Hello, thank you very much for coming.
I'd like to begin by asking you to do something for me.
Would you, please, put your hands to your head, and very gently feel your own head.
Now, that might seem like a very easy thing to do.
But, I can assure you - okay put them down now - I can assure you that a man-made instrument that did that
would be a very, very difficult thing to make, a very, very expensive thing to make.
As your arms go up there, precision instruments in your muscles,
are monitoring the exact position of all your muscles.
Thousands of sensory endings in your fingers
are feeling the exact texture of your hair, the shape of your ears, the shape of your skull.
Your brain is measuring the width of your skull with the greatest of precision.
If a human factory were to manufacture
an instrument, a robot arm capable of doing that, it would cost something in the region, I would think,
of 100 million pounds.
Now, think about what is between your hands when you do that:
your brain.
The brain is a kind of computer, but it's a computer such as
no human factory has ever turned out.
If we ever do succeed in making a computer with the performance of a human brain,
I would guess that the research and development costs would be in the region of thousands of millions of pounds.
Yet, heads like yours, and hands like yours
are manufactured daily, millions of times over.
A woman can do it with no research,
only nine months development, and only a little help from a friend.
Life makes the wonders of technology seem commonplace.
So, where does life come from? What is it?
Why are we here? What are we for? What is the meaning of life?
There's a conventional wisdom, which says
that science has nothing to say about such questions.
All I can say is that, if science has nothing to say,
it's certain that no other discipline can say anything at all.
But, in fact, of course, science has a great deal
to say about such questions.
And, that's what these five lectures are going to be about.
Life grows up in the Universe by gradual degrees - evolution.
And, we grow up in our understanding of our origins and our meaning.
Of all the world's societies, the majority
have practiced some form of ancestor worship.
This is a totem of one particular cult of ancestor worship.
Now, I'm not going to encourage you to worship your ancestors,
I'm not going to encourage you to worship anything.
But, it is true that ancestors hold the key to understanding the meaning of life.
You might think it is easy enough to be an ancestor.
It's easy enough to reproduce, or relatively easy.
But, to become an ancestor you've got to have descendants, alive many generations hence.
And that is more of a tall order.
We can think about it by going back
to one of the simplest sorts of animals - a bacterium -
right back at the beginning of life.
And think about how many bacteria there would be
after, say, 50 generations of reproduction.
We're going to illustrate this by folding paper.
Now, I wonder if I could have two volunteers to fold the paper.
Right, there and, yes, there.
Come down here, please, and take the paper from Bryson.
Right, now, every time you fold the paper,
that's going to represent one generation of reproduction.
So, we start with one bacterium, that's one thickness of paper.
Now, fold it.
If you both hold at the same end, it might be easier.
Now we have got two.
That's right. Please, sit down there, that's right, fold it.
And then, fold it across this way.
Thank you.
And just go on folding it until you have done it 50 times.
So, what have you got to now? Four?
Four bacteria? Right, eight.
Sixteen.
Thirty-two.
What, can't you do any more?
Right, that's it probably - Alright, it looks as though they're not going to make it.
We're going to have to resort to mathematics to calculate
how thick that paper would be.
Okay, thank you very much, do sit down.
In every generation, of course,
the thickness of the paper doubles.
So, we go 2, 4, 8, 16, 32, 64,. and so on.
We go on multiplying by two 50 times.
After we've multiplied by two
50 times, what have we got?
We've got a very big number, indeed. We got, in fact,
a thousand trillion - that's one with 15 zeros after it.
The sheet of paper is a tenth of a millimeter thick.
If you multiply that by a thousand trillion, you end up with -
I've got it written down here:
100 million kilometers.
The thickness of the paper would take us out to the orbit of Mars.
The number of bacteria after a mere 50 generations is that.
But, 50 generations is nothing to bacteria;
they can get through 50 generations in a day.
After about a week, the number of bacteria would be more than
a billion times the number of atoms in the known Universe.
Well, that's called exponential growth -
what mathematicians call it exponential growth -
we'll come back to it.
Needless to say, it doesn't happen,
to the same extent at least.
After a point, natural factors come to regulate
the size of the population of bacteria.
Our original assumption
that it was easy to become an ancestor was wrong.
Only an elite become ancestors.
You can do the same sort of calculation,
by the way, for ourselves -
or, for elephants, as Charles Darwin did -
and it just takes a little bit longer,
but the same idea is there.
After a fairly short number of years,
you'll find that the entire Universe is filled with elephant flesh,
or human flesh, or whatever it is.
