1
00:00:08,000 --> 00:00:11,000
Pegasus, Bucephalus, Champion,

2
00:00:11,000 --> 00:00:17,000
Trigger, Seabiscuit, Red Rum.

3
00:00:17,000 --> 00:00:19,000
I'm talking about the stuff

4
00:00:19,000 --> 00:00:21,000
of myth and legend.

5
00:00:31,000 --> 00:00:33,000
Just look at her.

6
00:00:33,000 --> 00:00:36,000
She's absolutely

7
00:00:36,000 --> 00:00:38,000
gorgeous, aren't you?

8
00:00:38,000 --> 00:00:42,000
Equus ferus caballus -
the horse, to you and I.

9
00:00:46,000 --> 00:00:48,000
A statuesque pinnacle

10
00:00:48,000 --> 00:00:50,000
of natural art.

11
00:00:54,000 --> 00:00:56,000
This is a creature

12
00:00:56,000 --> 00:01:00,000
supremely shaped to move.

13
00:01:18,000 --> 00:01:21,000
Thanks to 700 mighty muscles...

14
00:01:22,000 --> 00:01:25,000
..and a heart
the size of a football...

15
00:01:29,000 --> 00:01:32,000
..the horse is one of the fastest

16
00:01:32,000 --> 00:01:35,000
and most powerful animals
on the planet.

17
00:01:41,000 --> 00:01:44,000
They don't call it horsepower
for nothing.

18
00:01:48,000 --> 00:01:51,000
So how did the horse

19
00:01:51,000 --> 00:01:53,000
become one of nature's

20
00:01:53,000 --> 00:01:55,000
greatest athletes?

21
00:01:58,000 --> 00:02:00,000
To answer that...

22
00:02:02,000 --> 00:02:04,000
..we must travel back in time...

23
00:02:10,000 --> 00:02:11,000
..to meet the key

24
00:02:11,000 --> 00:02:13,000
movers and shakers...

25
00:02:15,000 --> 00:02:17,000
..before hooves thundered...

26
00:02:22,000 --> 00:02:25,000
..or hearts raced.

27
00:02:26,000 --> 00:02:28,000
Back to a time

28
00:02:28,000 --> 00:02:31,000
when almost nothing at all

29
00:02:31,000 --> 00:02:33,000
moved.

30
00:02:58,000 --> 00:02:59,000
The story of the horse

31
00:02:59,000 --> 00:03:03,000
and, in fact, the story of movement

32
00:03:03,000 --> 00:03:06,000
can be traced, incredibly,

33
00:03:06,000 --> 00:03:09,000
right to our own doorstep.

34
00:03:12,000 --> 00:03:14,000
This is a quintessential

35
00:03:14,000 --> 00:03:17,000
English landscape, a rural idyll of

36
00:03:17,000 --> 00:03:19,000
rolling hills and ancient woodlands.

37
00:03:23,000 --> 00:03:25,000
But I've got to tell you

38
00:03:25,000 --> 00:03:28,000
that I was standing here
just over half a billion years ago,

39
00:03:28,000 --> 00:03:30,000
the view would have been very
different. In fact, I wouldn't

40
00:03:30,000 --> 00:03:34,000
have been standing, I'd have been
submerged deep beneath the waves

41
00:03:34,000 --> 00:03:37,000
on the ocean floor.
And over millions of years,

42
00:03:37,000 --> 00:03:41,000
these rocks have been pushed up
and laid bare.

43
00:03:41,000 --> 00:03:44,000
And they tell us of
the history of that time,

44
00:03:44,000 --> 00:03:47,000
a history written in sand and silt.

45
00:03:47,000 --> 00:03:50,000
A history with some
fascinating clues.

46
00:03:54,000 --> 00:03:56,000
Hiding in plain sight

47
00:03:56,000 --> 00:03:59,000
are some of the most precious

48
00:03:59,000 --> 00:04:01,000
fossils on the planet.

49
00:04:03,000 --> 00:04:07,000
But millions of years of weathering
have warped these rocks,

50
00:04:07,000 --> 00:04:10,000
making them very hard to spot.

51
00:04:12,000 --> 00:04:14,000
Now, I did tell you
they were tricky to see,

52
00:04:14,000 --> 00:04:18,000
but there is one
right in front of me here.

53
00:04:18,000 --> 00:04:20,000
Just follow my fingers.

54
00:04:20,000 --> 00:04:22,000
It starts up here,

55
00:04:22,000 --> 00:04:25,000
then it arches down.

56
00:04:25,000 --> 00:04:27,000
You can see the ridges in the rock,

57
00:04:27,000 --> 00:04:29,000
particularly visible here.

58
00:04:29,000 --> 00:04:31,000
And then it comes up towards

59
00:04:31,000 --> 00:04:33,000
my shoulder, and this bit follows

60
00:04:33,000 --> 00:04:35,000
right up past my ear.

61
00:04:35,000 --> 00:04:37,000
These would have been made by fronds

62
00:04:37,000 --> 00:04:39,000
and they would have been attached

63
00:04:39,000 --> 00:04:40,000
around a centre point, which

64
00:04:40,000 --> 00:04:42,000
could have been somewhere here.

65
00:04:42,000 --> 00:04:45,000
This is a fossil of Bradgatia.

66
00:04:45,000 --> 00:04:48,000
And I know it doesn't
look like much, it might look like

67
00:04:48,000 --> 00:04:50,000
an old cabbage that's been pressed
in the rock to you,

68
00:04:50,000 --> 00:04:52,000
but it wasn't an old cabbage.

69
00:04:52,000 --> 00:04:54,000
It wasn't a plant at all.

70
00:04:54,000 --> 00:04:57,000
And this is a very,
very important fossil

71
00:04:57,000 --> 00:05:01,000
because it's a fossil
of one of the earliest animals

72
00:05:01,000 --> 00:05:03,000
that ever lived on Earth.

73
00:05:07,000 --> 00:05:10,000
{\an8}Over half a billion years ago,

74
00:05:10,000 --> 00:05:12,000
{\an8}this slab of rock...

75
00:05:16,000 --> 00:05:20,000
{\an8}..was home to some of
the very first animals.

76
00:05:26,000 --> 00:05:28,000
Theirs is a peaceful life.

77
00:05:36,000 --> 00:05:39,000
But this strange community

78
00:05:39,000 --> 00:05:41,000
does have a problem.

79
00:05:43,000 --> 00:05:46,000
When animals with large, complex

80
00:05:46,000 --> 00:05:48,000
bodies first evolved,

81
00:05:48,000 --> 00:05:50,000
they couldn't move.

82
00:05:51,000 --> 00:05:54,000
We call them sessile.

83
00:05:57,000 --> 00:05:59,000
Rooted to the ground,

84
00:05:59,000 --> 00:06:01,000
they must rely on the ocean

85
00:06:01,000 --> 00:06:03,000
to bring them what they need...

86
00:06:06,000 --> 00:06:07,000
..and they're powerless

87
00:06:07,000 --> 00:06:09,000
if it doesn't.

88
00:06:11,000 --> 00:06:13,000
Animal life could have remained

89
00:06:13,000 --> 00:06:16,000
stuck in this way forever,

90
00:06:16,000 --> 00:06:21,000
if it wasn't for
an evolutionary maverick.

91
00:06:24,000 --> 00:06:29,000
This is a cast of a fossil
that's about 565 million years old,

92
00:06:29,000 --> 00:06:33,000
which means it formed around the
same time as Bradgatia. Now,

93
00:06:33,000 --> 00:06:36,000
when the scientists first looked
at it, they were initially confused.

94
00:06:36,000 --> 00:06:38,000
It's quite difficult to see.

95
00:06:38,000 --> 00:06:41,000
Look, it starts up here
and it runs down here.

96
00:06:41,000 --> 00:06:44,000
It's almost as if someone
has been running their fingertip

97
00:06:44,000 --> 00:06:47,000
over some soft mud,

98
00:06:47,000 --> 00:06:49,000
and then it terminates down here.

99
00:06:49,000 --> 00:06:51,000
But if you look here,

100
00:06:51,000 --> 00:06:52,000
you can see there are a few little

101
00:06:52,000 --> 00:06:56,000
half-moon shapes. Now, the reason

102
00:06:56,000 --> 00:06:58,000
those scientists were initially
confused is they were probably

103
00:06:58,000 --> 00:07:02,000
looking for a fossil of an animal,
but this is not that.

104
00:07:02,000 --> 00:07:05,000
What it is is a fossil of something

105
00:07:05,000 --> 00:07:07,000
an animal left behind.

106
00:07:10,000 --> 00:07:14,000
Now, we think the story goes
something like this.

107
00:07:15,000 --> 00:07:20,000
In amongst the creatures stuck
to the seabed is a tiny animal,

108
00:07:20,000 --> 00:07:23,000
little more than a gelatinous blob.

109
00:07:25,000 --> 00:07:27,000
Like other animals here,

110
00:07:27,000 --> 00:07:28,000
it eats specks of food

111
00:07:28,000 --> 00:07:31,000
that drift on the ocean currents.

112
00:07:33,000 --> 00:07:35,000
But today,
the current has shifted...

113
00:07:37,000 --> 00:07:42,000
..and is now carrying the meagre
morsels just out of reach.

114
00:07:45,000 --> 00:07:48,000
Deprived of food, the only option

115
00:07:48,000 --> 00:07:50,000
for this stationary population

116
00:07:50,000 --> 00:07:52,000
is to sit and wait for their luck

117
00:07:52,000 --> 00:07:55,000
and the currents to change.

