1
00:00:03,320 --> 00:00:05,960
There are some great questions

2
00:00:05,960 --> 00:00:11,320
that have intrigued and haunted us
since the dawn of humanity.

3
00:00:12,840 --> 00:00:15,200
What is out there?

4
00:00:18,480 --> 00:00:20,280
How did we get here?

5
00:00:24,280 --> 00:00:27,120
What is the world made of?

6
00:00:30,160 --> 00:00:36,560
The story of our search
to answer those questions
is the story of science.

7
00:00:38,160 --> 00:00:42,920
Of all human endeavours,
science has had the
greatest impact on our lives,

8
00:00:42,920 --> 00:00:46,080
on how we see the world,
on how we see ourselves.

9
00:00:46,080 --> 00:00:53,600
Its ideas, its achievements,
its results are all around us.

10
00:00:53,600 --> 00:00:58,120
So, how did we arrive
at the modern world?

11
00:00:58,120 --> 00:01:02,640
Well, that is more surprising
and more human than you might think.

12
00:01:07,320 --> 00:01:11,840
The history of science is often told
as a series of eureka moments,

13
00:01:11,840 --> 00:01:14,520
the ultimate triumph
of the rational mind.

14
00:01:14,520 --> 00:01:17,800
But the truth is that
power and passion,

15
00:01:17,800 --> 00:01:23,080
rivalry and sheer blind chance have
played equally significant parts.

16
00:01:25,600 --> 00:01:31,400
In this series,
I'll be offering a different view
of how science happens.

17
00:01:31,400 --> 00:01:36,160
It's been shaped as much by what's
outside the laboratory as inside.

18
00:01:39,360 --> 00:01:44,160
This is the story
of how history made science
and science made history

19
00:01:44,160 --> 00:01:47,880
and how the ideas that
were generated changed our world.

20
00:01:48,960 --> 00:01:51,360
It is a tale of power...

21
00:01:52,600 --> 00:01:54,600
..proof...

22
00:01:54,600 --> 00:01:56,760
and passion.

23
00:02:05,720 --> 00:02:09,800
This time, perhaps
the greatest puzzle of existence.

24
00:02:12,280 --> 00:02:15,080
What is the secret of life?

25
00:02:21,480 --> 00:02:26,360
Inside every one of us
there lies a mystery.

26
00:02:28,520 --> 00:02:35,280
Something creates the rich and
intense experience of being alive.

27
00:02:37,160 --> 00:02:39,840
But what exactly is it?

28
00:02:42,000 --> 00:02:47,520
What is it that makes
a living thing so utterly different
from a non-living thing?

29
00:02:48,720 --> 00:02:53,600
The struggle to explain
the sheer wonder of life

30
00:02:53,600 --> 00:02:59,040
has been one of the most productive
challenges science has ever faced.

31
00:03:01,360 --> 00:03:08,080
But the search for answers has
also proved tantalising and elusive.

32
00:03:11,320 --> 00:03:17,760
This is the story of how we came
to understand many of the secrets
of life by studying the creature

33
00:03:17,760 --> 00:03:20,720
that interests us the most,
ourselves.

34
00:03:36,920 --> 00:03:43,520
Across the ancient world,
there were long-running arguments
about what constitutes life.

35
00:03:45,360 --> 00:03:50,360
One particular view
came to dominate Western thought.

36
00:03:53,680 --> 00:03:58,920
For 1,500 years, physicians in the
West slavishly followed the ideas

37
00:03:58,920 --> 00:04:01,400
of a Roman called Claudius Galen.

38
00:04:01,400 --> 00:04:05,760
Now, he's undoubtedly
one of the most
influential thinkers in history.

39
00:04:05,760 --> 00:04:09,080
Born not long after
the death of Jesus of Nazareth,

40
00:04:09,080 --> 00:04:14,000
his books were still being used by
doctors well into the 17th century.

41
00:04:14,000 --> 00:04:18,280
His ideas about life were
shaped by one of the most bloody

42
00:04:18,280 --> 00:04:21,880
and violent spectacles
provided by the Roman emperor.

43
00:04:24,120 --> 00:04:28,760
For Galen started out as physician
to the gladiators.

44
00:04:31,080 --> 00:04:35,800
Picture the scene - swords clash
then bite through flesh.

45
00:04:35,800 --> 00:04:40,120
Howls of pain from the gladiators
would have been drowned
by the roar of the crowd.

46
00:04:40,120 --> 00:04:46,160
This was often a fight to the death,
where even for the victor,
survival was not always an option.

47
00:04:48,640 --> 00:04:53,520
Victorious gladiators often had
life-threatening injuries.

48
00:04:53,520 --> 00:04:56,680
Galen was determined
to keep them alive.

49
00:05:00,520 --> 00:05:04,120
Galen did not believe that
the matter of life and death

50
00:05:04,120 --> 00:05:07,280
should be left
simply in the hands of the gods.

51
00:05:07,280 --> 00:05:12,640
He was convinced from personal
experience that there were plenty
of things a physician could do

52
00:05:12,640 --> 00:05:15,520
that would preserve
and prolong life.

53
00:05:15,520 --> 00:05:18,040
Trying to understand
the workings of the human body

54
00:05:18,040 --> 00:05:23,240
and write his findings down became
his lifelong passion and his legacy.

55
00:05:25,480 --> 00:05:31,200
He built up
a system of medical treatment
that was extremely effective.

56
00:05:33,120 --> 00:05:37,240
His predecessor had lost
sixty wounded gladiators.

57
00:05:37,240 --> 00:05:39,880
Galen only lost four.

58
00:05:42,520 --> 00:05:48,080
But he wasn't just interested
in preserving life,
he wanted to explain it.

59
00:05:50,320 --> 00:05:54,640
Galen was particularly interested
in one organ, the liver.

60
00:05:54,640 --> 00:05:57,160
He had noticed when he was doing
his dissections

61
00:05:57,160 --> 00:05:59,840
that the liver has lots
of different vessels going

62
00:05:59,840 --> 00:06:04,440
in and out of it,
and he concluded that the liver
produces all the blood

63
00:06:04,440 --> 00:06:08,520
in the human body and it's drawn
from the liver and spread around.

64
00:06:10,280 --> 00:06:17,000
He also believed that blood contains
within it spirits - the spirits come
from the liver, they also come from

65
00:06:17,000 --> 00:06:23,880
the heart and from the brain,
and it's these spirits that give
blood the essence of life.

66
00:06:25,840 --> 00:06:29,200
He wrote 300 books and pamphlets

67
00:06:29,200 --> 00:06:33,400
covering almost everything about
the human body and how it works.

68
00:06:33,400 --> 00:06:36,720
It was encyclopaedic.

69
00:06:36,720 --> 00:06:40,240
But it was also
fundamentally flawed.

70
00:06:42,320 --> 00:06:47,000
Now, Galen's entire system
was based on his anatomical studies.

71
00:06:47,000 --> 00:06:53,480
The only thing was
that he himself, as far as we know,
never did any human dissections.

72
00:06:53,480 --> 00:06:58,840
He relied on cutting up animals,
such as pigs and Barbary apes.

73
00:07:01,680 --> 00:07:06,720
Nevertheless, his system was seen
as superior to anything else.

74
00:07:08,240 --> 00:07:11,200
He became wealthy
and hugely influential.

75
00:07:18,920 --> 00:07:25,680
Remarkably,
a set of beliefs about the body
laid down by one man in ancient Rome

76
00:07:25,680 --> 00:07:28,720
went on to become medical gospel.