So, it follows
that most organisms that are born must die without becoming ancestors,
without becoming distant ancestors.
Only an elite are destined to become ancestors.
Well, some people do not like the word elite.
But, I just mean that
it won't be all luck
which ones end up ancestors.
The ones that are going to be ancestors
will tend to be the ones that are good at it.
They'll tend to be the ones that have what it takes;
that have what it takes to survive, to get a mate,
to reproduce, to avoid being eaten,
to find food, to be good parents, and so on.
That's really just a way of putting
Darwin's Theory of Natural Selection.
Because we that are left, we that survived,
will have inherited the genes of a long line of successful ancestors.
We'll have inherited whatever it took
to make them successful as ancestors.
But, for the moment, I want to emphasize something else,
which is that we are lucky to be alive.
We're lucky to be alive
because it would have been so easy for our ancestors not to have been here.
It would have been so astronomically probable that somebody else
would have been here, rather than us.
And we're lucky to be alive
for another reason.
Think about it this way:
the Universe is about 14 thousand million years old.
That's 140 million centuries.
Some 60 million centuries from now,
the Sun will become a Red Giant, and engulf the Earth.
So, there are about 200 million centuries
from the origin of the Universe to the end of the world.
Now, of the 140 million centuries since time began,
every one of them was once the present century.
And, of the 60 million centuries to the end of the world,
every one of them will be the present century.
The present century is a tiny spotlight
inching its way along a gigantic ruler of time.
Everything before the spotlight is in the darkness of the dead past.
Everything after the spotlight is in the darkness of the unknown future
We live in the spotlight.
Of all the 200 million centuries along the ruler of time,
199 million 999 thousand 999 centuries are in darkness.
Only one is lit up,
and that's the one in which we happen,
by sheer luck, to be alive.
The odds against our century's happening to be the present century
are the same as the odds against a penny
tossed out at random on the road from London to Istanbul
happening to fall on a particular ant.
Well, in spite of those odds,
you may have noticed that we are, as a matter of fact, here,
and it really, of course, it's not surprising, because
we are the ones doing the calculation.
If somebody has just done the calculation that we've just done,
then that somebody, of course, has to be alive.
Nevertheless, I do feel rather lucky to be alive,
and for another reason too.
Now, the smoke going into the beam represent stars.
Each particle of smoke represents one star.
And, you can think of the beam as a gigantic searchlight,
beamed out from space and signaling
from our planet, in the hope that somebody else
on another world will pick up the message.
We don't know how likely it is that there is anybody up there.
We can say that, if our message does hit another planet
then, almost certainly, it will be so far away
that if those people up there had a telescope looking back at us,
then what they would be seeing is not us at all,
but the dinosaurs that were here 65 millions years ago.
Or, in other words, our message will reach people millions of years into the future.
People vary in their estimates of how much life there is likely to be,
how likely there is to be life on other planets.
Some people think that, some scientists think
that as many as 10 million technologically advanced civilizations are out there.
Other people feel that this life, here, on this planet, is the only life that there is.
But, even on the most extremely optimistic estimate,
it's still true that most of those worlds out there are going to be deserts.
Most of them are not going to have any life on them at all; nor even any possibility of life on them, at all.
Now, imagine a spaceship full of sleeping,
perhaps deep frozen, explorers, would-be colonists of another world.
Perhaps they are the last population of Earth,
despairing that Earth is about to be destroyed.
Sending out a colony to look for another planet,
anywhere, in order to carry on humanity.
Imagine the spaceship
turns out to be almost unthinkably lucky.
It does chance to arrive at one of the very, very rare planets
capable of sustaining our kind of life.
A planet of the right temperature, with oxygen, and so on.
The passengers wake up and stumble out into the light.
And they see a beautiful world of waterfalls, green leaves, mountains,
colored animals and birdlike creatures flitting about.
Can you imagine how it would feel
if you woke up,
100 million years of sleep in a spaceship,
and found yourself on such a world?
A whole new world, a world such as you could live on, a beautiful world.
You'd surely bless your luck
in arriving on such a rare world,
walk around in a daze, a trance,
unable to believe the wonders that met your eyes and ears.
Well, this will almost certainly never happen to us.
And yet, in a way, it is just what has happened to us.
We have woken up after hundreds of millions of years of sleep.
Admittedly, we didn't arrive by a spaceship, we arrived by being born,
but the wonder of the planet, the dazzling surprise of it,
is the same, whether we arrived by spaceship
or by birth canal.
We are amazingly lucky to be here,
privileged,
and we must not waste that privilege.