118
00:07:57,000 --> 00:08:00,000
But this animal is a pioneer.

119
00:08:06,000 --> 00:08:09,000
You see, this little blob

120
00:08:09,000 --> 00:08:11,000
can do something

121
00:08:11,000 --> 00:08:13,000
that the other animals can't.

122
00:08:25,000 --> 00:08:28,000
Abandon the safety of its home...

123
00:08:29,000 --> 00:08:31,000
..and move.

124
00:08:39,000 --> 00:08:41,000
With every heave...

125
00:08:42,000 --> 00:08:44,000
..it leaves a mark.

126
00:08:47,000 --> 00:08:51,000
Some of the earliest
animal tracks on the planet.

127
00:09:03,000 --> 00:09:07,000
One small step for this tiny blob,

128
00:09:07,000 --> 00:09:10,000
one giant leap for animalkind.

129
00:09:18,000 --> 00:09:22,000
Now, we'll never know exactly
when the first step was taken.

130
00:09:22,000 --> 00:09:25,000
We can presume that there were
some missteps -

131
00:09:25,000 --> 00:09:29,000
evolutionary stumbles, if you like -

132
00:09:29,000 --> 00:09:34,000
but that leap between being sessile
and motile was a profound one.

133
00:09:36,000 --> 00:09:38,000
Today...

134
00:09:41,000 --> 00:09:43,000
..whether they are finding food...

135
00:09:45,000 --> 00:09:46,000
..or mates...

136
00:09:48,000 --> 00:09:49,000
..or shelter...

137
00:09:51,000 --> 00:09:54,000
..our planet is an extravaganza

138
00:09:54,000 --> 00:09:56,000
of motion.

139
00:09:57,000 --> 00:10:01,000
An estimated 97% of animals

140
00:10:01,000 --> 00:10:05,000
moving in weird and wonderful ways.

141
00:10:06,000 --> 00:10:08,000
And none of this would be possible

142
00:10:08,000 --> 00:10:12,000
without one key ingredient.

143
00:10:19,000 --> 00:10:20,000
Muscle.

144
00:10:20,000 --> 00:10:21,000
HORSES WHINNY

145
00:10:25,000 --> 00:10:30,000
To understand just how
powerful muscle can be,

146
00:10:30,000 --> 00:10:33,000
we need a demonstration
from an expert.

147
00:10:33,000 --> 00:10:37,000
{\an8}I give you...the leech.

148
00:10:39,000 --> 00:10:42,000
I know, not everyone's
favourite animal,

149
00:10:42,000 --> 00:10:45,000
but it won't surprise you to know

150
00:10:45,000 --> 00:10:48,000
that I'm rather a fan of the leech.

151
00:10:48,000 --> 00:10:49,000
What are they?

152
00:10:49,000 --> 00:10:51,000
Well, they're a type of worm,

153
00:10:51,000 --> 00:10:53,000
and there are about 700 species

154
00:10:53,000 --> 00:10:55,000
in the world.

155
00:10:55,000 --> 00:10:58,000
Many, like this one, are parasitic.

156
00:10:58,000 --> 00:10:59,000
This is a medicinal leech,

157
00:10:59,000 --> 00:11:01,000
and it's been used by

158
00:11:01,000 --> 00:11:02,000
medical practitioners

159
00:11:02,000 --> 00:11:07,000
to suck the blood from humans
for 3,500 years.

160
00:11:07,000 --> 00:11:09,000
But I digress.

161
00:11:09,000 --> 00:11:10,000
What about its movement?

162
00:11:12,000 --> 00:11:14,000
Well, let's take a look at
their body.

163
00:11:14,000 --> 00:11:16,000
First thing you'll notice - no legs.

164
00:11:16,000 --> 00:11:18,000
Its body is made up almost

165
00:11:18,000 --> 00:11:20,000
entirely of muscles.

166
00:11:27,000 --> 00:11:31,000
{\an8}Muscles are built
from tiny cells called myocytes.

167
00:11:33,000 --> 00:11:36,000
We sometimes call them
muscle fibres.

168
00:11:38,000 --> 00:11:39,000
Within the leech,

169
00:11:39,000 --> 00:11:42,000
there are thousands,

170
00:11:42,000 --> 00:11:44,000
while an animal like the horse

171
00:11:44,000 --> 00:11:46,000
contains millions

172
00:11:46,000 --> 00:11:48,000
and millions of them.

173
00:11:48,000 --> 00:11:53,000
They work thanks to
their superpower -

174
00:11:53,000 --> 00:11:56,000
their ability to contract.

175
00:11:58,000 --> 00:12:01,000
Now, this leech's muscle cells

176
00:12:01,000 --> 00:12:03,000
are arranged in opposing sets.

177
00:12:03,000 --> 00:12:04,000
There are circular muscles

178
00:12:04,000 --> 00:12:06,000
that run around its body

179
00:12:06,000 --> 00:12:07,000
and longitudinal muscles,

180
00:12:07,000 --> 00:12:10,000
which run from one end to the other.

181
00:12:10,000 --> 00:12:13,000
So how exactly does it move? Well,

182
00:12:13,000 --> 00:12:14,000
I'll try and demonstrate that here.

183
00:12:14,000 --> 00:12:16,000
Come on.

184
00:12:21,000 --> 00:12:23,000
{\an8}It stretches forward

185
00:12:23,000 --> 00:12:26,000
{\an8}using those circular muscles,

186
00:12:26,000 --> 00:12:29,000
{\an8}and then contracts
its longitudinal muscles

187
00:12:29,000 --> 00:12:31,000
{\an8}and pulls itself forward...

188
00:12:33,000 --> 00:12:36,000
..so that it can slowly inch across

189
00:12:36,000 --> 00:12:38,000
the palm of my hand

190
00:12:38,000 --> 00:12:39,000
and down my fingers.

191
00:12:41,000 --> 00:12:43,000
{\an8}Something that I find

192
00:12:43,000 --> 00:12:45,000
{\an8}quite therapeutic.

193
00:12:46,000 --> 00:12:48,000
{\an8}You may consider it perverse,

194
00:12:48,000 --> 00:12:50,000
{\an8}but I'm rather enjoying this.

195
00:12:58,000 --> 00:13:01,000
Today, it's easy to take muscles
for granted...

196
00:13:03,000 --> 00:13:06,000
..but half a billion years ago,

197
00:13:06,000 --> 00:13:08,000
it was primitive muscle cells

198
00:13:08,000 --> 00:13:11,000
that turned contraction

199
00:13:11,000 --> 00:13:13,000
into action...

200
00:13:14,000 --> 00:13:17,000
..allowing pioneering animals

201
00:13:17,000 --> 00:13:20,000
to take a leap into the unknown.

202
00:13:25,000 --> 00:13:27,000
And the importance of this

203
00:13:27,000 --> 00:13:30,000
simply can't be underestimated,

204
00:13:30,000 --> 00:13:34,000
because from this point on,
movement would become

205
00:13:34,000 --> 00:13:39,000
one of the most powerful
driving forces in animal evolution.

206
00:13:41,000 --> 00:13:44,000
To reach the next step
in the story of the horse,

207
00:13:44,000 --> 00:13:46,000
we must hit fast-forward.

208
00:13:49,000 --> 00:13:52,000
For the next 40 million years,

209
00:13:52,000 --> 00:13:55,000
evolution gallops on.

210
00:14:02,000 --> 00:14:04,000
THUNDERCLAP

211
00:14:04,000 --> 00:14:06,000
Muscles stretch

212
00:14:06,000 --> 00:14:08,000
and shape animal life,

213
00:14:08,000 --> 00:14:11,000
and more and more time is spent...

214
00:14:15,000 --> 00:14:17,000
..on the go.

215
00:14:34,000 --> 00:14:39,000
{\an8}As they say, necessity
is the mother of invention,

216
00:14:39,000 --> 00:14:42,000
{\an8}and that was certainly the case
for animals experimenting

217
00:14:42,000 --> 00:14:45,000
with early locomotion.

218
00:14:48,000 --> 00:14:51,000
Down here, every trip across

219
00:14:51,000 --> 00:14:54,000
the seafloor demands energy,

220
00:14:54,000 --> 00:14:56,000
and lots of it.

221
00:15:00,000 --> 00:15:03,000
And to get from A to B,

222
00:15:03,000 --> 00:15:08,000
it's thought that ancestors of
the horse had evolved to use muscle

223
00:15:08,000 --> 00:15:11,000
in a totally new way. Incredibly,

224
00:15:11,000 --> 00:15:13,000
evidence of this

225
00:15:13,000 --> 00:15:16,000
can still be seen today.

226
00:15:16,000 --> 00:15:20,000
Inside this little plastic tub here,

227
00:15:20,000 --> 00:15:24,000
I have a beautiful animal.

228
00:15:26,000 --> 00:15:29,000
It's called a sea squirt,
or a tunicate,

229
00:15:29,000 --> 00:15:32,000
and it's a chordate, which means
we're actually related to this.

230
00:15:32,000 --> 00:15:35,000
I know it's difficult to believe,
but it's true.

231
00:15:35,000 --> 00:15:38,000
And the benefit of looking
at this particular species

232
00:15:38,000 --> 00:15:41,000
is that it's transparent.

233
00:15:41,000 --> 00:15:42,000
I can see inside it.

