This is a stick insect.
It may look fairly conspicuous on my hand,
although I have made an effort to make it feel at home with my shirt,
but you have to see it in its natural surrounding in order to see it at its best.
There, it would blend in almost totally.
The attention to detail is astonishing.
You can even see little marks suggesting bark on its back.
You could almost say that it fits its environment like a key fits a lock.
And I've got something else under my hat.
This is a different kind of stick insect, a leaf insect.
It mainly resembles leaves, dead leaves.
You see how it rocks like that.
I suspect that it's got a second line of defense
which is that when it's startled and when a bird might almost have got it,
it mimics a scorpion.
You see how the tail has looped over the back there.
If I saw that I might be momentarily startled, thinking that it was a scorpion.
Let's put these away. I will get that one -
I may have to call for a volunteer who is not frightened of stick insects. There we are.
Thank you very much!
Bryson and I are always doing double acts like this.
Here are a couple of more -
There's a branch of a tree.
Seems to be moving.
There goes its head. It's a bird.
It flies off. It's a potoo.
Those are rose thorns.
That is not a rose thorn. It's a bug.
It gains protection by looking like a rose thorn.
You could almost say
that it's like a key that fits into the brain of a bird and the bird mistakes it for a thorn.
The bird has a rose thorn shaped lock.
If that sounds a little bit mysterious I hope I'll explain it in a moment.
Because I'm going to use the analogy of a lock and key,
whenever we see an apparently well designed animal or plant,
it's as if nature has the lock and the creature has the key.
The thing about a lock and key is that the key has an intricate structure
which is very hard to imitate and that structure exactly fits the lock.
This key fits precisely into the lock
and the holes in the key fit the teeth in the lock.
And the lock therefore opens.
Just any old bit of bent wire won't do.
It has to be the right key.
The principle of a lock and key
is that there's something intrinsically improbable in the shape of the key.
You need that key to open the lock.
In the case of an ordinary lock that you open with a key
it's not easy to measure how improbable the key is.
But here's a combination lock, an ordinary bicycle lock.
Here we know exactly how improbable it is
because there are three dials and each one has six positions.
That means that there are six times six times six possibilities, which is 216.
There is a 1 in 216 chance of opening it by luck.
And here's a model of the same combination lock so we can see how it works.
You have to get all three of the dials into position.
This one's combination is 6, 5, 1 and the lock opens.
All three of the teeth have to be lined up.
It isn't enough just to have one of them.
But the lock is just a parable.
Let's get back to real life.
If the thorn bug is a key,
what this means is that just any old shape won't do.
It must be the exact shape of a rose thorn.
A stick insect must be the exact shape of a stick.
An upper tooth must fit, bite snuggly against, the lower teeth in your jaw.
Yet the theory of evolution says
that all these things evolved gradually, stage by stage.
This means that they must have gone through intermediates,
when they were not a perfect key fitting a lock.
The thorn bug must have been half like a thorn,
the stick insect must have been half like a stick.
But whoever heard of a key that only half fitted a lock?
A key either fits a lock or it doesn't.
So how do real living creatures managed to evolve their perfection?
How do they manage to survive the intermediate stages?
How do they work when they're only half a key?
Well, let's approach the problem by going back to the combination lock.
While I've been talking Bryson has been discretely doctoring his lock
so that it behaves in a different way.
Imagine a lock
where instead of having to get all the dials in place at once...
Suppose I was trying to crack a safe and there was money in there.
As it is I can't do it
because I've got to get all the dials in place at once
and I've only got a 1 in 216 chance of doing that.
In a real bank safe it would be one in billions.
I can't do it.
But suppose that I were able to try the first one at random
and eventually find out how to open that.
And then the safe door peeps open a little bit, a little bit of money drops out.
I've done that one, now I can go on to the next one.
And I find out how to open that one, I have only got 1 in 6 chance, that's fine.
And a little bit more money spills out.
And now the final wheel, I've only got 1 in 6 chance, that's easy and I open the entire safe.
It's now become a gradualistic combination lock,
whereas before it was an all or nothing combination lock.
With this lock, the maximum number of tries that you need in order to open it by luck
is not 216 but a mere 18.
So it is easy to open a gradualistic combination lock
and I call this "smearing out the luck".
Because we do not have to get our luck all in one ridiculously large dollop.
Instead we can get our luck in dribs and drabs.
