1
00:00:01,033 --> 00:00:05,533
{\an8}♪♪

2
00:00:05,566 --> 00:00:08,500
{\an1}-No environment's static
over time.

3
00:00:08,533 --> 00:00:11,033
{\an1}The climate will change,
the composition of organisms

4
00:00:11,066 --> 00:00:13,266
{\an1}that live in that environment
will change.

5
00:00:16,000 --> 00:00:19,033
-As a species,
we've endured massive changes

6
00:00:19,066 --> 00:00:22,733
{\an1}in our surroundings...
cataclysmic shifts.

7
00:00:22,766 --> 00:00:26,666
{\an1}Our greatest challenge
has always been adapting.

8
00:00:26,700 --> 00:00:31,033
{\an8}♪♪

9
00:00:31,066 --> 00:00:32,866
And that means
constantly defending

10
00:00:32,900 --> 00:00:34,866
{\an1}against all of the threats

11
00:00:34,900 --> 00:00:38,300
{\an1}we face in the organisms
that live among us.

12
00:00:41,033 --> 00:00:45,100
{\an1}The immune system, essential
to our survival every second,

13
00:00:45,133 --> 00:00:49,933
{\an1}is the most complex and least
understood piece of our biology.

14
00:00:49,966 --> 00:00:53,466
{\an1}And that's because
it's always changing.

15
00:00:53,500 --> 00:00:59,400
{\an1}As new enemies crop up, this
system meets the challenge...

16
00:01:01,333 --> 00:01:03,366
{\an1}...and is transformed.

17
00:01:03,400 --> 00:01:07,300
{\an1}-The immune system is basically
our body's defense system

18
00:01:07,333 --> 00:01:09,600
{\an1}against all things foreign.

19
00:01:12,900 --> 00:01:16,766
{\an1}Not only is our immune system
effective at killing.

20
00:01:16,800 --> 00:01:20,600
{\an1}It's also really effective
at communication, memory,

21
00:01:20,633 --> 00:01:23,133
{\an1}tagging other cells
when it needs the help.

22
00:01:23,166 --> 00:01:25,833
{\an1}It's a huge specialized army.

23
00:01:25,866 --> 00:01:30,266
{\an1}-And to the naked human eye,
it's invisible.

24
00:01:32,400 --> 00:01:35,266
{\an1}Unlike other systems,
where we can point to a center,

25
00:01:35,300 --> 00:01:37,233
{\an1}like the heart or the brain,

26
00:01:37,266 --> 00:01:41,533
{\an1}the immune system is a unique
in that it lives...everywhere.

27
00:01:41,566 --> 00:01:44,233
{\an1}And it is always on the move.

28
00:01:44,266 --> 00:01:53,133
{\an8}♪♪

29
00:01:53,166 --> 00:02:02,066
{\an8}♪♪

30
00:02:02,100 --> 00:02:10,966
{\an8}♪♪

31
00:02:11,000 --> 00:02:13,566
{\an1}-Survival out here is extreme.

32
00:02:13,600 --> 00:02:18,333
{\an8}♪♪

33
00:02:18,366 --> 00:02:20,500
{\an1}There are days when I feel like
I'm floating

34
00:02:20,533 --> 00:02:23,866
{\an1}across the landscape
and everything is beautiful.

35
00:02:24,900 --> 00:02:28,066
{\an1}And then there are other days
where I'm totally wrecked,

36
00:02:28,100 --> 00:02:33,600
{\an1}exhausted, dehydrated,
very sleep-deprived.

37
00:02:33,633 --> 00:02:35,066
{\an1}[ Insects chirping ]

38
00:02:35,100 --> 00:02:40,000
{\an1}I know full well that at any
point in time I could die here.

39
00:02:40,033 --> 00:02:44,433
{\an8}♪♪

40
00:02:44,466 --> 00:02:47,333
{\an7}My name is Cat Bigney,

41
00:02:47,366 --> 00:02:50,633
{\an7}and I have been teaching
and consulting in the wilderness

42
00:02:50,666 --> 00:02:52,766
{\an7}for over two decades.

43
00:02:54,066 --> 00:02:56,566
{\an1}In many ways, this is my home.

44
00:02:56,600 --> 00:03:03,466
{\an8}♪♪

45
00:03:03,500 --> 00:03:07,766
{\an1}At times I'll spend months
out here

46
00:03:07,800 --> 00:03:12,200
{\an1}with very limited contact
with the outside world.

47
00:03:12,233 --> 00:03:17,000
{\an1}To survive in this environment
requires a lot of awareness

48
00:03:17,033 --> 00:03:20,400
{\an1}and the ability to embrace
hardship and discomfort.

49
00:03:20,433 --> 00:03:22,066
Ouch.