77
00:07:30,240 --> 00:07:37,960
For more than a thousand years,
Galen's work provided
THE reference book of life

78
00:07:37,960 --> 00:07:41,200
until developments
in Renaissance Italy

79
00:07:41,200 --> 00:07:43,640
changed the way we see the world.

80
00:08:03,240 --> 00:08:06,320
It may not look very impressive
from here, but I'm actually

81
00:08:06,320 --> 00:08:09,680
standing in-between the inner
and the outer wall
of what I think is one

82
00:08:09,680 --> 00:08:15,720
of the most beautiful buildings in
the world, and the view is certainly
going to be worth going to see.

83
00:08:19,000 --> 00:08:22,880
It's the magnificent Duomo
in Florence.

84
00:08:25,080 --> 00:08:31,560
It was built at a time
when the city states of Italy
were undergoing dramatic change.

85
00:08:31,560 --> 00:08:37,240
These upheavals would go on
to affect our understanding of life.

86
00:08:37,240 --> 00:08:41,720
One change in particular began here,
with an architect.

87
00:08:43,240 --> 00:08:48,000
The dome I'm standing on was
designed and built
by Filippo Brunelleschi,

88
00:08:48,000 --> 00:08:51,240
one of the most influential figures
of the Renaissance.

89
00:08:51,240 --> 00:08:56,560
The Renaissance was a period of
rebirth, the liberating
of the human imagination.

90
00:08:56,560 --> 00:09:01,200
Brunelleschi was one of those
polymaths, those brilliant geniuses

91
00:09:01,200 --> 00:09:07,920
that the Renaissance just simply
seemed to spawn effortlessly -
engineer, architect, mathematician.

92
00:09:07,920 --> 00:09:14,280
Many of the skills he used
to build this dome he also used to
create a new vision of reality.

93
00:09:16,400 --> 00:09:20,360
He introduced a
new way of seeing the world.

94
00:09:20,360 --> 00:09:23,800
It involved mathematics.

95
00:09:23,800 --> 00:09:28,280
Using the cathedral buildings,
he demonstrated how it worked.

96
00:09:32,200 --> 00:09:36,920
What Brunelleschi did is he
drew a painting,
like this one of the Baptistery -

97
00:09:36,920 --> 00:09:39,760
actually, probably rather better
than this one -

98
00:09:39,760 --> 00:09:43,000
and he took a mirror and he got
his friends to try this trick.

99
00:09:43,000 --> 00:09:47,520
You look through a hole there,
then you try and line up

100
00:09:47,520 --> 00:09:49,960
the mirror with the buildings.

101
00:09:49,960 --> 00:09:53,200
Now, it's a very

102
00:09:53,200 --> 00:09:57,320
charming little trick, this one,
because you realise when you do this

103
00:09:57,320 --> 00:10:05,080
that the painting is actually
a very good three-dimensional
representation of that building.

104
00:10:06,600 --> 00:10:11,280
It's so realistic because of
his novel approach to painting.

105
00:10:11,280 --> 00:10:17,200
Lines which are actually parallel
he drew as converging
to a vanishing point.

106
00:10:19,480 --> 00:10:23,400
This was counterintuitive -
to many, it still is -

107
00:10:23,400 --> 00:10:26,760
but this made the painting
accurately reflect

108
00:10:26,760 --> 00:10:29,040
what was seen in the real world.

109
00:10:31,280 --> 00:10:35,920
It was the start of
modern perspective painting. Hm!

110
00:10:40,280 --> 00:10:45,240
The understanding of perspective
didn't just affect art
and architecture,

111
00:10:45,240 --> 00:10:49,600
it also profoundly altered the way
that people viewed the human body.

112
00:10:52,560 --> 00:10:56,560
It created a new hunger for realism.

113
00:11:13,720 --> 00:11:19,840
The impact of the new approach
can be seen on the bodies
locked away in Windsor Castle.

114
00:11:22,120 --> 00:11:26,880
The castle houses around
600 drawings by Leonardo da Vinci,

115
00:11:26,880 --> 00:11:29,800
beautiful, exquisite
drawings of the human body.

116
00:11:29,800 --> 00:11:34,400
And I'm really excited,
because I've seen copies but
I've never seen the originals.

117
00:11:41,160 --> 00:11:45,000
The detail is astonishing.

118
00:11:48,480 --> 00:11:52,400
These drawings
are over 500 years old.

119
00:11:55,720 --> 00:11:57,920
I must admit, I do feel a shiver.

120
00:11:57,920 --> 00:12:02,360
There is something about holding it
and thinking of him doing this.

121
00:12:05,200 --> 00:12:09,600
In these pen strokes, you can
see something ground-breaking.

122
00:12:12,600 --> 00:12:17,760
Here, he started to cut muscles away
and lift them away from their points
of insertion and origin and so on

123
00:12:17,760 --> 00:12:20,840
to show how the bones are
connected to them, to the muscles.

124
00:12:20,840 --> 00:12:23,360
It's that sort
of diagrammatic innovation

125
00:12:23,360 --> 00:12:25,440
which is
so impressive of his time.

126
00:12:25,440 --> 00:12:27,200
And so three-dimensional.

127
00:12:27,200 --> 00:12:29,560
Mm. The perspective on it
is just extraordinary.

128
00:12:29,560 --> 00:12:34,200
Well, uniquely, he was able to unite
this anatomical understanding with

129
00:12:34,200 --> 00:12:37,880
artistic ability, and it's why these
drawings are still so impressive.

130
00:12:37,880 --> 00:12:39,400
Mm.

131
00:12:41,040 --> 00:12:44,760
Leonardo's drawings
are wonderfully realistic.

132
00:12:47,920 --> 00:12:52,040
Very different
from many pre-Renaissance drawings
of the body,

133
00:12:52,040 --> 00:12:55,640
which tended to be stylised
or symbolic.

134
00:12:57,840 --> 00:13:03,720
And Leonardo drew bodies for reasons
that went well beyond art.

135
00:13:03,720 --> 00:13:08,720
I mean, this really is an
evocation of life, and he was
really trying to understand life.

136
00:13:08,720 --> 00:13:12,680
Understanding where life came from
or what made a living being rather

137
00:13:12,680 --> 00:13:17,360
than a static being was of
fundamental importance to Leonardo.

138
00:13:23,960 --> 00:13:30,160
Those are exquisite drawings
by an exceptional artist,
but they're also more than that.

139
00:13:30,160 --> 00:13:33,400
They are, if you like,
the beginnings of a period

140
00:13:33,400 --> 00:13:37,120
when people began
to truly understand the human body.

141
00:13:40,320 --> 00:13:46,000
Artists helped give a fresh impetus
to the study of human anatomy.

142
00:13:48,080 --> 00:13:52,920
Knowing what's really beneath
the skin would open up new avenues

143
00:13:52,920 --> 00:13:55,680
in the quest
to explain the living body.

144
00:14:14,280 --> 00:14:19,240
Anatomy studies flourished
in the Italian town of Padua,

145
00:14:19,240 --> 00:14:22,480
one of the great centres of learning
in the 16th century.

146
00:14:26,360 --> 00:14:29,160
Students flocked here
from all over Europe.

147
00:14:29,160 --> 00:14:34,960
They came because it was lively,
it was vibrant, but also because
they could get access to something

148
00:14:34,960 --> 00:14:39,640
which was in extremely short supply
everywhere else, dead human bodies.

149
00:14:42,960 --> 00:14:49,440
Medical students who came here
were not content to rely on animals.

150
00:14:49,440 --> 00:14:52,760
They wanted to study humans.

151
00:15:05,920 --> 00:15:08,120
Imagine, if you will,

152
00:15:08,120 --> 00:15:13,520
200 students crammed
layer after layer after layer.

