1
00:00:14,200 --> 00:00:20,560
I'm on a fantastic journey
to look for the origins of life.

2
00:00:20,560 --> 00:00:24,760
I shall be travelling not only
around the world, but back in time,

3
00:00:24,760 --> 00:00:26,640
to try and build a picture

4
00:00:26,640 --> 00:00:30,240
of what life was like
in that very early period.

5
00:00:31,760 --> 00:00:34,320
It will be a journey
full of wonders.

6
00:00:34,320 --> 00:00:37,720
Parts of it were unknown
until only a few years ago.

7
00:00:37,720 --> 00:00:42,920
In 50 years of programme-making,
I've been lucky enough to explore

8
00:00:42,920 --> 00:00:45,960
the living world
in all its splendour and complexity.

9
00:00:49,320 --> 00:00:55,080
The blue whale! The biggest creature
that exists on the planet!

10
00:00:59,600 --> 00:01:03,360
Now, I'm off to explore
the origins of all this.

11
00:01:03,360 --> 00:01:07,200
To look for the
very first living creatures
that appeared on the planet.

12
00:01:10,800 --> 00:01:15,720
In recent years, scientists have
unearthed dramatic evidence of what
those first creatures were like.

13
00:01:15,720 --> 00:01:20,080
We can also find clues
in living animals.

14
00:01:22,320 --> 00:01:25,760
And this enchanting little creature

15
00:01:25,760 --> 00:01:27,320
is what we were looking for.

16
00:01:27,320 --> 00:01:32,640
Using the latest technology,
it's possible to bring
those first animals to life

17
00:01:32,640 --> 00:01:36,280
for the first time
in half a billion years.

18
00:01:37,760 --> 00:01:40,000
From the moment they appeared

19
00:01:40,000 --> 00:01:43,760
to the time that they took their
pioneering steps on land,

20
00:01:43,760 --> 00:01:47,520
we can deduce how animals
acquired bodies that move,

21
00:01:47,520 --> 00:01:52,480
eyes that saw and mouths that ate.

22
00:01:55,840 --> 00:01:59,240
And we can understand
how those first organisms

23
00:01:59,240 --> 00:02:03,800
laid the foundations for modern
animals as we know them today.

24
00:02:05,080 --> 00:02:07,760
Hello, old boy. How are you?

25
00:02:07,760 --> 00:02:10,800
'Including you and me.'

26
00:02:20,440 --> 00:02:25,080
My 40,000 mile journey begins
very close to home, in Britain.

27
00:02:26,960 --> 00:02:32,560
This is the Charnwood Forest
in Leicestershire
in the middle of England.

28
00:02:32,560 --> 00:02:35,960
As a schoolboy, I grew up near here.

29
00:02:35,960 --> 00:02:38,560
And in these rocks,
a discovery was made

30
00:02:38,560 --> 00:02:41,440
that transformed our understanding

31
00:02:41,440 --> 00:02:45,360
of that mystery of mysteries,
the origin of life.

32
00:02:50,560 --> 00:02:55,400
The history of life can be
thought of as a many-branched tree,

33
00:02:55,400 --> 00:02:57,520
with all the species alive today

34
00:02:57,520 --> 00:03:00,920
related to common ancestors
down near the base.

35
00:03:02,680 --> 00:03:08,760
The five kingdoms of life, the main
branches, were established early on.

36
00:03:08,760 --> 00:03:11,240
Bacteria.

37
00:03:11,240 --> 00:03:14,880
Protists - amoeba-like creatures.

38
00:03:16,240 --> 00:03:18,920
Fungi.

39
00:03:19,880 --> 00:03:23,080
Plants.

40
00:03:23,080 --> 00:03:28,320
And animals. That for me is the
most fascinating question of all.

41
00:03:28,320 --> 00:03:33,160
How and when did they first appear?

42
00:03:33,160 --> 00:03:36,800
The answers
are only now beginning to emerge -

43
00:03:36,800 --> 00:03:41,120
and some of the first clues
came from here in Charnwood Forest.

44
00:03:42,640 --> 00:03:46,040
I was a passionate fossil collector.

45
00:03:46,040 --> 00:03:50,280
But I never came to look for them
in this part of Charnwood,

46
00:03:50,280 --> 00:03:54,040
because the rocks here are
among the most ancient in the world.

47
00:03:54,040 --> 00:03:56,840
Around 600 million years old,
in fact.

48
00:03:56,840 --> 00:04:01,920
And every geologist knew or
at least was convinced that rocks of

49
00:04:01,920 --> 00:04:07,400
such extreme age couldn't possibly
contain fossils of any kind.

50
00:04:07,400 --> 00:04:12,040
And then a boy from
my very own school,
just a few years after I left it,

51
00:04:12,040 --> 00:04:15,000
made an astounding discovery.

52
00:04:16,040 --> 00:04:19,440
Against all the predictions
of scientific know-alls,

53
00:04:19,440 --> 00:04:24,640
he found a fossil in these
ancient Leicestershire rocks.

54
00:04:24,640 --> 00:04:27,640
And this is it.

55
00:04:27,640 --> 00:04:32,120
It's called and is known
around the world as Charnia,

56
00:04:32,120 --> 00:04:35,320
after the forest
in which it was discovered.

57
00:04:35,320 --> 00:04:36,880
But what is it?

58
00:04:36,880 --> 00:04:39,520
Is it animal or plant?

59
00:04:39,520 --> 00:04:42,880
The fact is
it comes from such a remote period

60
00:04:42,880 --> 00:04:47,080
that the distinction between those
two forms of life was not yet clear.

61
00:04:47,080 --> 00:04:49,240
But one thing is certain.

62
00:04:49,240 --> 00:04:51,640
It clearly was alive.

63
00:04:53,960 --> 00:04:57,960
Charnia was a marine organism,
part of an ancient community

64
00:04:57,960 --> 00:05:02,520
of living things that lived in
darkness at the bottom of an ocean.

65
00:05:02,520 --> 00:05:05,360
That much we do know.

66
00:05:05,360 --> 00:05:08,800
But what was this strange creature?

67
00:05:08,800 --> 00:05:11,440
When did it first appear?

68
00:05:11,440 --> 00:05:14,320
And how is it related
to modern animals?

69
00:05:14,320 --> 00:05:18,560
The answers to these questions
are only now beginning to emerge.

70
00:05:21,000 --> 00:05:26,000
There were further finds
in Charnwood forest, like this disk,

71
00:05:26,000 --> 00:05:28,360
which was probably the holdfast

72
00:05:28,360 --> 00:05:32,160
which secured the frond of Charnia
to the sea floor.

73
00:05:32,160 --> 00:05:37,040
And then people began to look in
rocks of this great age

74
00:05:37,040 --> 00:05:39,200
all around the world.

75
00:05:39,200 --> 00:05:43,520
And lo and behold they discovered
a whole range of fossils

76
00:05:43,520 --> 00:05:48,920
that enable us now to put together
in extraordinary detail

77
00:05:48,920 --> 00:05:51,840
the first chapters
in the history of life.

78
00:05:51,840 --> 00:05:56,800
That all happened
a very long time ago.

79
00:05:56,800 --> 00:06:00,920
Imagine travelling back
through time.

80
00:06:09,640 --> 00:06:15,920
Humans have been around for
two million years.

81
00:06:15,920 --> 00:06:21,280
The dinosaurs were wiped out
65 million years ago.

82
00:06:28,240 --> 00:06:32,720
Charnia is more than eight times
older than the oldest dinosaur.

83
00:06:32,720 --> 00:06:36,800
It lived
about 560 million years ago.

84
00:06:39,040 --> 00:06:44,480
But compared with the age of
life itself, that's nothing.

85
00:06:44,480 --> 00:06:48,360
Before Charnia
and other complex organisms existed,

86
00:06:48,360 --> 00:06:53,480
the only living things
were microscopic single cells.

87
00:06:53,480 --> 00:06:57,440
They first appeared about
three and a half billion years ago

88
00:06:57,440 --> 00:07:00,280
when the Earth
was a very different place.

89
00:07:05,320 --> 00:07:07,880
The early continents
were still forming.