50
00:03:22,100 --> 00:03:24,233
{\an8}♪♪

51
00:03:24,266 --> 00:03:25,466
{\an1}Every time I'm out,

52
00:03:25,500 --> 00:03:28,266
{\an1}I end up having some sort of cut
or abrasion,

53
00:03:28,300 --> 00:03:30,166
{\an1}cactus spines in my hands
and feet.

54
00:03:30,200 --> 00:03:32,300
{\an1}It's just part of it.

55
00:03:34,233 --> 00:03:35,800
{\an1}-On a microscopic level,

56
00:03:35,833 --> 00:03:39,166
{\an1}our bodies are in a constant
struggle with the environment.

57
00:03:40,000 --> 00:03:44,966
{\an1}And the immune system manages
every second of that struggle.

58
00:03:45,000 --> 00:03:47,333
{\an8}♪♪

59
00:03:47,366 --> 00:03:50,333
{\an7}-Our skin has cells
that are very specialized

60
00:03:50,366 --> 00:03:54,400
{\an7}to create a boundary between us
and the outside world.

61
00:03:54,433 --> 00:03:59,500
{\an1}-Imagine you're in the midday
desert heat.

62
00:03:59,533 --> 00:04:04,466
{\an1}You're walking on hot,
loose rocks.

63
00:04:04,500 --> 00:04:08,100
{\an1}What are you relying on most
to stay alive?

64
00:04:08,133 --> 00:04:10,966
{\an1}It's your biggest organ,

65
00:04:11,000 --> 00:04:15,300
{\an1}and it also happens to be the
bedrock of the immune system.

66
00:04:17,300 --> 00:04:18,666
Skin.

67
00:04:18,700 --> 00:04:22,066
{\an1}-From the moment we are born,

68
00:04:22,100 --> 00:04:27,200
{\an1}we are exposed to the external
environment and the sun's rays,

69
00:04:27,233 --> 00:04:31,600
{\an1}but also the extraordinarily
complex environment

70
00:04:31,633 --> 00:04:34,666
{\an1}that's generated from
our own body's inner workings.

71
00:04:34,700 --> 00:04:38,100
{\an8}♪♪

72
00:04:38,133 --> 00:04:42,033
{\an1}-The outermost layer of our skin
is like a brick wall...

73
00:04:42,066 --> 00:04:44,933
that can breathe.

74
00:04:44,966 --> 00:04:48,166
{\an1}It's made up of cells
that bind tightly together

75
00:04:48,200 --> 00:04:52,500
{\an1}to keep out UV rays
and foreign objects.

76
00:04:52,533 --> 00:04:57,033
{\an1}And the oil that sits on top of
these cells is antibacterial,

77
00:04:57,066 --> 00:04:59,866
{\an1}another first line of defense.

78
00:04:59,900 --> 00:05:03,333
{\an1}And in our 20 or so square feet
of skin

79
00:05:03,366 --> 00:05:05,933
{\an1}are tens of millions
of immune cells

80
00:05:05,966 --> 00:05:08,566
that activate
when there's a threat.

81
00:05:08,600 --> 00:05:11,266
{\an8}♪♪

82
00:05:11,300 --> 00:05:13,733
{\an1}But as tight a barrier as it is,

83
00:05:13,766 --> 00:05:16,733
{\an1}occasionally something
does end up slipping through

84
00:05:16,766 --> 00:05:18,100
the top layer.

85
00:05:19,166 --> 00:05:21,600
{\an1}Microscopic bugs, or microbes,

86
00:05:21,633 --> 00:05:24,600
{\an1}can hitch a ride in
on almost anything.

87
00:05:26,233 --> 00:05:30,400
When they do,
there's an immediate reaction.

88
00:05:31,700 --> 00:05:34,466
{\an1}-On the outside of microbes

89
00:05:34,500 --> 00:05:37,433
{\an1}there are these little molecules
called antigens.

90
00:05:37,466 --> 00:05:39,533
{\an8}Our immune system
is specifically trained

91
00:05:39,566 --> 00:05:43,333
{\an7}to recognize foreign antigen,
friendly antigen.

92
00:05:43,366 --> 00:05:45,033
{\an7}And if it recognizes foreign,

93
00:05:45,066 --> 00:05:47,600
{\an7}that's when the cascade
of defense starts.

94
00:05:47,633 --> 00:05:49,566
{\an8}♪♪

95
00:05:49,600 --> 00:05:54,133
{\an1}-Below that top layer of skin
is another one...

96
00:05:54,166 --> 00:05:56,466
20 times thicker.

97
00:05:58,200 --> 00:06:00,800
{\an1}When something foreign gets down
deep enough,

98
00:06:00,833 --> 00:06:03,833
{\an1}the immune cells sense it
immediately.

99
00:06:03,866 --> 00:06:06,100
{\an1}They send a signal
inside the body.

100
00:06:06,133 --> 00:06:09,033
Blood will rush
to the damaged area.