153
00:15:13,520 --> 00:15:17,200
But the star of the show was
down here on a marble slab,

154
00:15:17,200 --> 00:15:19,480
a dead human body.

155
00:15:22,240 --> 00:15:28,920
They were normally
freshly executed malefactors,
ne'er-do-wells, criminals.

156
00:15:33,400 --> 00:15:39,800
The university was not constrained
by religious limits
placed on human dissection.

157
00:15:39,800 --> 00:15:42,520
It was independent of the Church.

158
00:15:45,320 --> 00:15:48,160
What was striking about the
dissections performed here

159
00:15:48,160 --> 00:15:52,760
was not only they were more
frequent, but they were also done
in a completely different way.

160
00:15:52,760 --> 00:15:56,400
Now, the old way,
which had been done for many
centuries, was the professor

161
00:15:56,400 --> 00:15:59,200
would read from Galen's book,
saying,

162
00:15:59,200 --> 00:16:01,600
"Here's a liver, three lobes,"

163
00:16:01,600 --> 00:16:04,840
the demonstrator would show the
liver, which plainly didn't have

164
00:16:04,840 --> 00:16:09,480
three lobes, but all the students
would basically nod and agree.

165
00:16:09,480 --> 00:16:12,800
And I can sort of understand that,
because when I was a medical student

166
00:16:12,800 --> 00:16:15,120
there was a tremendous pressure 
to conform.

167
00:16:15,120 --> 00:16:17,640
But here in Padua,
things were different.

168
00:16:17,640 --> 00:16:21,040
People were encouraged to describe
what they actually saw

169
00:16:21,040 --> 00:16:25,560
as opposed to what Galen's book
said they should see.

170
00:16:27,760 --> 00:16:34,280
This new style of anatomy lesson
was a brazen challenge
to accepted wisdom.

171
00:16:34,280 --> 00:16:37,760
It had been pioneered by
Andreas Vesalius,

172
00:16:37,760 --> 00:16:42,480
who was made Professor of Surgery
and Anatomy aged just 23.

173
00:16:44,560 --> 00:16:48,880
He'd published a detailed atlas
of the human body.

174
00:16:51,880 --> 00:16:54,640
A new book of life.

175
00:17:09,800 --> 00:17:13,440
Based on his own
careful observations,

176
00:17:13,440 --> 00:17:19,600
Vesalius boldly corrected mistake
after mistake in orthodox beliefs.

177
00:17:21,760 --> 00:17:23,480
Come and have a look at this.

178
00:17:23,480 --> 00:17:27,120
Vesalius noticed a number of
anatomical features that were

179
00:17:27,120 --> 00:17:31,360
wrong in Galen's descriptions,
for example the jaw bone.

180
00:17:31,360 --> 00:17:37,240
Now, Vesalius correctly
recognised that humans have a
single bone that forms the jaw,

181
00:17:37,240 --> 00:17:38,680
it's not split in two.

182
00:17:38,680 --> 00:17:42,880
You get that in dogs.
Then there were the number of ribs.

183
00:17:42,880 --> 00:17:45,720
Vesalius recognised
and demonstrated that men

184
00:17:45,720 --> 00:17:47,440
have the same number of ribs

185
00:17:47,440 --> 00:17:53,080
as women, not, as some people
claimed, one less, because,
obviously, the Bible says God took

186
00:17:53,080 --> 00:17:56,240
one of man's ribs
and made Eve out it.

187
00:17:56,240 --> 00:18:00,760
But Vesalius demonstrated
quite clearly that if he did,
he obviously grew a new one.

188
00:18:00,760 --> 00:18:04,480
And then we had the thigh bone.

189
00:18:04,480 --> 00:18:07,200
Galen had claimed that
the thigh bone was curved,

190
00:18:07,200 --> 00:18:09,200
again because he saw that in dogs,

191
00:18:09,200 --> 00:18:13,240
whereas Vesalius correctly
recognised that it's straight.

192
00:18:13,240 --> 00:18:18,000
Some people found it so hard
to accept that Galen
could possibly have been wrong.

193
00:18:18,000 --> 00:18:20,840
They claimed that the
straightening of the thigh bone

194
00:18:20,840 --> 00:18:24,560
must have been caused by a recent
fashion for wearing tight trousers.

195
00:18:28,040 --> 00:18:33,360
But Vesalius did more
than simply correct Galen's errors.

196
00:18:33,360 --> 00:18:37,560
What is so special about his work
is his approach.

197
00:18:40,520 --> 00:18:46,160
He carefully observed,
stripping away layer after layer.

198
00:18:47,680 --> 00:18:53,200
This would start
Western medical science on
a distinct and powerful course.

199
00:18:54,240 --> 00:19:00,880
From now on, the essence of life
would be sought by looking
deeper and deeper into the body,

200
00:19:00,880 --> 00:19:04,640
breaking it down
into its component parts,

201
00:19:04,640 --> 00:19:11,000
an approach that would in time
lead to major advances

202
00:19:11,000 --> 00:19:12,680
in medicine

203
00:19:12,680 --> 00:19:14,320
and in surgery.

204
00:19:18,840 --> 00:19:24,160
In many ways, here in Padua
they laid the foundations for
a new understanding of life.

205
00:19:24,160 --> 00:19:26,480
But anatomy is not the full story.

206
00:19:26,480 --> 00:19:31,320
There's also the question
of how does the body work,
the processes, physiology.

207
00:19:33,560 --> 00:19:38,200
The search for the secret of life
turned from simply observing

208
00:19:38,200 --> 00:19:43,080
the structure of the body
to trying to find out how it works.

209
00:19:44,840 --> 00:19:51,240
That would require a very different
approach, one based on experiment.

210
00:19:59,880 --> 00:20:03,760
England, a thousand miles
from Renaissance Italy.

211
00:20:05,360 --> 00:20:08,960
A country riven by religious
and political differences.

212
00:20:12,760 --> 00:20:16,600
17th century England
was heading for civil war.

213
00:20:21,400 --> 00:20:25,080
There was tension between
old and new,

214
00:20:25,080 --> 00:20:31,200
a conflict embodied
in the inquisitive mind
of a London physician.

215
00:20:40,160 --> 00:20:45,240
William Harvey was not a radical,
he was not looking to cause a stir.

216
00:20:45,240 --> 00:20:48,800
But like a detective who comes
across something he can't explain,

217
00:20:48,800 --> 00:20:52,640
he gathered evidence,
he collected clues, until finally,

218
00:20:52,640 --> 00:20:59,120
he had built such a powerful case
that he brought Galen's remaining
system clattering to the floor.

219
00:20:59,120 --> 00:21:05,280
For me, William Harvey is one of
the greats, a founding father
of modern experimental medicine.

220
00:21:10,120 --> 00:21:15,160
Harvey had learnt the advantages of
a probing, questioning approach

221
00:21:15,160 --> 00:21:18,240
when he was a student
at Padua University.

222
00:21:20,320 --> 00:21:25,240
But where Vesalius had just
observed, Harvey went further.

223
00:21:25,240 --> 00:21:26,880
He investigated.

224
00:21:38,080 --> 00:21:41,200
He questioned
the widely accepted belief

225
00:21:41,200 --> 00:21:46,040
that blood is made by the liver and
consumed by the rest of the body.

226
00:21:48,400 --> 00:21:54,840
Harvey conducted a series
of experiments,
studying animals living and dead.

227
00:21:57,360 --> 00:22:04,320
One of his most famous experiments
was to calculate the volume of
blood that passes through the heart.

228
00:22:06,600 --> 00:22:12,360
Now, I've got a pig's heart here,
which is about the same
volume as a human heart.