Here, it seems to me, lies the best answer to those narrow-minded people
who are always carping on about the use of science.
The founder of these Christmas lectures, Michael Faraday,
was once asked by the then prime minister, Sir Robert Peel,
"what was the use of science?"
"Sir," Faraday replied, "what is the use of a baby?"
She says her name's Hannah.
Faraday said "what is the use of a baby?"
and I've always thought that, what he meant by that,
must be that a baby has such potential.
It may not be able to do very much now, but it will be able to do a lot.
But it's also possible that what Faraday meant
was that there's no point in bringing a baby into the world,
if all it's going to do is work to go on living,
to go on living, and work to go on living, again.
If that's all point of life, then what are we here for?
There's got to be more to it than that.
Thank you very much.
Some of life must be devoted to living itself,
some of life must be devoted
to doing something worthwhile with one's life,
not just to perpetuating it.
This is, of course, how people, quite rightly,
justify spending taxpayers' money on the arts
and on conserving rare species.
But sometimes, when we justify academic science on these grounds,
people get rather philistine and say things like:
"oh, so you think the government should spend the money on
your scientific research because your research is fun for you, do you?"
'Fun' isn't really the right word, is it?
After sleeping for 140 million centuries
we have finally woken up in the Universe.
We have opened our eyes on a wonderful planet,
filled with color, teeming with life.
Before very long, we shall have to close our eyes again.
Finding out about the Universe in which we have woken up,
answering questions like:
What are we doing here? What is this Universe in which we've woken up?
What is life, and what, if anything, is it for?
Surely the enterprise that answers questions like that, science,
deserves a better title than "fun".
Put like that, doesn't science sound, to you,
like about the most worthwhile way in which you could possibly spend
your short time in the spotlight?
Now, of course, if you spent all your time wandering around the world,
gasping at everything and saying - "How wonderful, how amazing!
I've woken up after a 100 million centuries, what a trip!"
people would think you were a bit odd, and you might even get arrested.
We do, of course, have an ordinary life to get on with,
we do have a living to earn, we've got to earn our living being
a solicitor, a lavatory cleaner or something like that.
But, nevertheless, it is worthwhile, also, from time to time
shaking off the anesthetic of familiarity, and awakening
to the wonder that is really all around us all the time.
So, how are we going to shake off the anesthetic?
We can't actually go to another planet,
but fortunately we do not need to.
Because we can go to regions of our own planet
which are so unfamiliar that they almost might be another planet.
This is another planet. This is Jupiter.
It's a fantasy picture of Jupiter,
conceived by the astronomer Carl Sagan,
and he is imagining life forms
that might live in the upper atmosphere of Jupiter, called "floaters".
If there were life forms in Jupiter,
they would be called Jovians.
So let's use word "By-Jovians"
for creatures on this Earth that are so odd that they might almost be from another planet.
Here, for instance, is a deep sea fish.
You would have to go on a long journey in a submarine
in a diving suit, to see that fish.
This is exactly the same species of fish.
The only difference is that this has just had a meal and that hasn't:
that's looking for a meal as you can tell from its ravening jaws.
These creatures look pretty monstrous to us.
I suppose by their standards we might be thought monstrous.
This one is another deep sea fish,
this has a luminous lure,
made by bacteria, luminous bacteria,
and it uses this as a bait to lure prey into its vicinity,
it then slams its fishing rod down in the vicinity of its jaws, opens them and gulps in the prey.
A very weird, By-Jovian creature.
We don't even have to go to the deep sea, as a matter of fact,
to see pretty weird creatures.
I was once attending a lecture by a colleague who worked on octopuses,
and he said the fascination with octopuses is that "these are the Martians."
And he meant that, look at this,
this creature could easily be from Mars, couldn't it?
Watch the color change; that creature, that cuttlefish -
it's not an octopus, it's a cuttlefish - is changing color at will.
Look at the waves of color falling over it.
That's not shadows falling over it from the outside.
That's internally controlled by the animal, by its own nervous system.
It's registering emotion, signaling to other creatures, others of its own species.
By-Jovian creature.
We don't even have to go to the sea at all.
These are all insects; they all have the same basic insect body plan,
which they inherited from a common insect ancestor,
which lived about 350 million years ago.
They all look like insects, because they've inherited those attributes.
They all have a head, a thorax, an abdomen,
and, in this case, it's enormously elongated, to look like a stick.
Here, the same body is flattened out in this bug,
again the head, thorax, abdomen,
three pairs of legs, antennae, wings.