90
00:07:10,640 --> 00:07:14,800
The days were a mere six hours long,
because at that time

91
00:07:14,800 --> 00:07:19,760
the Earth was spinning much faster
on its axis than it does today.

92
00:07:29,160 --> 00:07:33,600
The land was
dominated by volcanoes -

93
00:07:33,600 --> 00:07:36,160
hostile and lifeless.

94
00:07:45,080 --> 00:07:50,720
But deep in the oceans,
life had begun.

95
00:07:50,720 --> 00:07:55,920
The latest theory
is that chemicals spewing from
underwater volcanic vents

96
00:07:55,920 --> 00:07:59,360
solidified and created
towers like these,

97
00:07:59,360 --> 00:08:03,520
and this produced the conditions
needed for the first cells to form.

98
00:08:05,040 --> 00:08:12,040
Some of these began to harness the
energy of sunlight, just as plants
do today, and formed colonies.

99
00:08:13,640 --> 00:08:17,400
These rocky stromatolites
in western Australia

100
00:08:17,400 --> 00:08:21,200
have been constructed by very
similar photosynthesising bacteria.

101
00:08:27,680 --> 00:08:31,400
Others managed to survive by
extracting nourishment directly

102
00:08:31,400 --> 00:08:37,400
from the environment, like the fungi
and animals that would later evolve.

103
00:08:42,760 --> 00:08:47,720
This state of affairs continued
for a vast period of time.

104
00:08:51,360 --> 00:08:57,120
For some three billion years,
simple microscopic organisms

105
00:08:57,120 --> 00:09:00,600
were the most advanced form of life
on the planet.

106
00:09:00,600 --> 00:09:05,840
That's way over half
the entire history of life on Earth.

107
00:09:05,840 --> 00:09:10,520
And then suddenly, within the space
of a few million years, a mere

108
00:09:10,520 --> 00:09:15,640
blink of the eye in evolutionary
terms, advanced organisms appeared.

109
00:09:15,640 --> 00:09:18,160
Why is a mystery,

110
00:09:18,160 --> 00:09:24,040
but we may find some clues to it
on the coastline down here.

111
00:09:25,960 --> 00:09:30,320
On the Eastern coast of Canada,
there is evidence of an event that

112
00:09:30,320 --> 00:09:34,360
may well have been the spark that
started the evolution of animals.

113
00:09:36,920 --> 00:09:41,920
These rocks
have been dated by radioactivity

114
00:09:41,920 --> 00:09:45,960
to just before the moment
that life became very complex.

115
00:09:45,960 --> 00:09:51,000
So if we can understand
the circumstances under which
these rocks were formed,

116
00:09:51,000 --> 00:09:56,400
we may get a clue
as to why it was that life
suddenly became more complex.

117
00:09:58,600 --> 00:10:04,120
Fragments of red stone
are embedded in the darker rock.

118
00:10:04,120 --> 00:10:06,480
They look out of place.

119
00:10:06,480 --> 00:10:08,480
And, in fact, they are.

120
00:10:10,000 --> 00:10:13,840
Geologists call them drop stones.

121
00:10:13,840 --> 00:10:18,240
They were transported here
by glaciers.

122
00:10:18,240 --> 00:10:19,840
As the ice moved off the land,

123
00:10:19,840 --> 00:10:22,760
it floated out over the sea
in a great shelf,

124
00:10:22,760 --> 00:10:26,440
carrying with it stones that
it had gathered on the continents.

125
00:10:26,440 --> 00:10:28,920
And when the ice eventually melted,

126
00:10:28,920 --> 00:10:32,600
the stones fell into
the sediments on the sea floor.

127
00:10:32,600 --> 00:10:35,840
This wasn't the only place
covered by ice.

128
00:10:35,840 --> 00:10:40,240
Drop stones of the same age
have been found in deposits
all over the world.

129
00:10:41,920 --> 00:10:46,960
The evidence points to
a global spread of glaciation.

130
00:10:46,960 --> 00:10:51,240
Just before complex life appeared,
the world was in the grip

131
00:10:51,240 --> 00:10:54,360
of the biggest ice age
in its entire history.

132
00:11:29,120 --> 00:11:33,440
It's been called Snowball Earth.

133
00:11:37,720 --> 00:11:40,920
The Earth was plunged into
a deep freeze

134
00:11:40,920 --> 00:11:43,080
so severe it probably extended

135
00:11:43,080 --> 00:11:44,880
from pole to pole.

136
00:11:44,880 --> 00:11:47,880
The surface of the seas
were frozen over.

137
00:11:47,880 --> 00:11:51,360
On the continents, ice caps
and glaciers developed.

138
00:11:51,360 --> 00:11:55,920
In places, the ice was probably
a kilometre or so thick.

139
00:11:55,920 --> 00:11:59,840
We still don't know enough about
the details, but it's likely that

140
00:11:59,840 --> 00:12:03,400
those conditions lasted
for millions of years.

141
00:12:07,600 --> 00:12:12,560
Stromatolites and similar bacterial
colonies that dominated the Earth

142
00:12:12,560 --> 00:12:15,480
were crushed under
the advancing glaciers.

143
00:12:20,320 --> 00:12:25,000
Life was nearly annihilated
before it had truly begun.

144
00:12:29,760 --> 00:12:34,960
It's difficult to imagine
how life managed to survive
in those circumstances.

145
00:12:34,960 --> 00:12:37,400
But survive it did.

146
00:12:42,120 --> 00:12:44,680
Microbiologist Dr Hazel Barton

147
00:12:44,680 --> 00:12:49,200
believes that modern glaciers
can tell us how it did so.

148
00:12:51,120 --> 00:12:55,200
She has come to the Columbia
Icefield in the Rocky Mountains

149
00:12:55,200 --> 00:13:01,280
in search of organisms
that are still able to
endure such extremes today.

150
00:13:01,280 --> 00:13:02,840
The thing about being here

151
00:13:02,840 --> 00:13:05,600
is it looks like everything's been
wiped clean,

152
00:13:05,600 --> 00:13:08,600
the glacier's come through
and it's destroyed all life,

153
00:13:08,600 --> 00:13:10,000
there's nothing living.

154
00:13:10,000 --> 00:13:12,760
But to a microbiologist this
looks a bit like a rainforest.

155
00:13:12,760 --> 00:13:16,080
From here you can see discolouration
on the surface of the ice,

156
00:13:16,080 --> 00:13:18,400
but that's not dirt -

157
00:13:18,400 --> 00:13:22,040
that is photosynthetic bacteria
that are surviving there

158
00:13:22,040 --> 00:13:24,920
and that creates an ecosystem
where you have plants

159
00:13:24,920 --> 00:13:28,160
and you have predators come in
and feed on those organisms.

160
00:13:28,160 --> 00:13:31,760
So even though it looks dead,
it's actually wildly alive with life.

161
00:13:33,280 --> 00:13:37,760
The kind of life you can see here
is pretty ancient.

162
00:13:37,760 --> 00:13:41,280
They've had to adapt to a lot of
global catastrophes.

163
00:13:41,280 --> 00:13:44,680
They had to adapt to Snowball Earth.

164
00:13:45,560 --> 00:13:49,720
Microorganisms that live
in these harsh environments
we call extremophiles.

165
00:13:49,720 --> 00:13:55,560
They have an amazing amount
of adaptability
that's hardwired in their genomes.

166
00:13:55,560 --> 00:13:59,320
You can freeze them, you can
bury them a mile down in ice

167
00:13:59,320 --> 00:14:02,800
and its not much of a hindrance
because of their adaptable nature.

168
00:14:06,440 --> 00:14:12,240
We owe our existence
to ice-dwelling extremophiles.

169
00:14:12,240 --> 00:14:15,640
Snowball Earth
almost extinguished life,

170
00:14:15,640 --> 00:14:20,080
but tiny organisms like these
hung on for millions of years.

171
00:14:22,640 --> 00:14:24,800
I think what you had is

172
00:14:24,800 --> 00:14:27,720
organisms that could
withstand extreme environments

173
00:14:27,720 --> 00:14:30,840
conditioning themselves
to this changing ecosystem.