101
00:06:09,066 --> 00:06:12,366
{\an1}White blood cells called
neutrophils will swarm in

102
00:06:12,400 --> 00:06:16,500
{\an1}and kill the microbes by...
eating them.

103
00:06:16,533 --> 00:06:24,033
{\an8}♪♪

104
00:06:24,066 --> 00:06:27,966
{\an1}To us, inflammation might seem
like a bad thing.

105
00:06:28,000 --> 00:06:30,133
{\an1}But really it's just proof

106
00:06:30,166 --> 00:06:33,866
{\an1}that the immune cells are doing
their job.

107
00:06:33,900 --> 00:06:35,800
{\an8}♪♪

108
00:06:35,833 --> 00:06:39,366
{\an1}-I trust that my body can handle
superficial infections out here.

109
00:06:39,400 --> 00:06:41,733
{\an1}The desert environment is
pretty forgiving in some ways

110
00:06:41,766 --> 00:06:45,266
{\an1}because it's so arid and dry,
it is somewhat sterile.

111
00:06:45,300 --> 00:06:47,400
{\an1}So if I have a scratch
in the desert,

112
00:06:47,433 --> 00:06:50,233
{\an1}my body will naturally be able
to fight that off a lot better

113
00:06:50,266 --> 00:06:52,200
than if I were in
a jungle environment.

114
00:06:52,233 --> 00:06:54,400
{\an8}♪♪

115
00:06:54,433 --> 00:06:57,266
{\an1}-After the infection has been
brought under control,

116
00:06:57,300 --> 00:06:59,600
{\an1}the body then has to repair

117
00:06:59,633 --> 00:07:02,866
{\an1}that spot where the microbe
got through.

118
00:07:02,900 --> 00:07:06,733
-Our bodies have
this innate capacity to repair,

119
00:07:06,766 --> 00:07:09,900
{\an1}and some of our tissues repair
themselves more than others.

120
00:07:09,933 --> 00:07:14,400
{\an1}Like skin, for example,
is constantly regenerating.

121
00:07:14,433 --> 00:07:17,033
{\an1}-Even without a breach,

122
00:07:17,066 --> 00:07:21,466
{\an1}we shed about 40,000 skin cells
a minute,

123
00:07:21,500 --> 00:07:23,600
{\an1}or 50 million every day.

124
00:07:23,633 --> 00:07:25,500
{\an1}So when a wound heals,

125
00:07:25,533 --> 00:07:28,633
{\an1}that outer layer of cells dies
and falls off.

126
00:07:28,666 --> 00:07:30,766
{\an1}But beneath them are cells

127
00:07:30,800 --> 00:07:33,466
{\an1}that constantly replenish
the skin above it,

128
00:07:33,500 --> 00:07:36,933
{\an1}and those new cells have
a memory.

129
00:07:36,966 --> 00:07:40,333
{\an1}Inflammation from damage
sensitizes those cells,

130
00:07:40,366 --> 00:07:44,833
{\an1}so the next time around,
they actually respond faster.

131
00:07:44,866 --> 00:07:47,833
{\an1}Skin, it turns out,
that's been roughed up before

132
00:07:47,866 --> 00:07:50,300
{\an1}can heal twice as fast.

133
00:07:52,133 --> 00:07:55,133
So after decades
of cactus thorns,

134
00:07:55,166 --> 00:08:00,366
{\an1}Cat's primary defenses are
way tougher than most of ours.

135
00:08:00,400 --> 00:08:03,733
{\an8}♪♪

136
00:08:03,766 --> 00:08:06,033
{\an1}-I didn't know that survival
was a thing

137
00:08:06,066 --> 00:08:08,066
{\an1}until I was 19 years old.

138
00:08:08,100 --> 00:08:10,233
{\an1}I had a very atypical upbringing

139
00:08:10,266 --> 00:08:12,566
and grew up
in a very remote environment,

140
00:08:12,600 --> 00:08:15,800
{\an1}and many of the things
that people consider

141
00:08:15,833 --> 00:08:18,300
{\an1}to be survival skills
were part of my everyday life.

142
00:08:18,333 --> 00:08:20,200
It's important
for people to trust

143
00:08:20,233 --> 00:08:22,166
what's going on
inside their bodies

144
00:08:22,200 --> 00:08:25,333
{\an1}as well as what their body
can physically do

145
00:08:25,366 --> 00:08:27,166
{\an1}with the outside world.

146
00:08:27,200 --> 00:08:29,066
{\an1}This is why survival
is important to me

147
00:08:29,100 --> 00:08:31,300
{\an1}and it's important for me
to teach it.

148
00:08:31,333 --> 00:08:33,633
{\an1}Panic, exposure, and dehydration

149
00:08:33,666 --> 00:08:36,200
{\an1}are the number-one killers
out here.

150
00:08:36,233 --> 00:08:39,000
{\an8}♪♪

151
00:08:39,033 --> 00:08:42,033
{\an1}So I need to know what resources
are available,

152
00:08:42,066 --> 00:08:44,300
{\an1}how much water is in the area.