Here, butterflies. The same basic body plan,
pulled and stretched, kneaded into different shapes.
But, basically, the same shape.
They've never quite shaken off their ancestral influence.
But, we were talking about shaking off our anesthetic of soporific familiarity.
And, another way to achieve the illusion of waking up on a distant planet
is to shrink ourselves, to go on a different kind of journey,
to a much smaller scale than we're used to.
This is a dust mite.
It's the sort of thing that you've met often in the carpets of your own home, but didn't know it.
It is hugely magnified by an instrument like this,
which is a scanning electron microscope.
And we can use the scanning electron microscope
just as though it was a telescope pointing at some distant planet,
so strange are the sights that it shows us.
I think we have a volunteer there to work the electron microscope.
Now, your name is?
Louise. Louise.
Do sit down, Louise.
Now, on the screen at the moment we have what looks like a jungle,
we can think of this as a jungle on another planet.
Now, you know how to work the joystick and navigate around,
you also know how to zoom out and in.
What about zooming out, and seeing what this jungle really is?
Okay, let's go slowly, now.
There are some curious rounded objects there. Go further.
Two little patches of rounded objects.
Go further. Go on.
Right, now, I think what we're seeing is the head of a mosquito.
There are the compound eyes, lots of different facets of the compound eyes on either side.
In the middle are the sockets of the antennae.
Zoom out further.
And there's the whole head;
you can see the whole round head with sockets for the antennae
and the rounded compound eyes, with all the different facets.
Now, perhaps we could navigate to a different insect.
The machine has been pre-programmed
to move to a different part of this strange landscape.
And I hope we are going to see something else in a minute, what's this here?
Looks like another jungle.
So let's move around and explore what we think it is.
I can't see anything yet.
Wait a minute, let's zoom out a bit,
and see whether we can see better then.
Again.
Oh, that's looking like something.
I think that's a pair of wings, off to the left side, isn't it?
So, I think that might be the thorax of an insect of some sort.
Let's try moving that way and see what we see.
Other way.
And speed it up a little bit.
That's right. Oh, that is the abdomen of a bee, I would think.
Go on.
More.
Now, what's that?
There's something curious poking out.
Try to steer around so that's in the middle.
Other way.
And then down a bit.
Now zoom into it.
Keep - I'll keep steering, shall I?
Right, zoom in.
You need a bit of focus, I think. Can we do that?
It looks to me like a head of something else.
Zoom out again.
What that is, as a matter of fact, is a tiny parasite.
Thank you very much indeed, Louise.
It's a tiny insect parasite called a Strepsipteran,
which is parasitizing a bee,
and what you saw was the Strepsipteran
poking out below the armor plating of the bee, there.
There's its compound eyes, there's its body,
and that is one armor plate of the bee.
So we have been on a journey
using the scanning electron microscope to the world of the very small,
and that's another way of capturing the strangeness of our own world.
Yet another way is to go into our own bodies
and look at the detailed structure of our own bodies.
For example, this is a picture of a human brain.
And each of these black things is one brain cell.
You can see how many they are -
there are only a tiny fraction stained to be seen here -
and the bewildering forest of interconnections between them.
The total length of nerve cells in a human brain,
if laid end-to-end, would stretch right round the circumference of the world;
not just once, but 25 times.
Well, that's not in itself a very interesting fact - for one thing,
if you actually did that,
and you sent a message from one end of this vast, great nerve to the other,
it would take about 6 years to get to the other end of the nerve.
What's truly impressive about the nervous system
is not the sheer number of elements but their connectedness.
The complexity of the connections is truly awesome.
Here are just 4 or 3 nerve cells
and these are the connections between them.
There are about 2000 wires connecting each nerve cell to each other nerve cell.
So the total number of connections in the brain must be about 200 million million.
To put that into perspective:
if we assume that each of these connections
is equivalent to one switching unit of a computer,
this gives the brain about 10 million times as many switching elements
as a typical desktop computer.
Brains are impressive because of the number
and connections of their cells,
but there are lots of other different kind of cells in the body,
and they all have the same basic structure inside.
This is a typical animal cell;
a model of a typical animal cell,
and it's not just a bag of juice.
It's filled with membranes, it has got a structure, an internal structure.
Each of these blue things here is a membrane.
And every cell has them, in large amounts,
such that the total area of membrane inside a typical human body
is about 200 acres, that's a good-sized farm.
What are they all doing?
Well, they are not just sort of stuffing or folded wadding.