Each drib being allowed to come before the next drab
and we go on to wait for the next bit of luck.
It cumulates.
So, what have we seen so far?
Although an animal may look like a key fitting a lock
it's not a totally good analogy
because in this case half a key is better than no key.
If nature is a combination lock, it's a gradualistic combination lock,
not an all or nothing one.
Now let's look at the same thing from another direction.
It's been said that a monkey typing at random on a typewriter
could eventually write the complete works of Shakespeare.
I once did this experiment with my then 11-month-old daughter, Juliet,
and this is what she typed.
I let her go for a bit -
And so on and so on.
I realized after a bit
that I would have to let her go on for at least a billion years
before she got even a single phrase of Shakespeare.
The eminent astronomer, Sir Fred Hoyle,
has pointed out that it's just about as unlikely
that any complex living structure could spring into existence suddenly, by luck alone.
He said: "It is rather like taking a junkyard and letting a hurricane blow through it
and the hurricane has the luck
to spontaneously assemble a Boeing 747".
So here is our the junkyard, and the hurricane comes along, it's blowing like this.
Hoyle's point is that the luck that would be necessary to spontaneously
assemble a Boeing 747 like that is equivalent to the luck
that you'd need in order to get something like an eye or a stick insect or hemoglobin molecule by sheer luck.
My reason for mentioning Hoyle's 747 is that I'm going to
take his name in vain in the next demonstration.
We're going to have a computer monkey or rather we' re going to have two computer monkeys,
one called Hoyle and one called Darwin.
Both monkeys have the same task.
Both have to type, not the complete works of Shakespeare,
but one phrase from as you like it
"More giddy in my desires than a monkey".
Hoyle types entirely at random.
After every line that he types the computer checks
to see if he has managed to hit the target line.
If he does, the computer will stop, bells will ring,
it'll be the most improbable coincidence in the history of the world
and I solemnly promise to eat my hat.
I'll go further than that.
I bet you everything I possess that it won't reach the phrase,
shall we say, in the next 10 billion years.
I won't bet you.
I will undertake to give everything I possess to the Royal Institution
and here's the legal document signed by me
which undertakes to make over everything I own to the Royal Institution
in the event that the monkey Hoyle reaches the target phrase.
But, of course, this is just to illustrate my confidence
that chance on its own could never make an eye or a 747.
The real point of the demonstration is that the other monkey, Darwin, will get the target phrase.
So what does Darwin do?
The same, but with a crucial difference.
The Darwin monkey begins by typing a random phrase.
So far the same as the Hoyle monkey.
But now the computer breeds from that phrase.
It breeds 50 offspring which are identical to the first phrase
but with a tiny mutation, a tiny random difference in each of the 50 cases.
The computer then looks at those 50 offspring and chooses the one
which most resembles the target phrase, however slightly it resembles the target phrase.
So the generations go by and, generation after generation,
it gradually becomes more and more like the target phrase.
Now, when I agreed to give these lectures
I was told that I should always call members of the audience out to assist.
But I was also told that it was silly to do this
if all I was going to ask them to do was to come out and hit the return button on a computer.
However, on this particular occasion, since so much is at stake
I thought it would be better if I did ask somebody
who knows a lot about computers
and is very good at pressing buttons,
to come out and perform this onerous task.
So, if anybody would like to volunteer -
Yes, right.
Now, what's your name?
Andrew.
Well, you understand what's at stake, Andrew, do you?
Okay,
here's the target phrase, "More giddy in my desires than a monkey".
There's the box where the Hoyle monkey is going to type.
And there's the box where the Darwin monkey is going to type.
Unless Bryson has been messing about with the program in order to
deprive me of my worldly goods that is the way it is going to be.
So, are you ready? Go!
Now you see the Hoyle monkey typing away entirely at random.
The Darwin monkey is down here
and I think we can begin to see something appearing in the Darwin's row.
"More giddy in my desires than the -
Bang. And he has got there.
How long did that take? Anybody timed it?
Not very long, I think. Andrew, thank you very much.
So I don't have to eat my hat and my worldly goods,
such as they are, are safe.
But the point really is not that Hoyle failed to reach the target.
The point is that Darwin did reach the target and astonishingly quickly.
Well, there is a lot wrong with that as a demonstration of
Darwinian natural selection.
For one thing, it has a distant target in mind, which natural selection does not have.
But it does, once again, show us the key to the way out of the problem of mammoth improbability.
