 20 sperm in my tubes that we counted.
Thanks to such dedication, we now have a clearer sense
of what happens during the final stage of the voyage to the egg.
The sperm's objective, to wait for the egg to appear ahead of them,
find it, swim through its outer layer
and be the first to reach its inner core and seal victory.
But how will they know when the egg has been released from its follicle?
We're just beginning to understand this, but there are receptors
that communicate between the egg and the sperm,
and the sperm smell the egg.
They're able to sense where that egg is. And you can even see this
in the Petri dish when you're doing in vitro fertilisation.
If you put an egg in there,
boy, those sperm just right away orient themselves towards that egg.
They're not wandering aimlessly around the dish hoping to encounter it.
It's not left up to chance. They know what they want to go find.
It's believed sperm wait in the fallopian tubes until they pick up an irresistible scent signal,
which intensifies as the egg draws near.
One study has shown the scent attracting the sperm smells just like lily-of-the-valley perfume.
The egg basically lays out a red carpet and asks the sperm,
"This way. This is where you want to go. This is the end of your journey."
So, instead of swimming backwards into the uterus,
they head straight up that fallopian tube right to the egg,
and that's how that final step of the sperm race is won.
Back in the scaled-up world of our great sperm race,
an egg is finally released,
making its way towards one end of the fallopian tube.
The finish line is tantalisingly close,
and from here on in, timing is everything.
She has no idea,
but Emily could just be minutes away from being pregnant.
Beating incredible odds,
Glen's sperm have fought their way through her body and have reached
one of her fallopian tubes where, hopefully, an egg will be waiting.
Just single figures have made it this far.
Scaled up to people size,
what happens next?
Imagine an Olympic freestyle swimming final
where the winner gains immortality and the rest are killed.
Scent signals released during ovulation will make the sperm
hyperactive, giving them the ability to actually fertilise the egg,
shedding layers of proteins in a process called capacitation.
Up until now, they've been swimming in quite straight lines,
but now their swimming becomes much more erratic.
That tail beat will give them power
and proportion in order to get through the outer coat of the egg.
All of a sudden, they are 100% on target.
They want to find that egg,
they want to penetrate that egg and it is a race to the finish.
Once they capacitate, sperm die
within just a few hours. So it is no going back.
On the sperm-people scale, the egg drifts just a mile or so ahead,
but as our reproductivescientists can testify, the egg's 24-hour
lifespan will present the sperm with one final, fatal hurdle.
What needs to be kept in mind
for this whole great sperm race...
is timing.
Timing, timing, timing.
The egg has a limited lifetime.
What if the egg arrives a little earlier?
It wants some sperm to be able to capacitate relatively early.
What if that egg comes in a few hours from now or another day?
You don't want all of the sperm to be capacitated
at the beginning because they're going to die.
Having arrived hours before the egg,
these sperm reach the end of the line,
falling into the abyss beyond the fallopian tubes.
Behind them, just two heroic sperm remain,
all that survives of a quarter of a billion.
These two, a Y-chromosome bearing male sperm
and an X chromosome female, left Glen's testicles 14 hours ago.
SCREAMING
DRAMATIC MUSIC
They've endured an incredible journey,
and against overwhelming odds...
they've got their timing just right.
At the farthest reaches of Emily's reproductive system,
the egg is waiting.
If you or I were a sperm,
the egg would soar into the sky as high as Nelson's Column.
During the great sperm race, there's been a great attrition of sperm
from the point of ejaculation through to the fallopian tube.
Actually at the site of fertilisation when the egg is being fertilised,
there may only be one sperm, there may be two or three.
Only very few sperm are actually fighting for that final prize.
Eventually, one...sperm
will hit the outer coat of the egg.
And this is it, this is the moment they've been waiting for.
To secure victory, all this sperm has to do now
is find a way inside.
The sperm is carrying this genetic payload for delivery.
But that genetic payload has to be able...
to get into the egg.
The way that it gets into the egg is the sperm literally blows its top.
Above the head of the sperm, there is a bag of juices, a bag of enzymes
that are really important at this stage of the process.
By touching an egg, that bag bursts and those enzymes will facilitate
the sperm in finally penetrating through the outer coat of the egg.
The great sperm race has been won.
The victorious male sperm is instantly devoured
as Glen's genetic information merges with Emily's waiting DNA.
You get this elegant dance of male chromosomes and female chromosomes
coming together, which will officially announce the fact that
that egg is fertilised and that new life has been created and development
of a new individual has started.
Just 14 hours ago, hundreds of millions of sperm
embarked on the most incredible adventure in the natural world,
an adventure that claimed all their lives.
So what made that winning sperm special?
Why did it succeed over billions of others?
When you think about the odds that any single one of us are here right
now compared to the hundreds and millions of other sperm that in that
ejaculate were left behind, there could have been smarter offspring,
more handsome, more athletic, better in every way, ones that didn't
make it because they either weren't in the right place at the right time.
Or they just didn't find their way through the cervix
or the uterilogical junction.
Or maybe they capacitated too early before the egg got there.
Or maybe they were a little too late to capacitate.
So there's just a lot of luck involved with it as well
as to which sperm is able to fertilise.
Yet one unremarkable sperm,
against odds of trillions to one,
did not die in vain.
It has given its life
to start an utterly uniquenew one.
Subtitles by Red Bee Media Ltd