Those membranes, in many cases, are chemical factories:
particularly the ones in these bodies, called mitochondria.
The orange ones here.
They are made of membrane,
in every bit of those membranes, is going on chemistry.
They are chemical factories.
This here is a map of the chemical reactions in every cell.
Mindbogglingly complicated, stupefyingly complicated.
Every one of these arrows is one chemical reaction.
Yet all of that, all of that is going on all the time inside the membranes
of every mitochondrion in every cell in you.
And, the number of mitochondria in which that is going on, all the time,
is such that if you laid all your mitochondria
end to end
they would go round the world not once, not 25 times, but 2000 times
In the nucleus of the cell, right in the center, is the DNA.
The DNA, the magic molecule, the molecule of life,
the most important molecule in the world.
That molecule conveys the information from generation to generation
about how to build a body.
The total amount of information is such that, if you were to eat a steak,
every time you do it
your teeth are mangling, are shredding the equivalent of a billion copies of the Encyclopedia Britannica.
That's the kind of destructive work you can do with your teeth!
Hemoglobin is the molecule that carries oxygen in the blood;
you can see it, the shape of it is complicated,
it is very complicated.
And what's remarkable about it is that the same shape is going on all the time
in all the different molecules.
You can think of a hemoglobin molecule
as rather like a truck for carrying oxygen.
Each hemoglobin molecule drives around
carrying oxygen from one part of the body to another.
It's a vehicle for carrying oxygen.
But, I have just got six little trucks here.
What's remarkable about hemoglobin is that the number of them in your bloodstream is not just six,
it is six thousand million million million.
And they're are all very complicated,
they all look like that,
they all look exactly the same as each other.
And they are all being destroyed
and new ones being created, all the time in your blood, at a rate of 400 million million every second.
Another way to shake off the anesthetic of familiarity,
another way to experience something a little bit like going to another planet,
is to go on another kind of journey - backwards in time
on our own planet.
The best way to do this would be in a time machine,
but even Bryson Gore and the Royal Institution
can't lay on a time machine for us,
so we have to use fossils.
One of the most difficult things to grasp about fossils
like this Trilobite here, is how old they are.
You can have no conception how old that animal is.
In case that sounds patronizing, let me rephrase it.
I can have no conception how old it is.
I can tell you in words how old it is:
it's about 500 million years old, perhaps a bit more.
But to tell you in words and really to understand what that means, is another matter.
Our brains have evolved to comprehend
the timescales of our own lifetimes.
We can understand seconds, minutes, days, weeks, years -
even centuries we can understand.
When we come to millennia, thousands of years, our spines start to tingle.
Epic myths, like Homer's Odyssey, tales of the Greek gods,
Zeus and Apollo and the others, the Jewish heroes, Moses and Joshua
and their god Yahweh, the ancient Egyptians and the Sun god, Ra,
these all give us an eerie feeling of immense age.
We feel that we are peering back into the mists of antiquity.
Yet, on the time scale of this fossil,
those mists of antiquity don't even count as yesterday.
This is a cuneiform tablet from Mesopotamia,
somewhere around the 7th century BC.
It's - let me see, my cuneiform's a bit rusty -
yes, this is a legal document on the sale of some land near Nineveh.
Yes, that's right.
This, here, is another thing that gives one the same feeling.
This is a bronze age warrior's mask
which was dug up in the last century
by a famous 19th century archaeologist, Schliemann.
And he said: "I have gazed upon the face of Agamemnon".
As a matter of fact, it wasn't the face of Agamemnon, but he thought it was.
And, to him, that was his way of being awed,
awed at the immense age of it.
He was feeling himself going back through those mists of antiquity.
Let's try to get a feel how old things really are,
and then try to fit our Trilobite onto the same scale.
I am going to take one pace to represent 1000 years,
and I'm going to start at the time of the first Christmas.
So, this little broach here
dates from the time of the first Christmas, 0 BC.
If I take one pace I am back at 1000 BC,
about the time of the tablet that we have just been looking at,
about the time of King David.
Another pace, 2000 BC
and this bronze age axe head.
Another pace, 3000 BC,
about the time just before the building of Egyptian pyramids.
Another pace, this piece of pottery, 4000 BC,
about the time when Archbishop Usher calculated
the beginning of the world and Adam and Eve.
But we've hardly started yet.
We've a long way to go.
Walking from one side of the green bench to the other,
we've gone back to 4000 BC.
This is Homo habilis.
She, or someone very like her, is our direct ancestor.
She lived 2 million years ago.
To get back to her time,
you would need, on the same scale of pacing, to go about 2 kilometers.