153
00:08:44,333 --> 00:08:48,200
{\an1}If your skin isn't hydrated,
it can't do what it needs to do.

154
00:08:48,233 --> 00:08:51,300
{\an8}♪♪

155
00:08:51,333 --> 00:08:54,000
{\an1}I've been in situations
where I've been so dehydrated,

156
00:08:54,033 --> 00:08:56,666
{\an1}I'm begging my body to continue

157
00:08:56,700 --> 00:08:59,266
for the potential
of finding water.

158
00:08:59,300 --> 00:09:02,966
{\an1}I may be climbing up some huge
feature to look out for water,

159
00:09:03,000 --> 00:09:05,900
just praying
that I can keep going.

160
00:09:07,600 --> 00:09:10,166
{\an1}Dehydration at a level where
your body doesn't want to work

161
00:09:10,200 --> 00:09:13,033
{\an1}and you're talking yourself
into every footstep.

162
00:09:14,433 --> 00:09:16,166
{\an1}-As strong as it can be,

163
00:09:16,200 --> 00:09:19,900
{\an1}the immune system's ability
to protect us isn't unshakable.

164
00:09:19,933 --> 00:09:23,700
{\an1}It depends on how healthy
the body is as a whole.

165
00:09:23,733 --> 00:09:26,933
{\an1}Water is essential
to immune function.

166
00:09:26,966 --> 00:09:28,600
{\an8}♪♪

167
00:09:28,633 --> 00:09:31,266
{\an1}And it's monitored by the brain.

168
00:09:31,300 --> 00:09:33,233
{\an7}-Thirst is primarily regulated

169
00:09:33,266 --> 00:09:35,700
{\an7}by a part of the brain
called the hypothalamus.

170
00:09:35,733 --> 00:09:37,366
{\an8}♪♪

171
00:09:37,400 --> 00:09:39,666
{\an1}And the hypothalamus
has receptors

172
00:09:39,700 --> 00:09:41,900
{\an1}that can sense a concentration
of the blood

173
00:09:41,933 --> 00:09:44,033
{\an1}and decide whether we need
a little more fluid

174
00:09:44,066 --> 00:09:45,933
{\an1}to thin the blood out
a little bit

175
00:09:45,966 --> 00:09:47,966
or whether maybe
we're overhydrated

176
00:09:48,000 --> 00:09:50,000
{\an1}and we don't need to drink
anymore.

177
00:09:50,033 --> 00:09:51,900
{\an1}The kidneys also play a role.

178
00:09:51,933 --> 00:09:55,133
{\an1}So like lots of things in the
body, this is a team approach,

179
00:09:55,166 --> 00:09:57,333
{\an1}with multiple different organs
involved.

180
00:09:57,366 --> 00:10:00,166
{\an8}♪♪

181
00:10:00,200 --> 00:10:02,900
{\an1}-The body is always paying
attention to water

182
00:10:02,933 --> 00:10:06,100
{\an1}because it's essential
to everything,

183
00:10:06,133 --> 00:10:08,400
{\an1}especially clearing out toxins.

184
00:10:08,433 --> 00:10:12,500
{\an1}Fluid is constantly flowing
through us, carrying bacteria

185
00:10:12,533 --> 00:10:16,066
{\an1}and other toxins to our
lymph nodes to be destroyed.

186
00:10:16,100 --> 00:10:18,300
{\an1}These grapelike bunches
of immune cells

187
00:10:18,333 --> 00:10:23,133
{\an1}are little filters that cleanse
our internal environment.

188
00:10:23,166 --> 00:10:26,200
{\an1}Dehydration backs up the system.

189
00:10:26,233 --> 00:10:27,866
{\an1}Without enough water,

190
00:10:27,900 --> 00:10:30,533
{\an1}waste can't be flushed out
as efficiently,

191
00:10:30,566 --> 00:10:33,333
{\an1}and immune function suffers...

192
00:10:35,866 --> 00:10:38,766
{\an1}...which can lead to
an infection.

193
00:10:38,800 --> 00:10:41,633
{\an1}-Out here, you can consume
quite a bit of water

194
00:10:41,666 --> 00:10:44,900
{\an1}and still your mouth will be dry
because it's so arid.

195
00:10:44,933 --> 00:10:47,566
{\an1}It's important to constantly
be monitoring that.

196
00:10:50,133 --> 00:10:53,966
Running water.
This is golden.

197
00:10:56,200 --> 00:11:00,033
I have to boil it
to kill any parasites.

198
00:11:00,066 --> 00:11:01,700
{\an1}So I won't drink it now,

199
00:11:01,733 --> 00:11:04,133
but I'll get some
to bring with me.

