1
00:00:52,100 --> 00:00:53,570
This is a stick insect.

2
00:00:54,540 --> 00:00:57,240
It may look fairly conspicuous
on my hand,

3
00:00:57,670 --> 00:01:00,710
although I have made an effort
to make it feel at home with my shirt,

4
00:01:02,880 --> 00:01:07,150
but you have to see it
in its natural surrounding
in order to see it at its best.

5
00:01:07,420 --> 00:01:09,890
There, it would blend in
almost totally.

6
00:01:10,020 --> 00:01:12,520
The attention to detail
is astonishing.

7
00:01:12,650 --> 00:01:17,060
You can even see little marks
suggesting bark on its back.

8
00:01:18,490 --> 00:01:24,430
You could almost say
that it fits its environment
like a key fits a lock.

9
00:01:25,600 --> 00:01:27,800
And I've got something else
under my hat.

10
00:01:34,440 --> 00:01:36,980
This is a different kind of
stick insect, a leaf insect.

11
00:01:37,110 --> 00:01:40,150
It mainly resembles leaves,
dead leaves.

12
00:01:40,320 --> 00:01:41,680
You see how it rocks like that.

13
00:01:41,820 --> 00:01:44,190
I suspect that it's got
a second line of defense

14
00:01:44,320 --> 00:01:49,460
which is that when it's startled
and when a bird might almost
have got it,

15
00:01:49,590 --> 00:01:51,530
it mimics a scorpion.

16
00:01:51,660 --> 00:01:55,230
You see how the tail has looped
over the back there.

17
00:01:55,370 --> 00:02:00,340
If I saw that I might be
momentarily startled,
thinking that it was a scorpion.

18
00:02:02,270 --> 00:02:05,510
Let's put these away.
I will get that one -

19
00:02:05,640 --> 00:02:10,480
I may have to call for a volunteer
who is not frightened of stick insects.
There we are.

20
00:02:19,560 --> 00:02:20,690
Thank you very much!

21
00:02:33,200 --> 00:02:35,540
Bryson and I are always doing
double acts like this.

22
00:02:58,630 --> 00:02:59,860
Here are a couple of more -

23
00:03:00,730 --> 00:03:03,070
There's a branch of a tree.

24
00:03:05,530 --> 00:03:06,940
Seems to be moving.

25
00:03:08,140 --> 00:03:09,810
There goes its head.
It's a bird.

26
00:03:09,940 --> 00:03:11,410
It flies off. It's a potoo.

27
00:03:11,870 --> 00:03:13,740
Those are rose thorns.

28
00:03:14,480 --> 00:03:16,550
That is not a rose thorn.
It's a bug.

29
00:03:17,380 --> 00:03:20,880
It gains protection
by looking like a rose thorn.

30
00:03:21,550 --> 00:03:22,620
You could almost say

31
00:03:22,750 --> 00:03:30,690
that it's like a key
that fits into the brain of a bird
and the bird mistakes it for a thorn.

32
00:03:31,190 --> 00:03:33,860
The bird has a rose
thorn shaped lock.

33
00:03:35,430 --> 00:03:39,170
If that sounds a little bit mysterious
I hope I'll explain it in a moment.

34
00:03:39,300 --> 00:03:43,210
Because I'm going to use
the analogy of a lock and key,

35
00:03:43,470 --> 00:03:46,980
whenever we see an apparently
well designed animal or plant,

36
00:03:47,110 --> 00:03:51,680
it's as if nature has the lock
and the creature has the key.

37
00:03:52,650 --> 00:03:58,190
The thing about a lock and key is that
the key has an intricate structure

38
00:03:58,320 --> 00:04:03,560
which is very hard to imitate and
that structure exactly fits the lock.

39
00:04:04,660 --> 00:04:08,060
This key fits precisely
into the lock

40
00:04:08,330 --> 00:04:11,830
and the holes in the key
fit the teeth in the lock.

41
00:04:12,130 --> 00:04:14,070
And the lock therefore opens.

42
00:04:14,440 --> 00:04:17,270
Just any old bit of bent wire
won't do.

43
00:04:17,770 --> 00:04:20,440
It has to be the right key.

44
00:04:25,150 --> 00:04:26,750
The principle of a lock and key

45
00:04:26,880 --> 00:04:30,190
is that there's something intrinsically
improbable in the shape of the key.

46
00:04:30,320 --> 00:04:32,750
You need that key to open the lock.

47
00:04:33,860 --> 00:04:36,360
In the case of an ordinary lock
that you open with a key

48
00:04:36,490 --> 00:04:39,560
it's not easy to measure
how improbable the key is.

49
00:04:40,330 --> 00:04:43,430
But here's a combination lock,
an ordinary bicycle lock.

50
00:04:43,770 --> 00:04:46,370
Here we know exactly
how improbable it is

51
00:04:46,500 --> 00:04:50,870
because there are three dials
and each one has six positions.

52
00:04:51,640 --> 00:04:57,780
That means that there are six times
six times six possibilities, which is 216.

53
00:04:58,010 --> 00:05:01,520
There is a 1 in 216 chance
of opening it by luck.

54
00:05:02,750 --> 00:05:07,920
And here's a model
of the same combination lock
so we can see how it works.

55
00:05:10,260 --> 00:05:14,730
You have to get all three
of the dials into position.

56
00:05:14,900 --> 00:05:22,370
This one's combination is 6, 5, 1
and the lock opens.

57
00:05:22,500 --> 00:05:24,870
All three of the teeth
have to be lined up.

58
00:05:25,010 --> 00:05:27,710
It isn't enough
just to have one of them.

59
00:05:30,580 --> 00:05:33,050
But the lock is just a parable.

60
00:05:33,180 --> 00:05:35,050
Let's get back to real life.

61
00:05:35,580 --> 00:05:37,650
If the thorn bug is a key,

62
00:05:37,820 --> 00:05:41,060
what this means is that
just any old shape won't do.

63
00:05:41,190 --> 00:05:43,860
It must be the exact shape
of a rose thorn.

64
00:05:44,030 --> 00:05:46,830
A stick insect must be
the exact shape of a stick.

65
00:05:47,000 --> 00:05:53,000
An upper tooth must fit,
bite snuggly against,
the lower teeth in your jaw.

66
00:05:54,070 --> 00:05:56,440
Yet the theory of evolution says

67
00:05:56,570 --> 00:06:00,940
that all these things evolved
gradually, stage by stage.

68
00:06:01,080 --> 00:06:03,750
This means that they must
have gone through intermediates,

69
00:06:03,880 --> 00:06:07,480
when they were not a perfect key
fitting a lock.

70
00:06:08,650 --> 00:06:11,350
The thorn bug must have been
half like a thorn,

71
00:06:11,520 --> 00:06:14,460
the stick insect must have been
half like a stick.

72
00:06:15,190 --> 00:06:19,760
But whoever heard of a key
that only half fitted a lock?

73
00:06:19,900 --> 00:06:22,430
A key either fits a lock
or it doesn't.

74
00:06:22,560 --> 00:06:27,000
So how do real living creatures
managed to evolve their perfection?

75
00:06:27,140 --> 00:06:30,240
How do they manage to survive
the intermediate stages?

76
00:06:30,370 --> 00:06:33,480
How do they work
when they're only half a key?

77
00:06:34,310 --> 00:06:38,050
Well, let's approach the problem
by going back to the combination lock.

78
00:06:38,180 --> 00:06:42,350
While I've been talking Bryson
has been discretely doctoring his lock

79
00:06:42,520 --> 00:06:45,890
so that it behaves
in a different way.

80
00:06:48,820 --> 00:06:50,930
Imagine a lock

81
00:06:51,060 --> 00:06:55,830
where instead of having to get
all the dials in place at once...

82
00:06:56,430 --> 00:06:59,370
Suppose I was trying to crack a safe
and there was money in there.

83
00:07:00,000 --> 00:07:01,440
As it is I can't do it

84
00:07:01,570 --> 00:07:04,640
because I've got to get
all the dials in place at once

85
00:07:04,770 --> 00:07:07,940
and I've only got a
1 in 216 chance of doing that.

86
00:07:08,080 --> 00:07:09,750
In a real bank safe it would be
one in billions.

87
00:07:09,880 --> 00:07:11,110
I can't do it.

88
00:07:11,280 --> 00:07:14,720
But suppose that I were able to
try the first one at random

89
00:07:15,080 --> 00:07:17,720
and eventually find out
how to open that.

90
00:07:17,850 --> 00:07:22,420
And then the safe door
peeps open a little bit,
a little bit of money drops out.

91
00:07:22,560 --> 00:07:25,090
I've done that one,
now I can go on to the next one.

92
00:07:25,230 --> 00:07:29,930
And I find out how to open that one,
I have only got 1 in 6 chance, that's fine.

93
00:07:30,070 --> 00:07:32,300
And a little bit more money
spills out.

94
00:07:32,430 --> 00:07:39,510
And now the final wheel,
I've only got 1 in 6 chance,
that's easy and I open the entire safe.

95
00:07:40,080 --> 00:07:43,680
It's now become a gradualistic
combination lock,

96
00:07:43,810 --> 00:07:48,150
whereas before it was an all
or nothing combination lock.

97
00:07:51,250 --> 00:07:57,060
With this lock, the maximum number
of tries that you need
in order to open it by luck

98
00:07:57,190 --> 00:08:00,860
is not 216 but a mere 18.

99
00:08:01,030 --> 00:08:04,700
So it is easy to open
a gradualistic combination lock

100
00:08:04,830 --> 00:08:08,000
and I call this "smearing out the luck".