Quite a long way.
Now, we've got some more ancestral portraits,
and I'm going to call them up in order.
So, will the person who is standing, who's sitting behind Australopithecus,
the first one, please, stand up. Thank you.
That's Australopithecus.
He is probably a direct ancestor of this one.
He lived about 3 million years ago.
So we'd have to walk
3 kilometers to get to his time.
Now the next person, please.
Thank you.
That's Ramapithecus,
that would be possibly an ancestor, not just of us, but also of all the great apes,
and he is about 14 kilometers away on our scale.
The next one, please.
Thank you.
That's an early primate,
you would have to walk to about Hemel Hempstead
to get to the age of that creature.
The next one, please.
An early mammal, about Luton,
that distance. The next one.
An insectivore, with a little millipede in its jaws.
Maybe, Newport Pagnell.
The next one, please.
That's an early mammalian-like reptile,
and its distance is about Manchester.
The next one.
An amphibian - Middlesborough.
And the next.
Right, that's a fish, just coming out of the water;
just leaving the water, and coming to the land.
And, its distance is about Carlisle.
And I've left - do sit down, now, thank you very much. Those are all your ancestors.
This one is the oldest of all we've got here,
it's about the same age as the Trilobite
that we started with;
they might have met.
This is Pikaia, and in order to find its age
you would have to slog it out all the way from here to Glasgow.
And, remember that our perception of historical time, back to the mists of antiquity,
is a couple of paces across this green table.
And, even with Pikaia, we have not finished.
Because there are lots and lots of ancestors before Pikaia.
If we go back to the origin of life, to the first bacteria,
we are going back three and a half thousand million years.
And, in order to pace our way back to that age,
we would have to march all the way from here to Moscow.
These are the sorts of ages that we have to understand,
if we're going to understand evolution,
and our brains are not equipped to do so.
When we were looking at our ancestors around there,
we could be misled,
because it gives the idea
that evolution is marching inexorably towards a climax;
the climax being, of course, us.
And that's not the way it was.
Evolution was marching in thousands and millions of different directions, at once.
This, here, is not the Royal Institution Christmas tree,
it's the tree of life and it's a representation of a tiny, tiny fraction
of the lines of evolution that there were.
The origin of life is down here.
This is the first 1000 million years of life here.
Coming up here. Now, each of these branch points represent an ancestor
of whatever lies up the branches from it.
So, for example, these - there are the plants.
This, I should say, is definitely not to scale.
I just noticed.
So, never mind that.
Forget everything about scale on this tree.
What is correct is the order of branching, but not the detailed distances of the branches.
So, this branch represents the plants.
Those two are closer cousins of each other then they are of that one
This branch represents the primates, with a gorilla and a human,
and their common ancestor is there.
This branch here represents carnivores,
and there's a branch with a lion and a tiger,
and their common ancestor there -
which is more recent than the common ancestor of the bear and the dog -
that's the common ancestor of all the carnivores.
Here, we have a zebra and a rhino, not to scale,
and you can see that they are more closely related to one other,
than either of them is to
these cloven-hoofed animals: the bison, the sheep, and the goat.
The sheep and the goat have a very recent common ancestor,
they're cousins. The bison has a slightly older common ancestor.
Here, we have two insects, a fly and a grasshopper,
and they have an ancestor there.
And then, they share an ancestor with the spiders a little bit earlier on
This is a tiny fraction of the number of animals and plants
that there should be on this tree.
This tree should have some 10 or 20 million twigs around there.
And, the ancestors of all these animals are in the middle of the tree,
going inwards like that.
So all the ancestral portraits that we have just seen around there,
they would be laid out along there.
What we're looking at here are all modern animals.
All those animals are cousins of one another and they're cousins of us.
These hamsters here are also cousins of us.
Everything that's alive today is a cousin of us.
These fish are our cousins, this elephant,
these elephants - by the way extinct elephants - are our cousins,
this swift is our cousin.
We know that they are all our cousins
because we know that they all have the same DNA code.
The DNA code of all living things alive today is the same.
And, that is too improbable to have come about
unless we have an ancestor.
We're all descend from one remote ancestor
which lived probably between 3-4 thousand million years ago,
and we are all, therefore, cousins.
If we ever meet life from another planet,
the creatures from there will not be our cousins.
They will have evolved entirely independently.
They won't have DNA, it would be my guess.
However, I would be prepared to say
that they are likely to have quite a lot in common with us,
simply because there's a lot of similar problems to be solved in living.