229
00:22:12,360 --> 00:22:17,600
Fill it with some nice
fake blood and then...

230
00:22:19,200 --> 00:22:21,120
..tip it in there.

231
00:22:21,120 --> 00:22:24,360
Ooh, gorgeous!

232
00:22:25,520 --> 00:22:29,480
And then - this is really quite
unpleasant and quite gunky -

233
00:22:29,480 --> 00:22:31,040
now you've got to weigh it,

234
00:22:31,040 --> 00:22:35,640
which involves
somehow getting the glove off

235
00:22:35,640 --> 00:22:37,680
and this onto some scales.

236
00:22:37,680 --> 00:22:39,600
I've pre-weighed the glass.

237
00:22:41,960 --> 00:22:44,560
Right, that's just...

238
00:22:44,560 --> 00:22:46,120
over two ounces.

239
00:22:47,640 --> 00:22:52,840
Harvey did some quick calculations
based on how often the heart beats

240
00:22:52,840 --> 00:22:56,720
and came up with a figure of
five hundred ounces.

241
00:22:56,720 --> 00:23:01,480
That's how much blood
is passing through the heart
every half an hour.

242
00:23:01,480 --> 00:23:06,320
It is more than the entire
volume of blood in the human body.

243
00:23:08,760 --> 00:23:13,120
Harvey's figures showed that the
heart can propel an astonishing

244
00:23:13,120 --> 00:23:16,400
4,000 litres of blood
every single day.

245
00:23:20,520 --> 00:23:24,000
That's an awful lot of blood.

246
00:23:25,720 --> 00:23:33,200
Now, if accepted wisdom was correct,
then the body was making
and using up this much blood

247
00:23:33,200 --> 00:23:35,400
every 24 hours.

248
00:23:38,400 --> 00:23:42,160
This, plus all the other experiments
he'd done, suggested to Harvey

249
00:23:42,160 --> 00:23:44,920
there could only be one explanation,

250
00:23:44,920 --> 00:23:48,200
that the blood
circulates around the body.

251
00:23:48,200 --> 00:23:51,280
This went completely against
everything he had been taught,

252
00:23:51,280 --> 00:23:54,400
but he had to trust
the evidence of his own eyes.

253
00:23:56,080 --> 00:24:02,600
Harvey concluded
that the heart's real function
was to propel blood around the body.

254
00:24:04,200 --> 00:24:08,720
The heart was no longer
purely a mysterious organ
that infuses blood

255
00:24:08,720 --> 00:24:10,480
with the essence of life.

256
00:24:12,200 --> 00:24:14,560
It was now more like a pump.

257
00:24:18,280 --> 00:24:25,600
Harvey proved that the blood
circulates round the body
and overthrew 1,500 years of dogma.

258
00:24:25,600 --> 00:24:27,800
But perhaps more importantly
than that,

259
00:24:27,800 --> 00:24:33,280
he established the experimental
method, which is still
crucial to science today.

260
00:24:33,280 --> 00:24:39,400
He also inadvertently opened the
door to a new understanding of life.

261
00:24:42,360 --> 00:24:47,960
It was a more physical explanation
of how the body works.

262
00:24:56,240 --> 00:25:02,400
This change was born out of the
realism of perspective painting,

263
00:25:02,400 --> 00:25:06,240
a new observational school
of anatomy

264
00:25:06,240 --> 00:25:08,840
and Harvey's experimental method.

265
00:25:10,800 --> 00:25:16,920
The stage was set for a more
materialistic approach
to the body and to life.

266
00:25:30,160 --> 00:25:35,640
This town clock near Padua was
built in the 17th century,

267
00:25:35,640 --> 00:25:40,240
a time when mechanics was helping
explain the world around us.

268
00:25:42,720 --> 00:25:48,000
Men like Galileo and Newton
were offering a completely new view
of the cosmos

269
00:25:48,000 --> 00:25:51,120
based on mathematics and physics.

270
00:25:53,760 --> 00:25:57,720
Its internal workings
were likened to those of a clock -

271
00:25:57,720 --> 00:26:05,360
cogs, weights, pulleys,
simple components that together make
a complex machine.

272
00:26:07,840 --> 00:26:13,040
People began to wonder if there
were things in nature that were
also driven by hidden clockwork,

273
00:26:13,040 --> 00:26:17,640
whether nature itself moved
to the beat of a mechanical drum.

274
00:26:19,000 --> 00:26:21,520
Could the same be true of us?

275
00:26:23,160 --> 00:26:26,360
Are we just mechanical beings?

276
00:26:28,440 --> 00:26:33,080
Go on, test me,
give me another on another finger.

277
00:26:33,080 --> 00:26:36,160
OK! It doesn't hurt a bit! OK!

278
00:26:36,160 --> 00:26:40,480
An Italian mathematician called
Giovanni Borelli took the rigorous

279
00:26:40,480 --> 00:26:43,200
analytical methods
from mechanics

280
00:26:43,200 --> 00:26:46,120
and applied them
to the study of life.

281
00:26:49,200 --> 00:26:51,040
OK. OK, we're up to eleven.

282
00:26:51,040 --> 00:26:53,080
OK.

283
00:26:53,080 --> 00:26:55,280
Pick another one, go on.

284
00:26:57,360 --> 00:26:59,360
OK! OK!
Go ahead and bring your arm down.

285
00:26:59,360 --> 00:27:01,920
Oh, that's really easy now.

286
00:27:01,920 --> 00:27:03,560
Yeah, it's much, much easier.

287
00:27:03,560 --> 00:27:10,080
In his attempts to understand
the body, Borelli broke it down
into simple components.

288
00:27:11,880 --> 00:27:16,080
Borelli described the body as a set
of levers and pulleys,

289
00:27:16,080 --> 00:27:19,400
so these pulleys
here connect the two levers,

290
00:27:19,400 --> 00:27:23,120
which are the bones of the body,
and around the pulley goes a rope,

291
00:27:23,120 --> 00:27:26,120
and that's how he described
the muscles of the body.

292
00:27:26,120 --> 00:27:32,240
He deduced that our musculoskeletal
system is less about strength,

293
00:27:32,240 --> 00:27:34,160
more about movement.

294
00:27:34,160 --> 00:27:37,520
Because it's attached here, just
a small movement in the muscle,

295
00:27:37,520 --> 00:27:39,800
a small contraction,
creates a huge motion.

296
00:27:39,800 --> 00:27:43,720
Ah! But you have to have quite
a lot of force to do it,
because it's closer to that.

297
00:27:43,720 --> 00:27:49,360
Exactly. But you can get quite
a lot of movement from a relatively
short... You get a lot of motion.

298
00:27:49,360 --> 00:27:56,560
It was a significant step
towards explaining
how our bodies really work.

299
00:27:56,560 --> 00:28:01,560
Having broken it down,
Borelli could now put the body
back together again.

300
00:28:11,240 --> 00:28:13,360
It's very clever, isn't it?

301
00:28:16,000 --> 00:28:18,760
Er, right, where is that coming out?

302
00:28:18,760 --> 00:28:22,000
Oh, yes.

303
00:28:24,120 --> 00:28:25,720
Here we go. There we go. Ta-da!

304
00:28:28,240 --> 00:28:32,680
Fabulous! And Borelli
didn't just look at movement,

305
00:28:32,680 --> 00:28:35,320
he analysed the internal organs,
too,

306
00:28:35,320 --> 00:28:40,360
calculating the volume of the lungs
and the force of the pumping heart.

307
00:28:43,280 --> 00:28:47,840
So this is, I suppose, the
development of the idea of man as
a machine, which is... Absolutely.