174
00:14:30,840 --> 00:14:33,720
You had a skin of microbes
on the surface of the planet,

175
00:14:33,720 --> 00:14:38,480
and you had these organisms living
between where the, the glaciers
contacted the rock,

176
00:14:38,480 --> 00:14:41,160
and that was enough life
trickling over so that

177
00:14:41,160 --> 00:14:45,000
when those conditions retreated,
and it became more favourable,

178
00:14:45,000 --> 00:14:48,080
then it was like, pff,
and everything took off again.

179
00:14:56,360 --> 00:14:59,920
Finally,
Snowball Earth began to warm.

180
00:15:05,280 --> 00:15:08,440
There is evidence that
around this time,

181
00:15:08,440 --> 00:15:12,040
there was a global surge
in volcanic activity.

182
00:15:16,160 --> 00:15:21,640
Eruptions punched through the ice,
spewing carbon dioxide into the air.

183
00:15:25,720 --> 00:15:29,480
As it spread through the atmosphere,
it produced a greenhouse effect,

184
00:15:29,480 --> 00:15:34,880
trapping heat so that
the earth warmed and the ice melted.

185
00:15:55,000 --> 00:15:58,600
We still have a lot to discover
about what happened next,

186
00:15:58,600 --> 00:16:03,040
but it seems likely that it was
the melting of Snowball Earth

187
00:16:03,040 --> 00:16:06,760
that led to the next
great development of life.

188
00:16:18,360 --> 00:16:21,000
As the glaciers retreated,

189
00:16:21,000 --> 00:16:26,200
so nutrient-rich meltwater
flooded into the oceans.

190
00:16:41,240 --> 00:16:47,600
For the surviving cells, this flood
of ground-up rock was a bonanza.

191
00:16:47,600 --> 00:16:51,520
For the microbes
that could photosynthesise,

192
00:16:51,520 --> 00:16:54,600
the pulverised rock
was a potent fertiliser.

193
00:16:54,600 --> 00:17:01,000
And their growth would have a direct
influence on early animal cells.

194
00:17:01,000 --> 00:17:05,360
Cyanobacteria
and other oxygen-producing microbes

195
00:17:05,360 --> 00:17:08,040
began to bloom across the globe.

196
00:17:11,720 --> 00:17:15,640
These flourished in colonies of
plant-like microbes

197
00:17:15,640 --> 00:17:18,880
that pumped out
enormous volumes of oxygen.

198
00:17:20,400 --> 00:17:22,680
And it was this increase in oxygen

199
00:17:22,680 --> 00:17:26,160
that was the key to the rise
of the animal kingdom.

200
00:17:28,960 --> 00:17:31,480
Now, simple microscopic life

201
00:17:31,480 --> 00:17:36,360
had the fuel it needed
to develop into something bigger.

202
00:17:40,640 --> 00:17:44,320
After billions of years of
single-celled life,

203
00:17:44,320 --> 00:17:47,760
something amazing
happened in the deep sea.

204
00:17:49,640 --> 00:17:54,400
Up to this moment, living cells
that had been produced by division

205
00:17:54,400 --> 00:17:57,240
simply drifted away from
one another.

206
00:18:01,640 --> 00:18:04,520
But now,
with the aid of increased oxygen,

207
00:18:04,520 --> 00:18:07,040
some cells were sticking together.

208
00:18:09,240 --> 00:18:13,920
Some of these clumps
ultimately evolved into animals.

209
00:18:15,440 --> 00:18:18,320
To find out how oxygen
drove this process,

210
00:18:18,320 --> 00:18:21,120
I have come to
Australia's Barrier Reef,

211
00:18:21,120 --> 00:18:24,920
to look at one of the most primitive
of animals alive today -

212
00:18:24,920 --> 00:18:27,840
one that can truly be called
a living fossil.

213
00:18:30,160 --> 00:18:34,240
It is one of the simplest
multi-celled organisms that we know,

214
00:18:34,240 --> 00:18:37,640
but its basic body structure
has nonetheless enabled it

215
00:18:37,640 --> 00:18:43,000
to survive virtually unchanged for
around 600 million years.

216
00:18:43,000 --> 00:18:45,160
It's a sponge.

217
00:18:45,160 --> 00:18:50,480
Sponges are just
collections of simple cells

218
00:18:50,480 --> 00:18:53,680
that have clumped together
and got stuck together.

219
00:18:53,680 --> 00:18:57,440
They don't have a digestive system
or a nervous system

220
00:18:57,440 --> 00:18:59,560
or a blood circulatory system,

221
00:18:59,560 --> 00:19:02,120
and they get their food
and their oxygen

222
00:19:02,120 --> 00:19:07,520
by just pumping seawater
through channels in the body.

223
00:19:07,520 --> 00:19:12,840
But they can give us an indication
of how it was that cells

224
00:19:12,840 --> 00:19:17,080
first clumped together
to form bodies of any real size.

225
00:19:19,320 --> 00:19:22,800
At the microscopic level,
sponge cells are bound together

226
00:19:22,800 --> 00:19:28,280
by a tangle of hairy, stringy
protein molecules called collagen.

227
00:19:29,840 --> 00:19:35,320
This collagen glue is found
only animals, and nowhere else.

228
00:19:37,560 --> 00:19:43,720
Collagen is sometimes called
the sticky tape of the animal world.

229
00:19:43,720 --> 00:19:46,520
It's the commonest protein
in our body.

230
00:19:46,520 --> 00:19:49,400
It forms the framework of our skins.

231
00:19:49,400 --> 00:19:52,040
Plastic surgeons use it
to pump up our lips.

232
00:19:52,040 --> 00:19:56,440
You need oxygen
to manufacture collagen

233
00:19:56,440 --> 00:19:59,520
and with the rising amount
of oxygen in the atmosphere

234
00:19:59,520 --> 00:20:04,760
at the end of Snowball Earth,
cells were able to manufacture it.

235
00:20:07,240 --> 00:20:11,040
At the Research Station on Heron
Island on the Great Barrier Reef,

236
00:20:11,040 --> 00:20:13,320
scientists are working
to understand

237
00:20:13,320 --> 00:20:16,800
how it was that
multi-celled organisms

238
00:20:16,800 --> 00:20:18,640
began to colonise the earth.

239
00:20:19,440 --> 00:20:23,920
To find the answer, marine biologist
Professor Bernard Degnan

240
00:20:23,920 --> 00:20:27,120
is studying sponges.

241
00:20:27,120 --> 00:20:30,560
The things that connect sponges to
the rest of the animal kingdom

242
00:20:30,560 --> 00:20:34,040
we can find at the level of
the cell and the gene.

243
00:20:34,040 --> 00:20:38,120
When we look at its genes,
it's clearly an animal.

244
00:20:38,120 --> 00:20:41,320
We look for the things that
bind all animals together,

245
00:20:42,000 --> 00:20:45,520
so what does a human share
not only with a chimpanzee

246
00:20:45,520 --> 00:20:49,000
and for that matter a tiger
but what it shares with a sponge.

247
00:20:50,080 --> 00:20:52,160
If we can find any common threads,

248
00:20:52,160 --> 00:20:55,680
we're getting really to the heart of
the matter of multicellularity

249
00:20:55,680 --> 00:20:58,120
in the animal kingdom,
so that's the key.

250
00:21:02,120 --> 00:21:06,880
A classic experiment
gives us some insight.

251
00:21:06,880 --> 00:21:11,160
First, a sponge
is cut into small pieces.

252
00:21:17,200 --> 00:21:21,880
Then it is pushed through a sieve
on the end of a syringe.

253
00:21:21,880 --> 00:21:25,200
This breaks the animal down
into its individual cells.

254
00:21:29,280 --> 00:21:33,200
This may seem a brutal thing
to do to a living organism,

255
00:21:33,200 --> 00:21:36,760
but to a sponge
this is of no consequence.

256
00:21:39,760 --> 00:21:44,880
In response,
it does something quite astonishing.

257
00:21:46,600 --> 00:21:50,680
The cells begin to move...

258
00:21:50,680 --> 00:21:53,080
and then they form clumps.

259
00:21:55,280 --> 00:21:58,880
Soon the clumps form bigger clumps,

260
00:21:58,880 --> 00:22:05,080
until three weeks later,
a miniature sponge has formed.

261
00:22:05,080 --> 00:22:10,320
Sponges have this amazing capacity
to regenerate themselves.