234
00:15:42,000 --> 00:15:45,000
And I can see a tube
running around its body,

235
00:15:45,000 --> 00:15:48,000
and that tube is filled full of

236
00:15:48,000 --> 00:15:51,000
oxygen, minerals and sugar.

237
00:15:53,000 --> 00:15:55,000
It's its blood.

238
00:15:55,000 --> 00:15:59,000
And that tube is contracting.

239
00:16:00,000 --> 00:16:04,000
Waves of muscle contraction are
pushing that blood around the body.

240
00:16:06,000 --> 00:16:08,000
Fundamentally,

241
00:16:08,000 --> 00:16:12,000
this is a simple heart.

242
00:16:12,000 --> 00:16:15,000
It's thought that systems like this

243
00:16:15,000 --> 00:16:18,000
allowed this ancestor of the horse

244
00:16:18,000 --> 00:16:20,000
to enjoy an active lifestyle.

245
00:16:30,000 --> 00:16:33,000
Just like the rest of its kind,

246
00:16:33,000 --> 00:16:34,000
nutrient-rich blood

247
00:16:34,000 --> 00:16:36,000
is being pumped through its body,

248
00:16:36,000 --> 00:16:40,000
making its muscles fizz with energy.

249
00:16:45,000 --> 00:16:47,000
Now, most of these creatures

250
00:16:47,000 --> 00:16:49,000
wouldn't win any races,

251
00:16:49,000 --> 00:16:50,000
spending their energy just

252
00:16:50,000 --> 00:16:53,000
wriggling along the seabed.

253
00:16:53,000 --> 00:16:56,000
But the ancestor of the horse

254
00:16:56,000 --> 00:17:00,000
seems to have had an extra boost,

255
00:17:00,000 --> 00:17:02,000
meaning...

256
00:17:06,000 --> 00:17:10,000
..it can swim harder, better,

257
00:17:10,000 --> 00:17:12,000
faster, stronger.

258
00:17:39,000 --> 00:17:42,000
Its remarkable athletic ability

259
00:17:42,000 --> 00:17:45,000
is thanks to an innovative use
of muscle

260
00:17:45,000 --> 00:17:49,000
that unlocked the full potential
of the heart.

261
00:17:58,000 --> 00:18:03,000
At this point, evolution all starts
to go a bit Frankenstein.

262
00:18:03,000 --> 00:18:05,000
You see, for any muscle to contract,

263
00:18:05,000 --> 00:18:07,000
it requires a stimulus, an order,

264
00:18:07,000 --> 00:18:11,000
and that typically comes
in the form of a tiny electric zap.

265
00:18:13,000 --> 00:18:14,000
{\an8}And it's thought that some

266
00:18:14,000 --> 00:18:16,000
{\an8}muscle cells inside some of

267
00:18:16,000 --> 00:18:19,000
{\an8}the earliest hearts took charge,

268
00:18:19,000 --> 00:18:22,000
{\an8}specialised and started to send out

269
00:18:22,000 --> 00:18:25,000
a series of rhythmic zaps.

270
00:18:25,000 --> 00:18:29,000
And all of the surrounding muscle
cells complied by contracting,

271
00:18:29,000 --> 00:18:33,000
generating a single powerful pulse.

272
00:18:35,000 --> 00:18:38,000
Now, these mutant zapping cells

273
00:18:38,000 --> 00:18:41,000
are called pacemakers,
and almost all animals have them.

274
00:18:41,000 --> 00:18:46,000
We have a single primary pacemaker
called the sinoatrial node.

275
00:18:46,000 --> 00:18:51,000
And as soon as those
ancient pacemakers began to pulse,

276
00:18:51,000 --> 00:18:54,000
they instigated a revolution.

277
00:18:58,000 --> 00:19:01,000
In the ancestor of the horse,

278
00:19:01,000 --> 00:19:04,000
those specialised pacemaker cells

279
00:19:04,000 --> 00:19:05,000
have now clustered together

280
00:19:05,000 --> 00:19:07,000
in a localised region...

281
00:19:07,000 --> 00:19:09,000
HEARTBEAT

282
00:19:11,000 --> 00:19:12,000
..giving its heart

283
00:19:12,000 --> 00:19:14,000
a more powerful beat.

284
00:19:20,000 --> 00:19:22,000
And over many generations...

285
00:19:24,000 --> 00:19:26,000
..the beat gets stronger.

286
00:19:30,000 --> 00:19:33,000
The muscle walls around
the pacemaker thicken...

287
00:19:36,000 --> 00:19:38,000
..chambers form...

288
00:19:40,000 --> 00:19:41,000
..and valves...

289
00:19:42,000 --> 00:19:44,000
..directing blood flow

290
00:19:44,000 --> 00:19:46,000
around the body...

291
00:19:51,000 --> 00:19:53,000
..becoming an iconic,

292
00:19:53,000 --> 00:19:55,000
life-sustaining organ.

293
00:19:58,000 --> 00:20:01,000
It's an ingenious use of muscle,

294
00:20:01,000 --> 00:20:05,000
one that transformed
animal locomotion.

295
00:20:07,000 --> 00:20:10,000
When hearts went from being
a simple pump to a more complex

296
00:20:10,000 --> 00:20:12,000
muscular mechanism,

297
00:20:12,000 --> 00:20:17,000
it led to a step change
in the evolution of movement.

298
00:20:17,000 --> 00:20:20,000
It allowed animals to become
bigger, stronger, faster.

299
00:20:20,000 --> 00:20:25,000
It allowed them to get off of
that seabed into the world above.

300
00:20:25,000 --> 00:20:27,000
And from that point on,

301
00:20:27,000 --> 00:20:30,000
life would become a slithering,

302
00:20:30,000 --> 00:20:32,000
crawling, walking, running,

303
00:20:32,000 --> 00:20:35,000
jumping and climbing adventure.

304
00:20:35,000 --> 00:20:37,000
Today...

305
00:20:38,000 --> 00:20:41,000
..across the globe,

306
00:20:41,000 --> 00:20:43,000
beating hearts are pumping oxygen

307
00:20:43,000 --> 00:20:45,000
through all sorts of bodies.

308
00:20:48,000 --> 00:20:51,000
Around 2.5 billion heartbeats

309
00:20:51,000 --> 00:20:53,000
will supply your muscles with

310
00:20:53,000 --> 00:20:55,000
the energy they need...

311
00:20:56,000 --> 00:20:59,000
..from your first breath

312
00:20:59,000 --> 00:21:02,000
till your last.

313
00:21:04,000 --> 00:21:08,000
It's a rhythm that connects us all

314
00:21:08,000 --> 00:21:11,000
to the first beats,

315
00:21:11,000 --> 00:21:14,000
over half a billion years ago.

316
00:21:18,000 --> 00:21:21,000
Time to take a leap forward...

317
00:21:22,000 --> 00:21:25,000
..as the descendants of those

318
00:21:25,000 --> 00:21:27,000
early swimmers get bigger,

319
00:21:27,000 --> 00:21:29,000
stronger and faster.

320
00:21:30,000 --> 00:21:33,000
They shapeshift through countless

321
00:21:33,000 --> 00:21:35,000
iterations until

322
00:21:35,000 --> 00:21:38,000
140 million years later...

323
00:21:41,000 --> 00:21:43,000
{\an8}..they have become...

324
00:21:44,000 --> 00:21:45,000
{\an8}..fish.

325
00:21:51,000 --> 00:21:55,000
This is an ocean
full of powerful bodies.

326
00:21:57,000 --> 00:22:00,000
But here, it's not how many muscles

327
00:22:00,000 --> 00:22:02,000
you've got that counts,

328
00:22:02,000 --> 00:22:04,000
it's how you use them.

329
00:22:08,000 --> 00:22:10,000
Now, there are many forces

330
00:22:10,000 --> 00:22:12,000
shaping evolution.

331
00:22:13,000 --> 00:22:16,000
The need to find food,
the need to find mates.

332
00:22:18,000 --> 00:22:22,000
But there are even greater forces
at play,

333
00:22:22,000 --> 00:22:24,000
those forces which shape
the entire universe.

334
00:22:24,000 --> 00:22:28,000
I'm talking about
the laws of physics.

335
00:22:28,000 --> 00:22:30,000
And when it comes to locomotion,

336
00:22:30,000 --> 00:22:33,000
harnessing these would be key.

337
00:22:33,000 --> 00:22:37,000
And fish have achieved that
with a remarkable innovation,

338
00:22:37,000 --> 00:22:40,000
something that's startling
in its simplicity,

339
00:22:40,000 --> 00:22:43,000
but significant in its importance.

340
00:22:47,000 --> 00:22:49,000
Something that, today,

341
00:22:49,000 --> 00:22:54,000
has helped make fish
the success story of our oceans.

342
00:22:57,000 --> 00:23:00,000
Attached to their
streamlined bodies,

343
00:23:00,000 --> 00:23:02,000
structures of flesh, cartilage

344
00:23:02,000 --> 00:23:04,000
and bone have evolved.

345
00:23:06,000 --> 00:23:08,000
Tools which their muscles

346
00:23:08,000 --> 00:23:13,000
can control, expanding the mechanics

347
00:23:13,000 --> 00:23:15,000
of movement available to them.

348
00:23:18,000 --> 00:23:20,000
They can be gliders,

349
00:23:20,000 --> 00:23:22,000
thrusters,

350
00:23:22,000 --> 00:23:24,000
rudders.

351
00:23:24,000 --> 00:23:28,000
I'm talking about fins.