Things like eyes and 747s that couldn't possibly spring into existence in a single,
lucky shake of a dice,
can come into existence if the luck is smeared out
in many tiny steps and is accumulated.
That is what this lecture is about: smearing out the luck,
accumulating it, turned out to be an immensely important process.
It's the process that makes it possible for us to be here,
and by "us" I mean all stick insects, lions, elephants and bacteria, everything that's here.
And now let's look at a physical parable for this gradualistic solution
to a difficult problem.
This is a mountain.
It's called Mount Improbable.
Sitting on the top of the mountain is equivalent
to being very well designed, to being an eye that works well, for example.
Being at the bottom of the mountain is equivalent to being a distant ancestor
that's not yet very well designed,
that hasn't yet acquired its good fitness to the environment.
Facing you now is a precipice, a cliff which is called Sheer Luck. It's a sheer cliff.
Jumping from the bottom of the cliff to the top corresponds to assembling a 747 by means of a hurricane
or it corresponds to getting a complete eye in a single lucky mutation.
It can't be done,
you could no more do that than a mountaineer could leap from the bottom of a cliff to the top.
But this isn't the only route up Mount Improbable.
We have to go round the other side.
And you notice that round here is a gradual, sloping path, steadily inching its way up the mountain.
And if you follow it round you'll find that even though some bits of it are a little steep,
you can get from the bottom to the top without ever having to jump up a step.
It's a gradual, inch by inch, path up.
Anybody who didn't know about the Ramp Evolution,
which is what that is called, would, if they saw an animal perched on the top,
a beautifully designed animal, and only saw the cliff, they would assume
that it had to be the result of a miracle.
But in fact the only way up Mount Improbable is the slow,
gradual climb up the Ramp Evolution.
You have to add all the little steps up together
and after a very large number of steps you can climb very, very high indeed.
But we are still talking in parables.
How in practice do living things climb Mount Improbable?
Well, of course, individuals don't climb it.
It's lineages, groups of animals, species, that climb it, and they do it in evolutionary time.
They and their descendants, and their descendants' descendants,
they do it by going through an extremely large number of generations,
and we do have the time for an extremely large number of generations,
because we have geological time at our disposal.
This generation by generation accumulation works only
if there is reproduction with true heredity, to carry the message through.
And I must explain what that means, because just plain reproduction without heredity
won't do, it's not enough
It's possible to imagine reproduction without heredity.
Fires, for example, have a form of reproduction without heredity.
If you imagine that this is a savanna, a dry savanna, the dry grass all over it.
And a fire suddenly starts in one place.
Sparks fly up and are carried in the wind and suddenly a spark lands there and a new fire starts.
Both these fires are now flaming up and sparks are going off, and another fire starts up
which may be the daughter of this one.
One starts up here which may be the daughter of that one.
These fires are propagating, these fires are having children.
The sparks are causing this fire to be the parent of that one,
and in the next one we can see that you can have both, not mother and daughter, but grandmother, grandchildren fires.
The fires may differ a bit.
In this picture we've represented them by red, green and blue.
Fires may, indeed, differ.
But they get their qualities not from their parents and grandparents.
A fire gets its qualities from its surroundings, from its environment.
A fire gets its qualities from the direction of the wind, where it happens to be,
or from the chemistry of the soil or from the dampness of the vegetation.
Fires do not get their qualities from the spark that comes from their parent fire.
Now we're going to do the same thing with a Bryson special.
And I'm going to stand well back. Where do I have to stand?
Here?
We always have to have fireworks at the Royal Institution, so go ahead, Bryson, please.
There's the first fire, there's the parent, the sparks are flying up.
It started another one there. That's the daughter fire.
And a granddaughter, and a second daughter of this one.
But the point is that to the extent that there are any differences between these fires,
they do not get their qualities from their parents.
There are sparks that flow from fire to fire but all that the sparks do though is to start a new fire.
Nothing is carried in the spark. There is no information carried in the spark.
And this, of course, is where rabbits and humans and stick insects differ from fires.
Don't be misled by the fact that rabbits and humans have a mother and a father.
Stick insects only have a mother, like fires.
In this particular respect stick insects are like fires.
But in the important respect that I'm talking about, stick insects do not resemble fires.
Because, unlike fires, stick insects have true heredity.
At least some of their qualities: color, shape, size, spininess and so on,
they actually get from their mother, not only from their surroundings.