262
00:22:12,040 --> 00:22:15,080
And what we can do is
actually rebuild a sponge

263
00:22:15,080 --> 00:22:17,280
from the cell level up.

264
00:22:24,160 --> 00:22:27,480
From this experiment,
we can maybe infer a few things

265
00:22:27,480 --> 00:22:31,040
that happened 600 million years ago
with the very first animals.

266
00:22:31,040 --> 00:22:36,000
We can infer that there were
cells coming together,

267
00:22:36,000 --> 00:22:39,960
they could adhere to each other,
they used extracellular proteins

268
00:22:39,960 --> 00:22:43,520
like collagen
to glue themselves together.

269
00:22:43,520 --> 00:22:46,240
They had the ability to
communicate with each other

270
00:22:46,240 --> 00:22:50,960
and a certain amount of flexibility
that allowed them to interact

271
00:22:50,960 --> 00:22:54,280
to give rise to something
that's bigger and greater,

272
00:22:54,280 --> 00:22:58,040
a large macroscopic
multicellular animal.

273
00:22:59,880 --> 00:23:04,200
The advantages of being
multi-celled were many.

274
00:23:04,200 --> 00:23:06,960
Colonies of cells
could collect more food,

275
00:23:06,960 --> 00:23:09,680
control their internal environment

276
00:23:09,680 --> 00:23:12,760
and act efficiently
by working as a team.

277
00:23:14,280 --> 00:23:16,320
It was just the beginning.

278
00:23:19,080 --> 00:23:21,920
In Canada,
there is an extraordinary place

279
00:23:21,920 --> 00:23:24,120
that reveals what happened next.

280
00:23:25,680 --> 00:23:30,440
Here you can see how
just a few million years after
the melting of Snowball Earth,

281
00:23:30,440 --> 00:23:35,240
the earliest multi-celled organisms
became much more sophisticated...

282
00:23:35,240 --> 00:23:37,600
and much bigger.

283
00:23:41,040 --> 00:23:44,680
This is Mistaken Point
in Newfoundland.

284
00:23:44,680 --> 00:23:50,000
It got that name because in
years gone by sailors coming up
the eastern coast of North America

285
00:23:50,000 --> 00:23:52,920
but lost in the fogs
that are so frequent here

286
00:23:52,920 --> 00:23:55,120
would head north for the open ocean

287
00:23:55,120 --> 00:23:57,720
but be wrecked
on these savage rocks.

288
00:23:59,640 --> 00:24:05,960
But today Mistaken Point has
a completely different reputation.

289
00:24:05,960 --> 00:24:07,960
Today it is recognized as one of

290
00:24:07,960 --> 00:24:13,120
the most important fossil-bearing
sites in all the world.

291
00:24:13,120 --> 00:24:17,000
For here you can see fossils

292
00:24:17,000 --> 00:24:22,080
of the very first animals
that evolved on this planet.

293
00:24:36,400 --> 00:24:41,360
The fossils in these rocks
are both wonderful and bizarre.

294
00:24:45,360 --> 00:24:47,200
When the sun is low in the sky,

295
00:24:47,200 --> 00:24:51,160
the slanting light shows up
their structure in great detail.

296
00:24:54,760 --> 00:24:56,960
Organisms were no longer

297
00:24:56,960 --> 00:25:01,000
just clumps of undifferentiated
cells, like sponges.

298
00:25:01,000 --> 00:25:05,280
They were organized
into defined shapes.

299
00:25:05,280 --> 00:25:09,520
And among them are some
that look exactly like Charnia

300
00:25:09,520 --> 00:25:13,320
that had been first recognised
in Charnwood Forest.

301
00:25:15,800 --> 00:25:19,520
Here, there are not only
hundreds of examples of Charnia,

302
00:25:19,520 --> 00:25:22,800
but a whole community of other
strange creatures.

303
00:25:22,800 --> 00:25:27,880
Everywhere you look there are
complex markings and indentations

304
00:25:27,880 --> 00:25:29,400
of one kind or another -

305
00:25:29,400 --> 00:25:33,600
it's almost as though children
have been playing in wet sand.

306
00:25:33,600 --> 00:25:37,840
It's like walking through
a carpet of ancient creatures.

307
00:25:37,840 --> 00:25:42,800
It's difficult to imagine that
565 million years ago

308
00:25:42,800 --> 00:25:45,760
this was the bottom of the ocean

309
00:25:45,760 --> 00:25:49,920
and these were some of the first
animals to live on this planet.

310
00:26:04,920 --> 00:26:07,440
Here at Mistaken Point,

311
00:26:07,440 --> 00:26:11,320
exceptional conditions have
preserved these delicate life forms.

312
00:26:16,720 --> 00:26:19,720
Each one of these layers of rock

313
00:26:19,720 --> 00:26:24,080
was once mud
lying at the bottom of an ocean.

314
00:26:25,960 --> 00:26:29,600
An ocean so deep it was very cold,

315
00:26:29,600 --> 00:26:31,680
and very poor in oxygen,

316
00:26:31,680 --> 00:26:36,720
so any organism that died here
took a very long time to decay.

317
00:26:36,720 --> 00:26:40,120
But those that did
have been preserved

318
00:26:40,120 --> 00:26:43,920
with an astonishing degree
of perfection.

319
00:26:43,920 --> 00:26:46,640
What makes this place so different?

320
00:26:50,800 --> 00:26:55,160
There was a volcano rising from
the sea floor close by,

321
00:26:55,160 --> 00:26:58,480
and it spewed out
millions of tons of ash.

322
00:27:09,440 --> 00:27:11,480
The ash sank to the bottom,

323
00:27:11,480 --> 00:27:15,520
blanketing everything
like a sub-marine Pompeii.

324
00:27:17,040 --> 00:27:22,560
Over millions of years, the ash
itself was buried by muddy sediments

325
00:27:22,560 --> 00:27:25,320
and then all was turned into rock.

326
00:27:25,320 --> 00:27:28,520
And then, over hundreds of
millions of years,

327
00:27:28,520 --> 00:27:32,000
mountain-building forces thrust
the whole sea-floor upwards

328
00:27:32,000 --> 00:27:35,200
to its present position
on the coast of Canada.

329
00:27:38,120 --> 00:27:42,960
Dr Guy Narbonne is a world expert
on the fossils of Mistaken Point.

330
00:27:45,160 --> 00:27:48,520
What you can see on this surface

331
00:27:48,520 --> 00:27:52,800
is the grey is the muddy sea bottom

332
00:27:52,800 --> 00:27:55,960
and this is where
the creatures all lived.

333
00:27:55,960 --> 00:28:01,880
And they were knocked down and
covered by a bed of volcanic ash.

334
00:28:01,880 --> 00:28:06,320
And you can see it here
and all of this pink and white

335
00:28:06,320 --> 00:28:09,240
speckled stuff is volcanic ash.

336
00:28:09,240 --> 00:28:12,880
The volcanic ash
cast every part of them,

337
00:28:12,880 --> 00:28:16,640
like putting plaster around your arm
if you break it,

338
00:28:16,640 --> 00:28:20,960
and that led to
a perfect preservation

339
00:28:20,960 --> 00:28:23,480
of every detail of the outside.

340
00:28:25,520 --> 00:28:29,080
Radioactivity in this
light-coloured ash layer

341
00:28:29,080 --> 00:28:33,120
allows Guy Narbonne
to date precisely the eruptions,

342
00:28:33,120 --> 00:28:35,760
and therefore the fossils.

343
00:28:35,760 --> 00:28:40,360
Some are as old as
579 million years.

344
00:28:40,360 --> 00:28:44,720
Here we can see one of the best
of the fossils on the surface.

345
00:28:44,720 --> 00:28:50,680
It consists of disks,
and they all have these pustules

346
00:28:50,680 --> 00:28:55,080
on them and that's why we rather
affectionately call them pizza disks.

347
00:28:55,080 --> 00:28:58,880
And they were very simple in form,

348
00:28:58,880 --> 00:29:03,800
but the first truly large creatures
in Earth evolution.

349
00:29:06,160 --> 00:29:10,240
The pizza discs are only one
of the species found here.

350
00:29:13,320 --> 00:29:18,640
Most are fern-like fronds, like
this enormous species of Charnia.