101
00:08:08,140 --> 00:08:12,240
Because we do not have to get our luck
all in one ridiculously large dollop.

102
00:08:12,370 --> 00:08:16,180
Instead we can get our luck
in dribs and drabs.

103
00:08:16,310 --> 00:08:19,220
Each drib being allowed to come
before the next drab

104
00:08:19,310 --> 00:08:22,220
and we go on to wait for the
next bit of luck.

105
00:08:22,350 --> 00:08:23,690
It cumulates.

106
00:08:25,120 --> 00:08:26,890
So, what have we seen so far?

107
00:08:27,020 --> 00:08:30,560
Although an animal may look like
a key fitting a lock

108
00:08:30,830 --> 00:08:33,000
it's not a totally good analogy

109
00:08:33,130 --> 00:08:37,100
because in this case half a key
is better than no key.

110
00:08:37,530 --> 00:08:41,470
If nature is a combination lock,
it's a gradualistic combination lock,

111
00:08:41,600 --> 00:08:43,510
not an all or nothing one.

112
00:08:44,510 --> 00:08:47,280
Now let's look at the same thing
from another direction.

113
00:08:47,410 --> 00:08:51,880
It's been said that a monkey
typing at random on a typewriter

114
00:08:52,010 --> 00:08:54,650
could eventually write
the complete works of Shakespeare.

115
00:08:55,250 --> 00:08:59,490
I once did this experiment with my
then 11-month-old daughter, Juliet,

116
00:08:59,890 --> 00:09:01,890
and this is what she typed.

117
00:09:02,020 --> 00:09:03,730
I let her go for a bit -

118
00:09:03,860 --> 00:09:05,860
And so on and so on.

119
00:09:05,990 --> 00:09:07,460
I realized after a bit

120
00:09:07,630 --> 00:09:10,500
that I would have to let her go on
for at least a billion years

121
00:09:10,630 --> 00:09:14,370
before she got even
a single phrase of Shakespeare.

122
00:09:15,500 --> 00:09:18,140
The eminent astronomer,
Sir Fred Hoyle,

123
00:09:18,740 --> 00:09:21,480
has pointed out
that it's just about as unlikely

124
00:09:22,010 --> 00:09:28,420
that any complex living structure
could spring into existence suddenly,
by luck alone.

125
00:09:28,880 --> 00:09:35,230
He said: "It is rather like
taking a junkyard and letting
a hurricane blow through it

126
00:09:35,280 --> 00:09:37,230
and the hurricane has the luck

127
00:09:37,360 --> 00:09:41,730
to spontaneously assemble
a Boeing 747".

128
00:09:41,860 --> 00:09:47,370
So here is our the junkyard,
and the hurricane comes along,
it's blowing like this.

129
00:09:47,500 --> 00:09:51,740
Hoyle's point is that the luck that
would be necessary to spontaneously

130
00:09:51,870 --> 00:09:56,110
assemble a Boeing 747
like that is equivalent to the luck

131
00:09:56,250 --> 00:10:03,620
that you'd need in order to get
something like an eye or a stick insect
or hemoglobin molecule by sheer luck.

132
00:10:06,120 --> 00:10:09,320
My reason for mentioning Hoyle's 747
is that I'm going to

133
00:10:09,490 --> 00:10:13,200
take his name in vain
in the next demonstration.

134
00:10:13,860 --> 00:10:19,230
We're going to have a computer monkey
or rather we' re going to have
two computer monkeys,

135
00:10:19,400 --> 00:10:22,200
one called Hoyle
and one called Darwin.

136
00:10:23,010 --> 00:10:24,940
Both monkeys have the same task.

137
00:10:25,070 --> 00:10:28,240
Both have to type, not the
complete works of Shakespeare,

138
00:10:28,380 --> 00:10:30,850
but one phrase from as you like it

139
00:10:30,980 --> 00:10:34,250
"More giddy in my desires
than a monkey".

140
00:10:37,620 --> 00:10:40,360
Hoyle types entirely at random.

141
00:10:40,760 --> 00:10:43,860
After every line that he types
the computer checks

142
00:10:44,030 --> 00:10:47,830
to see if he has managed
to hit the target line.

143
00:10:48,260 --> 00:10:51,730
If he does, the computer
will stop, bells will ring,

144
00:10:51,900 --> 00:10:54,700
it'll be the most improbable coincidence
in the history of the world

145
00:10:54,840 --> 00:10:57,870
and I solemnly promise
to eat my hat.

146
00:10:59,880 --> 00:11:01,640
I'll go further than that.

147
00:11:02,880 --> 00:11:06,250
I bet you everything I possess
that it won't reach the phrase,

148
00:11:06,380 --> 00:11:08,920
shall we say,
in the next 10 billion years.

149
00:11:09,520 --> 00:11:10,050
I won't bet you.

150
00:11:10,190 --> 00:11:12,750
I will undertake to give everything
I possess to the Royal Institution

151
00:11:12,890 --> 00:11:16,090
and here's the legal document
signed by me

152
00:11:16,230 --> 00:11:19,630
which undertakes
to make over everything I own
to the Royal Institution

153
00:11:19,760 --> 00:11:23,900
in the event that the monkey Hoyle
reaches the target phrase.

154
00:11:24,400 --> 00:11:27,400
But, of course, this is just
to illustrate my confidence

155
00:11:27,540 --> 00:11:32,140
that chance on its own
could never make an eye or a 747.

156
00:11:32,270 --> 00:11:37,680
The real point of the demonstration
is that the other monkey, Darwin,
will get the target phrase.

157
00:11:37,850 --> 00:11:39,280
So what does Darwin do?

158
00:11:40,150 --> 00:11:42,850
The same,
but with a crucial difference.

159
00:11:42,990 --> 00:11:46,590
The Darwin monkey begins
by typing a random phrase.

160
00:11:46,720 --> 00:11:48,460
So far the same as the Hoyle monkey.

161
00:11:48,590 --> 00:11:52,230
But now the computer
breeds from that phrase.

162
00:11:52,360 --> 00:11:56,100
It breeds 50 offspring
which are identical to the first phrase

163
00:11:56,230 --> 00:12:02,500
but with a tiny mutation,
a tiny random difference
in each of the 50 cases.

164
00:12:02,640 --> 00:12:06,880
The computer then looks at those
50 offspring and chooses the one

165
00:12:07,010 --> 00:12:12,280
which most resembles the target phrase,
however slightly it resembles
the target phrase.

166
00:12:12,410 --> 00:12:16,590
So the generations go by
and, generation after generation,

167
00:12:16,720 --> 00:12:20,760
it gradually becomes more and more
like the target phrase.

168
00:12:20,890 --> 00:12:24,030
Now, when I agreed
to give these lectures

169
00:12:24,160 --> 00:12:28,000
I was told that
I should always call members
of the audience out to assist.

170
00:12:28,130 --> 00:12:30,400
But I was also told
that it was silly to do this

171
00:12:30,530 --> 00:12:35,840
if all I was going to ask them to do
was to come out and hit the
return button on a computer.

172
00:12:37,240 --> 00:12:41,510
However, on this particular occasion,
since so much is at stake

173
00:12:41,640 --> 00:12:44,080
I thought it would be better
if I did ask somebody

174
00:12:44,210 --> 00:12:45,250
who knows a lot about computers

175
00:12:45,380 --> 00:12:46,880
and is very good at pressing buttons,

176
00:12:47,020 --> 00:12:49,650
to come out
and perform this onerous task.

177
00:12:49,790 --> 00:12:51,250
So, if anybody would like
to volunteer -

178
00:12:51,390 --> 00:12:52,790
Yes, right.

179
00:12:57,630 --> 00:12:59,130
Now, what's your name?

180
00:12:59,630 --> 00:13:00,530
Andrew.

181
00:13:01,100 --> 00:13:03,430
Well, you understand
what's at stake, Andrew, do you?

182
00:13:03,600 --> 00:13:04,170
Okay,

183
00:13:04,300 --> 00:13:07,370
here's the target phrase,
"More giddy in my desires
than a monkey".

184
00:13:08,000 --> 00:13:10,910
There's the box where the
Hoyle monkey is going to type.

185
00:13:11,040 --> 00:13:13,940
And there's the box where
the Darwin monkey is going to type.

186
00:13:14,110 --> 00:13:16,510
Unless Bryson has been messing about
with the program in order to

187
00:13:16,650 --> 00:13:20,880
deprive me of my worldly goods
that is the way it is going to be.

188
00:13:21,520 --> 00:13:25,890
So, are you ready? Go!

189
00:13:28,390 --> 00:13:32,230
Now you see the Hoyle monkey
typing away entirely at random.

190
00:13:32,360 --> 00:13:35,230
The Darwin monkey is down here

191
00:13:35,400 --> 00:13:39,600
and I think we can begin to see
something appearing in the Darwin's row.

192
00:13:39,740 --> 00:13:45,240
"More giddy in my desires than the -

193
00:13:45,340 --> 00:13:47,440
Bang. And he has got there.

194
00:13:47,580 --> 00:13:49,480
How long did that take?
Anybody timed it?

195
00:13:49,910 --> 00:13:53,380
Not very long, I think.
Andrew, thank you very much.

196
00:13:59,890 --> 00:14:02,220
So I don't have to eat my hat
and my worldly goods,

197
00:14:02,390 --> 00:14:04,130
such as they are, are safe.

198
00:14:04,260 --> 00:14:07,230
But the point really is not that
Hoyle failed to reach the target.