200
00:11:04,166 --> 00:11:06,333
{\an8}♪♪

201
00:11:06,366 --> 00:11:09,166
{\an1}-Cat's ability to survive
comes from knowing

202
00:11:09,200 --> 00:11:13,100
{\an1}how to use natural resources
to her advantage

203
00:11:13,133 --> 00:11:15,866
{\an1}and understanding the limits
her body can be pushed to.

204
00:11:15,900 --> 00:11:19,533
{\an8}♪♪

205
00:11:19,566 --> 00:11:23,933
{\an1}Over time, some of those
limits have gotten more extreme.

206
00:11:25,500 --> 00:11:28,500
{\an1}-Your body will adapt
to surviving in these elements

207
00:11:28,533 --> 00:11:29,666
over time.

208
00:11:29,700 --> 00:11:32,400
But initially,
while your body's adjusting,

209
00:11:32,433 --> 00:11:35,466
{\an1}it's incredibly difficult.

210
00:11:35,500 --> 00:11:39,733
{\an1}I have been in situations
where I'm in a bad place,

211
00:11:39,766 --> 00:11:42,600
{\an1}but the most important thing
is that I trust my body.

212
00:11:42,633 --> 00:11:46,233
{\an1}The desert's an interesting
place in terms of temperature.

213
00:11:46,266 --> 00:11:50,233
{\an1}It can get really, really hot
during the day,

214
00:11:50,266 --> 00:11:53,200
{\an1}but at night, the desert
can become very, very cold

215
00:11:53,233 --> 00:11:55,933
{\an1}because there's nothing
to keep that heat in.

216
00:11:57,833 --> 00:12:00,700
{\an1}I've literally had
my water freeze during the night

217
00:12:00,733 --> 00:12:03,833
{\an1}and then been in temperatures
over 100 degrees during the day.

218
00:12:03,866 --> 00:12:07,033
{\an8}♪♪

219
00:12:07,066 --> 00:12:10,333
{\an1}-After years of training,
Cat's body is uniquely equipped

220
00:12:10,366 --> 00:12:13,166
to handle these
massive fluctuations,

221
00:12:13,200 --> 00:12:16,000
{\an1}through a process called
acclimatization.

222
00:12:16,033 --> 00:12:20,066
{\an8}♪♪

223
00:12:20,100 --> 00:12:24,533
{\an1}And, like hydration,
it involves the brain.

224
00:12:24,566 --> 00:12:29,233
{\an7}-There is a capacity for
the brain to regulate hormones

225
00:12:29,266 --> 00:12:32,666
{\an8}that impact
our body temperature,

226
00:12:32,700 --> 00:12:34,266
{\an7}our basic homeostasis.

227
00:12:35,766 --> 00:12:38,200
{\an1}-So in sweltering heat
of the day,

228
00:12:38,233 --> 00:12:42,233
{\an1}Cat's baseline body temperature
is naturally higher.

229
00:12:42,266 --> 00:12:46,433
{\an1}She'll also sweat more, and
her sweat will be diluted more,

230
00:12:46,466 --> 00:12:50,233
{\an1}which leaves more salt
inside her body for energy.

231
00:12:50,266 --> 00:12:52,466
{\an8}♪♪

232
00:12:52,500 --> 00:12:55,833
{\an1}And during the freezing nights,
she'll shiver less,

233
00:12:55,866 --> 00:12:58,666
{\an1}allowing her to retain
more heat.

234
00:12:58,700 --> 00:13:00,966
-Maintaining
a core body temperature

235
00:13:01,000 --> 00:13:03,233
is paramount
in a survival situation.

236
00:13:03,266 --> 00:13:05,400
{\an1}That's why shelter is essential.

237
00:13:06,933 --> 00:13:09,066
The environment
wants to suck heat from me

238
00:13:09,100 --> 00:13:12,100
{\an1}while my body's desperate
to gain any heat that it can,

239
00:13:12,133 --> 00:13:14,466
so what I'm doing
is changing the environment

240
00:13:14,500 --> 00:13:18,333
{\an1}so I've buffered myself
from the landscape.

241
00:13:20,166 --> 00:13:24,800
{\an1}-It's a constant negotiation
between body and nature.

242
00:13:24,833 --> 00:13:26,666
{\an8}♪♪

243
00:13:26,700 --> 00:13:30,200
{\an1}And survival means trusting
that you can handle

244
00:13:30,233 --> 00:13:31,700
{\an1}more than you think.

245
00:13:31,733 --> 00:13:33,066
{\an1}-I've faced many nights

246
00:13:33,100 --> 00:13:35,200
{\an1}wondering if I would be alive
in the morning,

247
00:13:35,233 --> 00:13:38,633
{\an1}with heat, with hypothermia,
through monsoons,

248
00:13:38,666 --> 00:13:41,833
flash floods,
through extreme dehydration.

249
00:13:41,866 --> 00:13:46,166
{\an8}♪♪

250
00:13:46,200 --> 00:13:49,833
{\an1}I think that people
are innate survivors.