352
00:23:34,000 --> 00:23:38,000
And 380 million years ago,

353
00:23:38,000 --> 00:23:40,000
the ancestor of the horse

354
00:23:40,000 --> 00:23:43,000
was a fish, with fins like this.

355
00:23:46,000 --> 00:23:49,000
You can see the fin here.

356
00:23:49,000 --> 00:23:50,000
But look at the base.

357
00:23:50,000 --> 00:23:52,000
It's made up of a series of

358
00:23:52,000 --> 00:23:55,000
robust, strong bones
which anchor it to the body,

359
00:23:55,000 --> 00:23:59,000
and they would have been covered
with powerful muscles.

360
00:23:59,000 --> 00:24:01,000
And it's this stalk, or lobe,

361
00:24:01,000 --> 00:24:04,000
which gives this group of fishes
their name.

362
00:24:04,000 --> 00:24:08,000
We call them the lobe-finned fishes.

363
00:24:08,000 --> 00:24:11,000
Now, I've got to be honest with you,
in the open ocean,

364
00:24:11,000 --> 00:24:14,000
this set-up probably didn't
confer them with much of

365
00:24:14,000 --> 00:24:15,000
a competitive advantage,

366
00:24:15,000 --> 00:24:17,000
but under certain circumstances,

367
00:24:17,000 --> 00:24:20,000
it proved to be a real bonus.

368
00:24:30,000 --> 00:24:32,000
This is Onychodus...

369
00:24:34,000 --> 00:24:35,000
..an ancient predator

370
00:24:35,000 --> 00:24:37,000
as big as a crocodile...

371
00:24:39,000 --> 00:24:42,000
..with muscular lobed fins.

372
00:24:46,000 --> 00:24:48,000
Now, its size and weight

373
00:24:48,000 --> 00:24:51,000
should be an advantage,

374
00:24:51,000 --> 00:24:54,000
making Onychodus a formidable foe.

375
00:24:56,000 --> 00:24:57,000
But when it swims...

376
00:25:00,000 --> 00:25:03,000
..the water around it is churned up,

377
00:25:03,000 --> 00:25:04,000
giving the game away.

378
00:25:10,000 --> 00:25:14,000
So how does this ocean giant
catch its dinner?

379
00:25:20,000 --> 00:25:23,000
The answer lies in those lobed fins.

380
00:25:23,000 --> 00:25:27,000
Inside there is a tool
that's just begging to be used,

381
00:25:27,000 --> 00:25:30,000
a tool with enormous potential.

382
00:25:30,000 --> 00:25:32,000
I'm talking about a lever.

383
00:25:38,000 --> 00:25:41,000
You see, the relatively small
distance travelled by my hand

384
00:25:41,000 --> 00:25:47,000
and arm here is magnified out there
at the tip of the oar,

385
00:25:47,000 --> 00:25:49,000
which is moving far further.

386
00:25:56,000 --> 00:25:59,000
{\an8}When it comes to
generating movement,

387
00:25:59,000 --> 00:26:01,000
{\an8}muscles are fantastic,

388
00:26:01,000 --> 00:26:03,000
{\an8}but they do have their limitations.

389
00:26:06,000 --> 00:26:11,000
The lever
is life's great multiplier.

390
00:26:16,000 --> 00:26:19,000
Look, a small amount of force

391
00:26:19,000 --> 00:26:22,000
applied by my arms in the boat

392
00:26:22,000 --> 00:26:24,000
is transferred to the tip of
those oars,

393
00:26:24,000 --> 00:26:29,000
and it allows me to propel
the boat forward.

394
00:26:29,000 --> 00:26:32,000
Not exactly with Olympic prowess,
I have to confess,

395
00:26:32,000 --> 00:26:35,000
but with a degree of efficiency.

396
00:26:41,000 --> 00:26:44,000
And it's thought this same principle

397
00:26:44,000 --> 00:26:46,000
helped this hulking fish

398
00:26:46,000 --> 00:26:48,000
to move with incredible delicacy...

399
00:26:50,000 --> 00:26:52,000
..by doing something

400
00:26:52,000 --> 00:26:54,000
very unfish-like.

401
00:26:59,000 --> 00:27:02,000
Using four of its lobed fins,

402
00:27:02,000 --> 00:27:05,000
along with the physics of levers,

403
00:27:05,000 --> 00:27:08,000
Onychodus turns minimum effort

404
00:27:08,000 --> 00:27:10,000
into maximum movement

405
00:27:10,000 --> 00:27:12,000
and propels itself

406
00:27:12,000 --> 00:27:16,000
stealthily across the seafloor.

407
00:27:30,000 --> 00:27:32,000
Swapping swimming for walking,

408
00:27:32,000 --> 00:27:38,000
it saves its energy for one final,

409
00:27:38,000 --> 00:27:40,000
powerful thrust.

410
00:27:47,000 --> 00:27:51,000
Thanks to its four lobed fins,

411
00:27:51,000 --> 00:27:54,000
Onychodus is a master of the ambush.

412
00:28:00,000 --> 00:28:03,000
So, with skills like these,

413
00:28:03,000 --> 00:28:07,000
you'd expect there to be plenty
of lobe-finned fish in the sea,

414
00:28:07,000 --> 00:28:13,000
{\an8}but today, they have almost entirely
vanished from our waters.

415
00:28:19,000 --> 00:28:21,000
My goodness!

416
00:28:22,000 --> 00:28:25,000
That was a bit of a workout.

417
00:28:25,000 --> 00:28:28,000
Now, look, levers
are very useful in water,

418
00:28:28,000 --> 00:28:32,000
but they could become
even more useful somewhere else.

419
00:28:36,000 --> 00:28:38,000
When fish like Onychodus begin

420
00:28:38,000 --> 00:28:41,000
to use their lobed fins to walk,

421
00:28:41,000 --> 00:28:43,000
rather than swim,

422
00:28:43,000 --> 00:28:46,000
they set off a chain reaction.

423
00:28:52,000 --> 00:28:55,000
Over millions of years...

424
00:28:56,000 --> 00:28:58,000
..the thick bridge of bones

425
00:28:58,000 --> 00:29:01,000
inside those four fins lengthen...

426
00:29:04,000 --> 00:29:06,000
..and the muscles surrounding them

427
00:29:06,000 --> 00:29:08,000
shift and alter...

428
00:29:10,000 --> 00:29:14,000
..creating strong, tough appendages.

429
00:29:15,000 --> 00:29:18,000
No longer fins at all...

430
00:29:20,000 --> 00:29:23,000
..but four levered limbs.

431
00:29:25,000 --> 00:29:29,000
This was the birth of the tetrapods.

432
00:29:31,000 --> 00:29:33,000
And today, there are more than

433
00:29:33,000 --> 00:29:36,000
30,000 species,

434
00:29:36,000 --> 00:29:37,000
inhabiting every continent.

435
00:29:45,000 --> 00:29:48,000
A diverse supergroup,

436
00:29:48,000 --> 00:29:50,000
all descendants of those fish

437
00:29:50,000 --> 00:29:52,000
{\an8}with four lobed fins,

438
00:29:52,000 --> 00:29:55,000
are now putting them to use

439
00:29:55,000 --> 00:29:57,000
in very different ways.

440
00:29:58,000 --> 00:30:01,000
Including the horse.

441
00:30:07,000 --> 00:30:09,000
For many tetrapods today,

442
00:30:09,000 --> 00:30:13,000
moving on land is second nature,

443
00:30:13,000 --> 00:30:17,000
but for their ancestors
crawling out of the sea,

444
00:30:17,000 --> 00:30:19,000
it was a very different story.

445
00:30:22,000 --> 00:30:25,000
Moving from one ecosystem

446
00:30:25,000 --> 00:30:27,000
to another
which is completely different,

447
00:30:27,000 --> 00:30:33,000
requires a painfully slow process
of adaptation.

448
00:30:33,000 --> 00:30:35,000
But the creatures that were making
that transition

449
00:30:35,000 --> 00:30:38,000
looked a little bit like this.

450
00:30:42,000 --> 00:30:44,000
Oh, yes.

451
00:30:46,000 --> 00:30:49,000
Look at that.

452
00:30:49,000 --> 00:30:50,000
That's special.

453
00:30:50,000 --> 00:30:53,000
One of nature's jewels.

454
00:30:53,000 --> 00:30:55,000
Absolutely beautiful.

455
00:30:55,000 --> 00:30:58,000
This is a marbled newt.

456
00:30:58,000 --> 00:31:02,000
You see how it got its name,
with that marbling running down

457
00:31:02,000 --> 00:31:04,000
its back there.

458
00:31:05,000 --> 00:31:07,000
It's an amphibian.

459
00:31:07,000 --> 00:31:11,000
It spends its spring in ponds
going through its breeding cycle

460
00:31:11,000 --> 00:31:13,000
and then at the end of summer,
it emerges onto land,

461
00:31:13,000 --> 00:31:15,000
where it spends
the rest of the year.

462
00:31:15,000 --> 00:31:20,000
But, of course, it's gone through
millions of years of evolution,

463
00:31:20,000 --> 00:31:23,000
which allow it to exploit
the best of both worlds -

464
00:31:23,000 --> 00:31:26,000
the wet and the dry.

465
00:31:26,000 --> 00:31:28,000
But what about its movement?

466
00:31:28,000 --> 00:31:31,000
Well, in the ponds, it's
a fairly good swimmer, to be fair.

467
00:31:31,000 --> 00:31:33,000
What about on land?

468
00:31:33,000 --> 00:31:35,000
Let's give it a go.