Something travels from mother to daughter,
something in the spark that travels from mother to daughter -
there is information.
So what is this mysterious information that eggs contain and sparks don't?
Well, it's DNA. This astounding molecule
which contains in the sequence of its bases all the information,
or almost all the information that you need to build a stick insect or a rabbit.
DNA comes like an ever-flowing river down the generations.
The river of DNA that flows through us into the future
is a pure river that leaves us exactly as it finds us. With one exception.
There are occasional, very occasional, random changes called mutations.
Because of these there is variation, genetic variation in the population.
And that opens the way for natural selection.
Those varieties of DNA that just happen to be good at building ancestors,
at building bodies that have good eyes, good legs, good anything else, survive.
So the world automatically becomes filled with good DNA.
This mean good at making bodies that are themselves good at surviving.
This is the Darwinian explanation for why living things are so good at doing what they do.
They're good because of the accumulated wisdom of their ancestors.
But it's not wisdom that they have learned.
It's wisdom that they chanced upon by luck,
lucky random mutations, which were subsequently selected.
And in each generation the amount of luck was very small.
But because the luck has been accumulated over so many generations we are impressed by the end product.
I want to apply this lesson to three particular cases,
three particular problems that have given difficulty: the eye, the wing and camouflage.
And I choose them because they're famously regarded as difficult.
First, the eye.
Charles Darwin himself said: "To this day the eye makes me shudder".
Creationists are particularly fond of the eye because they like saying,
"What is the use of half an eye?"
An eye only works, they say, if every little detail is in place.
Until you got that, the eye won't see anything at all.
So how could it possibly have evolved?
And even serious scientists have sometimes queried
whether there has been enough time for the evolution of the eye.
Suppose we start with an ancestor who didn't really have an eye at all
but just a single, simple sheet of light-sensitive cells.
That's represented by this screen here and there's a television camera behind,
looking at the screen, so that we on the screen, on the television screen,
shall see what this primitive animal would see.
So this animal with hardly any eye at all
would at least be able to tell the difference between light and dark.
Light and dark.
Now, the next stage in evolution would be to have a shallow cup.
This animal would be able to tell the direction that light is coming from,
because a shadow would appear.
A shadow would appear there.
And if you can tell the direction a light is coming from,
then you can tell the direction a predator is coming from.
Now, although we represented this as a cup coming out from the wall,
it would in fact, probably be an indentation and it would be a gradual indentation.
It's inconvenient to make a gradual indentation.
It has to be made as a rather abrupt cup that comes out six inches at a time.
But it's easy to see that that shadow effect that we have just been witnessing
would work progressively and gradually as the cup gets bigger.
Let's make it bigger still now, Bryson.
And this cup is even more effective
and if we go on to the next stage
when we make the cup gradually bigger again,
so big that it becomes just a little hole in the end.
Now this animal has a very good idea of exactly where the light is
and by the same token exactly where, for example, a predator is.
And I think with this eye we might even get a little image.
See if we can get an image of Bryson's hand.
That smudge there is Bryson's hand and you can just about see a very dim image of his fingers.
So an animal with an eye like this would be able to see perhaps just little bit
what kind of predator it was.
Let's go to the logical conclusion which will be a pinhole.
Remember, it's all gradual, gradual change in evolution.
Let's see if we can see your hand again, Bryson.
Now I can see a rather precise picture of Bryson's hand.
It's not a very bright one but I can see every finger clearly delimited.
So I could see, if I were this animal,
I could see my predator in some detail.
There is an animal that has a pinhole camera for an eye.
It's a mollusk called Nautilus.
It's a relative of the octopus but it lives in a shell, and there is its eye.
It just has a simple hole and sea water can flow in and out of that hole.
Here is the shell of Nautilus.
This bit of rock here shows ammonites, which are a now extinct relative of Nautilus.
They were once immensely common, as this rock suggests.
I like to think of all those hundred million-years-old dramas
that must have been witnessed through the pinhole camera eyes of ammonites.
We can't be sure they had pinhole camera eyes
but it seems quite likely.
Now, a pinhole camera is not a very good way of seeing.
It does produce a sharp image but because it's so narrow you hardly get any light in.
The answer to this problem is that ingenious device: the lens.
Nautilus has a pretty poor eye compared to its relatives, the squids and octopuses,
because they do have a lens.
We can't help wondering why doesn't Nautilus have a lens?