251
00:13:49,866 --> 00:13:51,800
{\an1}I wouldn't be here right now

252
00:13:51,833 --> 00:13:54,666
{\an1}if someone in my past hadn't
been an excellent survivor.

253
00:13:54,700 --> 00:13:57,333
{\an1}And that's true of everyone
on the planet.

254
00:13:57,366 --> 00:14:00,200
{\an1}The hallmark of our species
is being innovative and creative

255
00:14:00,233 --> 00:14:02,666
{\an1}and overcoming and adapting.

256
00:14:02,700 --> 00:14:04,433
{\an1}But we've lost faith
in that ability.

257
00:14:04,466 --> 00:14:07,600
{\an1}We've lost faith in our ability
not to conquer nature,

258
00:14:07,633 --> 00:14:09,900
{\an1}but to live in it.

259
00:14:09,933 --> 00:14:13,466
{\an1}It's really important
for us to reconnect with nature

260
00:14:13,500 --> 00:14:16,633
{\an1}because it teaches us something
about ourselves.

261
00:14:16,666 --> 00:14:23,800
{\an8}♪♪

262
00:14:23,833 --> 00:14:26,966
{\an8}-The human body
is often characterized

263
00:14:27,000 --> 00:14:28,900
{\an7}as being sort of weak, right?

264
00:14:28,933 --> 00:14:32,200
{\an1}Like, compare ourselves
to predators,

265
00:14:32,233 --> 00:14:34,366
{\an1}like lions and tigers
or something.

266
00:14:34,400 --> 00:14:37,133
{\an1}We don't have big, sharp teeth
or claws.

267
00:14:37,166 --> 00:14:40,033
{\an1}We're not incredibly strong
for our body size.

268
00:14:40,066 --> 00:14:43,300
{\an1}So when we think about humans
that way, I'm always surprised

269
00:14:43,333 --> 00:14:47,500
{\an1}by the sorts of situations
that humans can survive.

270
00:14:48,666 --> 00:14:52,300
{\an1}-Although raw nature feels
more dangerous...

271
00:14:52,333 --> 00:14:54,033
{\an8}♪♪

272
00:14:54,066 --> 00:14:56,600
{\an1}...the reality is that
every environment on earth

273
00:14:56,633 --> 00:15:00,233
{\an1}is teeming with threats
that we can't see.

274
00:15:01,933 --> 00:15:04,300
{\an1}-Our immune system
is incredibly effective

275
00:15:04,333 --> 00:15:05,900
{\an1}at defending our bodies.

276
00:15:05,933 --> 00:15:09,033
We encounter
thousands of pathogens

277
00:15:09,066 --> 00:15:11,300
{\an1}or microbes every single day,
from kitchen counters

278
00:15:11,333 --> 00:15:14,133
to doorknobs
to sitting on a subway.

279
00:15:14,166 --> 00:15:17,433
{\an1}And the vast majority of
the time, we don't even notice.

280
00:15:17,466 --> 00:15:20,933
{\an8}♪♪

281
00:15:20,966 --> 00:15:25,633
{\an1}-But how does our body know
what to do in the first place?

282
00:15:25,666 --> 00:15:30,300
{\an1}And why is it that some things
make us sick and others don't?

283
00:15:31,800 --> 00:15:35,066
What we do know
is that everyone's immune system

284
00:15:35,100 --> 00:15:37,066
is different

285
00:15:37,100 --> 00:15:40,366
{\an1}and how it functions is altered
constantly,

286
00:15:40,400 --> 00:15:44,266
{\an1}starting from the very moment
we're born.

287
00:15:44,300 --> 00:15:49,233
{\an8}♪♪

288
00:15:49,266 --> 00:15:52,233
{\an7}[ Birds chirping, horse neighs ]

289
00:15:52,266 --> 00:15:56,066
{\an8}♪♪

290
00:15:56,100 --> 00:15:57,566
{\an1}-So we'll say it together.

291
00:15:57,600 --> 00:15:59,266
{\an1}-You start it. Yeah.
-We'll both say we're twins.

292
00:15:59,300 --> 00:16:00,500
-Okay.
So you start it.

293
00:16:00,533 --> 00:16:01,966
{\an8}-Hi. I'm Magaly.
-I'm Carolina.

294
00:16:02,000 --> 00:16:03,600
{\an8}And we're twins.
-[ Laughs ] Sorry.

295
00:16:03,633 --> 00:16:06,266
{\an7}-No. Say, "And we're twins,"
and then look at --

296
00:16:06,300 --> 00:16:09,066
{\an8}♪♪

297
00:16:09,100 --> 00:16:13,633
{\an1}I see us as two completely
different people,

298
00:16:13,666 --> 00:16:14,933
{\an1}We don't dress alike.