308
00:28:47,840 --> 00:28:52,440
..a very useful metaphor, isn't it?
Yeah. It's really ingenious
how he broke the body down into such

309
00:28:52,440 --> 00:28:58,360
simple components and could come up
with quite ingenious
reasons for how the body works.

310
00:29:05,640 --> 00:29:10,400
So here you have it,
a human arm stripped down
to its bare essentials.

311
00:29:10,400 --> 00:29:15,880
Borelli really had shown
that you could describe
the human body in mechanical terms.

312
00:29:15,880 --> 00:29:21,440
It was a machine -
an incredibly sophisticated machine,
but a machine nonetheless.

313
00:29:27,480 --> 00:29:31,200
Borelli inspired a
new science of biomechanics.

314
00:29:34,640 --> 00:29:37,520
The living body broken down

315
00:29:37,520 --> 00:29:39,760
into component parts...

316
00:29:42,920 --> 00:29:49,080
..life reduced to simple
physical laws.

317
00:29:51,600 --> 00:29:56,120
For those who believed in
the mechanical body,
there was a significant problem.

318
00:29:56,120 --> 00:30:01,440
Now, this clock needs to be wound up
every 47 hours,

319
00:30:01,440 --> 00:30:04,800
otherwise it simply...stops.

320
00:30:04,800 --> 00:30:09,080
But what is the equivalent
in the human body?

321
00:30:09,080 --> 00:30:12,720
What is the life force
that drives you and me?

322
00:30:14,240 --> 00:30:21,200
This question rekindled an
ancient idea known as vitalism,

323
00:30:21,200 --> 00:30:26,120
the belief that there was something
more to life than a physical body,

324
00:30:26,120 --> 00:30:28,640
something intangible.

325
00:30:33,640 --> 00:30:38,200
In the 18th century,
many believed that extra something

326
00:30:38,200 --> 00:30:42,560
might lie in the very latest
scientific marvel.

327
00:30:47,560 --> 00:30:49,800
Electricity.

328
00:30:49,800 --> 00:30:53,160
No-one knew quite what it was,

329
00:30:53,160 --> 00:30:56,440
no-one knew quite where
it came from.

330
00:30:57,680 --> 00:31:00,680
All over Europe, people were
investigating electricity,

331
00:31:00,680 --> 00:31:03,600
and they were making
some extraordinary claims,

332
00:31:03,600 --> 00:31:08,200
for example that you could
use it to make your
fruit trees bear more fruit.

333
00:31:08,200 --> 00:31:11,840
You could also use it to make
your dinner a bit more tasty.

334
00:31:11,840 --> 00:31:16,560
But what really grabbed
people's imagination was the idea
that it was electricity

335
00:31:16,560 --> 00:31:21,680
that was responsible
for bringing the cold machine
of the body to life.

336
00:31:23,200 --> 00:31:27,320
In the 1780s, a physician called
Luigi Galvani

337
00:31:27,320 --> 00:31:32,880
had made one of the most
perplexing and important
discoveries of the century.

338
00:31:35,200 --> 00:31:40,440
He had found that touching
frogs' legs with different metals

339
00:31:40,440 --> 00:31:41,960
would make them twitch.

340
00:31:43,720 --> 00:31:47,760
I can remember when I was a medical
student and we first started

341
00:31:47,760 --> 00:31:51,200
using electrical currents
on frogs' legs,
and I saw one twitch like that.

342
00:31:51,200 --> 00:31:56,200
It was incredibly disturbing,
because I knew it was dead
but it seemed to be coming to life.

343
00:31:56,200 --> 00:32:03,600
Now, Galvani himself was convinced
that electricity was being generated
from within the tissue of the frog.

344
00:32:03,600 --> 00:32:08,280
He called it "animal electricity",
and he saw a
very powerful connection

345
00:32:08,280 --> 00:32:12,880
between electricity,
animation and life itself.

346
00:32:13,880 --> 00:32:21,400
Galvani claimed
to have discovered the vital force,
the thing that makes tissue alive.

347
00:32:23,280 --> 00:32:27,480
Was this evidence of a link
between matter and spirit?

348
00:32:28,880 --> 00:32:33,040
Could animal electricity be
the spark of life?

349
00:32:39,080 --> 00:32:45,360
Across Europe, eminent
researchers set out to find out.

350
00:32:47,200 --> 00:32:50,440
One man who took it to extremes

351
00:32:50,440 --> 00:32:55,680
was the German scholar
Alexander von Humboldt.

352
00:32:57,760 --> 00:33:01,880
He was one of the
great romantic figures of his time.

353
00:33:01,880 --> 00:33:06,080
His epic journeys around
South America made him famous.

354
00:33:06,080 --> 00:33:12,160
Charles Darwin described him as
"the greatest scientific
traveller who ever lived".

355
00:33:12,160 --> 00:33:19,440
But his early passion was
electricity, and he did numerous
experiments on frogs and on himself.

356
00:33:21,080 --> 00:33:27,000
At Humboldt's old university, I'm
in the hands of Dr David Liebetanz.

357
00:33:27,000 --> 00:33:31,920
We have two channels, and I will
activate them separately.

358
00:33:31,920 --> 00:33:33,600
Tell me when you feel something.

359
00:33:35,120 --> 00:33:38,720
Nothing? OK, I have to switch it on!

360
00:33:38,720 --> 00:33:40,840
Ooh, I could feel a little... Yeah?

361
00:33:40,840 --> 00:33:42,960
..little twitch.

362
00:33:42,960 --> 00:33:47,240
'Von Humboldt wanted
to see if animal electricity
was the life force

363
00:33:47,240 --> 00:33:49,320
'that animated the human machine.'

364
00:33:51,840 --> 00:33:54,280
Oh! Finger.

365
00:33:54,280 --> 00:33:58,080
I have no voluntary control
over my hands at the moment,
and I can't put it down.

366
00:33:58,080 --> 00:34:02,440
'My muscles are contracting
due to carefully
controlled electric shocks.

367
00:34:02,440 --> 00:34:06,800
'In Von Humboldt's time,
this was a lot more rudimentary.'

368
00:34:06,800 --> 00:34:12,320
I know what's going on,
but von Humboldt had no idea,

369
00:34:12,320 --> 00:34:16,960
so this must have been quite
literally a major shock for him.

370
00:34:16,960 --> 00:34:20,960
It's quite strange that
it doesn't want to go down.

371
00:34:20,960 --> 00:34:23,120
Right.

372
00:34:23,120 --> 00:34:29,880
To recapture the sheer bewildering
strangeness of those electrical
experiments two hundred years ago,

373
00:34:29,880 --> 00:34:36,680
David has devised an experiment,
adapting his machine
to respond to music.

374
00:34:38,160 --> 00:34:40,440
MUSICAL NOTES PLAY

375
00:35:03,200 --> 00:35:06,160
Oh, God, thank goodness
that is over!

376
00:35:06,160 --> 00:35:11,320
That was one of
the most unpleasant and
interesting experiences of my life.

377
00:35:11,320 --> 00:35:14,640
I had no idea but it looked like,
but it felt unbelievably strange.

378
00:35:14,640 --> 00:35:17,320
I could feel just my face
just jumping all over the place.

379
00:35:17,320 --> 00:35:19,200
Oh, it was nasty!

380
00:35:19,200 --> 00:35:22,280
Nasty, nasty, nasty! But very funny.

381
00:35:22,280 --> 00:35:25,000
It looked very, very funny.

382
00:35:25,280 --> 00:35:29,640
That was like possession. Oh,
that was really, really unpleasant.

383
00:35:29,640 --> 00:35:34,440
Unbelievably,
Humboldt spent five years
doing these sort of experiments.