And those problems are likely to be the same all over the Universe
So, although they won't have DNA,
they'll have something very similar in function.
It'll do something very like DNA,
and it'll work in a similar way to DNA.
I'd also be prepared to put my shirt on the bet
that they will have evolved by the equivalent of Darwinian natural selection.
If we're ever visited by life forms from another planet,
they will certainly have evolved the power to think
and do science.
Otherwise, they couldn't have got here.
And their science is bound to be essentially the same as our science.
This is because the principles of physics and chemistry are the same all over the Universe.
They'll have the same values of the constants - of constant pi as we have,
they'll have Pythagoras's theorem, they will have relativity,
although they won't attribute it to Einstein.
They'll probably find us pretty childish,
but they will be quite kind about our science.
They'll pat us on the head and say,
"Well, what you know about Universe is pretty much correct.
You got at lot to learn yet, but you are doing fine. Keep it up."
That's what they would say if they were talking to our scientists.
What if they were talking to our best lawyers
or literary critics or theologians?
I doubt if they'd be so impressed.
Their anthropologists, the equivalent of their anthropologists
might be interested in us,
but they would be bound to notice that our cultural beliefs are very local and parochial;
not just by their standards, their universal standards, where they certainly would be,
but even by our own standards.
Because what people believe on our planet
depends so much on whereabouts on the planet they happen to be born, which is a fairly odd thing.
The Adam and Eve myth is believed by a lot of people in certain parts of the world,
but if you go to the other parts of the world
you will find them believing very different myths.
This is a Hindu myth which is also very beautiful and there are other Hindu myths as well.
This is another Hindu myth of churning the milk of the ocean
with a churn. Gods and demons churning an axle with a turtle on the bottom,
and out of the ocean came - as butter comes out of milk - came all living creatures.
These creation myths are very beautiful,
but they're all different from one another, and they can't all be true.
And it's very odd if people believe simply
what the other people in their country happen to believe, just because they are in that country.
Look how scientists handle their disagreements now.
Take a particular disagreement: why did dinosaurs go extinct?
There are various theories.
This is the theory that a comet or meteorite hit the Earth,
and caused a catastrophe that drove the dinosaurs extinct.
And a lot of scientists believe that.
A lot of scientists, on the other hand, believe that a virus killed the dinosaurs.
And another lot of scientists believe that
the mammals arose and ate the dinosaurs eggs.
I've no doubt that there is something going for all those theories.
But, the point is that different scientists believe them,
and the reason why they disagree
is that there isn't enough evidence yet.
Everybody knows, everybody agrees about
what sort of evidence would be needed in order to make them change their mind.
But, suppose science worked like creation myths, or like languages.
Here we have a map of world languages.
In this red area English is spoken.
There Spanish is spoken, there Russian is spoken.
And it's quite natural that you should be able to plot a map like that;
that people should speak the language of their country.
But what if scientific theories were like that?
What if we had the similar map of the distribution of scientific theories?
Suppose, in the red area, everyone believed
the meteor theory of the dinosaurs' extinction.
And in that area everybody believed the virus theory,
and in that area everybody believed the mammals-eating-the-eggs theory.
Wouldn't that be a pretty silly sort of science?
Imagine the scene: two scientists arguing, and one of them says,
"I believe the dinosaurs went extinct
because a comet hit the Earth.
Why do I believe that?
Because that is what my father and grandfather believed,
and that's what people in my country have always believed."
"But I believe that it was a virus that drove the dinosaurs extinct. Why do I believe that?
Because my father and grandfather believed it,
and that's what people in my country have always believed."
Or, suppose the conversation went like this:
"Never mind the evidence,
I just know that a comet struck the Earth
because it has been privately revealed to me that a comet struck the Earth."
"But I just know that it was a virus because I just know it,
because I have faith that it was a virus."
If you overheard conversation like that
you would think they were pretty odd scientists, wouldn't you?
You'd see no reason to believe any of them.
Growing up in the Universe
partly means evolving from simple to complicated,
inefficient to efficient, brainless to brainy.
But it also means growing out of parochial
and superstitious views of the Universe.
Growing up to a proper scientific understanding of the Universe,
based upon evidence, public argument,
rather than authority or tradition or private revelation.
Growing up means trying to understand how the Universe works,
not copping out
with supernatural ideas that only seem to explain things but actually explain nothing.
You might say: "Can you really afford to be snooty about the supernatural?
After all, many of us have probably had uncanny experiences, like telepathy.