199
00:14:07,400 --> 00:14:11,030
The point is that Darwin did reach
the target and astonishingly quickly.

200
00:14:11,500 --> 00:14:13,800
Well, there is a lot wrong with that
as a demonstration of

201
00:14:13,970 --> 00:14:15,340
Darwinian natural selection.

202
00:14:15,470 --> 00:14:20,110
For one thing,
it has a distant target in mind,
which natural selection does not have.

203
00:14:20,280 --> 00:14:26,650
But it does, once again,
show us the key to the way out of
the problem of mammoth improbability.

204
00:14:26,780 --> 00:14:31,620
Things like eyes and 747s
that couldn't possibly spring
into existence in a single,

205
00:14:31,750 --> 00:14:33,390
lucky shake of a dice,

206
00:14:33,520 --> 00:14:37,260
can come into existence
if the luck is smeared out

207
00:14:37,390 --> 00:14:40,830
in many tiny steps
and is accumulated.

208
00:14:40,960 --> 00:14:43,870
That is what this lecture is about:
smearing out the luck,

209
00:14:44,000 --> 00:14:48,370
accumulating it, turned out to be
an immensely important process.

210
00:14:48,500 --> 00:14:51,870
It's the process that makes it
possible for us to be here,

211
00:14:52,010 --> 00:14:57,280
and by "us" I mean all stick insects,
lions, elephants and bacteria,
everything that's here.

212
00:14:58,050 --> 00:15:02,850
And now let's look at a physical parable
for this gradualistic solution

213
00:15:02,920 --> 00:15:05,520
to a difficult problem.

214
00:15:05,650 --> 00:15:07,220
This is a mountain.

215
00:15:07,390 --> 00:15:09,630
It's called Mount Improbable.

216
00:15:10,290 --> 00:15:13,330
Sitting on the top
of the mountain is equivalent

217
00:15:13,460 --> 00:15:19,100
to being very well designed, to being
an eye that works well, for example.

218
00:15:19,230 --> 00:15:23,510
Being at the bottom of the mountain
is equivalent to being a distant ancestor

219
00:15:23,640 --> 00:15:25,340
that's not yet very well designed,

220
00:15:25,470 --> 00:15:29,080
that hasn't yet acquired
its good fitness to the environment.

221
00:15:29,880 --> 00:15:37,950
Facing you now is a precipice,
a cliff which is called Sheer Luck.
It's a sheer cliff.

222
00:15:39,520 --> 00:15:46,860
Jumping from the bottom of the cliff
to the top corresponds to assembling
a 747 by means of a hurricane

223
00:15:47,030 --> 00:15:52,130
or it corresponds to getting a
complete eye in a single lucky mutation.

224
00:15:52,270 --> 00:15:53,240
It can't be done,

225
00:15:53,370 --> 00:15:59,010
you could no more do that
than a mountaineer could leap
from the bottom of a cliff to the top.

226
00:15:59,780 --> 00:16:03,880
But this isn't the only route
up Mount Improbable.

227
00:16:04,010 --> 00:16:07,020
We have to go round the other side.

228
00:16:11,890 --> 00:16:22,870
And you notice that round here is
a gradual, sloping path, steadily
inching its way up the mountain.

229
00:16:23,030 --> 00:16:27,570
And if you follow it round
you'll find that even though
some bits of it are a little steep,

230
00:16:27,700 --> 00:16:32,710
you can get from the bottom to the top
without ever having to jump up a step.

231
00:16:32,840 --> 00:16:36,780
It's a gradual,
inch by inch, path up.

232
00:16:38,650 --> 00:16:42,250
Anybody who didn't know
about the Ramp Evolution,

233
00:16:42,380 --> 00:16:49,260
which is what that is called, would,
if they saw an animal perched on the top,

234
00:16:49,390 --> 00:16:54,200
a beautifully designed animal,
and only saw the cliff,
they would assume

235
00:16:54,330 --> 00:16:57,400
that it had to be the result
of a miracle.

236
00:17:00,500 --> 00:17:04,270
But in fact the only way
up Mount Improbable is the slow,

237
00:17:04,410 --> 00:17:06,580
gradual climb
up the Ramp Evolution.

238
00:17:06,740 --> 00:17:09,240
You have to add all
the little steps up together

239
00:17:09,410 --> 00:17:14,520
and after a very large number of steps
you can climb very, very high indeed.

240
00:17:15,520 --> 00:17:17,420
But we are still talking in parables.

241
00:17:17,550 --> 00:17:21,660
How in practice do living things
climb Mount Improbable?

242
00:17:22,260 --> 00:17:24,730
Well, of course,
individuals don't climb it.

243
00:17:25,160 --> 00:17:30,430
It's lineages, groups of animals,
species, that climb it,
and they do it in evolutionary time.

244
00:17:30,570 --> 00:17:34,040
They and their descendants,
and their descendants' descendants,

245
00:17:34,200 --> 00:17:38,840
they do it by going through an extremely
large number of generations,

246
00:17:39,010 --> 00:17:43,350
and we do have the time for an
extremely large number of generations,

247
00:17:43,510 --> 00:17:46,580
because we have geological time
at our disposal.

248
00:17:47,320 --> 00:17:51,390
This generation by generation
accumulation works only

249
00:17:51,520 --> 00:17:56,760
if there is reproduction
with true heredity,
to carry the message through.

250
00:17:56,930 --> 00:18:01,630
And I must explain what that means,
because just plain reproduction
without heredity

251
00:18:01,760 --> 00:18:03,200
won't do, it's not enough

252
00:18:03,330 --> 00:18:07,440
It's possible to imagine
reproduction without heredity.

253
00:18:07,570 --> 00:18:12,710
Fires, for example, have a form
of reproduction without heredity.

254
00:18:13,180 --> 00:18:19,110
If you imagine that this is a savanna,
a dry savanna, the dry grass all over it.

255
00:18:19,280 --> 00:18:23,020
And a fire suddenly starts
in one place.

256
00:18:24,750 --> 00:18:30,690
Sparks fly up and are carried in the wind
and suddenly a spark lands there
and a new fire starts.

257
00:18:30,830 --> 00:18:35,900
Both these fires are now flaming up
and sparks are going off,
and another fire starts up

258
00:18:36,030 --> 00:18:37,570
which may be the daughter
of this one.

259
00:18:37,700 --> 00:18:40,670
One starts up here which may be
the daughter of that one.

260
00:18:40,770 --> 00:18:45,340
These fires are propagating,
these fires are having children.

261
00:18:45,510 --> 00:18:51,650
The sparks are causing this fire
to be the parent of that one,

262
00:18:51,780 --> 00:19:00,560
and in the next one we can see
that you can have both,
not mother and daughter,
but grandmother, grandchildren fires.

263
00:19:00,790 --> 00:19:03,360
The fires may differ a bit.

264
00:19:03,490 --> 00:19:07,660
In this picture we've represented
them by red, green and blue.

265
00:19:07,800 --> 00:19:09,870
Fires may, indeed, differ.

266
00:19:10,000 --> 00:19:14,340
But they get their qualities not
from their parents and grandparents.

267
00:19:14,470 --> 00:19:18,840
A fire gets its qualities from its
surroundings, from its environment.

268
00:19:18,970 --> 00:19:22,650
A fire gets its qualities
from the direction of the wind,
where it happens to be,

269
00:19:22,780 --> 00:19:26,920
or from the chemistry of the soil
or from the dampness of the vegetation.

270
00:19:27,450 --> 00:19:33,390
Fires do not get their qualities
from the spark that comes
from their parent fire.

271
00:19:33,520 --> 00:19:37,260
Now we're going to do the same
thing with a Bryson special.

272
00:19:38,230 --> 00:19:40,300
And I'm going to stand well back.
Where do I have to stand?

273
00:19:40,460 --> 00:19:42,070
Here?

274
00:19:43,600 --> 00:19:48,540
We always have to have fireworks
at the Royal Institution,
so go ahead, Bryson, please.

275
00:19:49,770 --> 00:19:54,110
There's the first fire,
there's the parent,
the sparks are flying up.

276
00:19:54,280 --> 00:19:57,150
It started another one there.
That's the daughter fire.

277
00:20:01,750 --> 00:20:06,320
And a granddaughter,
and a second daughter of this one.

278
00:20:10,790 --> 00:20:16,000
But the point is that to the extent
that there are any differences
between these fires,

279
00:20:16,130 --> 00:20:20,500
they do not get their qualities
from their parents.

280
00:20:21,570 --> 00:20:28,310
There are sparks that flow from fire
to fire but all that the sparks
do though is to start a new fire.

281
00:20:28,480 --> 00:20:35,480
Nothing is carried in the spark.
There is no information carried in the spark.

282
00:20:47,400 --> 00:20:54,400
And this, of course,
is where rabbits and humans
and stick insects differ from fires.

283
00:20:54,940 --> 00:20:58,870
Don't be misled by the fact
that rabbits and humans
have a mother and a father.

284
00:20:59,010 --> 00:21:01,440
Stick insects only have a mother,
like fires.

285
00:21:01,580 --> 00:21:03,650
In this particular respect
stick insects are like fires.

286
00:21:03,780 --> 00:21:10,320
But in the important respect
that I'm talking about,
stick insects do not resemble fires.

287
00:21:11,020 --> 00:21:15,660
Because, unlike fires,
stick insects have true heredity.