351
00:29:21,360 --> 00:29:23,760
This is a two-metre-long frond.

352
00:29:23,760 --> 00:29:26,800
Astounding!
And this is not the biggest.

353
00:29:26,800 --> 00:29:29,480
We have about
200 specimens of this here.

354
00:29:31,680 --> 00:29:35,760
The frond of Charnia found
in Charnwood was isolated.

355
00:29:37,360 --> 00:29:43,760
But here at Mistaken Point,
a whole community of organisms
has been preserved together...

356
00:29:43,760 --> 00:29:48,160
and that
could give us new information.

357
00:29:48,160 --> 00:29:52,800
You're calling this an animal but is
it justified to call it an animal?

358
00:29:52,800 --> 00:29:54,680
Well... It's rather plant-like.

359
00:29:54,680 --> 00:29:57,960
Well, "What is it?"
is a big question.

360
00:29:57,960 --> 00:30:00,560
We know for a fact
it can't be a plant

361
00:30:00,560 --> 00:30:03,640
because we're in water thousands
of metres deep,

362
00:30:03,640 --> 00:30:06,720
there wouldn't have been enough
light to read a newspaper.

363
00:30:06,720 --> 00:30:11,000
We're several orders of magnitude
too little light for photosynthesis.

364
00:30:11,000 --> 00:30:14,440
OK, so it's not photosynthesising
because it's too deep

365
00:30:14,440 --> 00:30:17,360
and therefore it's not a plant.
What's it living on?

366
00:30:17,360 --> 00:30:23,880
What we believe they're living on
is dissolved carbon and other
nutrients in the deep oceans.

367
00:30:23,880 --> 00:30:29,480
So it's absorbing these nutrients
through its entire body.

368
00:30:29,480 --> 00:30:34,880
Very thin. Probably
not much thicker than your thumbnail.

369
00:30:34,880 --> 00:30:37,160
Very primitive.

370
00:30:39,400 --> 00:30:43,880
These organisms were
very simple animals.

371
00:30:43,880 --> 00:30:49,440
Beyond the reach of light,
they had to survive by
absorbing chemical sustenance.

372
00:30:49,440 --> 00:30:54,320
But most animals we know today
are able to move about.

373
00:30:54,320 --> 00:30:58,520
Even sponges and corals
have swimming larvae.

374
00:30:58,520 --> 00:31:01,400
But there's no evidence
of that here.

375
00:31:03,160 --> 00:31:06,840
The creatures were all immobile.

376
00:31:06,840 --> 00:31:08,680
Nothing could move.

377
00:31:08,680 --> 00:31:10,880
Nothing had a mouth,

378
00:31:10,880 --> 00:31:13,400
nothing had muscles.

379
00:31:14,920 --> 00:31:17,440
Probably none of them had colour,

380
00:31:17,440 --> 00:31:21,520
probably an eerie whiteish colour
to everything.

381
00:31:23,560 --> 00:31:29,040
These are the oldest large
multi-cellular creatures on Earth,

382
00:31:29,040 --> 00:31:32,680
the oldest things that
might be called proto-animals.

383
00:31:34,200 --> 00:31:38,280
This is not like anything
that exists on earth today.

384
00:31:38,280 --> 00:31:41,600
Even though they're not directly
related to us,

385
00:31:41,600 --> 00:31:47,320
like some distant relative,
they provide us with
a view of our own beginnings.

386
00:31:50,920 --> 00:31:55,480
One of the most peculiar things
about these wonderful proto-animals

387
00:31:55,480 --> 00:31:58,440
is the way they
constructed their bodies.

388
00:32:00,360 --> 00:32:05,280
Unlike modern creatures, they had
a very simple pattern of branching.

389
00:32:10,120 --> 00:32:14,280
Despite their size,
these are still very simple animals.

390
00:32:14,280 --> 00:32:18,360
They can be put together with just
six to eight genetic commands,

391
00:32:18,360 --> 00:32:25,520
as against some 25,000
such commands that were needed
to construct a mammal like me.

392
00:32:25,520 --> 00:32:28,040
You can see this
if you look at them in detail.

393
00:32:28,040 --> 00:32:31,840
You see that they are made up
of a series of very small modules

394
00:32:31,840 --> 00:32:35,640
which are attached to one another
in a number of different ways.

395
00:32:37,320 --> 00:32:43,760
Their modular or fractal way of
building their bodies is one of Guy
Narbonne's main areas of research.

396
00:32:46,080 --> 00:32:50,000
His study is centred on
one particular species.

397
00:32:51,560 --> 00:32:53,080
This is Fractofusus.

398
00:32:53,080 --> 00:32:56,040
It's the most common fossil in
the Mistaken Point assemblage.

399
00:32:56,040 --> 00:32:58,600
We have literally
thousands of specimens.

400
00:32:58,600 --> 00:33:01,640
And it would have lain on the
sea bottom like you see there.

401
00:33:01,640 --> 00:33:05,520
A spindle-shaped mass, very thin.

402
00:33:05,520 --> 00:33:08,640
It consists of these elements.

403
00:33:08,640 --> 00:33:10,720
And there are 20 of
them on either side.

404
00:33:10,720 --> 00:33:13,440
And if you look at
an individual element,

405
00:33:13,440 --> 00:33:15,760
it's remarkably finely-branched.

406
00:33:15,760 --> 00:33:18,640
It's a style we called
fractal or self-similar.

407
00:33:20,160 --> 00:33:24,280
These fractal organisms
grew by repetitive branching,

408
00:33:24,280 --> 00:33:27,840
with each branch
exactly the same as its predecessor

409
00:33:27,840 --> 00:33:30,200
from the microscopic level upwards.

410
00:33:32,760 --> 00:33:37,440
It was a simple, yet extremely,
effective way of building a body.

411
00:33:44,720 --> 00:33:50,320
Such finely-divided branches gave
the organism a huge surface area,

412
00:33:50,320 --> 00:33:55,480
and this allowed them to
absorb nutrients directly
without mouths and without guts.

413
00:33:58,120 --> 00:34:02,160
This simple fractal body plan
proved very successful.

414
00:34:03,680 --> 00:34:09,080
So animals using it grew large
for the first time in the
history of life on Earth.

415
00:34:13,160 --> 00:34:19,720
Fractal design was perfect for
getting these earliest creatures
off and running

416
00:34:19,720 --> 00:34:21,800
and its easy to see why.

417
00:34:21,800 --> 00:34:26,160
It takes a minimum of genetic
programming in order to make one.

418
00:34:26,160 --> 00:34:29,320
You could probably do it with
six or eight codes in your PC

419
00:34:29,320 --> 00:34:32,720
to make something that
was fractally branching.

420
00:34:32,720 --> 00:34:37,520
And then combining them to make up
larger elements is literally
child's play,

421
00:34:37,520 --> 00:34:43,560
like a toddler might take Lego
blocks and put them all together in
order to make up a larger structure.

422
00:34:47,640 --> 00:34:54,920
The fossils of Mistaken Point
provide a detailed record of
fractal animals.

423
00:34:54,920 --> 00:35:00,040
But the absence of anything like
them in more recent rocks
is very significant.

424
00:35:02,560 --> 00:35:07,720
Just a few million years after
they first evolved, they vanished.

425
00:35:09,240 --> 00:35:11,600
They have no living descendents.

426
00:35:11,600 --> 00:35:14,280
They were an evolutionary dead end.

427
00:35:15,800 --> 00:35:17,480
And the reason?

428
00:35:17,480 --> 00:35:21,280
The very simplicity
of their fractal way of growing.

429
00:35:22,800 --> 00:35:30,120
They utterly dominate about the first
20 million years of the evolution of
complex multi-cellular proto-animals.

430
00:35:30,120 --> 00:35:34,320
However, this fast start
was also their demise.

431
00:35:34,320 --> 00:35:38,120
Because they were incapable
of evolving things like

432
00:35:38,120 --> 00:35:43,120
guts and brains and muscles and teeth
that later animals did.

433
00:35:45,920 --> 00:35:49,240
If animals were to
acquire these things,

434
00:35:49,240 --> 00:35:53,640
they would have to build
their bodies in a completely
different way.