Why didn't it evolve a lens?
Well, I suspect that Nautilus may have got itself stuck on a little peak
some way up Mount Improbable.
You see, that although we've got one big peak there, there are various other peaks on the way.
There are quite a lot of them.
And since the rule in evolution is just to keep going uphill,
when the ancestors of Nautilus came up the track here, up the path here
and got to this point, that way uphill looked just as inviting,
so to speak, evolutionarily, as that way.
Both of them were uphill.
Evolution has no foresight, evolution has no way of knowing
that, if you travel up that way, you're going to end up with a lens.
For the moment this appears to be a perfectly good way to travel
because the pinhole camera at this level of illumination is an effective eye.
So I wonder whether perhaps Nautilus has got itself trapped on top of this little hillock
and is now unable to escape,
because escaping would mean going downhill into the valley
and the one thing you cannot do on Mount Improbable is ever go downhill.
But let's imagine what the ancestors of the squid and octopus did
when they got to this junction point here.
They just happened to go on up this way.
And they started evolving a lens and we did at a different time in history.
How might the lens have evolved?
Let's imagine that it started with just a single, transparent sheet
of some transparent material.
And all this was doing, it's not a lens yet, all that it's doing is protecting the eye.
In Nautilus sea water flows right inside the eye.
This animal now has some protection.
And the eye is really just the same
as though there wasn't any transparent material there.
Now we're going to use an optician's set of lenses here.
It would be nice to be able to have just one bit of transparent material
which we would then squeeze and make thicker, but we can't do that.
So we are going to replicate that effect by a whole series of little lenses.
So this is the next stage in evolution. This animal here -
let's get an image of that.
That's a rather better and, above all, brighter image of the hand.
Let's have the next lens in.
If an animal had an eye like that it would have a really very, very clear view of its world.
It could tell exactly what its predator was.
Would anybody like to come out and have their face looked at?
What is your name?
Davina
Davina, do you remember where Bryson put his hand?
Can you put your face just down there?
We need the lights down for this, I think, don't we?
There we are. Very nice.
This animal can even see what its predator's face looks like.
Upside down. But we all see upside down.
Thank you very much, Davina.
So we have a gradual pathway all the way up Mount Improbable, from no eye to an eye.
But has there been enough time for the evolution of the eye?
Recently a Swedish scientist called Dan Nilsson has tried to answer that question.
He did pretty much the same as we've just been doing here, but he did it with a computer.
So, instead of growing up in big steps as we had to do with our wooden model,
he was able to do it in very small steps on his computer. Very small steps indeed,
deliberately. He assumed that each step, which means each mutation,
caused only a 1% change in the size of something, like, say, the steepness of a cup.
He also devised a way of measuring the efficiency of an eye.
He did this by telling the computer to measure various things about the eye
that it had just drawn itself.
And then the computer worked out, using the rules of physics,
how good an image that eye would be capable of producing.
And the question was, with those rules built into it,
would there be a smooth gradient of improvement,
starting out with a flat retina and ending with the proper eye, like ours.
And you've guessed it, the answer is yes.
This was Nilsson's starting point, with just a flat retina under a flat, transparent layer.
And now let's just run the simulation of the successive stages that Nilsson got
and they're pretty similar to the successive stages
that Bryson got with his model.
So far we haven't learned anything that we didn't already know.
There is a smooth progression up Mount Improbable for the eye.
But Nilsson went on to estimate how many generations it would take to accomplish this evolution.
In order to do this he had to make some more detailed assumptions.
I won't bother you with exactly what they were.
All you need to know is that they were quantities
which geneticists out in the field can measure and have measured.
And Nilsson put into his computer model, values of these quantities that were conservative.
Conservative means that he was erring
on the side of deliberately biasing his calculation to make it slow.
To give it an estimate on the slow side of evolution.
Make evolution come out slower than it might otherwise have done.
But in spite of this, in spite of his being conservative
and in spite of assuming that each mutation could only cause a 1% change,
which is another conservative assumption,
Nilsson found that the evolution of the eye, which we've just seen,
would take a surprisingly short time.
It would take about 250,000 thousand generations.
That might sound like a lot of generations
but we have a rather warped perspective.
Because, after all, each one of us is only good for one generation.
But our human perspective is not the one that matters.
One that matters is the geological time scale.
And on the geological time scale 250,000 generations is next to nothing.