288
00:21:16,560 --> 00:21:20,060
At least some of their qualities:
color, shape, size, spininess and so on,

289
00:21:20,130 --> 00:21:24,830
they actually get from their mother,
not only from their surroundings.

290
00:21:25,000 --> 00:21:27,070
Something travels
from mother to daughter,

291
00:21:27,100 --> 00:21:30,070
something in the spark that
travels from mother to daughter -

292
00:21:30,240 --> 00:21:32,170
there is information.

293
00:21:32,310 --> 00:21:37,380
So what is this mysterious information
that eggs contain and sparks don't?

294
00:21:38,180 --> 00:21:42,520
Well, it's DNA.
This astounding molecule

295
00:21:42,680 --> 00:21:48,090
which contains in the sequence
of its bases all the information,

296
00:21:48,260 --> 00:21:54,700
or almost all the information that you
need to build a stick insect or a rabbit.

297
00:22:02,240 --> 00:22:07,940
DNA comes like an ever-flowing river
down the generations.

298
00:22:08,580 --> 00:22:11,020
The river of DNA that flows
through us into the future

299
00:22:11,150 --> 00:22:18,890
is a pure river that leaves us exactly
as it finds us. With one exception.

300
00:22:19,760 --> 00:22:25,930
There are occasional, very occasional,
random changes called mutations.

301
00:22:26,060 --> 00:22:31,770
Because of these there is variation,
genetic variation in the population.

302
00:22:31,900 --> 00:22:34,370
And that opens the way
for natural selection.

303
00:22:34,500 --> 00:22:39,010
Those varieties of DNA
that just happen to be good
at building ancestors,

304
00:22:39,140 --> 00:22:43,850
at building bodies that have good eyes,
good legs, good anything else, survive.

305
00:22:43,980 --> 00:22:49,220
So the world automatically
becomes filled with good DNA.

306
00:22:49,350 --> 00:22:54,590
This mean good at making bodies
that are themselves good at surviving.

307
00:22:55,520 --> 00:23:00,300
This is the Darwinian explanation
for why living things are so good
at doing what they do.

308
00:23:00,460 --> 00:23:04,430
They're good because of the
accumulated wisdom of their ancestors.

309
00:23:04,570 --> 00:23:07,870
But it's not wisdom
that they have learned.

310
00:23:08,000 --> 00:23:11,810
It's wisdom that
they chanced upon by luck,

311
00:23:11,940 --> 00:23:16,410
lucky random mutations,
which were subsequently selected.

312
00:23:16,550 --> 00:23:20,680
And in each generation
the amount of luck was very small.

313
00:23:21,250 --> 00:23:28,090
But because the luck has been
accumulated over so many generations
we are impressed by the end product.

314
00:23:29,360 --> 00:23:33,060
I want to apply this lesson
to three particular cases,

315
00:23:33,230 --> 00:23:39,370
three particular problems
that have given difficulty:
the eye, the wing and camouflage.

316
00:23:39,500 --> 00:23:42,770
And I choose them because
they're famously regarded as difficult.

317
00:23:43,270 --> 00:23:44,510
First, the eye.

318
00:23:45,510 --> 00:23:50,950
Charles Darwin himself said:
"To this day the eye makes me shudder".

319
00:23:51,080 --> 00:23:54,250
Creationists are particularly fond
of the eye because they like saying,

320
00:23:54,420 --> 00:23:56,080
"What is the use of half an eye?"

321
00:23:56,250 --> 00:23:59,520
An eye only works, they say,
if every little detail is in place.

322
00:23:59,660 --> 00:24:02,290
Until you got that,
the eye won't see anything at all.

323
00:24:02,460 --> 00:24:04,660
So how could it possibly
have evolved?

324
00:24:05,330 --> 00:24:08,800
And even serious scientists
have sometimes queried

325
00:24:08,960 --> 00:24:12,400
whether there has been enough time
for the evolution of the eye.

326
00:24:13,770 --> 00:24:17,970
Suppose we start with an ancestor
who didn't really have an eye at all

327
00:24:18,110 --> 00:24:22,810
but just a single,
simple sheet of light-sensitive cells.

328
00:24:22,980 --> 00:24:27,420
That's represented by this screen here
and there's a television camera behind,

329
00:24:27,550 --> 00:24:31,750
looking at the screen,
so that we on the screen,
on the television screen,

330
00:24:31,920 --> 00:24:35,760
shall see what this primitive
animal would see.

331
00:24:36,330 --> 00:24:40,530
So this animal with hardly
any eye at all

332
00:24:40,660 --> 00:24:44,870
would at least be able to tell
the difference between light and dark.

333
00:24:45,660 --> 00:24:48,170
Light and dark.

334
00:24:51,810 --> 00:24:57,280
Now, the next stage in evolution
would be to have a shallow cup.

335
00:25:01,980 --> 00:25:08,660
This animal would be able to tell
the direction that light is coming from,

336
00:25:09,860 --> 00:25:12,260
because a shadow would appear.

337
00:25:15,430 --> 00:25:16,830
A shadow would appear there.

338
00:25:17,000 --> 00:25:19,200
And if you can tell the direction
a light is coming from,

339
00:25:19,330 --> 00:25:23,510
then you can tell the direction
a predator is coming from.

340
00:25:23,670 --> 00:25:27,380
Now, although we represented this
as a cup coming out from the wall,

341
00:25:27,510 --> 00:25:32,680
it would in fact, probably be an indentation
and it would be a gradual indentation.

342
00:25:32,820 --> 00:25:35,320
It's inconvenient
to make a gradual indentation.

343
00:25:35,450 --> 00:25:39,420
It has to be made as a rather abrupt cup
that comes out six inches at a time.

344
00:25:39,560 --> 00:25:42,960
But it's easy to see
that that shadow effect
that we have just been witnessing

345
00:25:43,090 --> 00:25:46,700
would work progressively and
gradually as the cup gets bigger.

346
00:25:46,830 --> 00:25:48,960
Let's make it bigger still now,
Bryson.

347
00:25:53,940 --> 00:25:57,070
And this cup is even more effective

348
00:25:58,740 --> 00:26:00,080
and if we go on to the next stage

349
00:26:00,110 --> 00:26:04,010
when we make the cup
gradually bigger again,

350
00:26:04,910 --> 00:26:09,320
so big that it becomes
just a little hole in the end.

351
00:26:14,290 --> 00:26:20,630
Now this animal has a very good idea
of exactly where the light is

352
00:26:20,760 --> 00:26:24,770
and by the same token exactly where,
for example, a predator is.

353
00:26:24,930 --> 00:26:28,040
And I think with this eye
we might even get a little image.

354
00:26:28,200 --> 00:26:29,870
See if we can get
an image of Bryson's hand.

355
00:26:30,010 --> 00:26:37,350
That smudge there is Bryson's hand
and you can just about see
a very dim image of his fingers.

356
00:26:37,510 --> 00:26:41,650
So an animal with an eye
like this would be able to see
perhaps just little bit

357
00:26:41,780 --> 00:26:43,890
what kind of predator it was.

358
00:26:44,020 --> 00:26:47,220
Let's go to the logical conclusion
which will be a pinhole.

359
00:26:48,520 --> 00:26:51,860
Remember, it's all gradual,
gradual change in evolution.

360
00:26:52,030 --> 00:26:55,100
Let's see if we can see
your hand again, Bryson.

361
00:26:55,260 --> 00:26:58,530
Now I can see a rather precise
picture of Bryson's hand.

362
00:26:58,700 --> 00:27:03,010
It's not a very bright one
but I can see every finger
clearly delimited.

363
00:27:03,170 --> 00:27:05,010
So I could see,
if I were this animal,

364
00:27:05,170 --> 00:27:07,940
I could see my predator
in some detail.

365
00:27:14,150 --> 00:27:17,890
There is an animal that
has a pinhole camera for an eye.

366
00:27:18,020 --> 00:27:20,990
It's a mollusk called Nautilus.

367
00:27:21,760 --> 00:27:27,030
It's a relative of the octopus
but it lives in a shell,
and there is its eye.

368
00:27:27,160 --> 00:27:32,000
It just has a simple hole and sea water
can flow in and out of that hole.

369
00:27:33,740 --> 00:27:36,000
Here is the shell of Nautilus.

370
00:27:38,010 --> 00:27:45,610
This bit of rock here shows ammonites,
which are a now extinct relative of Nautilus.

371
00:27:45,780 --> 00:27:49,250
They were once immensely common,
as this rock suggests.

372
00:27:50,020 --> 00:27:54,920
I like to think of all those
hundred million-years-old dramas

373
00:27:55,060 --> 00:27:59,530
that must have been witnessed through
the pinhole camera eyes of ammonites.

374
00:27:59,660 --> 00:28:01,560
We can't be sure
they had pinhole camera eyes

375
00:28:01,730 --> 00:28:03,770
but it seems quite likely.

376
00:28:04,770 --> 00:28:07,500
Now, a pinhole camera
is not a very good way of seeing.

377
00:28:07,670 --> 00:28:12,740
It does produce a sharp image
but because it's so narrow
you hardly get any light in.

378
00:28:12,910 --> 00:28:17,410
The answer to this problem
is that ingenious device:
the lens.

379
00:28:18,410 --> 00:28:23,290
Nautilus has a pretty poor eye
compared to its relatives,
the squids and octopuses,

380
00:28:23,450 --> 00:28:25,150
because they do have a lens.

381
00:28:25,290 --> 00:28:28,920
We can't help wondering
why doesn't Nautilus have a lens?

382
00:28:29,060 --> 00:28:31,390
Why didn't it evolve a lens?