469
00:31:44,000 --> 00:31:47,000
They're tentative, they're slow,

470
00:31:47,000 --> 00:31:49,000
they're laborious,
they're calculated.

471
00:31:49,000 --> 00:31:52,000
Their little bodies
bending from side to side,

472
00:31:52,000 --> 00:31:54,000
as they rather lethargically

473
00:31:54,000 --> 00:31:56,000
move through the environment.

474
00:31:57,000 --> 00:32:00,000
I've never seen a newt
galloping or frolicking.

475
00:32:00,000 --> 00:32:02,000
I'm never going to. But this does

476
00:32:02,000 --> 00:32:05,000
tell us something very important.

477
00:32:07,000 --> 00:32:10,000
Movement on land is hard.

478
00:32:10,000 --> 00:32:11,000
Very hard.

479
00:32:18,000 --> 00:32:22,000
This newt can get away with having

480
00:32:22,000 --> 00:32:25,000
four left feet because in a pinch,

481
00:32:25,000 --> 00:32:28,000
it can retreat to a habitat

482
00:32:28,000 --> 00:32:30,000
it finds easier to negotiate.

483
00:32:37,000 --> 00:32:41,000
But 350 million years ago,

484
00:32:41,000 --> 00:32:43,000
if the ancestors of the horse

485
00:32:43,000 --> 00:32:44,000
were to pursue a life

486
00:32:44,000 --> 00:32:47,000
solely on solid ground,

487
00:32:47,000 --> 00:32:51,000
they would need to be
far more coordinated.

488
00:32:51,000 --> 00:32:56,000
And the answer to their coordination
conundrum came, once again,

489
00:32:56,000 --> 00:32:58,000
with an evolutionary innovation

490
00:32:58,000 --> 00:33:02,000
from the ever-adaptable muscle.

491
00:33:02,000 --> 00:33:06,000
Inside almost every muscle
in my body,

492
00:33:06,000 --> 00:33:09,000
I have something called
a stretch sensor.

493
00:33:09,000 --> 00:33:13,000
And stretch sensors
are highly specialised muscle fibres

494
00:33:13,000 --> 00:33:17,000
that are constantly monitoring
how and when

495
00:33:17,000 --> 00:33:19,000
those muscles are moving.

496
00:33:19,000 --> 00:33:24,000
The key thing is that they are all
linked together in a complex web,

497
00:33:24,000 --> 00:33:27,000
so each individual muscle knows

498
00:33:27,000 --> 00:33:30,000
exactly when every...other muscle

499
00:33:30,000 --> 00:33:34,000
is moving. Now, despite the fact
that this is an incredibly

500
00:33:34,000 --> 00:33:39,000
complicated system, I bet that
you've never even thought about it,

501
00:33:39,000 --> 00:33:41,000
and that's because
you don't have to,

502
00:33:41,000 --> 00:33:43,000
despite the fact that it's crucial

503
00:33:43,000 --> 00:33:46,000
for every single move that we make.

504
00:33:55,000 --> 00:33:59,000
Tiny stretch sensors allow
the muscles to communicate

505
00:33:59,000 --> 00:34:02,000
with the central nervous system,

506
00:34:02,000 --> 00:34:05,000
giving us and most living tetrapods

507
00:34:05,000 --> 00:34:07,000
the ability to co-ordinate movement

508
00:34:07,000 --> 00:34:09,000
with astonishing precision.

509
00:34:09,000 --> 00:34:13,000
Often, faster than you can think.

510
00:34:20,000 --> 00:34:21,000
Look at that.

511
00:34:28,000 --> 00:34:29,000
Just look at the legs there.

512
00:34:29,000 --> 00:34:33,000
Every part of them
is moving independently,

513
00:34:33,000 --> 00:34:35,000
in isolation, at the same time.

514
00:34:35,000 --> 00:34:38,000
And then the weight -

515
00:34:38,000 --> 00:34:42,000
that's got to be balanced
between all four feet.

516
00:34:42,000 --> 00:34:44,000
And running down those legs -

517
00:34:44,000 --> 00:34:47,000
just going to speed it up,
look at that -

518
00:34:47,000 --> 00:34:50,000
are ripples of muscles.

519
00:34:50,000 --> 00:34:52,000
That's the glutes, that's the quads,

520
00:34:52,000 --> 00:34:56,000
that's the hamstrings,
all working in unison.

521
00:34:59,000 --> 00:35:02,000
Without these little gizmos,

522
00:35:02,000 --> 00:35:04,000
these stretch sensors
hiding in muscles

523
00:35:04,000 --> 00:35:07,000
and the complex network
that joins them all together,

524
00:35:07,000 --> 00:35:11,000
animals with bodies like this simply
would not have been able to evolve.

525
00:35:15,000 --> 00:35:18,000
It was down to this innovation

526
00:35:18,000 --> 00:35:19,000
that animal bodies could become

527
00:35:19,000 --> 00:35:22,000
radically more coordinated,

528
00:35:22,000 --> 00:35:25,000
and those tiny little bones,
once hidden in those fish's fins,

529
00:35:25,000 --> 00:35:27,000
could really come into their own.

530
00:35:29,000 --> 00:35:33,000
Those fully terrestrial animals

531
00:35:33,000 --> 00:35:38,000
could put one foot in front of
the other with extreme precision...

532
00:35:40,000 --> 00:35:42,000
..and this was a game-changer.

533
00:35:47,000 --> 00:35:50,000
Time for us to motor on.

534
00:35:53,000 --> 00:35:56,000
Over the next 300 million years,

535
00:35:56,000 --> 00:35:59,000
the tetrapods
scattered across the Earth.

536
00:36:05,000 --> 00:36:08,000
Whilst life faced
some cosmic curveballs...

537
00:36:10,000 --> 00:36:12,000
..it was never fully derailed.

538
00:36:14,000 --> 00:36:16,000
And evolution carried on...

539
00:36:19,000 --> 00:36:21,000
..tumbling us...

540
00:36:24,000 --> 00:36:26,000
{\an8}..into a new world...

541
00:36:30,000 --> 00:36:32,000
{\an8}..where the way you move...

542
00:36:33,000 --> 00:36:37,000
..can be a matter of life

543
00:36:37,000 --> 00:36:39,000
and death.

544
00:36:44,000 --> 00:36:46,000
This is Phenacodus.

545
00:36:54,000 --> 00:36:57,000
Life looks pretty serene,

546
00:36:57,000 --> 00:37:00,000
but Phenacodus must constantly

547
00:37:00,000 --> 00:37:04,000
be on guard, because this world

548
00:37:04,000 --> 00:37:06,000
is full of expert movers...

549
00:37:06,000 --> 00:37:08,000
BRANCH SNAPS

550
00:37:08,000 --> 00:37:09,000
..whose bodies...

551
00:37:11,000 --> 00:37:14,000
..have evolved for the chase.

552
00:37:18,000 --> 00:37:20,000
When the hunt is on...
GROWLING

553
00:37:20,000 --> 00:37:23,000
..surging adrenaline,
thumping hearts

554
00:37:23,000 --> 00:37:26,000
and straining muscles
will only take you so far.

555
00:37:31,000 --> 00:37:33,000
Faced with a situation it can't

556
00:37:33,000 --> 00:37:34,000
muscle its way out of...

557
00:37:36,000 --> 00:37:38,000
..the secret to Phenacodus's

558
00:37:38,000 --> 00:37:43,000
survival lies in its feet.

559
00:37:47,000 --> 00:37:50,000
Come on, Siddy! Nance, come on!

560
00:37:50,000 --> 00:37:51,000
DOG BARKS

561
00:37:56,000 --> 00:38:00,000
Do you know, sometimes, people say,
"Why poodles?

562
00:38:00,000 --> 00:38:03,000
"Why poodles?" they say.
And I facetiously reply,

563
00:38:03,000 --> 00:38:05,000
"Are there other breeds of dog?"

564
00:38:05,000 --> 00:38:06,000
I mean, look at them.

565
00:38:06,000 --> 00:38:09,000
Boundless energy, incredibly loyal,

566
00:38:09,000 --> 00:38:11,000
and they can also help us

567
00:38:11,000 --> 00:38:14,000
with an important part of our story.

568
00:38:14,000 --> 00:38:15,000
You see, hidden beneath

569
00:38:15,000 --> 00:38:18,000
this curly fur here is a crucial

570
00:38:18,000 --> 00:38:21,000
step change in evolution.

571
00:38:21,000 --> 00:38:24,000
Now, I don't need to tell you
about my foot and leg,

572
00:38:24,000 --> 00:38:26,000
you've got your own.
Starts off at the toe,

573
00:38:26,000 --> 00:38:28,000
goes across the foot to the ankle,

574
00:38:28,000 --> 00:38:32,000
then you've got the shin,
the knee, the thigh.

575
00:38:32,000 --> 00:38:34,000
{\an8}We put our feet down

576
00:38:34,000 --> 00:38:35,000
{\an8}onto the ground, we plant them

577
00:38:35,000 --> 00:38:38,000
{\an8}flat on the ground like that.

578
00:38:38,000 --> 00:38:39,000
{\an8}We're what we call

579
00:38:39,000 --> 00:38:43,000
plantigrade animals. It's quite
an efficient way of walking.

580
00:38:43,000 --> 00:38:46,000
Nancy, on the other hand,
is altogether different.

581
00:38:46,000 --> 00:38:48,000
Let's take a look at her
back leg here.