Probably only about a quarter of a million years since the animals we're talking about
would probably have a generation time of about a year.
And a quarter of a million years is really too short for geologists to even measure.
It's like trying to count seconds using the hour hand of your watch.
So there really was no need for Darwin to shudder.
Half an eye is better than no eye.
Half an eye is better than 49% of an eye, 1% of an eye is better than no eye at all.
And far from there not being enough time for the evolution of the eye,
the evolution of the eye is so quick and easy
that it must have happened many, many times over.
Eyes can evolve at a drop of a hat.
And in fact, if we look around the animal kingdom,
there are lots of different kinds of eyes dotted around.
Each of them is different, many of them work on completely different principles
and they have evolved quite independently of each other, many times over.
This is the shell of a scallop, a kind of shellfish.
These things are not pearls, they are eyes.
And they're a very different kind of eye
from anything we've seen and anything that we normally think about.
Those eyes are reflector eyes.
They have mirrors instead of lenses.
Each one of these is a little curved mirror
which works like the Jodrell Bank telescope.
It forms an image in a way that a reflecting telescope does,
not the way our eyes do.
This is a compound eye of an insect.
Each one of these little facets is one little eye
and the whole assembly together is interpreted by the brain
to make one big image.
Next eye, next one.
These headlights belong to a spider.
Once again, this is entirely independent evolution of the eye.
It has nothing to do with the other eyes we've seen.
And next
And finally, an eye of a squid.
This is the skin of a squid, there is its eye.
The squid has a very excellent eye.
Very like ours, with the proper lens, proper camera principle.
But you can tell by looking at the details of it, especially how it develops,
that it evolved entirely independently of ours.
The same principle was hit on entirely independently of ours.
Once again, remember, that each step is a small piece of random luck.
As such, each step is not particularly impressive, in fact,
it had better not be impressive, because if it was,
it would be a miracle and we'd no longer have a true explanation.
The whole point of evolution is that it gets us up Mount Improbable without miracles.
Now I want to welcome two magnificent pinnacles of evolution
on different peaks of Mount Improbable.
This is an imperial eagle and this is an eagle owl.
Look at the eagle first.
It's a superb machine for catching prey.
Its eyes are more acute than anything that we can offer.
We have no idea of acuity of vision like the eagle has.
Its claws are capable of gripping in such a way
that it's almost impossible, once they've gripped you, to get them off.
They have a ratchet mechanism inside
so that the bone just catches and the eagle can hardly be prised off your hand.
Look at the beak. Superb instrument for tearing up its prey.
The owl is sitting upon a different pinnacle of Mount Improbable.
It has good eyes but they are used in a very dim light
and it relies more upon its ears.
It has asymmetrical ears
which enable it to localize its prey
with pinpoint accuracy in total and complete darkness.
Its wings are very different from the eagle's wings. They're shaped
so that they make it fly very quietly at night. It's a stealth fighter.
Both these birds, in addition to having beautiful eyes and ears, have superb wings,
which brings us in to our next topic.
Could we see some wings, do you think? Is it possible to - look at those wings.
Does the owl do it as well? Lovely. Beautiful. Thank you very, very much indeed.
Let's see some film of wings in action.
This is a hawk.
And watch the way it controls the shape of the wing in gliding. Now watch it flapping.
Not entirely surprising, creationists are also very fond of wings
and they, once again, make a similar point about,
"What's the good of half a wing? What's the good of three quarters of a wing?
How could something like those wings have evolved from the silly little wing stubs
that must have been there at the beginning of the evolution of wings?"
Well, let's tackle this with another little Bryson special.
These are not exactly flying creatures.
They live up trees and they have wings to show that they are creatures,
they have also little eyes to show that they are creatures.
They live up trees and if they were to fall they'd risk breaking their necks.
Thank you.
Both of them in this case, from this low height, one with a little skirt
and without a little skirt, survived the breakage.
At this depth you do not need a little wing.
This is a wing stub, call it a phalange or a wing stub.
It's not become a wing but we are looking at the ancestral stub
that might eventually evolved into a wing.
When the height is sufficiently low then nobody is going to break their neck.
But if we raise the thing a bit, very carefully -
Sometimes these animals are going to find themselves leaping from higher branches.
And from higher branches it may be that even these pathetic little wing stubs might make a difference.
Let's see what happens now.
Right. Now, in this case, from that higher level -
From that higher level even a little wing stub like this
can make a difference.