383
00:28:31,530 --> 00:28:37,430
Well, I suspect that
Nautilus may have got itself
stuck on a little peak

384
00:28:37,570 --> 00:28:40,500
some way up Mount Improbable.

385
00:28:41,800 --> 00:28:46,010
You see, that although
we've got one big peak there,
there are various other peaks on the way.

386
00:28:46,180 --> 00:28:47,610
There are quite a lot of them.

387
00:28:47,780 --> 00:28:51,110
And since the rule in evolution
is just to keep going uphill,

388
00:28:51,280 --> 00:28:56,120
when the ancestors of Nautilus
came up the track here,
up the path here

389
00:28:56,250 --> 00:29:01,760
and got to this point,
that way uphill
looked just as inviting,

390
00:29:01,890 --> 00:29:04,930
so to speak, evolutionarily,
as that way.

391
00:29:05,060 --> 00:29:06,560
Both of them were uphill.

392
00:29:06,730 --> 00:29:10,130
Evolution has no foresight,
evolution has no way of knowing

393
00:29:10,270 --> 00:29:13,140
that, if you travel up that way,
you're going to end up with a lens.

394
00:29:13,270 --> 00:29:16,140
For the moment this appears to be
a perfectly good way to travel

395
00:29:16,270 --> 00:29:21,610
because the pinhole camera
at this level of illumination
is an effective eye.

396
00:29:21,740 --> 00:29:27,250
So I wonder whether perhaps Nautilus
has got itself trapped on top
of this little hillock

397
00:29:27,420 --> 00:29:29,690
and is now unable to escape,

398
00:29:29,820 --> 00:29:32,820
because escaping would mean
going downhill into the valley

399
00:29:32,990 --> 00:29:37,790
and the one thing
you cannot do on Mount Improbable
is ever go downhill.

400
00:29:39,330 --> 00:29:42,400
But let's imagine what the ancestors
of the squid and octopus did

401
00:29:42,530 --> 00:29:45,830
when they got
to this junction point here.

402
00:29:46,000 --> 00:29:48,470
They just happened to go on
up this way.

403
00:29:48,940 --> 00:29:53,510
And they started evolving a lens
and we did at a different time
in history.

404
00:29:56,280 --> 00:29:58,680
How might the lens have evolved?

405
00:29:58,810 --> 00:30:04,120
Let's imagine that it started
with just a single, transparent sheet

406
00:30:04,250 --> 00:30:06,420
of some transparent material.

407
00:30:06,560 --> 00:30:11,360
And all this was doing,
it's not a lens yet, all that it's doing
is protecting the eye.

408
00:30:11,530 --> 00:30:14,630
In Nautilus sea water
flows right inside the eye.

409
00:30:14,760 --> 00:30:17,400
This animal now has some protection.

410
00:30:17,530 --> 00:30:20,140
And the eye is really just the same

411
00:30:20,270 --> 00:30:24,470
as though there wasn't any
transparent material there.

412
00:30:25,040 --> 00:30:30,050
Now we're going to use
an optician's set of lenses here.

413
00:30:30,180 --> 00:30:32,420
It would be nice to be able to have
just one bit of transparent material

414
00:30:32,550 --> 00:30:35,950
which we would then squeeze and
make thicker, but we can't do that.

415
00:30:36,080 --> 00:30:39,890
So we are going to replicate that effect
by a whole series of little lenses.

416
00:30:40,020 --> 00:30:43,560
So this is the next stage in evolution.
This animal here -

417
00:30:43,730 --> 00:30:45,430
let's get an image of that.

418
00:30:46,530 --> 00:30:51,100
That's a rather better and, above all,
brighter image of the hand.

419
00:30:51,270 --> 00:30:52,940
Let's have the next lens in.

420
00:30:59,940 --> 00:31:03,550
If an animal had an eye like that
it would have a really very,
very clear view of its world.

421
00:31:03,710 --> 00:31:07,050
It could tell exactly
what its predator was.

422
00:31:07,180 --> 00:31:09,820
Would anybody like to come out
and have their face looked at?

423
00:31:12,520 --> 00:31:13,590
What is your name?

424
00:31:15,060 --> 00:31:16,190
Davina

425
00:31:16,330 --> 00:31:18,760
Davina, do you remember
where Bryson put his hand?

426
00:31:18,890 --> 00:31:20,960
Can you put your face
just down there?

427
00:31:21,100 --> 00:31:23,900
We need the lights down for this,
I think, don't we?

428
00:31:25,500 --> 00:31:28,070
There we are. Very nice.

429
00:31:28,240 --> 00:31:32,810
This animal can even see what
its predator's face looks like.

430
00:31:33,910 --> 00:31:36,080
Upside down.
But we all see upside down.

431
00:31:36,250 --> 00:31:37,350
Thank you very much, Davina.

432
00:31:43,920 --> 00:31:51,630
So we have a gradual pathway
all the way up Mount Improbable,
from no eye to an eye.

433
00:31:51,760 --> 00:31:55,530
But has there been enough time
for the evolution of the eye?

434
00:31:56,100 --> 00:32:01,440
Recently a Swedish scientist
called Dan Nilsson has tried
to answer that question.

435
00:32:01,570 --> 00:32:06,880
He did pretty much the same
as we've just been doing here,
but he did it with a computer.

436
00:32:07,010 --> 00:32:11,410
So, instead of growing up
in big steps as we had to do
with our wooden model,

437
00:32:11,550 --> 00:32:17,320
he was able to do it in very
small steps on his computer.
Very small steps indeed,

438
00:32:17,450 --> 00:32:22,560
deliberately.
He assumed that each step,
which means each mutation,

439
00:32:22,720 --> 00:32:29,260
caused only a 1% change
in the size of something, like,
say, the steepness of a cup.

440
00:32:30,000 --> 00:32:34,270
He also devised a way of measuring
the efficiency of an eye.

441
00:32:34,400 --> 00:32:38,570
He did this by telling the computer
to measure various things about the eye

442
00:32:38,740 --> 00:32:40,610
that it had just drawn itself.

443
00:32:41,080 --> 00:32:43,850
And then the computer worked out,
using the rules of physics,

444
00:32:43,980 --> 00:32:49,120
how good an image that eye
would be capable of producing.

445
00:32:49,380 --> 00:32:52,120
And the question was,
with those rules built into it,

446
00:32:52,250 --> 00:32:56,090
would there be a smooth gradient
of improvement,

447
00:32:56,230 --> 00:33:01,130
starting out with a flat retina
and ending with the proper eye,
like ours.

448
00:33:01,260 --> 00:33:03,630
And you've guessed it,
the answer is yes.

449
00:33:03,770 --> 00:33:10,840
This was Nilsson's starting point,
with just a flat retina under a flat,
transparent layer.

450
00:33:11,010 --> 00:33:16,010
And now let's just run the simulation
of the successive stages that Nilsson got

451
00:33:16,180 --> 00:33:18,410
and they're pretty similar
to the successive stages

452
00:33:18,550 --> 00:33:21,250
that Bryson got with his model.

453
00:33:23,990 --> 00:33:27,160
So far we haven't learned anything
that we didn't already know.

454
00:33:27,290 --> 00:33:32,760
There is a smooth progression
up Mount Improbable for the eye.

455
00:33:32,930 --> 00:33:41,000
But Nilsson went on to estimate
how many generations it would take
to accomplish this evolution.

456
00:33:41,570 --> 00:33:44,870
In order to do this he had to make
some more detailed assumptions.

457
00:33:45,010 --> 00:33:47,380
I won't bother you with
exactly what they were.

458
00:33:47,510 --> 00:33:50,280
All you need to know is
that they were quantities

459
00:33:50,410 --> 00:33:54,880
which geneticists out in the field
can measure and have measured.

460
00:33:55,020 --> 00:34:01,620
And Nilsson put into his computer
model, values of these quantities
that were conservative.

461
00:34:01,760 --> 00:34:04,530
Conservative means that he was erring

462
00:34:04,700 --> 00:34:11,300
on the side of deliberately biasing
his calculation to make it slow.

463
00:34:11,470 --> 00:34:14,040
To give it an estimate
on the slow side of evolution.

464
00:34:14,640 --> 00:34:17,740
Make evolution come out slower
than it might otherwise have done.

465
00:34:17,910 --> 00:34:21,240
But in spite of this, in spite
of his being conservative

466
00:34:21,380 --> 00:34:26,850
and in spite of assuming that each mutation
could only cause a 1% change,

467
00:34:26,980 --> 00:34:28,850
which is another conservative
assumption,

468
00:34:28,980 --> 00:34:32,550
Nilsson found that the evolution
of the eye, which we've just seen,

469
00:34:32,720 --> 00:34:35,800
would take a surprisingly
short time.

470
00:34:35,920 --> 00:34:40,800
It would take about
250,000 thousand generations.

471
00:34:41,260 --> 00:34:44,200
That might sound like
a lot of generations

472
00:34:44,330 --> 00:34:46,770
but we have a rather
warped perspective.

473
00:34:46,900 --> 00:34:51,070
Because, after all, each one of us
is only good for one generation.

474
00:34:51,240 --> 00:34:54,340
But our human perspective
is not the one that matters.

475
00:34:54,510 --> 00:34:57,780
One that matters is
the geological time scale.

476
00:34:57,950 --> 00:35:03,650
And on the geological time scale
250,000 generations is next to nothing.

477
00:35:03,790 --> 00:35:07,660
Probably only about a quarter
of a million years since
the animals we're talking about

478
00:35:07,690 --> 00:35:11,530
would probably have a generation
time of about a year.