435
00:35:53,640 --> 00:35:58,440
And eventually, animals appeared
that did exactly that.

436
00:36:00,600 --> 00:36:05,120
To see them, I'm travelling south
from Newfoundland across the equator

437
00:36:05,120 --> 00:36:06,880
to South Australia.

438
00:36:12,720 --> 00:36:15,320
The Ediacara Hills.

439
00:36:17,560 --> 00:36:25,560
Here lie animals whose body plans
are fundamentally the same as those
of almost all animals alive today...

440
00:36:25,560 --> 00:36:27,240
including us.

441
00:36:29,800 --> 00:36:35,920
The creatures that are preserved
here lived just after fractal
animals began to die out.

442
00:36:41,720 --> 00:36:48,840
And about 550 million years ago,
their differently-organised bodies
gave them something quite new...

443
00:36:52,320 --> 00:36:53,840
..mobility.

444
00:36:56,200 --> 00:37:01,320
But how and why
did animals first begin to move?

445
00:37:01,320 --> 00:37:06,040
Scientists are beginning to find
answers to those
fascinating questions.

446
00:37:06,040 --> 00:37:11,040
And much of the detail
comes from these
extraordinary fossils behind me.

447
00:37:15,280 --> 00:37:20,600
A team of scientists, led by
palaeontologist Dr Jim Gehling

448
00:37:20,600 --> 00:37:23,280
is uncovering the
evidence in great detail.

449
00:37:25,520 --> 00:37:27,880
When you have these
beds covered in red clay

450
00:37:27,880 --> 00:37:31,880
you have a good chance of the beds
having well-preserved fossils.

451
00:37:31,880 --> 00:37:34,800
This is the original sea floor.

452
00:37:36,880 --> 00:37:42,160
And this sea-floor
was very different from that in the
deep waters of Mistaken Point.

453
00:37:42,160 --> 00:37:44,360
This was once a shallow reef.

454
00:37:44,360 --> 00:37:47,120
It is 550 million years old.

455
00:37:48,960 --> 00:37:53,360
The surface of the ocean floor
was covered with organic ooze.

456
00:37:53,360 --> 00:37:56,520
It may have even been green or
orange. We don't know the colour.

457
00:37:56,520 --> 00:38:03,560
But there was a lot of organic
material made up by bacteria and
all sorts of microorganisms.

458
00:38:03,560 --> 00:38:10,480
But sitting in and amongst that
garden of slime, we would have
seen these strange creatures.

459
00:38:13,560 --> 00:38:16,960
Jim Gehling's team is working
to decipher the fossils.

460
00:38:16,960 --> 00:38:21,400
But it is not easy
because these creatures still lacked
any hard parts to their bodies.

461
00:38:25,480 --> 00:38:29,480
If I was working on dinosaurs,
I'd go to a spot,

462
00:38:29,480 --> 00:38:34,760
find the bones and carefully dig
them up, take them back into the
lab, reconstruct the dinosaur.

463
00:38:34,760 --> 00:38:40,640
But I'm not dealing with bones. I'm
dealing with soft-bodied creatures.

464
00:38:40,640 --> 00:38:46,280
All you've got are imprints
of squishy things living
flat on the seafloor.

465
00:38:47,800 --> 00:38:52,160
Despite the challenges, Jim has
discovered compelling evidence here

466
00:38:52,160 --> 00:38:55,320
that these animals
had begun to move.

467
00:38:58,200 --> 00:39:02,280
On this fossil bed, we find
something very interesting.

468
00:39:02,280 --> 00:39:06,560
It's a series of faint,
but very definite circles.

469
00:39:06,560 --> 00:39:11,160
They are almost identical in size
and they overlap quite often.

470
00:39:11,160 --> 00:39:15,200
And then when you go to the end
of the series of discs,

471
00:39:15,200 --> 00:39:21,560
you find a hollow with the imprint
of a very distinct fossil,

472
00:39:21,560 --> 00:39:23,120
that of Dickinsonia.

473
00:39:25,080 --> 00:39:28,600
Dickinsonia was
a cushion-like creature

474
00:39:28,600 --> 00:39:31,120
that lay flat on the seafloor.

475
00:39:31,120 --> 00:39:36,000
It ranged from the size of a penny
to that of a bath mat.

476
00:39:39,360 --> 00:39:43,360
These imprints represent
something very important.

477
00:39:43,360 --> 00:39:45,080
They are the first evidence

478
00:39:45,080 --> 00:39:48,600
of a kind of mobility
of animals on the seafloor.

479
00:39:50,600 --> 00:39:56,600
The first animal movements
were undoubtedly slow,
but perhaps even too slow to notice.

480
00:39:56,600 --> 00:40:00,880
To see them in action,
you have to speed them up.

481
00:40:04,520 --> 00:40:08,200
Dickinsonia crept from one
feeding place to the next,

482
00:40:08,200 --> 00:40:13,160
absorbing the organic matter beneath
it and then moving on once again.

483
00:40:13,160 --> 00:40:19,880
Perhaps it moved with the help of
hundreds of tiny tubular feet,
as starfish do today.

484
00:40:24,280 --> 00:40:32,280
The excavations at Ediacara
reveal that Dickinsonia wasn't
the only mobile creature around.

485
00:40:32,280 --> 00:40:37,560
Animals everywhere were on the move,
actively seeking food.

486
00:40:37,560 --> 00:40:45,320
This shape here
is a resting place of a slug-like
animal called Kimberella.

487
00:40:45,320 --> 00:40:50,560
And these here, marks,
are showing how it fed.

488
00:40:50,560 --> 00:40:52,160
It had a proboscis, a snout,

489
00:40:52,160 --> 00:40:59,440
and it fed by sifting through the
mud, making these scratch marks.

490
00:40:59,440 --> 00:41:03,360
But it tells us more
than how this animal fed.

491
00:41:03,360 --> 00:41:07,680
It also tells us how it moved
because if you look back this way,

492
00:41:07,680 --> 00:41:09,480
this is where is started feeding

493
00:41:09,480 --> 00:41:13,800
and then it moved along here with
more feeding marks and grooves,

494
00:41:13,800 --> 00:41:16,720
and then it settled down here

495
00:41:16,720 --> 00:41:19,240
into the mud
where its final resting place was.

496
00:41:19,240 --> 00:41:23,200
So this shows that the animal
not only fed like that,

497
00:41:23,200 --> 00:41:25,440
it actually moved like that.

498
00:41:27,200 --> 00:41:32,400
Kimberella was a very early
ancestor of today's molluscs.

499
00:41:32,400 --> 00:41:34,960
It probably had
a single muscular foot,

500
00:41:34,960 --> 00:41:37,440
just as snails and slugs have today

501
00:41:37,440 --> 00:41:41,280
with which it pulled
itself along the sea bottom.

502
00:41:41,280 --> 00:41:45,000
Our speeded-up view of
the Ediacaran seafloor

503
00:41:45,000 --> 00:41:48,880
gives an idea of what a busy place
the oceans had now become.

504
00:42:01,040 --> 00:42:05,560
Whether that movement is by creeping
or crawling over the seafloor,

505
00:42:05,560 --> 00:42:07,840
it doesn't matter
because that animal

506
00:42:07,840 --> 00:42:12,600
has advantages over an animal
that is fixed to the seafloor.

507
00:42:12,600 --> 00:42:14,720
It can move away from danger.

508
00:42:14,720 --> 00:42:18,240
It can move towards
richer sources of food.

509
00:42:18,240 --> 00:42:23,760
It can move
away from places which are
over-colonised by its neighbours.

510
00:42:23,760 --> 00:42:28,120
That gives it an enormous
advantage in the history of life.

511
00:42:38,000 --> 00:42:45,000
This new mobility was only made
possible by a major change in
the layout of animals' bodies.

512
00:42:46,520 --> 00:42:51,640
When we get to Ediacara,
we still have some of those
beautiful fractal-like forms

513
00:42:51,640 --> 00:42:59,520
that you see at Mistaken Point
but in the Ediacara Hills
we see something very different

514
00:42:59,520 --> 00:43:01,480
and that is, for the first time,

515
00:43:01,480 --> 00:43:08,360
you see a blueprint for all animals
from then on, including ourselves.