And once you got the evolution of wing stub this long
then natural selection may favor
the wings that start getting a bit longer still, because it's going to be an even higher height
that you might fall from, where the difference between a wing stub that high
and between a wing stub that high might make a difference.
And the point is that we have a smooth gradient all the way, up higher and higher,
heights that you could fall from to drive the lineage,
to drive the species towards ever longer wings.
Controlled gliding has, in fact, evolved many times over.
There are many creatures that have the equivalent of half a wing.
This is a snake, a tree snake
crawling along a tree.
So far it looks like an ordinary snake.
Now it launches itself off, slow motion picture.
The body flattens out sideways and catches the air.
It's steering itself down and it's going to land on another tree without hurting itself.
This you can think of as the first step towards evolving wings.
Snakes never have evolved wings but that's one possible pathway towards evolving wings.
Here is a squirrel, a tree squirrel, so-called flying squirrel.
It has flaps of skin between its arms and its legs, and it glides with them.
This is a very beautifully controlled glide.
Downhill all the way.
It doesn't flap, it doesn't climb, but it lands gracefully on a neighboring tree,
and is completely unhurt when it does so.
This is an animal again with something like 50% of a wing.
And a third example is a lizard. In this case it has skin stretched between its ribs.
All these are different ways in which wings might have evolved.
In no case did they properly evolve but they show
what the beginnings of wings might have looked like.
So not only can you do well if you have half a wing,
or a quarter of a wing, but lots of animals actually do.
This is a flying lemur.
Looks like the flying squirrel we just saw but it is totally unrelated,
it comes from South-East Asia. It has nothing to do with it.
I think you can easily imagine how that could eventually give rise to something like that
a flying fox,
which is a bat. That has proper wings that's as good as a hawk,
that can fly and flap properly.
So we have dealt with two problems of "what is the use" kind: the eye and the wing.
Our third difficult problem, camouflage, has been thought difficult for a slightly different reason.
Think back to our stick insects.
Think about the fantastic detail with which they mimic sticks.
A stick insect you could think of as being right at the top of Mount Improbable.
So let's put it up there, it's a lovely one. Thank you.
But that has somehow evolved from something at the bottom.
And I'm going to put at the bottom something that doesn't look remotely like a stick: this brown bug.
And somehow we have to imagine that there was a gradual progression,
all the way up the slope, all the way round the path here, from something like that to something like that.
Now, here is the problem.
It's birds selecting insects that are propelling these animals up Mount Improbable.
They are propelling evolution.
And in order for the birds to have propelled the last 1%,
from 99% like a stick to 100% like a stick, the birds must have had astonishingly good vision.
They must have been very clever in order to be fooled,
in order to need, rather, the precise details of mimicry in order to fool them.
But here is the problem.
Those very same birds or relatives of them,
had to have been fooled down the bottom of Mount Improbable, by insects
that hardly looked like sticks at all.
Because it's the same birds propelling the insects from 1% like a stick to 2% like a stick,
that have to propel the insects all the way up the path, 20% to 21%, 99 to 100%.
And, say opponents of the Darwinian theory, you can't have it both ways:
either the birds are clever enough to do that job of natural selection
or they're stupid enough to do that job of natural selection,
but they can't be both.
You might like to think to yourselves about possible solutions to that riddle.
One thing you might think of is that it's not the same birds,
perhaps the birds have been evolving during the same time as the insects have been evolving.
But I don't like that theory for reasons I haven't time to go in to.
I rather prefer to think that it's the same birds,
just as clever at all stages of evolution,
had just as good eyesight, but the seeing conditions were not always as good.
Here we have a woodland floor which has 16 insects on it.
And from where you're sitting you can probably see some of them.
And that's really the point.
The seeing conditions from a distance are such that you can only see some of them.
Similarly, if I look out of the corner of my eye I can see one or two of them, but not all of them.
I'm going to narrow it down, narrow down the discussion
to just distance and I would like to call for a volunteer to help me with this.
Right.
What's your name?
Annie.
Come here, Annie, please.
Where is the pointer?
Thank you. Stand here.
Now, tell me, how many insects can you see?
Just point to one.
Would you like to take the pointer to point to it?
Which ones can you see? Can you see any?
There? What do you think that is? A butterfly.
That is a yellow butterfly. Right.
Probably most of you can see that yellow butterfly.