299
00:16:14,966 --> 00:16:18,300
{\an1}We don't have the same taste
in, like, outfits or food

300
00:16:18,333 --> 00:16:20,866
{\an1}or anything like that.

301
00:16:20,900 --> 00:16:24,433
{\an1}I dress very ranchy.

302
00:16:24,466 --> 00:16:26,566
{\an1}And she's more stylish.

303
00:16:26,600 --> 00:16:28,000
{\an1}She's more girly than I am.

304
00:16:28,033 --> 00:16:31,966
{\an1}She loves to do her makeup
and things like that.

305
00:16:32,000 --> 00:16:33,633
{\an1}-I like to go shopping.

306
00:16:33,666 --> 00:16:37,366
{\an1}I like to go to the mall,
go watch movies.

307
00:16:37,400 --> 00:16:39,866
{\an1}My room's always clean.

308
00:16:39,900 --> 00:16:43,366
{\an1}Carolina's room is a mess
all the time.

309
00:16:43,400 --> 00:16:44,766
{\an8}♪♪

310
00:16:44,800 --> 00:16:47,166
{\an1}-If I could not go home,
I would not go home.

311
00:16:47,200 --> 00:16:49,366
{\an1}I would just love to be
at the ranch every day,

312
00:16:49,400 --> 00:16:51,600
{\an1}almost all the time.

313
00:16:51,633 --> 00:16:55,933
{\an1}Twenty-four/seven,
I'll be here with the horses.

314
00:16:55,966 --> 00:16:59,500
{\an1}-When she comes back
from the ranch, she stinks.

315
00:16:59,533 --> 00:17:02,400
{\an1}Um, everybody tells her
to go shower.

316
00:17:02,433 --> 00:17:05,233
{\an8}♪♪

317
00:17:05,266 --> 00:17:09,166
{\an1}-Every person's immune system
is like a fingerprint.

318
00:17:09,200 --> 00:17:11,133
{\an1}[ Birds chirping ]

319
00:17:11,166 --> 00:17:16,833
{\an1}Even if you share DNA, a house,
or, in the case of twins...

320
00:17:16,866 --> 00:17:18,366
a womb.

321
00:17:18,400 --> 00:17:22,066
{\an1}-People ask a lot, "What do you
think it is, nature or nurture,

322
00:17:22,100 --> 00:17:24,866
that can affect
our susceptibility to disease?"

323
00:17:24,900 --> 00:17:27,266
{\an1}And the answer is for
a lot of things, it's both.

324
00:17:27,300 --> 00:17:30,933
{\an1}We can see within twins
with the same genetic material

325
00:17:30,966 --> 00:17:36,066
{\an1}there are definitely things that
are genetically predetermined,

326
00:17:36,100 --> 00:17:39,400
{\an1}but they're not fixed.

327
00:17:39,433 --> 00:17:42,033
{\an8}♪♪

328
00:17:42,066 --> 00:17:45,566
{\an1}Think about why people get sick.

329
00:17:48,033 --> 00:17:50,466
{\an1}If you think about the flu,
tons of people are exposed.

330
00:17:50,500 --> 00:17:52,933
{\an1}Some people get really sick.
Some people get a little sick.

331
00:17:52,966 --> 00:17:54,900
{\an1}And some people don't get sick
at all.

332
00:17:54,933 --> 00:17:57,633
{\an1}And that has a lot to do
with the health of the host,

333
00:17:57,666 --> 00:18:00,966
what I like
to call terrain theory.

334
00:18:01,000 --> 00:18:04,333
And your terrain
is really your immune system.

335
00:18:04,366 --> 00:18:09,133
{\an8}♪♪

336
00:18:09,166 --> 00:18:11,466
{\an1}-Locked into your DNA
are bits of code

337
00:18:11,500 --> 00:18:15,700
{\an1}that determine things about your
health long before you're born,

338
00:18:15,733 --> 00:18:18,733
like how cancer
runs in the family

339
00:18:18,766 --> 00:18:20,866
{\an1}or how a genetic mutation

340
00:18:20,900 --> 00:18:24,700
{\an1}can help predict the likelihood
you'll develop a disease.

341
00:18:24,733 --> 00:18:28,533
{\an1}That's the only piece of our
terrain that can't be changed.

342
00:18:28,566 --> 00:18:31,600
{\an1}Then there are parts
of our immune system we get

343
00:18:31,633 --> 00:18:35,566
{\an1}just before we're born,
from our mothers.

344
00:18:35,600 --> 00:18:40,500
{\an8}♪♪

345
00:18:40,533 --> 00:18:43,333
{\an1}[ Mixer whirring ]

346
00:18:43,366 --> 00:18:48,066
{\an1}-Both of my parents originated
from Zacatecas, Mexico.

347
00:18:48,100 --> 00:18:50,366
{\an1}-[ Speaking Spanish ]

348
00:18:50,400 --> 00:18:53,733
{\an1}-My mom was raised on a ranch
and away from the city.