582
00:38:48,000 --> 00:38:51,000
{\an8}You see, her toes stretch

583
00:38:51,000 --> 00:38:52,000
{\an8}from here to here.

584
00:38:52,000 --> 00:38:54,000
{\an8}The rest of her foot bones

585
00:38:54,000 --> 00:38:56,000
{\an8}all the way up to here, which looks

586
00:38:56,000 --> 00:38:57,000
{\an8}like a backward-pointing knee,

587
00:38:57,000 --> 00:39:00,000
{\an8}but this is, in fact, her ankle.

588
00:39:00,000 --> 00:39:02,000
Her knee is all the way

589
00:39:02,000 --> 00:39:04,000
up here. So Nancy

590
00:39:04,000 --> 00:39:06,000
{\an8}is effectively standing up

591
00:39:06,000 --> 00:39:09,000
{\an8}on her toe bones.

592
00:39:09,000 --> 00:39:13,000
She's a digitigrade animal,

593
00:39:13,000 --> 00:39:15,000
and that's altogether different.

594
00:39:15,000 --> 00:39:18,000
It means that you move in
a very different way, doesn't it?

595
00:39:18,000 --> 00:39:19,000
Shall we show them?

596
00:39:19,000 --> 00:39:22,000
Come on, let's go. Come on.

597
00:39:30,000 --> 00:39:33,000
Right, Sid, Nancy.

598
00:39:33,000 --> 00:39:35,000
Let's see them in action.

599
00:39:35,000 --> 00:39:36,000
{\an8}BARKING

600
00:39:41,000 --> 00:39:44,000
{\an8}BARKING
Woo-hoo-hoo!

601
00:39:44,000 --> 00:39:46,000
Look at them go! You see,

602
00:39:46,000 --> 00:39:50,000
this change in anatomy
allows the leg to become longer,

603
00:39:50,000 --> 00:39:52,000
the stride to become longer,

604
00:39:52,000 --> 00:39:55,000
and more efficient use of
all of that elastic energy

605
00:39:55,000 --> 00:39:58,000
stored in the muscles and tendons

606
00:39:58,000 --> 00:40:00,000
above their ankle.

607
00:40:00,000 --> 00:40:01,000
Look at that!

608
00:40:01,000 --> 00:40:03,000
{\an8}Bouncing about.

609
00:40:03,000 --> 00:40:04,000
{\an8}BARKING

610
00:40:04,000 --> 00:40:08,000
Alacrity, agility.

611
00:40:08,000 --> 00:40:10,000
Critically, speed.

612
00:40:10,000 --> 00:40:13,000
That is a happy poodle.

613
00:40:14,000 --> 00:40:17,000
And, you know, this adaptation
has occurred a number of times

614
00:40:17,000 --> 00:40:21,000
in terrestrial animals.
But having said that,

615
00:40:21,000 --> 00:40:24,000
if you really want to be a creature
living life in the fast lane,

616
00:40:24,000 --> 00:40:29,000
evolution can offer you
one more gear.

617
00:40:29,000 --> 00:40:31,000
Siddy, Nance, come on! Come on!

618
00:40:34,000 --> 00:40:38,000
When it comes to speed and
efficiency, plantigrade -

619
00:40:38,000 --> 00:40:41,000
that's us -
will get you from A to B.

620
00:40:41,000 --> 00:40:44,000
Digitigrade - like my dogs -

621
00:40:44,000 --> 00:40:46,000
ups the revs.

622
00:40:48,000 --> 00:40:51,000
But 56 million years ago,

623
00:40:51,000 --> 00:40:55,000
Phenacodus was
on the verge of something new.

624
00:40:56,000 --> 00:41:00,000
Not just bouncing
on the balls of its feet,

625
00:41:00,000 --> 00:41:05,000
but pushing off from the
very tips of its toes...

626
00:41:08,000 --> 00:41:11,000
..lengthening its stride
even further.

627
00:41:12,000 --> 00:41:16,000
So future generations
take the concept...

628
00:41:17,000 --> 00:41:18,000
..and run with it.

629
00:41:23,000 --> 00:41:25,000
As bones elongate

630
00:41:25,000 --> 00:41:27,000
and muscles bulk up...

631
00:41:28,000 --> 00:41:30,000
..they spend more

632
00:41:30,000 --> 00:41:32,000
and more time on tiptoe...

633
00:41:35,000 --> 00:41:37,000
..and in the process...

634
00:41:38,000 --> 00:41:40,000
..find the most efficiency

635
00:41:40,000 --> 00:41:42,000
in trading many toes

636
00:41:42,000 --> 00:41:45,000
for one large,

637
00:41:45,000 --> 00:41:47,000
powerful shock absorber.

638
00:41:52,000 --> 00:41:54,000
Look at this.

639
00:41:54,000 --> 00:41:57,000
This is clearly a cast

640
00:41:57,000 --> 00:41:59,000
of a fossil of a hoof.

641
00:41:59,000 --> 00:42:03,000
A hoof at the end of
a very long leg.

642
00:42:03,000 --> 00:42:07,000
A leg that's clearly
all about movement.

643
00:42:07,000 --> 00:42:11,000
A leg, though, that is surprisingly
different than ours.

644
00:42:11,000 --> 00:42:13,000
You see, essentially, it's foot

645
00:42:13,000 --> 00:42:15,000
all the way from here to here.

646
00:42:15,000 --> 00:42:18,000
This is the equivalent of our ankle.

647
00:42:18,000 --> 00:42:20,000
The bone here would be like those
in the sole of our foot.

648
00:42:20,000 --> 00:42:22,000
And down here,

649
00:42:22,000 --> 00:42:26,000
it's balancing on a single tiptoe.

650
00:42:26,000 --> 00:42:29,000
The hoof itself
would have been made of keratin,

651
00:42:29,000 --> 00:42:31,000
just like our fingernail.

652
00:42:31,000 --> 00:42:33,000
And also, what's interesting
is at the other end,

653
00:42:33,000 --> 00:42:36,000
the front legs weren't attached
to the skeleton.

654
00:42:36,000 --> 00:42:37,000
They were embedded

655
00:42:37,000 --> 00:42:40,000
in a heavy mass of powerful muscle,

656
00:42:40,000 --> 00:42:45,000
and this gave it the capacity
for a greater stride.

657
00:42:45,000 --> 00:42:47,000
You see this groove here?

658
00:42:47,000 --> 00:42:49,000
Running down here
would have been a tendon,

659
00:42:49,000 --> 00:42:51,000
perhaps half a metre long,

660
00:42:51,000 --> 00:42:54,000
a giant elastic band.

661
00:42:54,000 --> 00:42:57,000
But it is a leg with compromises.

662
00:42:57,000 --> 00:43:00,000
I mean, you can't pick anything up
with a hoof,

663
00:43:00,000 --> 00:43:01,000
you can't manipulate anything.

664
00:43:01,000 --> 00:43:04,000
It's lost all dexterity,

665
00:43:04,000 --> 00:43:06,000
at the expense of speed.

666
00:43:08,000 --> 00:43:12,000
This three-million-year-old hoof

667
00:43:12,000 --> 00:43:15,000
tells us of the arrival

668
00:43:15,000 --> 00:43:18,000
of a new group of animals.

669
00:43:18,000 --> 00:43:22,000
Animals we call Equus.

670
00:43:34,000 --> 00:43:36,000
{\an8}These single-hoofed mammals

671
00:43:36,000 --> 00:43:39,000
{\an8}first evolved on the plains of
North America...

672
00:43:41,000 --> 00:43:44,000
..before spreading across the globe.

673
00:43:46,000 --> 00:43:49,000
Among them

674
00:43:49,000 --> 00:43:52,000
was one remarkable species.

675
00:43:54,000 --> 00:43:57,000
{\an8}Equus ferus.

676
00:44:00,000 --> 00:44:04,000
Known to you and I as the horse.

677
00:44:10,000 --> 00:44:12,000
{\an8}Its body shaped

678
00:44:12,000 --> 00:44:14,000
{\an8}generation after generation...

679
00:44:19,000 --> 00:44:22,000
{\an8}..by the evolutionary drive to move.

680
00:44:25,000 --> 00:44:28,000
700 muscles, passed down

681
00:44:28,000 --> 00:44:31,000
over half a billion years,

682
00:44:31,000 --> 00:44:33,000
from a pioneer
who changed the world.

683
00:44:33,000 --> 00:44:37,000
A huge heart, with an ancient beat,

684
00:44:37,000 --> 00:44:40,000
that began deep beneath the waves.

685
00:44:40,000 --> 00:44:43,000
Long levered limbs

686
00:44:43,000 --> 00:44:46,000
that once helped a fish to walk...

687
00:44:48,000 --> 00:44:50,000
..and four large hooves,

688
00:44:50,000 --> 00:44:52,000
the legacy of ancestors

689
00:44:52,000 --> 00:44:56,000
who had to run for their lives.

690
00:44:57,000 --> 00:45:00,000
But there's one final twist

691
00:45:00,000 --> 00:45:03,000
in the story of the horse,

692
00:45:03,000 --> 00:45:05,000
because Equus ferus

693
00:45:05,000 --> 00:45:07,000
was about to encounter

694
00:45:07,000 --> 00:45:09,000
a new force of evolution.

695
00:45:17,000 --> 00:45:19,000
Another species

696
00:45:19,000 --> 00:45:22,000
on an evolutionary
journey of its own.