From that distance, I guess, you can probably see a blue beetle,
blue beetle, green beetle, perhaps that red one there?
So, if you're a bird, from that distance you could see quite a lot.
Now come a bit closer, Annie.
Can you see any more than you couldn't see before?
What can you see?
point
A black beetle and a green one there.
Yes.
And there's a cockroach.
I can see a cockroach there.
Now a bird from this distance could spot the cockroach,
whereas a bird from that distance could spot the yellow butterfly.
Now let's come in really close.
Now, can you see anything more?
A bird this distance might have a chance of seeing -
How about that?
What do you think that is?
There, look at that.
That's a leaf butterfly.
Look, Annie, look at this. What's that?
It's a leaf insect. There's its head, there's its body.
There's a stick insect.
Thank you very much, Annie.
So I think we have easily disposed of all three of our alleged difficulties:
the eye, the wing and camouflage.
I'm going to end with the particular favorite of creationists, the notorious bombardier beetle.
This is a recent headline that appeared in the Daily Telegraph:
"Beetle that may explode the ideas of Darwin."
The Telegraph thing goes on to say:
"If evolution were right it would have exploded."
The paper asks whether it offers proof of a Creator.
The story about the bombardier beetle is given in one creationist tract that I'm now going to read.
"The bombardier beetle squirts a lethal mixture
of hydroquinone and hydrogen peroxide into the face of its enemy.
These two chemicals, when mixed together, literally explode in the face of the enemy.
The chain of events that could have led to the evolution of such a complex,
coordinated and subtle process
is beyond biological explanation on a simple step by step process.
The slightest alteration in the chemical balance would result immediately
in a race of exploded beetles."
Well now, this does sound like a bit of a challenge, a difficult case.
I mustn't evade my responsibilities to take on difficult cases.
Here we have some hydrogen peroxide and here is some hydroquinone,
and this is what's going to explode violently when we...just a minute
Now, anybody who wants to, can leave the room.
We will start with hydrogen peroxide. So far so good. Now...
I better put it down, hadn't I.
What's happened? It's not even warm.
A bit of a damp squib.
There is some truth in the story.
By the way, of course, I knew that nothing would happen.
There was never any danger.
There is some truth in the story.
In fact the hydroquinone does nothing at all.
We can put that on one side.
The true story is that hydrogen peroxide on its own does decompose to form oxygen and water,
but it needs a catalyst under the normal conditions to do that.
This black powder here is a catalyst.
It's not the catalyst the bombardier beetle uses.
The bombardier beetle does use a catalyst
and it does, in fact, squirt this hot substance into the face of its enemy.
But if you put a catalyst into a weak solution of hydrogen peroxide
then you're going to get a little bit of bubbling and it is a little bit warm.
That might have some effect on the predator.
That might slightly deter a predator and it would be not particularly dangerous to the beetle.
Now we've got a smooth gradient.
A bit more concentration of hydrogen peroxide And that's distinctly warm.
That would work more effectively against a predator.
And by moving gradually up the slope,
gradually increasing the concentration of hydrogen peroxide, we can end up with -
So there is a smooth slope all the way up to the effective deterrent against a predator.
The myth that the bombardier beetle or any other feature of the natural world,
that has yet been described, cannot be explained by slow, gradual evolution, is a myth
that deserves to go up in smoke.
Making a complicated organ in one fell swoop is equivalent to a miracle.
It's equivalent to opening a bank safe combination lock in a single,
lucky spin of the dial.
It cannot be done.
In one way or another this lecture has been variations on the 747 theme.
You can't make complex, efficient, working objects
like eyes or wings in a single step.
Any theory that says that life or a part of life, an organ, an animal,
complexity or perfection came into being in a single step
starting from nothing, has got to be wrong.
Evolution is the one idea that has nothing to fear from the 747 argument.
Because evolution is the one idea that does not suggest
that complex perfection came into being in a single step.
It is the theory of miraculous creation that is really blown out of the water by the 747 argument.
Because it is miraculous creation that is equivalent to cracking the safe in a single step.
Equivalent to blowing together a 747 in a junkyard.
Evolution escapes the taint of miracle.
Escapes the taint of impossibly long odds
by the simple, yet hugely effective trick of smearing out the luck,
smearing it out over the vastness of geological time.
In the next lecture, The Ultraviolet Garden, we shall be looking at the question of
who benefits from evolution. Who is it good for?
Thank you very much.
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