479
00:35:12,360 --> 00:35:20,070
And a quarter of a million years
is really too short for geologists
to even measure.

480
00:35:20,240 --> 00:35:24,670
It's like trying to count seconds
using the hour hand of your watch.

481
00:35:27,280 --> 00:35:31,350
So there really was no need
for Darwin to shudder.

482
00:35:31,480 --> 00:35:34,220
Half an eye is better than no eye.

483
00:35:34,350 --> 00:35:41,290
Half an eye is better than 49% of an eye,
1% of an eye is better than no eye at all.

484
00:35:42,660 --> 00:35:46,400
And far from there not being enough
time for the evolution of the eye,

485
00:35:46,860 --> 00:35:49,870
the evolution of the eye
is so quick and easy

486
00:35:50,000 --> 00:35:52,870
that it must have happened
many, many times over.

487
00:35:53,000 --> 00:35:55,500
Eyes can evolve at a drop of a hat.

488
00:35:55,640 --> 00:35:58,640
And in fact, if we look around
the animal kingdom,

489
00:35:58,770 --> 00:36:01,880
there are lots of different
kinds of eyes dotted around.

490
00:36:02,010 --> 00:36:05,980
Each of them is different,
many of them work on completely
different principles

491
00:36:06,110 --> 00:36:10,950
and they have evolved quite independently
of each other, many times over.

492
00:36:11,890 --> 00:36:15,660
This is the shell of a scallop,
a kind of shellfish.

493
00:36:15,790 --> 00:36:19,130
These things are not pearls,
they are eyes.

494
00:36:19,260 --> 00:36:21,100
And they're a very different
kind of eye

495
00:36:21,230 --> 00:36:25,300
from anything we've seen and anything
that we normally think about.

496
00:36:25,470 --> 00:36:27,970
Those eyes are reflector eyes.

497
00:36:28,140 --> 00:36:30,370
They have mirrors instead of lenses.

498
00:36:30,540 --> 00:36:32,940
Each one of these
is a little curved mirror

499
00:36:33,080 --> 00:36:35,710
which works like
the Jodrell Bank telescope.

500
00:36:35,840 --> 00:36:40,480
It forms an image in a way that
a reflecting telescope does,

501
00:36:40,620 --> 00:36:42,280
not the way our eyes do.

502
00:36:42,450 --> 00:36:44,790
This is a compound eye of an insect.

503
00:36:44,920 --> 00:36:49,500
Each one of these little facets
is one little eye

504
00:36:49,620 --> 00:36:53,500
and the whole assembly together
is interpreted by the brain

505
00:36:53,630 --> 00:36:55,600
to make one big image.

506
00:36:55,730 --> 00:36:57,430
Next eye, next one.

507
00:36:57,600 --> 00:37:00,470
These headlights belong to a spider.

508
00:37:00,600 --> 00:37:03,870
Once again, this is entirely
independent evolution of the eye.

509
00:37:04,010 --> 00:37:06,640
It has nothing to do
with the other eyes we've seen.

510
00:37:06,810 --> 00:37:07,840
And next

511
00:37:08,010 --> 00:37:09,510
And finally, an eye of a squid.

512
00:37:09,680 --> 00:37:12,580
This is the skin of a squid,
there is its eye.

513
00:37:12,710 --> 00:37:14,480
The squid has a very excellent eye.

514
00:37:14,620 --> 00:37:18,120
Very like ours, with the proper lens,
proper camera principle.

515
00:37:18,290 --> 00:37:21,820
But you can tell by looking
at the details of it,
especially how it develops,

516
00:37:21,960 --> 00:37:24,590
that it evolved entirely
independently of ours.

517
00:37:24,760 --> 00:37:29,430
The same principle was hit on
entirely independently of ours.

518
00:37:31,600 --> 00:37:36,770
Once again, remember, that each step
is a small piece of random luck.

519
00:37:36,910 --> 00:37:40,180
As such, each step is not
particularly impressive, in fact,

520
00:37:40,210 --> 00:37:42,480
it had better not be impressive,
because if it was,

521
00:37:42,610 --> 00:37:46,350
it would be a miracle and
we'd no longer have a true explanation.

522
00:37:46,480 --> 00:37:52,920
The whole point of evolution is
that it gets us up Mount Improbable
without miracles.

523
00:37:53,860 --> 00:38:00,200
Now I want to welcome two
magnificent pinnacles of evolution

524
00:38:00,330 --> 00:38:03,300
on different peaks of Mount Improbable.

525
00:38:05,630 --> 00:38:12,010
This is an imperial eagle
and this is an eagle owl.

526
00:38:20,720 --> 00:38:22,280
Look at the eagle first.

527
00:38:22,450 --> 00:38:25,950
It's a superb machine for catching prey.

528
00:38:26,090 --> 00:38:30,890
Its eyes are more acute
than anything that we can offer.

529
00:38:31,060 --> 00:38:35,360
We have no idea of acuity of vision
like the eagle has.

530
00:38:35,530 --> 00:38:38,400
Its claws are capable
of gripping in such a way

531
00:38:38,530 --> 00:38:41,700
that it's almost impossible,
once they've gripped you,
to get them off.

532
00:38:41,870 --> 00:38:43,870
They have a ratchet mechanism inside

533
00:38:44,040 --> 00:38:50,050
so that the bone just catches
and the eagle can hardly
be prised off your hand.

534
00:38:50,750 --> 00:38:55,780
Look at the beak.
Superb instrument
for tearing up its prey.

535
00:38:57,690 --> 00:39:02,160
The owl is sitting upon a different
pinnacle of Mount Improbable.

536
00:39:07,700 --> 00:39:11,070
It has good eyes but they are used
in a very dim light

537
00:39:11,200 --> 00:39:13,900
and it relies more upon its ears.

538
00:39:14,670 --> 00:39:16,670
It has asymmetrical ears

539
00:39:16,810 --> 00:39:19,540
which enable it
to localize its prey

540
00:39:20,080 --> 00:39:24,180
with pinpoint accuracy in total
and complete darkness.

541
00:39:25,980 --> 00:39:31,320
Its wings are very different
from the eagle's wings. They're shaped

542
00:39:31,450 --> 00:39:38,460
so that they make it
fly very quietly at night.
It's a stealth fighter.

543
00:39:41,230 --> 00:39:46,770
Both these birds, in addition
to having beautiful eyes and ears,
have superb wings,

544
00:39:46,900 --> 00:39:49,670
which brings us
in to our next topic.

545
00:39:49,810 --> 00:39:54,980
Could we see some wings, do you think?
Is it possible to - look at those wings.

546
00:40:00,050 --> 00:40:06,320
Does the owl do it as well?
Lovely. Beautiful.
Thank you very, very much indeed.

547
00:40:17,670 --> 00:40:20,440
Let's see some film of wings
in action.

548
00:40:20,570 --> 00:40:21,900
This is a hawk.

549
00:40:23,540 --> 00:40:29,080
And watch the way it controls
the shape of the wing in gliding.
Now watch it flapping.

550
00:40:37,510 --> 00:40:42,480
Not entirely surprising,
creationists are also very fond of wings

551
00:40:42,690 --> 00:40:45,990
and they, once again,
make a similar point about,

552
00:40:46,130 --> 00:40:49,470
"What's the good of half a wing? What's
the good of three quarters of a wing?

553
00:40:49,600 --> 00:40:53,570
How could something like
those wings have evolved
from the silly little wing stubs

554
00:40:53,740 --> 00:40:58,470
that must have been there at the
beginning of the evolution of wings?"

555
00:40:58,610 --> 00:41:05,450
Well, let's tackle this with
another little Bryson special.

556
00:41:08,120 --> 00:41:11,050
These are not exactly
flying creatures.

557
00:41:11,190 --> 00:41:14,820
They live up trees and they have wings
to show that they are creatures,

558
00:41:14,960 --> 00:41:17,330
they have also little eyes to show
that they are creatures.

559
00:41:18,260 --> 00:41:25,030
They live up trees and if they were
to fall they'd risk breaking their necks.

560
00:41:26,440 --> 00:41:27,400
Thank you.

561
00:41:28,000 --> 00:41:32,850
Both of them in this case,
from this low height,
one with a little skirt

562
00:41:33,000 --> 00:41:36,650
and without a little skirt,
survived the breakage.

563
00:41:36,780 --> 00:41:39,780
At this depth you do not
need a little wing.

564
00:41:39,950 --> 00:41:42,820
This is a wing stub,
call it a phalange or a wing stub.

565
00:41:42,950 --> 00:41:47,320
It's not become a wing but we are
looking at the ancestral stub

566
00:41:47,460 --> 00:41:49,830
that might eventually
evolved into a wing.

567
00:41:49,960 --> 00:41:55,330
When the height is sufficiently
low then nobody
is going to break their neck.

568
00:41:55,460 --> 00:41:58,600
But if we raise the thing
a bit, very carefully -

569
00:42:02,770 --> 00:42:07,810
Sometimes these animals
are going to find themselves
leaping from higher branches.

570
00:42:07,940 --> 00:42:15,050
And from higher branches it may be
that even these pathetic little wing
stubs might make a difference.

571
00:42:15,180 --> 00:42:16,950
Let's see what happens now.

572
00:42:19,620 --> 00:42:23,360
Right. Now, in this case,
from that higher level -

573
00:42:29,200 --> 00:42:32,630
From that higher level
even a little wing stub like this

574
00:42:32,770 --> 00:42:33,940
can make a difference.