We, perhaps, dreamed about somebody whom we hadn't thought of for years,
and then, the very next day, we had a letter from them, and we think, what an amazing coincidence!
There must be something supernatural. It seems so spooky."
That is a supernatural explanation.
What would a natural explanation of an event like that be?
Well, what we have got to do is to come to a proper assessment of
how likely it would have been that this could have happened anyway by sheer luck?
And, there are ways of doing that. And we can run a very simple experiment here,
on a very small scale. We are going to do it by tossing pennies.
It may be that, somewhere in this audience,
is somebody who is "psychic,"
and is capable of willing a penny to come down heads or tails.
A what we have got to do is to identify that psychic individual.
So, Bryson is going to toss a penny,
and I want, I'm going to ask everybody on this side, let's forget about the gallery because I can't see them up there,
everybody on this side of me here,
is to will it to come down heads.
Really think of it coming down heads.
Try to make it to come down heads:
we'll try to see whether the psychic individual is on that side.
Or, on this side, everybody should will it to come down tails.
Okay, so, off we go.
Tails, right.
So if we've got a psychic individual, it must be on this side.
Now, will everybody this side, please, stand up.
We're going to try to do this by elimination.
Now, everybody on this side of the aisle, will it to become heads,
everybody on this side of the aisle, will it to come down tails.
Heads.
Sit down, please.
Stay standing up.
Now, we have got a bit of a problem here.
Let's say, everyone from behind the row that was holding up the ancestral portraits should will it to come down heads,
and everyone from the ancestral portraits downwards - tails.
Tails.
Right. The back rows then, sit down, please.
Right, now we're narrowing it down. How many tosses have we done? Three? Right.
Now, one, two, three, four -
let's say the back two rows of those standing, will it to be heads, and the remainder, tails.
Tails.
Back two rows, sit down, please.
Right, now, 1, 2, 3, 4, 5, 6 - okay, we we'll make it simple.
The back row heads and the front two rows, tails.
Tails.
Back row, sit down.
Right.
Back row heads, front row tails.
Tails.
Right,
let's say, from Coca Cola to the left, heads, and the other one, tails.
Heads -
down, please. No, Coca Cola, stand.
Right. Heads, tails?
Heads.
Right.
Well done.
How many tosses was that?
I do not know how many tosses that was, but congratulations.
Let us suppose that it was eight.
It was, was it? Right.
Now, what's your name?
Who got it? Donny.
Yes, well - Donny?
Now the question is; is he psychic?
He managed to get it right eight times in a row, and that's pretty impressive.
But, of course, there is absolutely no evidence whatever
that he's psychic.
He did, indeed, think about heads and tails and it did come down the right way.
But if you think about how we set the experiment up, with successive divisions,
he could have thought about ham and eggs, and it would have given the same result!
It had to come out, because of the number of people here.
It had to come out that somebody was, apparently, psychic.
Now, we have only got a few hundred people in this room.
But, if we could do this with a million people or two million people,
we could have gone on tossing pennies for a very long time, and in the end of that time,
we'd have got a very impressive result.
Now, when people write into the papers with uncanny experiences, it's just like that,
because the circulation of a tabloid newspaper is up in the million,
and if only one of them has to write in,
then you can see exactly what happens.
There's got to be somebody out there having an uncanny experience at this very moment,
and it means absolutely nothing.
So whenever you hear a story about
uncanny, spooky, telepathic experiences
think about this experiment and think about how likely it would be to come about anyway.
Put your trust in the scientific method, put your faith in the scientific method.
There's nothing wrong with having faith -
I'm going to move Faraday out of the way.
There's nothing wrong with having faith in a proper scientific prediction.
This is a heavy cannon ball.
I'm going to stand here, and I'm going to release it,
and it's going to come - it's going to go over there, and it is going to come roaring back towards me.
And all my instincts are going to tell me to 'run for it'.
But, I have enough faith in the scientific method to know that it is going to stop
just about an inch short, or perhaps less, of my head.
So here goes.
I felt the wind of it!
The Nobel Prize winning scientist Sir Peter Medawar,
in a joint book written jointly with his wife, wrote the following:
"Only human beings guide their behavior by a knowledge of what happened
before they were born
and a preconception of what may happen after they are dead.
Thus, only humans find their way by a light
that illuminates more than the patch of ground they stand on."
Well, that's all for today.
In the next lecture, I shall be turning to the problem of design,
and the difference between genuinely designed things, like that electron microscope,
and apparently designed things, that are not really designed,
like this elephant and like this swift.
Thank you very much.
forums.mvgroup.org