516
00:43:09,880 --> 00:43:15,680
'The modern animal body plan
is called bilateral symmetry.'

517
00:43:15,680 --> 00:43:17,840
What we see here is Spriggina.

518
00:43:21,680 --> 00:43:23,520
Let's make a cast of the fossil.

519
00:43:25,120 --> 00:43:30,280
Spriggina represents
the first ever animal

520
00:43:30,280 --> 00:43:33,800
which had
clear bilateral symmetry.

521
00:43:33,800 --> 00:43:38,280
It had a body with a head at
one end, a tail at the other.

522
00:43:38,280 --> 00:43:42,480
And almost identical halves,
if you split it down the middle.

523
00:43:45,400 --> 00:43:48,760
We see these together
with other creatures

524
00:43:48,760 --> 00:43:52,360
which have
this kind of body form.

525
00:43:52,360 --> 00:43:56,560
Spriggina is just one
of countless kinds of fossils

526
00:43:56,560 --> 00:44:00,160
in the Ediacara Hills
that had developed in this way.

527
00:44:01,680 --> 00:44:07,080
It had a head and a tail, and so
it moved in a particular direction.

528
00:44:10,800 --> 00:44:16,200
It's quite likely that
they had sensory organs
concentrated in the head.

529
00:44:16,200 --> 00:44:20,480
Now why does
my nose occur near my mouth?

530
00:44:20,480 --> 00:44:24,600
It's a very good reason. I want to
smell the food before I ingest it.

531
00:44:24,600 --> 00:44:27,520
Why are my eyes above my mouth?

532
00:44:27,520 --> 00:44:29,280
So I can see what I'm eating.

533
00:44:29,280 --> 00:44:36,520
This head demonstrates
that sensory capacity had evolved.

534
00:44:36,520 --> 00:44:41,560
It was able to sense where food was
likely to be on the seafloor.

535
00:44:41,560 --> 00:44:47,280
And, therefore,
clearly had a mechanism for actually
moving towards that food.

536
00:44:49,360 --> 00:44:54,640
Bilateral animals like Spriggina
had another advantage.

537
00:44:54,640 --> 00:44:58,680
Between the head and the tail,
there are numerous segments.

538
00:45:00,800 --> 00:45:06,760
So these animals could increase in
size by simply adding more segments.

539
00:45:06,760 --> 00:45:11,760
What is more, each segment
could do a particular job.

540
00:45:11,760 --> 00:45:13,040
Once you start to move,

541
00:45:13,040 --> 00:45:16,040
you develop a front end
and that becomes your head.

542
00:45:16,040 --> 00:45:19,160
And you also, by definition,
have a back end.

543
00:45:19,160 --> 00:45:23,120
And in between, segments
on which you can add appendages.

544
00:45:23,120 --> 00:45:26,680
On that basic pattern,
you can add further features.

545
00:45:26,680 --> 00:45:30,960
On the front end, that's where you
need sense organs, eyes, feelers.

546
00:45:30,960 --> 00:45:34,200
On the appendages, you can modify
them to be hooks and claws

547
00:45:34,200 --> 00:45:36,120
that would help you
to catch things.

548
00:45:36,120 --> 00:45:42,400
And at the back end, there will be
a pore from which you excrete
the waste products.

549
00:45:42,400 --> 00:45:48,440
And that is the basic body plan
of almost all the animals that
are alive on Earth today.

550
00:45:50,760 --> 00:45:57,360
It had taken 3,000 million
years for multi-celled organisms
to appear for the first time.

551
00:45:57,360 --> 00:46:03,240
But now, less than 100 million
years later, an evolutionary
blink of an eye,

552
00:46:03,240 --> 00:46:09,840
animals had appeared
that had the same basic body plan
as most that live today.

553
00:46:09,840 --> 00:46:13,040
They had heads and tails
and segmented bodies.

554
00:46:13,040 --> 00:46:16,000
And they were able
to move to find food.

555
00:46:17,520 --> 00:46:21,640
How was it that animals had
suddenly become so complex?

556
00:46:24,040 --> 00:46:29,600
The Ediacara Hills may hold
the evidence for an answer
to that question.

557
00:46:34,480 --> 00:46:38,080
Living organisms don't live forever.

558
00:46:38,080 --> 00:46:46,120
If a species is to survive
it has to reproduce and the first
simple animals did that very simply,

559
00:46:46,120 --> 00:46:48,480
by straightforwardly dividing.

560
00:46:48,480 --> 00:46:56,240
But if a species is to survive
it also has to have the ability to
change with a changing environment.

561
00:46:56,240 --> 00:47:01,920
And to do that involves reproducing
in a rather different way.

562
00:47:01,920 --> 00:47:09,040
Evidence of how that happened
can also be seen is these very
ancient Australian rocks.

563
00:47:20,640 --> 00:47:25,640
In 2007, palaeontologist
Dr Mary Droser

564
00:47:25,640 --> 00:47:30,040
discovered in these
550-million-year-old deposits

565
00:47:30,040 --> 00:47:34,360
evidence that animals
had started to reproduce sexually.

566
00:47:36,960 --> 00:47:41,320
The animal concerned
is called Funisia.

567
00:47:44,320 --> 00:47:48,880
If Droser's theory is right,
this wormlike creature produced
offspring

568
00:47:48,880 --> 00:47:53,440
by exchanging genetic material
with other individuals.

569
00:47:53,440 --> 00:47:56,560
This gene-swapping, or sex,

570
00:47:56,560 --> 00:48:02,680
shuffles the genetic pack,
greatly accelerating variation
and therefore evolution.

571
00:48:07,280 --> 00:48:10,800
Sexual reproduction is absolutely
one of the most fundamental steps

572
00:48:10,800 --> 00:48:12,120
in the history of life.

573
00:48:12,120 --> 00:48:14,600
It is why we have the
diversity that we have.

574
00:48:14,600 --> 00:48:16,240
It's the birds and the bees.

575
00:48:16,240 --> 00:48:20,680
As far as we know, this is the
first evidence of animals' sexual
reproduction,

576
00:48:20,680 --> 00:48:24,320
and we're not catching the animal
in the act of it,

577
00:48:24,320 --> 00:48:29,520
we're looking at the product of what
we conclude was sexual reproduction.

578
00:48:29,520 --> 00:48:33,240
This fossil is key to
Mary Droser's argument.

579
00:48:33,240 --> 00:48:37,240
The small circles show where the
animals were anchored to the ground.

580
00:48:38,760 --> 00:48:43,440
You can see
that these attachment structures
are basically all the same size.

581
00:48:43,440 --> 00:48:46,720
They're all about a couple
of millimetres in diameter.

582
00:48:46,720 --> 00:48:51,160
And you could go to another bed,
and all the Funisia are half
a centimetre in diameter.

583
00:48:51,160 --> 00:48:54,360
So the same size are
all occurring together.

584
00:48:54,360 --> 00:48:59,960
This uniformity of size in
a particular place is,
Mary Droser believes,

585
00:48:59,960 --> 00:49:04,560
strong evidence that a new way
of reproducing had arrived.

586
00:49:04,560 --> 00:49:06,760
We link this to sexual reproduction

587
00:49:06,760 --> 00:49:11,120
because if you look in modern
environments, when you have
this kind of size groupings,

588
00:49:11,120 --> 00:49:16,880
that is 99.9% of the time
a product of sexual reproduction.

589
00:49:18,240 --> 00:49:25,000
To understand why, I'm travelling
2,000 miles northeast of Ediacara
to the Great Barrier Reef.

590
00:49:29,120 --> 00:49:35,880
Here, there are modern creatures
that reproduce in the way that
Funisia is thought to have done.

591
00:49:35,880 --> 00:49:38,120
They're corals.

592
00:49:46,960 --> 00:49:51,600
Corals, like Funisia,
are anchored to the seabed.

593
00:49:51,600 --> 00:49:56,200
They feed
by filtering food from the water.

594
00:49:58,760 --> 00:50:04,400
And the way they breed
creates one of nature's
greatest annual spectacles.

595
00:50:06,800 --> 00:50:11,720
Once a year, there's an
important event among the corals.

596
00:50:11,720 --> 00:50:13,800
We're not sure how it's coordinated.