697
00:45:22,000 --> 00:45:24,000
A bipedal tetrapod,

698
00:45:24,000 --> 00:45:27,000
with opposable thumbs,

699
00:45:27,000 --> 00:45:31,000
and an overinflated
sense of self-worth.

700
00:45:48,000 --> 00:45:51,000
4,000 years ago, Homo sapiens -

701
00:45:51,000 --> 00:45:53,000
that's us - inhabited

702
00:45:53,000 --> 00:45:55,000
much of the planet.

703
00:45:55,000 --> 00:45:56,000
HORSE WHINNIES

704
00:45:56,000 --> 00:45:59,000
We had city states and agriculture.

705
00:45:59,000 --> 00:46:02,000
Empires were beginning to grow.

706
00:46:04,000 --> 00:46:07,000
And at this time,
in Europe and Asia,

707
00:46:07,000 --> 00:46:09,000
we begin to see evidence

708
00:46:09,000 --> 00:46:11,000
of a growing relationship

709
00:46:11,000 --> 00:46:13,000
between horses

710
00:46:13,000 --> 00:46:15,000
and humans.

711
00:46:18,000 --> 00:46:22,000
Now, no-one is exactly sure
how the first horse was tamed.

712
00:46:22,000 --> 00:46:25,000
Maybe someone caught
one of those wild horses,

713
00:46:25,000 --> 00:46:28,000
took it into captivity,
gave it shelter, food,

714
00:46:28,000 --> 00:46:32,000
cared for it, loved it
and trained it.

715
00:46:32,000 --> 00:46:35,000
But what we do know is that
in pretty short time,

716
00:46:35,000 --> 00:46:39,000
we took these strong, efficient,
powerful animals

717
00:46:39,000 --> 00:46:43,000
and turned them into
our perfect companions.

718
00:46:43,000 --> 00:46:46,000
And, you know,
we didn't just tame them.

719
00:46:46,000 --> 00:46:49,000
Over generation after generation,
we bred them,

720
00:46:49,000 --> 00:46:52,000
choosing those characteristics
which favoured the way

721
00:46:52,000 --> 00:46:55,000
we wanted horses to be.

722
00:46:55,000 --> 00:46:58,000
So in the end,
we took the wild horse

723
00:46:58,000 --> 00:47:01,000
and we turned it into the workhorse.

724
00:47:14,000 --> 00:47:16,000
We chose the strongest.

725
00:47:18,000 --> 00:47:19,000
We chose the most powerful.

726
00:47:21,000 --> 00:47:24,000
But we also chose the friendliest,

727
00:47:24,000 --> 00:47:26,000
the most amenable.

728
00:47:29,000 --> 00:47:32,000
And for better or for worse,

729
00:47:32,000 --> 00:47:34,000
over the generations,

730
00:47:34,000 --> 00:47:36,000
the horse was altered.

731
00:47:40,000 --> 00:47:42,000
The ancestors of the modern horse

732
00:47:42,000 --> 00:47:43,000
were a pretty wild bunch.

733
00:47:45,000 --> 00:47:47,000
Diverse not only in terms of
their physical appearance,

734
00:47:47,000 --> 00:47:50,000
but also, their genetic make-up.

735
00:47:50,000 --> 00:47:52,000
And about 4,000 years ago,

736
00:47:52,000 --> 00:47:55,000
we see two gene variants appear.

737
00:47:55,000 --> 00:47:56,000
HORSE WHINNIES

738
00:47:56,000 --> 00:47:59,000
Now, one of those appears to
make them less aggressive,

739
00:47:59,000 --> 00:48:01,000
more manageable.

740
00:48:03,000 --> 00:48:06,000
And the other, which appears
to give them a stronger back,

741
00:48:06,000 --> 00:48:09,000
making them easier to ride.

742
00:48:09,000 --> 00:48:11,000
Now, what's interesting is that

743
00:48:11,000 --> 00:48:13,000
within the space of
just a few hundred years,

744
00:48:13,000 --> 00:48:15,000
we'd spread those gene variants

745
00:48:15,000 --> 00:48:18,000
throughout the population.

746
00:48:20,000 --> 00:48:22,000
The wild horse was effectively gone.

747
00:48:22,000 --> 00:48:25,000
We had one global species,

748
00:48:25,000 --> 00:48:28,000
selected by humans.

749
00:48:28,000 --> 00:48:29,000
You.

750
00:48:29,000 --> 00:48:33,000
Yes. I know.

751
00:48:33,000 --> 00:48:35,000
It wasn't my fault.

752
00:48:35,000 --> 00:48:36,000
I wasn't around then.

753
00:48:48,000 --> 00:48:52,000
Today, the horse
goes by a new name.

754
00:48:53,000 --> 00:48:57,000
Equus ferus caballus.

755
00:48:57,000 --> 00:48:59,000
The domestic horse.

756
00:49:01,000 --> 00:49:03,000
Our relationship is a special one.

757
00:49:05,000 --> 00:49:07,000
Together, we've travelled to

758
00:49:07,000 --> 00:49:09,000
every corner of the globe.

759
00:49:11,000 --> 00:49:12,000
Step by step...

760
00:49:14,000 --> 00:49:15,000
..and side by side.

761
00:49:21,000 --> 00:49:23,000
We often think of evolution

762
00:49:23,000 --> 00:49:25,000
as a battle between species,

763
00:49:25,000 --> 00:49:27,000
a game of winners and losers,

764
00:49:27,000 --> 00:49:29,000
a game of survival of the fittest.

765
00:49:29,000 --> 00:49:32,000
But very occasionally,
species come together

766
00:49:32,000 --> 00:49:36,000
and the result is greater than
the sum of their parts.

767
00:49:36,000 --> 00:49:40,000
Now, there's no doubt we played
a hugely instrumental role

768
00:49:40,000 --> 00:49:42,000
in the evolution of the horse,

769
00:49:42,000 --> 00:49:45,000
but then the horse has had
an impact on us too,

770
00:49:45,000 --> 00:49:50,000
because without this remarkable
animal as our greatest partner,

771
00:49:50,000 --> 00:49:54,000
we simply wouldn't be
the species we are today.

772
00:49:58,000 --> 00:50:01,000
The horse's evolutionary journey

773
00:50:01,000 --> 00:50:03,000
is just one thread

774
00:50:03,000 --> 00:50:06,000
in an extraordinary tapestry...

775
00:50:07,000 --> 00:50:11,000
..that weaves together every animal,

776
00:50:11,000 --> 00:50:14,000
in fact, every living thing

777
00:50:14,000 --> 00:50:16,000
on our planet.

778
00:50:17,000 --> 00:50:20,000
It's taken four billion years

779
00:50:20,000 --> 00:50:23,000
to get here, but, boy,

780
00:50:23,000 --> 00:50:26,000
has life come a very, very long way!

781
00:50:29,000 --> 00:50:32,000
From the cell that began it all...

782
00:50:34,000 --> 00:50:36,000
..to sex...

783
00:50:37,000 --> 00:50:39,000
..to competition...

784
00:50:40,000 --> 00:50:42,000
..to predation and protection.

785
00:50:49,000 --> 00:50:52,000
From the oceans to the land

786
00:50:52,000 --> 00:50:56,000
and, for some, back again.

787
00:50:59,000 --> 00:51:03,000
For others, onwards to the skies.

788
00:51:05,000 --> 00:51:08,000
There was a bum
that changed the world.

789
00:51:09,000 --> 00:51:11,000
There were jaws, limbs,

790
00:51:11,000 --> 00:51:14,000
hearts and minds.

791
00:51:14,000 --> 00:51:17,000
Minds which have evolved to sense,

792
00:51:17,000 --> 00:51:20,000
to move, to love,

793
00:51:20,000 --> 00:51:21,000
to contemplate...

794
00:51:24,000 --> 00:51:27,000
..and, in our case,

795
00:51:27,000 --> 00:51:28,000
to begin to understand

796
00:51:28,000 --> 00:51:31,000
our own origins.

797
00:51:36,000 --> 00:51:39,000
A journey of knowledge

798
00:51:39,000 --> 00:51:41,000
that we're still on today.

799
00:51:44,000 --> 00:51:46,000
There's an outdated view,

800
00:51:46,000 --> 00:51:48,000
a mistaken idea,

801
00:51:48,000 --> 00:51:53,000
that we humans are the
be-all and end-all of evolution.

802
00:51:53,000 --> 00:51:56,000
That everything we've explored,
everything we've shown you

803
00:51:56,000 --> 00:52:02,000
in this series was just about
making us the perfect organism,

804
00:52:02,000 --> 00:52:04,000
the paragon of life on Earth.

805
00:52:04,000 --> 00:52:07,000
But it's simply not true.

806
00:52:07,000 --> 00:52:10,000
We're not perfect
and we weren't made.

807
00:52:10,000 --> 00:52:13,000
We've been shaped by
exactly the same forces

808
00:52:13,000 --> 00:52:19,000
that have shaped every organism
that's ever lived on this planet.

809
00:52:19,000 --> 00:52:21,000
And through a startling
twist of fate,

810
00:52:21,000 --> 00:52:24,000
we are now having a profound effect

811
00:52:24,000 --> 00:52:26,000
on evolution ourselves.

812
00:52:26,000 --> 00:52:29,000
A dramatic, rapid and scary one

813
00:52:29,000 --> 00:52:32,000
because of what we're doing
to our environment

814
00:52:32,000 --> 00:52:38,000
and because we're driving
a massive extinction event.

815
00:52:38,000 --> 00:52:43,000
Now, evolution
does feast on extinction.