384
00:35:34,440 --> 00:35:38,720
In fact, he did over 4,000 of them,
and when he published in 1797,

385
00:35:38,720 --> 00:35:42,400
it caused an absolute
sensation throughout Europe.

386
00:35:46,440 --> 00:35:49,000
Other experimenters agreed.

387
00:35:49,000 --> 00:35:52,520
This seemed to be evidence of a
link between matter and spirit.

388
00:35:54,800 --> 00:36:00,400
They tried to use electricity
to bring the dead back to life,

389
00:36:00,400 --> 00:36:02,360
and failed.

390
00:36:03,960 --> 00:36:10,560
However hard they tried,
they couldn't impart
life to flesh and blood.

391
00:36:11,600 --> 00:36:17,080
The promise of animal electricity
proved to be a false dawn
for vitalists.

392
00:36:29,680 --> 00:36:36,200
The search for the secret of life
would require
a whole new approach to science.

393
00:36:48,640 --> 00:36:51,040
19th century Berlin,

394
00:36:51,040 --> 00:36:54,600
capital of a nation on the rise.

395
00:36:57,280 --> 00:37:03,160
The Prussian establishment built
grand monuments and great armies,

396
00:37:03,160 --> 00:37:07,120
it invested in industry
and technology.

397
00:37:13,360 --> 00:37:18,600
Prussian aspirations spawned
innovative working methods.

398
00:37:20,320 --> 00:37:24,440
University students, for example,
instead of just taking notes,

399
00:37:24,440 --> 00:37:28,920
now collaborated with their
professors on new research,

400
00:37:28,920 --> 00:37:34,040
and that collaboration
was given a suitable home,

401
00:37:34,040 --> 00:37:35,560
the research laboratory.

402
00:37:39,480 --> 00:37:43,920
This was when the modern idea of
the research laboratory was born.

403
00:37:43,920 --> 00:37:47,080
Instead of lone geniuses,
there would be teams of scientists

404
00:37:47,080 --> 00:37:51,880
tackling problems,
doing experiments,
having their results peer-reviewed.

405
00:37:54,600 --> 00:37:59,800
This change in the way that
science is managed and carried out

406
00:37:59,800 --> 00:38:05,280
would prove to be just as important
as any individual discovery.

407
00:38:06,840 --> 00:38:13,440
Scientific research would now be
organised, systemised, legitimised.

408
00:38:15,440 --> 00:38:19,360
All this would have a direct effect
on the future of biology.

409
00:38:19,360 --> 00:38:24,080
The research laboratories of Prussia
were about to make a
series of stunning discoveries,

410
00:38:24,080 --> 00:38:28,640
discoveries that would fundamentally
alter our understanding of life -

411
00:38:28,640 --> 00:38:30,160
all life, everywhere.

412
00:38:32,600 --> 00:38:39,920
The new Prussian system exploited
a technology that had
been invented 200 years before...

413
00:38:45,880 --> 00:38:47,360
..the microscope.

414
00:38:50,680 --> 00:38:57,320
One of the first to use it had been
Robert Hook in the 17th century.

415
00:38:57,320 --> 00:39:03,800
His book Micrographia contains
illustrations of a hidden world.

416
00:39:05,840 --> 00:39:11,240
The microscope had revealed
the intricate structure of plants,

417
00:39:11,240 --> 00:39:13,920
snowflakes and natural fibres.

418
00:39:18,480 --> 00:39:23,480
Insects with body parts on a scale
no-one had imagined possible.

419
00:39:25,520 --> 00:39:29,640
It showed the world
in unprecedented detail.

420
00:39:42,400 --> 00:39:47,880
Now, this isn't the most beautiful
picture in this book, but it is
without doubt the most important.

421
00:39:47,880 --> 00:39:54,600
It's actually a slice of cork,
and when Hook looked at it, he could
see all these funny little boxes.

422
00:39:54,600 --> 00:39:57,880
For reasons best known to
himself, he decided they looked like

423
00:39:57,880 --> 00:40:03,360
rooms he had seen in a monastery,
so he gave them the same name,
cells.

424
00:40:04,880 --> 00:40:09,920
At the time,
no-one realised the true
significance of what he had seen,

425
00:40:09,920 --> 00:40:15,800
and the idea of the cell would
languish in obscurity for 200 years.

426
00:40:19,760 --> 00:40:24,760
The cell finally resurfaced
in the mid-19th century

427
00:40:24,760 --> 00:40:27,920
in the research laboratories
of Prussia.

428
00:40:33,480 --> 00:40:39,560
There were now
well-engineered microscopes
on every laboratory bench,

429
00:40:39,560 --> 00:40:41,800
used to expose new wonders.

430
00:40:46,120 --> 00:40:49,720
And researchers now saw cells,
not just in cork,

431
00:40:51,840 --> 00:40:55,160
but in other plants and in animals.

432
00:40:58,520 --> 00:41:02,560
In fact, they saw cells
in every living thing.

433
00:41:07,280 --> 00:41:11,360
This was
an absolutely incredible claim.

434
00:41:11,360 --> 00:41:17,400
Even now, it is hard to grasp
that every living thing,
whatever its outward appearance,

435
00:41:17,400 --> 00:41:21,680
from an ant to an elephant,
from a blade of grass to my thumb,

436
00:41:21,680 --> 00:41:24,600
is made up of the same
basic structures.

437
00:41:24,600 --> 00:41:28,360
But the revelations about the cell
had only just begun.

438
00:41:31,600 --> 00:41:38,720
A little-known German
called Robert Remak observed and
recorded a remarkable process.

439
00:41:38,720 --> 00:41:43,600
Studying frogspawn,
he saw the single egg divide...

440
00:41:45,120 --> 00:41:46,800
..and divide again.

441
00:41:50,600 --> 00:41:55,800
Seen in time lapse, at first
the cells are simply replicating.

442
00:42:03,280 --> 00:42:07,160
Then, slowly,
the cells start to specialise

443
00:42:07,160 --> 00:42:11,960
and form the different
body parts of the juvenile frog.

444
00:42:22,360 --> 00:42:26,440
And it isn't just the tadpole
that grows like this.

445
00:42:32,840 --> 00:42:36,920
And what is true of frogs
is also true of us.

446
00:42:36,920 --> 00:42:41,800
It is an extraordinary thought that
every one of the trillions of cells

447
00:42:41,800 --> 00:42:43,720
that make up my body

448
00:42:43,720 --> 00:42:47,840
originally
came from just a single cell.

449
00:42:52,440 --> 00:42:57,600
The microscope had revealed
two fundamental rules of life -

450
00:43:01,480 --> 00:43:05,320
every living thing on the planet
is made of cells...

451
00:43:07,520 --> 00:43:11,240
..and cells only come
from other cells.

452
00:43:14,520 --> 00:43:19,400
Understand the cell
and you'd understand what life was.

453
00:43:26,800 --> 00:43:31,720
Except it wasn't as easy
as all that,

454
00:43:31,720 --> 00:43:36,440
because
even with the best microscopes

455
00:43:36,440 --> 00:43:39,480
this is all they could see,

456
00:43:41,000 --> 00:43:44,680
a nucleus in a translucent mush.

457
00:43:57,600 --> 00:44:04,760
If biologists were to make further
progress, they had to find
a way to make the invisible visible.

458
00:44:04,760 --> 00:44:07,720
They would need help,
and they would get it

459
00:44:07,720 --> 00:44:12,520
from two very different worlds,
theoretical physics and fashion.

460
00:44:17,560 --> 00:44:23,400
In the 1850s, the first
synthetic dyes burst onto the scene,

461
00:44:25,880 --> 00:44:30,520
creating a
whole new range of colours.