597
00:50:13,800 --> 00:50:16,360
It probably has something to do
with the moon.

598
00:50:16,360 --> 00:50:22,240
But it gives us a hint
as to how sexual reproduction
might have first appeared.

599
00:50:30,080 --> 00:50:33,280
At exactly the same time,

600
00:50:33,280 --> 00:50:38,920
the corals release countless
millions of sperm and eggs
all at once.

601
00:50:48,760 --> 00:50:52,760
The event is precisely timed
to maximise the chances

602
00:50:52,760 --> 00:50:54,520
of fertilisation.

603
00:50:56,040 --> 00:50:59,840
Millions of offspring are
simultaneously conceived.

604
00:51:05,480 --> 00:51:09,680
So, as the coral grows,
the individuals that make up

605
00:51:09,680 --> 00:51:15,160
the colonies are all of
exactly the same age and size,

606
00:51:15,160 --> 00:51:17,360
just like Funisia.

607
00:51:22,040 --> 00:51:26,520
It's unlikely that Funisia was the
first animal to reproduce sexually.

608
00:51:26,520 --> 00:51:33,640
But its discovery suggests that many
other animals are also reproducing
by mixing their genes.

609
00:51:33,640 --> 00:51:39,440
And that might explain how
complex animals evolved so quickly.

610
00:51:44,120 --> 00:51:48,600
The arrival of sexual reproduction
speeded evolution.

611
00:51:48,600 --> 00:51:53,520
Here was a mechanism that produced
greater genetic variation
more quickly.

612
00:51:53,520 --> 00:51:59,560
So, over many generations,
species were able to adapt
to their changing environments.

613
00:52:01,080 --> 00:52:07,600
550 million years ago, animal life
was on the verge of a major advance.

614
00:52:09,160 --> 00:52:15,720
In an environment where animals
were becoming more mobile,
they would have to adapt fast.

615
00:52:15,720 --> 00:52:19,320
Movement requires a lot of energy.

616
00:52:19,320 --> 00:52:22,600
Simply absorbing nutrients
through the surface of the body

617
00:52:22,600 --> 00:52:26,120
as Dickinsonia did
was much too slow a process.

618
00:52:28,200 --> 00:52:32,360
Mobile animals would need to consume
huge quantities of food.

619
00:52:32,360 --> 00:52:37,000
And they would do that by
evolving the very first stomachs,
mouths and teeth.

620
00:52:39,960 --> 00:52:44,120
You can see how they might
have done so in Switzerland...

621
00:52:48,040 --> 00:52:53,360
..where a new kind of technology
provides a window into the past.

622
00:53:00,600 --> 00:53:06,400
This stadium-sized building
houses one of the world's
most powerful microscopes.

623
00:53:11,440 --> 00:53:14,480
It's called the synchrotron.

624
00:53:19,360 --> 00:53:25,080
Professor Philip Donoghue
is preparing the tiniest of fossils
for the synchrotron.

625
00:53:27,400 --> 00:53:33,080
These miniscule balls were excavated
from a quarry in South China.

626
00:53:33,080 --> 00:53:38,680
Each and every one of them
is the fossilised embryo
of an ancient creature.

627
00:53:42,840 --> 00:53:45,400
If we really want to understand
these fossils,

628
00:53:45,400 --> 00:53:48,080
what we need to do is not
just to look at the surface

629
00:53:48,080 --> 00:53:50,360
which we can do with
an electron microscope.

630
00:53:50,360 --> 00:53:51,520
We need to look inside.

631
00:53:51,520 --> 00:53:56,720
We have to use
some form of X-ray tomography,
a bit like CAT scanners in hospitals.

632
00:53:56,720 --> 00:54:03,160
But we have to use one that allows us
to look at the very tiniest details
down to a thousandth of a millimetre.

633
00:54:03,160 --> 00:54:06,280
The synchrotron is the only
X-ray type machine that provides

634
00:54:06,280 --> 00:54:11,760
the kinds of resolution that we
need to see all the tiny details
within the fossilised embryos.

635
00:54:13,280 --> 00:54:15,800
KLAXON SOUNDS

636
00:54:17,200 --> 00:54:21,640
It was astonishing, I mean
it was a real eureka moment

637
00:54:21,640 --> 00:54:26,040
that you could get to the very finest
levels of fossilisation,

638
00:54:26,040 --> 00:54:30,280
the very finest detail that the
fossil record could ever give up
using this technology.

639
00:54:38,920 --> 00:54:46,320
Powerful generators fire high-energy
electrons around a circular tube
at close to the speed of light.

640
00:54:50,200 --> 00:54:58,040
After one million orbits, the
electrons emit X-rays so powerful,
they can penetrate solid rock

641
00:54:58,040 --> 00:55:00,240
or these tiny fossils.

642
00:55:02,160 --> 00:55:05,160
Donoghue uses data
from the synchrotron

643
00:55:05,160 --> 00:55:08,600
to build a three-dimensional
picture of the fossils.

644
00:55:10,120 --> 00:55:15,600
We know it's a fossil embryo
because it's surrounded by
a preserved egg sac.

645
00:55:15,600 --> 00:55:20,200
And using tomography we can see
inside to the developing animal.

646
00:55:25,480 --> 00:55:30,520
This fossil is the embryo of
a tiny marine worm called Markuelia.

647
00:55:32,040 --> 00:55:36,680
It lived just twenty million
years after the animals of Ediacara.

648
00:55:43,440 --> 00:55:48,360
Using his 3D model,
Donoghue is able to see inside it

649
00:55:48,360 --> 00:55:51,880
and there he
found evidence of something new.

650
00:55:53,760 --> 00:55:58,160
These fossils provide the first clear
evidence for a gut within animals.

651
00:55:58,160 --> 00:56:03,360
We can clearly see that there's
a mouth right at one end

652
00:56:03,360 --> 00:56:06,280
surrounded by rings of teeth
that extend inside the mouth.

653
00:56:06,280 --> 00:56:10,840
And then there's a gut
that extends all the way through
to an anus at the other end.

654
00:56:12,360 --> 00:56:20,000
Internal digestion enabled Markuelia
to extract energy from its food
in a very efficient way.

655
00:56:23,280 --> 00:56:29,120
And the fact that it had teeth
suggests that it had a new diet -

656
00:56:29,120 --> 00:56:30,960
other animals.

657
00:56:33,400 --> 00:56:38,240
The fact that it's got
rings of teeth arranged by its mouth,
that it would have averted out

658
00:56:38,240 --> 00:56:43,080
or it would have ejected out of its
mouth to grasp prey items, tells us
that this thing was a predator.

659
00:56:47,520 --> 00:56:50,840
For the first time,
there were hunters in the oceans.

660
00:56:50,840 --> 00:56:55,800
And that had enormous
evolutionary implications.

661
00:57:04,400 --> 00:57:11,400
There was about to be an explosion
of life that would lay the
foundations for modern animals.

662
00:57:16,720 --> 00:57:19,040
In another wave of evolution,

663
00:57:19,040 --> 00:57:23,520
the animal basic body plan
became more and more elaborate.

664
00:57:23,520 --> 00:57:27,160
Fearsome predators
appeared in the seas,

665
00:57:27,160 --> 00:57:33,720
great monsters on the land
and animals became masters
of the Earth.

666
00:57:36,280 --> 00:57:42,400
Next time I continue my journey
in the Rocky Mountains of Canada,

667
00:57:42,400 --> 00:57:45,160
the deserts of North Africa

668
00:57:45,160 --> 00:57:49,880
and the tropical rainforests
of Australia.

669
00:57:49,880 --> 00:57:56,600
I will discover how and why animals
evolved skeletons and shells.

670
00:57:56,600 --> 00:57:59,920
How they developed true,
picture-forming eyes.

671
00:58:01,040 --> 00:58:04,280
How others
went to extraordinary lengths

672
00:58:04,280 --> 00:58:08,120
to protect themselves from attack.

673
00:58:08,120 --> 00:58:14,760
And I shall discover the first
animals that moved out of the sea
to conquer the land and the air.

674
00:58:36,520 --> 00:58:39,560
Subtitles by Red Bee Media Ltd

675
00:58:39,560 --> 00:58:42,600
E-mail subtitling@bbc.co.uk