575
00:42:34,070 --> 00:42:37,810
And once you got the evolution
of wing stub this long

576
00:42:37,940 --> 00:42:40,380
then natural selection may favor

577
00:42:40,510 --> 00:42:44,380
the wings that start getting
a bit longer still, because
it's going to be an even higher height

578
00:42:44,510 --> 00:42:47,720
that you might fall from,
where the difference
between a wing stub that high

579
00:42:47,850 --> 00:42:50,950
and between a wing stub
that high might make a difference.

580
00:42:51,090 --> 00:42:56,430
And the point is that we have
a smooth gradient all the way,
up higher and higher,

581
00:42:56,560 --> 00:43:00,160
heights that you could fall from
to drive the lineage,

582
00:43:00,300 --> 00:43:04,000
to drive the species
towards ever longer wings.

583
00:43:05,730 --> 00:43:09,670
Controlled gliding has, in fact,
evolved many times over.

584
00:43:09,810 --> 00:43:13,510
There are many creatures
that have the equivalent
of half a wing.

585
00:43:13,640 --> 00:43:15,440
This is a snake, a tree snake

586
00:43:16,780 --> 00:43:18,510
crawling along a tree.

587
00:43:19,280 --> 00:43:21,320
So far it looks like
an ordinary snake.

588
00:43:23,490 --> 00:43:28,290
Now it launches itself off,
slow motion picture.

589
00:43:28,420 --> 00:43:32,290
The body flattens out sideways
and catches the air.

590
00:43:34,500 --> 00:43:41,540
It's steering itself down
and it's going to land on another
tree without hurting itself.

591
00:43:43,270 --> 00:43:47,380
This you can think of as the first
step towards evolving wings.

592
00:43:47,510 --> 00:43:52,780
Snakes never have evolved wings
but that's one possible pathway
towards evolving wings.

593
00:43:52,920 --> 00:43:58,890
Here is a squirrel, a tree squirrel,
so-called flying squirrel.

594
00:43:59,020 --> 00:44:04,490
It has flaps of skin
between its arms and its legs,
and it glides with them.

595
00:44:06,500 --> 00:44:08,730
This is a very beautifully
controlled glide.

596
00:44:08,860 --> 00:44:09,870
Downhill all the way.

597
00:44:10,000 --> 00:44:19,140
It doesn't flap, it doesn't climb,
but it lands gracefully
on a neighboring tree,

598
00:44:23,250 --> 00:44:25,080
and is completely unhurt
when it does so.

599
00:44:25,210 --> 00:44:28,820
This is an animal again
with something like 50% of a wing.

600
00:44:28,950 --> 00:44:33,220
And a third example is a lizard.
In this case it has skin
stretched between its ribs.

601
00:44:35,820 --> 00:44:39,500
All these are different ways in which
wings might have evolved.

602
00:44:39,660 --> 00:44:42,830
In no case did they properly evolve
but they show

603
00:44:43,370 --> 00:44:46,200
what the beginnings
of wings might have looked like.

604
00:44:49,440 --> 00:44:53,410
So not only can you do well
if you have half a wing,

605
00:44:53,740 --> 00:44:56,710
or a quarter of a wing,
but lots of animals actually do.

606
00:44:57,580 --> 00:44:59,680
This is a flying lemur.

607
00:44:59,850 --> 00:45:02,890
Looks like the flying squirrel
we just saw but it is totally unrelated,

608
00:45:03,020 --> 00:45:05,190
it comes from South-East Asia.
It has nothing to do with it.

609
00:45:05,320 --> 00:45:09,590
I think you can easily imagine
how that could eventually give
rise to something like that

610
00:45:09,760 --> 00:45:10,630
a flying fox,

611
00:45:10,760 --> 00:45:13,830
which is a bat.
That has proper wings
that's as good as a hawk,

612
00:45:13,960 --> 00:45:16,370
that can fly and flap properly.

613
00:45:18,870 --> 00:45:24,440
So we have dealt with two problems
of "what is the use" kind:
the eye and the wing.

614
00:45:24,570 --> 00:45:30,250
Our third difficult problem,
camouflage, has been thought difficult
for a slightly different reason.

615
00:45:30,950 --> 00:45:33,220
Think back to our stick insects.

616
00:45:35,250 --> 00:45:39,190
Think about the fantastic detail
with which they mimic sticks.

617
00:45:40,060 --> 00:45:45,160
A stick insect you could
think of as being right
at the top of Mount Improbable.

618
00:45:50,570 --> 00:45:52,670
So let's put it up there,
it's a lovely one. Thank you.

619
00:45:54,040 --> 00:45:58,770
But that has somehow evolved
from something at the bottom.

620
00:46:02,340 --> 00:46:08,050
And I'm going to put at the bottom
something that doesn't look remotely
like a stick: this brown bug.

621
00:46:08,780 --> 00:46:12,650
And somehow we have to imagine
that there was a gradual progression,

622
00:46:12,790 --> 00:46:19,600
all the way up the slope, all the way
round the path here, from something
like that to something like that.

623
00:46:19,730 --> 00:46:21,260
Now, here is the problem.

624
00:46:22,160 --> 00:46:27,840
It's birds selecting insects
that are propelling these animals
up Mount Improbable.

625
00:46:27,970 --> 00:46:29,710
They are propelling evolution.

626
00:46:30,240 --> 00:46:34,210
And in order for the birds
to have propelled the last 1%,

627
00:46:34,340 --> 00:46:41,120
from 99% like a stick to 100% like
a stick, the birds must have had
astonishingly good vision.

628
00:46:41,250 --> 00:46:44,290
They must have been very clever
in order to be fooled,

629
00:46:44,420 --> 00:46:49,790
in order to need, rather,
the precise details of mimicry
in order to fool them.

630
00:46:49,930 --> 00:46:52,660
But here is the problem.

631
00:46:52,800 --> 00:46:55,860
Those very same birds
or relatives of them,

632
00:46:56,000 --> 00:47:00,370
had to have been fooled down the bottom
of Mount Improbable, by insects

633
00:47:00,500 --> 00:47:02,640
that hardly looked
like sticks at all.

634
00:47:02,770 --> 00:47:09,980
Because it's the same birds
propelling the insects from 1%
like a stick to 2% like a stick,

635
00:47:10,110 --> 00:47:17,620
that have to propel the insects
all the way up the path,
20% to 21%, 99 to 100%.

636
00:47:18,320 --> 00:47:23,330
And, say opponents of the Darwinian
theory, you can't have it both ways:

637
00:47:23,460 --> 00:47:27,230
either the birds are clever enough
to do that job of natural selection

638
00:47:27,360 --> 00:47:30,200
or they're stupid enough to do
that job of natural selection,

639
00:47:30,370 --> 00:47:31,770
but they can't be both.

640
00:47:33,670 --> 00:47:37,140
You might like to think to yourselves
about possible solutions to that riddle.

641
00:47:37,270 --> 00:47:39,640
One thing you might think of
is that it's not the same birds,

642
00:47:39,780 --> 00:47:44,050
perhaps the birds have been evolving
during the same time as the insects
have been evolving.

643
00:47:44,180 --> 00:47:47,380
But I don't like that theory for
reasons I haven't time to go in to.

644
00:47:47,520 --> 00:47:50,290
I rather prefer to think
that it's the same birds,

645
00:47:50,420 --> 00:47:52,690
just as clever at all stages
of evolution,

646
00:47:52,820 --> 00:47:58,060
had just as good eyesight,
but the seeing conditions
were not always as good.

647
00:47:59,500 --> 00:48:04,200
Here we have a woodland floor
which has 16 insects on it.

648
00:48:04,370 --> 00:48:07,470
And from where you're sitting
you can probably see some of them.

649
00:48:08,070 --> 00:48:09,470
And that's really the point.

650
00:48:09,610 --> 00:48:13,610
The seeing conditions
from a distance are such that
you can only see some of them.

651
00:48:13,780 --> 00:48:19,850
Similarly, if I look out
of the corner of my eye I can see one
or two of them, but not all of them.

652
00:48:20,380 --> 00:48:24,120
I'm going to narrow it down,
narrow down the discussion

653
00:48:24,290 --> 00:48:28,290
to just distance and I would
like to call for a volunteer
to help me with this.

654
00:48:28,420 --> 00:48:29,120
Right.

655
00:48:30,560 --> 00:48:31,630
What's your name?

656
00:48:32,260 --> 00:48:32,900
Annie.

657
00:48:33,060 --> 00:48:34,330
Come here, Annie, please.

658
00:48:34,460 --> 00:48:35,830
Where is the pointer?

659
00:48:37,400 --> 00:48:38,800
Thank you. Stand here.

660
00:48:39,430 --> 00:48:43,010
Now, tell me,
how many insects can you see?

661
00:48:43,770 --> 00:48:44,910
Just point to one.

662
00:48:45,040 --> 00:48:47,280
Would you like to take the pointer
to point to it?

663
00:48:47,410 --> 00:48:49,550
Which ones can you see?
Can you see any?

664
00:48:52,210 --> 00:48:54,850
There? What do you think that is?
A butterfly.

665
00:48:54,980 --> 00:48:56,490
That is a yellow butterfly. Right.

666
00:48:56,620 --> 00:48:59,020
Probably most of you can see
that yellow butterfly.

667
00:48:59,150 --> 00:49:03,130
From that distance, I guess,
you can probably see a blue beetle,

668
00:49:03,260 --> 00:49:06,260
blue beetle, green beetle,
perhaps that red one there?