462
00:44:30,520 --> 00:44:33,880
Fashion drove demand.

463
00:44:33,880 --> 00:44:37,560
Painting and the arts were also
revitalised.

464
00:44:42,560 --> 00:44:49,760
Artificial colours were made on an
industrial scale by German chemists.

465
00:44:49,760 --> 00:44:56,000
They not only stained clothes,
they also stained cells.

466
00:44:56,000 --> 00:44:59,440
Different colours were made
with different chemicals,

467
00:44:59,440 --> 00:45:04,720
which meant each dye would stain
a different part of the cell.

468
00:45:06,240 --> 00:45:10,720
Structures now began to appear
within the translucent mush.

469
00:45:10,720 --> 00:45:14,960
Surely one of these must contain
the secret of life.

470
00:45:14,960 --> 00:45:19,040
The reductionist journey, probing
deeper and deeper into the body,

471
00:45:19,040 --> 00:45:24,800
now began to gather pace
as researchers delved into the cell.

472
00:45:27,640 --> 00:45:34,120
They discovered internal membranes,
protein structures
and energy stores.

473
00:45:34,120 --> 00:45:38,480
But what stood out
inside the nucleus

474
00:45:38,480 --> 00:45:40,760
were chromosomes.

475
00:45:42,280 --> 00:45:49,520
Chromosomes, meaning "coloured
bodies", were named after the dyes
that had helped reveal them,

476
00:45:49,520 --> 00:45:54,560
and they clearly played
a crucial role when
a cell divides and replicates.

477
00:45:57,080 --> 00:46:02,000
It seemed this was where
the secret of life must lie.

478
00:46:08,080 --> 00:46:12,000
This new unit of life,
the chromosome,

479
00:46:12,000 --> 00:46:17,040
had emerged from the rise
of Germany as a world power,

480
00:46:17,040 --> 00:46:20,840
its creation
of research laboratories

481
00:46:20,840 --> 00:46:26,040
and its investment
in the chemical dye industry.

482
00:46:26,040 --> 00:46:32,920
These factors had brought us
tantalisingly close to a
new understanding of life.

483
00:46:38,840 --> 00:46:45,240
But it seems as if science
never solves one problem
without creating ten more.

484
00:46:49,040 --> 00:46:51,680
Having identified chromosomes,

485
00:46:51,680 --> 00:46:57,080
it was clear that researchers would
need to find out how they worked,

486
00:46:57,080 --> 00:46:59,440
how they replicated,

487
00:46:59,440 --> 00:47:02,520
and that was a massive problem.

488
00:47:10,520 --> 00:47:14,640
The story of science
has never been straightforward.

489
00:47:19,120 --> 00:47:23,120
The next development seems to
have little to do with biology.

490
00:47:24,920 --> 00:47:30,600
Instead, it featured the world's
greatest physicists
and mathematicians.

491
00:47:32,720 --> 00:47:36,480
They were brought together
with a single goal,

492
00:47:36,480 --> 00:47:41,600
a goal they would achieve
with devastating success.

493
00:47:41,600 --> 00:47:47,840
Yet, ironically enough, it was
their success and their burning
intellectual curiosity which would

494
00:47:47,840 --> 00:47:52,320
lead to a moral crisis,
and one which would have
far-reaching impacts

495
00:47:52,320 --> 00:47:54,920
on the quest
to understand what is life.

496
00:48:08,400 --> 00:48:12,640
It's hard to imagine now,
looking at these
derelict guard boxes,

497
00:48:12,640 --> 00:48:18,000
but this was once one of the
most highly classified
places in the entire United States.

498
00:48:18,000 --> 00:48:21,560
Through there, there were
50,000 people working on a project

499
00:48:21,560 --> 00:48:26,880
which was so secret that even
the people who lived just down there
had no idea what was going on.

500
00:48:29,880 --> 00:48:34,520
At the time,
it did not appear on maps,

501
00:48:34,520 --> 00:48:37,920
but it consumed
more electricity than New York.

502
00:48:39,840 --> 00:48:46,840
Oak Ridge, Tennessee, was part
of the biggest scientific and
technological project in history,

503
00:48:46,840 --> 00:48:49,360
the Manhattan Project.

504
00:48:49,360 --> 00:48:52,720
And its aim?
To create a nuclear bomb.

505
00:49:00,800 --> 00:49:05,640
The uranium in Little Boy,
the bomb that was
dropped on Hiroshima,

506
00:49:05,640 --> 00:49:07,560
was made here in Oak Ridge.

507
00:49:07,560 --> 00:49:11,000
The bomb contained
64 kilograms of uranium,

508
00:49:11,000 --> 00:49:15,600
of which less than 0.6 of a gram -
that's about this much -

509
00:49:15,600 --> 00:49:18,520
was turned into pure energy.

510
00:49:18,520 --> 00:49:20,320
But this was enough.

511
00:49:37,080 --> 00:49:42,680
There have been few more significant
moments for science than this.

512
00:49:44,200 --> 00:49:46,240
It changed so much.

513
00:49:49,440 --> 00:49:54,920
The creation of an
instrument of death would even shape
the science of life.

514
00:50:00,360 --> 00:50:04,720
Many of the intellectuals behind
the project were gentle souls.

515
00:50:04,720 --> 00:50:09,960
They had gone into physics
because of the sublime beauty that
could be uncovered,

516
00:50:09,960 --> 00:50:13,240
but instead they had built bombs
that had killed,

517
00:50:13,240 --> 00:50:18,400
poisoned and mutilated
hundreds of thousands of men,
women and children.

518
00:50:18,400 --> 00:50:22,880
They were dreamers
who had created their own nightmare.

519
00:50:22,880 --> 00:50:24,920
Many wanted out of physics.

520
00:50:24,920 --> 00:50:31,480
It was tainted. They wanted
something more life-affirming,
and they found it, in biology.

521
00:50:36,040 --> 00:50:40,120
They took with them their knowledge
of atomic structure

522
00:50:40,120 --> 00:50:44,360
and applied their techniques
to the stuff of life.

523
00:50:47,120 --> 00:50:51,280
After the War, a physicist
called Maurice Wilkins came here

524
00:50:51,280 --> 00:50:58,040
to King's College, London,
to study the enigmatic chromosome.

525
00:50:58,040 --> 00:51:01,040
What Maurice Wilkins started here
at King's

526
00:51:01,040 --> 00:51:05,880
would lead to one of
THE great scientific discoveries
of the 20th century

527
00:51:05,880 --> 00:51:08,240
and transform
our understanding of life.

528
00:51:11,720 --> 00:51:16,720
It began innocuously enough,
when Wilkins started to investigate

529
00:51:16,720 --> 00:51:20,720
one of the chemicals found inside
chromosomes.

530
00:51:21,760 --> 00:51:23,680
Let me show you.

531
00:51:23,680 --> 00:51:31,520
All it takes to extract is a little
salt water, some washing-up liquid
and a splash of ice-cold alcohol.

532
00:51:35,680 --> 00:51:37,720
So, this gunky stuff here...

533
00:51:39,600 --> 00:51:42,080
..is DNA.

534
00:51:42,080 --> 00:51:43,760
Isn't that wonderful?

535
00:51:43,760 --> 00:51:45,720
Never seen my own DNA before.

536
00:51:45,720 --> 00:51:48,560
All you need
to make another Michael Mosley.

537
00:51:50,280 --> 00:51:52,760
Or is it?

538
00:51:52,760 --> 00:51:57,840
Is DNA alone really the answer?

539
00:51:58,880 --> 00:52:04,080
Back in the 1950s, they realised
that DNA was special, they just
didn't know an awful lot about it.