816
00:52:43,000 --> 00:52:47,000
It loves the opportunities,
the vacancies.

817
00:52:47,000 --> 00:52:50,000
So whatever we do now,
life will go on.

818
00:52:50,000 --> 00:52:54,000
Life will be bright,
life will be beautiful,

819
00:52:54,000 --> 00:52:57,000
life will be wonderful.

820
00:52:57,000 --> 00:53:01,000
But in evolutionary terms,
what about us?

821
00:53:01,000 --> 00:53:04,000
Could we become shorter,

822
00:53:04,000 --> 00:53:06,000
slower, more short-sighted?

823
00:53:06,000 --> 00:53:10,000
Might we become smarter,
more stupid?

824
00:53:11,000 --> 00:53:16,000
I don't think it really matters
about our anatomy at this point.

825
00:53:17,000 --> 00:53:20,000
I think what matters
is how we think,

826
00:53:20,000 --> 00:53:25,000
imagine and create our way
out of our situation.

827
00:53:26,000 --> 00:53:31,000
I think that what needs to be
driving human evolution right now...

828
00:53:33,000 --> 00:53:34,000
..is hope.

829
00:53:57,000 --> 00:53:58,000
But before we go...

830
00:54:01,000 --> 00:54:03,000
..how did we bring the story

831
00:54:03,000 --> 00:54:05,000
of evolution to life?

832
00:54:08,000 --> 00:54:10,000
The way that one animal,

833
00:54:10,000 --> 00:54:11,000
over millions of years,

834
00:54:11,000 --> 00:54:14,000
can transform into something
radically different

835
00:54:14,000 --> 00:54:17,000
was once a mystery lost to time.

836
00:54:19,000 --> 00:54:21,000
If we think about a book,
we have lots of different pages

837
00:54:21,000 --> 00:54:23,000
that tell us the story
from start to finish.

838
00:54:24,000 --> 00:54:27,000
However, with evolution and fossils,
some of those pages are missing.

839
00:54:29,000 --> 00:54:31,000
But occasionally, evidence

840
00:54:31,000 --> 00:54:33,000
is unearthed of the process

841
00:54:33,000 --> 00:54:38,000
in action. In 2004, palaeontologists

842
00:54:38,000 --> 00:54:40,000
in the Canadian Arctic

843
00:54:40,000 --> 00:54:43,000
discovered a ground-breaking fossil.

844
00:54:43,000 --> 00:54:45,000
So this is a cast of Tiktaalik.

845
00:54:45,000 --> 00:54:49,000
Now, Tiktaalik lived about
375 million years ago,

846
00:54:49,000 --> 00:54:51,000
and it's got the scales very much

847
00:54:51,000 --> 00:54:53,000
like modern-day fish have today.

848
00:54:53,000 --> 00:54:56,000
And what's quite unusual
is that it actually has a neck.

849
00:54:56,000 --> 00:54:58,000
{\an8}And these bones
that are around there,

850
00:54:58,000 --> 00:54:59,000
{\an8}these are the sort of collar bone

851
00:54:59,000 --> 00:55:01,000
{\an8}or shoulder girdle. It looks like

852
00:55:01,000 --> 00:55:03,000
a cross between
a fish and an amphibian,

853
00:55:03,000 --> 00:55:06,000
and that's because
that's exactly what it is.

854
00:55:06,000 --> 00:55:08,000
{\an8}Tiktaalik was really this kind of

855
00:55:08,000 --> 00:55:10,000
{\an8}unique snapshot in evolutionary time

856
00:55:10,000 --> 00:55:12,000
{\an8}at this key moment

857
00:55:12,000 --> 00:55:14,000
{\an8}for the water-to-land transition.

858
00:55:15,000 --> 00:55:16,000
{\an8}So it's a perfect example of

859
00:55:16,000 --> 00:55:18,000
{\an8}a transitional fossil.

860
00:55:18,000 --> 00:55:20,000
Transitional fossils
are incredibly rare.

861
00:55:21,000 --> 00:55:23,000
{\an8}They play the really important role
of filling those gaps

862
00:55:23,000 --> 00:55:26,000
{\an8}between morphologies
that we kind of know are there,

863
00:55:26,000 --> 00:55:28,000
{\an8}but we don't really know exactly

864
00:55:28,000 --> 00:55:30,000
{\an8}what they might have looked like.

865
00:55:30,000 --> 00:55:33,000
{\an8}Transitional fossils represent

866
00:55:33,000 --> 00:55:35,000
{\an8}just one out of millions,

867
00:55:35,000 --> 00:55:37,000
possibly billions, of individuals

868
00:55:37,000 --> 00:55:39,000
that, over generations,

869
00:55:39,000 --> 00:55:41,000
contribute to evolutionary change.

870
00:55:41,000 --> 00:55:44,000
Coming up with a way
to illustrate this

871
00:55:44,000 --> 00:55:46,000
posed a huge challenge

872
00:55:46,000 --> 00:55:49,000
{\an8}to the visual effects team
behind the series.

873
00:55:49,000 --> 00:55:51,000
{\an8}Evolution does not move in
a straight line,

874
00:55:51,000 --> 00:55:54,000
{\an8}because it is purely opportunistic

875
00:55:54,000 --> 00:55:55,000
{\an8}and slightly haphazard.

876
00:55:55,000 --> 00:55:58,000
It's tinkering. It's messing with
what's already there,

877
00:55:58,000 --> 00:56:00,000
rather than kind of always

878
00:56:00,000 --> 00:56:03,000
necessarily inventing something
from scratch.

879
00:56:03,000 --> 00:56:05,000
It's all about
a great grand experiment

880
00:56:05,000 --> 00:56:07,000
and just seeing what happens.

881
00:56:08,000 --> 00:56:11,000
The team spent thousands of hours

882
00:56:11,000 --> 00:56:12,000
crafting and animating

883
00:56:12,000 --> 00:56:14,000
computer-generated models

884
00:56:14,000 --> 00:56:16,000
to bring ancient animals

885
00:56:16,000 --> 00:56:17,000
back to life.

886
00:56:17,000 --> 00:56:19,000
But to illustrate the randomness

887
00:56:19,000 --> 00:56:22,000
and variation seen as life evolves,

888
00:56:22,000 --> 00:56:25,000
they needed to experiment.

889
00:56:25,000 --> 00:56:28,000
After consulting scientists
to accurately model

890
00:56:28,000 --> 00:56:30,000
the key evolutionary changes,

891
00:56:30,000 --> 00:56:32,000
they used generative AI software

892
00:56:32,000 --> 00:56:36,000
to create hundreds of variations,

893
00:56:36,000 --> 00:56:39,000
representing countless generations.

894
00:56:39,000 --> 00:56:42,000
And by hand-selecting and merging

895
00:56:42,000 --> 00:56:44,000
the best results with their original

896
00:56:44,000 --> 00:56:46,000
animations, they were able

897
00:56:46,000 --> 00:56:48,000
to condense millions of years

898
00:56:48,000 --> 00:56:49,000
of evolution...

899
00:56:49,000 --> 00:56:51,000
Look at that! There's bones inside!

900
00:56:51,000 --> 00:56:52,000
No way!

901
00:56:52,000 --> 00:56:55,000
..into a matter of seconds.

902
00:56:55,000 --> 00:56:56,000
In reality, this would take

903
00:56:56,000 --> 00:56:58,000
millions of years.

904
00:57:00,000 --> 00:57:01,000
This is a fantastic way

905
00:57:01,000 --> 00:57:04,000
to illustrate the evolution of form.

906
00:57:04,000 --> 00:57:06,000
This is basically how I imagine it
playing out in my head.

907
00:57:17,000 --> 00:57:18,000
This series has been over

908
00:57:18,000 --> 00:57:21,000
four billion years in the making...

909
00:57:22,000 --> 00:57:24,000
..and as a certain Charles Darwin

910
00:57:24,000 --> 00:57:26,000
once wrote,

911
00:57:26,000 --> 00:57:29,000
"From so simple a beginning

912
00:57:29,000 --> 00:57:31,000
"endless forms most beautiful

913
00:57:31,000 --> 00:57:34,000
"and most wonderful have been,

914
00:57:34,000 --> 00:57:37,000
"and are being evolved."

915
00:57:37,000 --> 00:57:39,000
One of the big key life lessons that

916
00:57:39,000 --> 00:57:41,000
I've learned from studying evolution

917
00:57:41,000 --> 00:57:44,000
is that change is constant

918
00:57:44,000 --> 00:57:46,000
and change is the norm. So things

919
00:57:46,000 --> 00:57:48,000
have always changed and will always

920
00:57:48,000 --> 00:57:49,000
continue to change, and life

921
00:57:49,000 --> 00:57:50,000
will always continue to adapt.

922
00:57:53,000 --> 00:57:55,000
That's how it's always been,

923
00:57:55,000 --> 00:57:56,000
and there's no reason to believe

924
00:57:56,000 --> 00:57:58,000
that's not how
it's going to continue to be.

925
00:58:11,000 --> 00:58:14,000
Do you want to know how an elephant
is related to a clownfish?

926
00:58:14,000 --> 00:58:18,000
Discover more in a poster
from the Open University on

927
00:58:18,000 --> 00:58:20,000
{\an8}the tree of life.
To get your free copy,

928
00:58:20,000 --> 00:58:23,000
{\an8}scan the QR code
on-screen or ring...

929
00:58:26,000 --> 00:58:28,000
{\an8}..or visit...