669
00:49:06,830 --> 00:49:10,200
So, if you're a bird,
from that distance
you could see quite a lot.

670
00:49:10,370 --> 00:49:12,200
Now come a bit closer, Annie.

671
00:49:12,800 --> 00:49:15,240
Can you see any more than
you couldn't see before?

672
00:49:17,440 --> 00:49:18,570
What can you see?

673
00:49:20,710 --> 00:49:21,480
point

674
00:49:22,610 --> 00:49:25,510
A black beetle and a green one there.

675
00:49:25,650 --> 00:49:27,680
Yes.

676
00:49:27,820 --> 00:49:28,980
And there's a cockroach.

677
00:49:29,750 --> 00:49:31,550
I can see a cockroach there.

678
00:49:31,990 --> 00:49:35,560
Now a bird from this distance
could spot the cockroach,

679
00:49:35,690 --> 00:49:38,160
whereas a bird from that distance
could spot the yellow butterfly.

680
00:49:38,330 --> 00:49:40,360
Now let's come in really close.

681
00:49:41,030 --> 00:49:42,930
Now, can you see anything more?

682
00:49:47,740 --> 00:49:51,210
A bird this distance
might have a chance of seeing -

683
00:49:51,340 --> 00:49:53,140
How about that?

684
00:49:53,280 --> 00:49:54,610
What do you think that is?

685
00:49:54,780 --> 00:49:57,710
There, look at that.

686
00:49:58,450 --> 00:50:01,020
That's a leaf butterfly.

687
00:50:02,450 --> 00:50:06,190
Look, Annie, look at this.
What's that?

688
00:50:09,420 --> 00:50:13,660
It's a leaf insect.
There's its head, there's its body.

689
00:50:13,800 --> 00:50:16,370
There's a stick insect.

690
00:50:19,000 --> 00:50:20,970
Thank you very much, Annie.

691
00:50:28,810 --> 00:50:32,980
So I think we have easily disposed
of all three of our alleged difficulties:

692
00:50:33,120 --> 00:50:36,290
the eye, the wing and camouflage.

693
00:50:36,750 --> 00:50:42,490
I'm going to end with the particular
favorite of creationists,
the notorious bombardier beetle.

694
00:50:45,090 --> 00:50:48,760
This is a recent headline that
appeared in the Daily Telegraph:

695
00:50:48,930 --> 00:50:52,600
"Beetle that may explode
the ideas of Darwin."

696
00:50:55,540 --> 00:50:58,470
The Telegraph thing goes on to say:

697
00:50:58,610 --> 00:51:01,210
"If evolution were right
it would have exploded."

698
00:51:01,340 --> 00:51:05,350
The paper asks whether it
offers proof of a Creator.

699
00:51:06,650 --> 00:51:11,750
The story about the bombardier beetle
is given in one creationist tract
that I'm now going to read.

700
00:51:11,890 --> 00:51:15,220
"The bombardier beetle
squirts a lethal mixture

701
00:51:15,390 --> 00:51:19,960
of hydroquinone and hydrogen
peroxide into the face of its enemy.

702
00:51:21,000 --> 00:51:29,040
These two chemicals,
when mixed together, literally explode
in the face of the enemy.

703
00:51:29,470 --> 00:51:33,080
The chain of events that could have
led to the evolution of such a complex,

704
00:51:33,240 --> 00:51:35,340
coordinated and subtle process

705
00:51:35,480 --> 00:51:40,280
is beyond biological explanation
on a simple step by step process.

706
00:51:40,450 --> 00:51:44,820
The slightest alteration
in the chemical balance
would result immediately

707
00:51:44,990 --> 00:51:47,390
in a race of exploded beetles."

708
00:51:48,490 --> 00:51:51,090
Well now, this does sound like a bit
of a challenge, a difficult case.

709
00:51:51,260 --> 00:51:55,330
I mustn't evade my responsibilities
to take on difficult cases.

710
00:51:56,400 --> 00:52:02,370
Here we have some hydrogen peroxide
and here is some hydroquinone,

711
00:52:02,500 --> 00:52:06,810
and this is what's going to explode
violently when we...just a minute

712
00:52:12,380 --> 00:52:14,980
Now, anybody who wants to,
can leave the room.

713
00:52:17,490 --> 00:52:25,260
We will start with hydrogen peroxide.
So far so good. Now...

714
00:52:26,090 --> 00:52:28,930
I better put it down,
hadn't I.

715
00:52:33,040 --> 00:52:37,940
What's happened?
It's not even warm.

716
00:52:39,070 --> 00:52:40,740
A bit of a damp squib.

717
00:52:47,050 --> 00:52:48,950
There is some truth in the story.

718
00:52:49,120 --> 00:52:50,520
By the way, of course,
I knew that nothing would happen.

719
00:52:50,650 --> 00:52:52,790
There was never any danger.

720
00:52:52,920 --> 00:52:54,560
There is some truth in the story.

721
00:52:54,690 --> 00:52:58,160
In fact the hydroquinone
does nothing at all.

722
00:52:58,330 --> 00:52:59,560
We can put that on one side.

723
00:52:59,700 --> 00:53:07,100
The true story is that hydrogen
peroxide on its own does decompose
to form oxygen and water,

724
00:53:07,240 --> 00:53:10,570
but it needs a catalyst under
the normal conditions to do that.

725
00:53:10,740 --> 00:53:13,480
This black powder here
is a catalyst.

726
00:53:13,610 --> 00:53:15,640
It's not the catalyst
the bombardier beetle uses.

727
00:53:15,810 --> 00:53:17,250
The bombardier beetle
does use a catalyst

728
00:53:17,380 --> 00:53:22,920
and it does, in fact,
squirt this hot substance
into the face of its enemy.

729
00:53:23,050 --> 00:53:28,960
But if you put a catalyst into a
weak solution of hydrogen peroxide

730
00:53:29,090 --> 00:53:36,270
then you're going to get a little bit
of bubbling and it is a little bit warm.

731
00:53:36,400 --> 00:53:38,500
That might have some effect
on the predator.

732
00:53:38,630 --> 00:53:45,040
That might slightly deter a predator
and it would be not particularly
dangerous to the beetle.

733
00:53:45,170 --> 00:53:46,910
Now we've got a smooth gradient.

734
00:53:47,740 --> 00:53:52,180
A bit more concentration of hydrogen
peroxide And that's distinctly warm.

735
00:53:52,350 --> 00:53:54,650
That would work more effectively
against a predator.

736
00:53:54,780 --> 00:53:57,790
And by moving gradually
up the slope,

737
00:53:57,920 --> 00:54:04,660
gradually increasing
the concentration of hydrogen peroxide,
we can end up with -

738
00:54:08,500 --> 00:54:15,800
So there is a smooth slope
all the way up to the effective
deterrent against a predator.

739
00:54:26,480 --> 00:54:32,420
The myth that the bombardier beetle or
any other feature of the natural world,

740
00:54:32,550 --> 00:54:38,790
that has yet been described,
cannot be explained by slow,
gradual evolution, is a myth

741
00:54:38,930 --> 00:54:41,030
that deserves to go up in smoke.

742
00:54:42,430 --> 00:54:48,040
Making a complicated organ in one
fell swoop is equivalent to a miracle.

743
00:54:48,600 --> 00:54:52,570
It's equivalent to opening a bank
safe combination lock in a single,

744
00:54:52,710 --> 00:54:54,410
lucky spin of the dial.

745
00:54:54,540 --> 00:54:55,710
It cannot be done.

746
00:54:57,180 --> 00:55:02,150
In one way or another this lecture
has been variations on the 747 theme.

747
00:55:02,790 --> 00:55:06,360
You can't make complex,
efficient, working objects

748
00:55:06,490 --> 00:55:09,660
like eyes or wings in a single step.

749
00:55:10,190 --> 00:55:16,600
Any theory that says that life
or a part of life, an organ, an animal,

750
00:55:16,730 --> 00:55:21,240
complexity or perfection
came into being in a single step

751
00:55:21,370 --> 00:55:24,540
starting from nothing,
has got to be wrong.

752
00:55:25,440 --> 00:55:31,650
Evolution is the one idea that has nothing
to fear from the 747 argument.

753
00:55:31,780 --> 00:55:35,450
Because evolution is the one idea
that does not suggest

754
00:55:35,620 --> 00:55:40,160
that complex perfection
came into being in a single step.

755
00:55:41,560 --> 00:55:48,500
It is the theory of miraculous
creation that is really blown out
of the water by the 747 argument.

756
00:55:48,630 --> 00:55:54,670
Because it is miraculous creation
that is equivalent to cracking
the safe in a single step.

757
00:55:54,800 --> 00:55:59,310
Equivalent to blowing together
a 747 in a junkyard.

758
00:55:59,940 --> 00:56:03,180
Evolution escapes the taint
of miracle.

759
00:56:03,310 --> 00:56:06,080
Escapes the taint
of impossibly long odds

760
00:56:06,220 --> 00:56:11,950
by the simple, yet hugely effective
trick of smearing out the luck,

761
00:56:12,090 --> 00:56:16,690
smearing it out over the vastness
of geological time.

762
00:56:17,760 --> 00:56:22,730
In the next lecture,
The Ultraviolet Garden,
we shall be looking at the question of

763
00:56:22,870 --> 00:56:26,200
who benefits from evolution.
Who is it good for?

764
00:56:26,870 --> 00:56:28,040
Thank you very much.

765
00:56:28,500 --> 00:56:31,510
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