540
00:52:04,080 --> 00:52:07,120
When Maurice Wilkins
started looking into it,

541
00:52:07,120 --> 00:52:12,360
he decided to approach the problem
from a physicist's point of view,
looking at the physical structure.

542
00:52:12,360 --> 00:52:15,480
He was convinced that if you
could understand the structure,

543
00:52:15,480 --> 00:52:19,400
then you could understand,
if you like, its function,
how it managed to reproduce.

544
00:52:23,640 --> 00:52:28,440
His weapon of choice was a technique
called X-ray diffraction.

545
00:52:32,440 --> 00:52:37,520
X-rays fired at the DNA
hit the molecule and get scattered.

546
00:52:39,240 --> 00:52:44,800
The pattern of the scattering
can be used to calculate
the shape of the molecule.

547
00:52:47,200 --> 00:52:52,640
This, essentially, is a photograph
of a molecule's shadow.

548
00:52:59,160 --> 00:53:06,240
Joining Wilkins' department was
one of the best X-ray diffraction
experts around, Rosalind Franklin.

549
00:53:07,960 --> 00:53:10,480
Rosalind Franklin was
working with samples of DNA.

550
00:53:10,480 --> 00:53:13,040
What we have here in
this tube is an original sample.

551
00:53:13,040 --> 00:53:15,080
Can I? Yes.
It's her handwriting on the tube.

552
00:53:15,080 --> 00:53:20,240
Here we have now just on a mount made
out of a paper clip a drawn fibre,

553
00:53:20,240 --> 00:53:22,360
if you
can see that stretched fibre...

554
00:53:22,360 --> 00:53:24,320
Oh... ..which is still intact there.

555
00:53:24,320 --> 00:53:28,680
She knew that she was taking
the photographs and the data
that would eventually prove

556
00:53:28,680 --> 00:53:30,560
the structure.

557
00:53:30,560 --> 00:53:32,920
But she had competition.

558
00:53:32,920 --> 00:53:38,400
In Cambridge, another team was
also racing to make sense of DNA.

559
00:53:38,400 --> 00:53:42,000
Francis Crick,
another former physicist,

560
00:53:42,000 --> 00:53:45,000
and James Watson
were building models.

561
00:53:47,680 --> 00:53:52,800
In April 1953, they published
the famous double helix.

562
00:53:52,800 --> 00:53:55,960
Crick and Watson got the glory,

563
00:53:55,960 --> 00:54:01,000
but their model was actually
inspired by one
of Franklin's photographs,

564
00:54:01,000 --> 00:54:05,120
shown to Watson
WITHOUT Franklin's knowledge.

565
00:54:06,920 --> 00:54:08,880
Her famous one is this one here...

566
00:54:08,880 --> 00:54:14,480
Right. ..the famous photograph,
51... Right. ..which was
shown to Jim Watson... Indeed.

567
00:54:14,480 --> 00:54:17,360
..by Maurice Wilkins in early 1953.

568
00:54:17,360 --> 00:54:21,160
So was this photograph literally in
her drawer or something? Yes.

569
00:54:21,160 --> 00:54:25,680
She'd stuffed it away, and... Yeah,
I think so. He pulls it out and goes,
"Jim, have a look at this"?

570
00:54:25,680 --> 00:54:28,920
Exactly. Something like that? Yes.
And that was the historic moment?

571
00:54:28,920 --> 00:54:32,400
That was the moment when he realised
how clear the evidence was... Right.

572
00:54:32,400 --> 00:54:34,560
..for a helix.

573
00:54:38,200 --> 00:54:43,840
Now, the reason why
structure matters, why it mattered
that there were these two

574
00:54:43,840 --> 00:54:46,520
strands which were closely entwined,

575
00:54:46,520 --> 00:54:51,880
is because it neatly explains how
a cell divides, how it replicates.

576
00:54:51,880 --> 00:54:57,160
And until now, that had been one
of the biology's greatest mysteries.

577
00:54:59,120 --> 00:55:04,520
The flurry of research which
followed revealed DNA's
far-reaching influence on life.

578
00:55:06,440 --> 00:55:12,280
It controls the layout
of our bodies and the
workings of our biochemistry.

579
00:55:12,280 --> 00:55:15,240
It reveals our ancestry.

580
00:55:17,480 --> 00:55:21,000
It may soon direct
our medical treatment.

581
00:55:25,160 --> 00:55:29,360
DNA is the
foundation of a new science of life.

582
00:55:33,960 --> 00:55:40,360
Now, for a while, people must have
thought that they had the
secret of life within their grasp,

583
00:55:40,360 --> 00:55:44,480
but the more they looked into DNA,
the more complicated it got.

584
00:55:44,480 --> 00:55:47,600
Life is not as simple as all that.

585
00:55:52,120 --> 00:55:58,120
In the last 50 years, we've learnt
how to use and manipulate DNA.

586
00:55:58,120 --> 00:56:01,720
We can now do the previously
unthinkable -

587
00:56:01,720 --> 00:56:05,560
create it in the laboratory from
simple chemicals

588
00:56:05,560 --> 00:56:10,000
and make new forms of life
by inserting synthetic DNA

589
00:56:10,000 --> 00:56:11,880
into bacterial cells.

590
00:56:13,360 --> 00:56:18,400
But we have also discovered the DNA
is not all powerful.

591
00:56:19,560 --> 00:56:21,280
It is a set of instructions.

592
00:56:21,280 --> 00:56:26,720
But instructions
that can be modified
by other parts of the same cell.

593
00:56:29,360 --> 00:56:35,200
This circular feedback means life
cannot be pinned down
to one component.

594
00:56:37,000 --> 00:56:39,480
DNA cannot operate in isolation.

595
00:56:39,480 --> 00:56:45,520
It needs all the chemicals,
proteins and energy sources
that naturally surround it.

596
00:56:45,520 --> 00:56:50,840
In short, to create life you
absolutely need the whole cell.

597
00:56:53,800 --> 00:56:59,560
The process of delving ever deeper
into the body has revealed so much.

598
00:57:02,400 --> 00:57:04,800
It has created modern biology.

599
00:57:09,080 --> 00:57:15,560
But it's also shown that the secret
of life does not lie in simplicity,

600
00:57:15,560 --> 00:57:18,920
in any one chemical or process.

601
00:57:18,920 --> 00:57:23,800
The essence of life
lies in complexity.

602
00:57:24,800 --> 00:57:29,160
The hope of finding easy
answers has slipped away.

603
00:57:35,920 --> 00:57:37,760
But I'm optimistic.

604
00:57:37,760 --> 00:57:43,840
I'm convinced that
one day we WILL understand how the
components of the cell combine.

605
00:57:43,840 --> 00:57:47,760
We may even be able to create
life entirely from scratch.

606
00:57:47,760 --> 00:57:53,120
However, that will be primitive,
just one cell.

607
00:57:55,000 --> 00:57:57,680
It is a massive step
from that to this,

608
00:57:57,680 --> 00:58:03,160
the billions of cells that make up
my body and which communicate
with each other in ways

609
00:58:03,160 --> 00:58:06,120
that at the moment
we have not even begun to grasp.

610
00:58:06,120 --> 00:58:12,280
We have gone on an enormous journey
to get where we are today,
but when it comes to understanding

611
00:58:12,280 --> 00:58:16,920
the complexity of life, I think
we still have a huge way to go.

612
00:58:24,520 --> 00:58:31,160
In the final programme,
the most intimate question
of them all - who are we?

613
00:58:47,120 --> 00:58:50,160
Subtitles by Red Bee Media Ltd

614
00:58:50,160 --> 00:58:53,200
E-mail: subtitling@bbc.co.uk