349
00:18:53,766 --> 00:18:55,633
{\an1}So if she was sick,

350
00:18:55,666 --> 00:18:58,166
{\an1}it was an hour or two hours
away from the doctors,

351
00:18:58,200 --> 00:19:00,533
{\an1}so they had to figure
everything out at home.

352
00:19:00,566 --> 00:19:02,533
{\an1}[ Birds chirping ]

353
00:19:02,566 --> 00:19:05,000
{\an8}♪♪

354
00:19:05,033 --> 00:19:07,533
{\an1}[ Indistinct conversations ]

355
00:19:07,566 --> 00:19:09,033
{\an8}♪♪

356
00:19:09,066 --> 00:19:12,666
{\an1}Even now, it's very rare
to see her sick.

357
00:19:12,700 --> 00:19:15,300
{\an1}So I think that me and my mom
are a lot the same.

358
00:19:15,333 --> 00:19:17,300
{\an8}♪♪

359
00:19:17,333 --> 00:19:21,633
{\an1}-When mothers pass down
antibodies to their fetuses,

360
00:19:21,666 --> 00:19:24,200
{\an1}this is called passive immunity.

361
00:19:24,233 --> 00:19:26,200
{\an1}And this is really important

362
00:19:26,233 --> 00:19:28,800
{\an1}to protect their fetuses
and their newborn babies

363
00:19:28,833 --> 00:19:31,500
{\an1}when their immune systems
are still developing.

364
00:19:31,533 --> 00:19:34,666
{\an8}♪♪

365
00:19:34,700 --> 00:19:37,466
{\an1}-Along with all the nutrients
that a baby gets

366
00:19:37,500 --> 00:19:40,966
{\an1}from its mother in the womb,
it also absorbs her antibodies.

367
00:19:41,000 --> 00:19:43,400
{\an1}These chemicals are leftovers
from infections

368
00:19:43,433 --> 00:19:45,566
that she's fought
throughout her life.

369
00:19:45,600 --> 00:19:49,333
{\an1}And miraculously, she's able
to pass this protection on

370
00:19:49,366 --> 00:19:52,066
to her child
through the placenta...

371
00:19:53,866 --> 00:19:58,133
{\an1}...even if the infection
happened decades ago.

372
00:19:58,166 --> 00:20:00,400
{\an1}A baby won't be immune
to everything,

373
00:20:00,433 --> 00:20:04,233
{\an1}but enough to keep it safe for
the first period of its life.

374
00:20:04,266 --> 00:20:07,566
{\an1}After a few months,
those antibodies start to fade

375
00:20:07,600 --> 00:20:11,766
{\an1}as the baby encounters
different microbes...

376
00:20:11,800 --> 00:20:14,300
{\an1}and learns to fend for itself.

377
00:20:14,333 --> 00:20:16,800
{\an8}♪♪

378
00:20:16,833 --> 00:20:19,966
{\an1}What we encounter and when
is a huge part

379
00:20:20,000 --> 00:20:23,633
{\an1}of why everyone's immune system
is different.

380
00:20:24,733 --> 00:20:28,600
{\an1}-The longer I practice medicine,
the more I believe that nature

381
00:20:28,633 --> 00:20:32,733
{\an1}is less significant than nurture
for most diseases.

382
00:20:32,766 --> 00:20:35,266
{\an1}And the really great thing here

383
00:20:35,300 --> 00:20:39,766
{\an1}is that a lot of these factors
are under our control.

384
00:20:39,800 --> 00:20:42,400
{\an1}-I was raised on a ranch.

385
00:20:42,433 --> 00:20:47,500
{\an7}We would always be around cows,
pigs, chickens, sheep --

386
00:20:47,533 --> 00:20:48,666
{\an8}you name it.

387
00:20:48,700 --> 00:20:52,333
{\an8}♪♪

388
00:20:52,366 --> 00:20:54,600
{\an1}-During childhood,
our bodies come in contact

389
00:20:54,633 --> 00:20:57,566
{\an1}with all the microbes
in our surrounding world.

390
00:20:57,600 --> 00:21:00,233
{\an1}And our immune system
will see this and say,

391
00:21:00,266 --> 00:21:03,633
{\an1}"I'm gonna remember
that foreigner."

392
00:21:03,666 --> 00:21:06,066
{\an1}-It's the same as building
a muscle.

393
00:21:06,100 --> 00:21:10,233
{\an1}If you don't flex it,
it won't get stronger.

394
00:21:10,266 --> 00:21:12,933
{\an1}When a young body has to defend
against something,

395
00:21:12,966 --> 00:21:16,266
{\an1}cells release antibodies
that kill the threat.

396
00:21:16,300 --> 00:21:19,500
{\an1}Other cells then remember
how to make that antibody

397
00:21:19,533 --> 00:21:21,866
{\an1}so that if the same bug
comes back,

398
00:21:21,900 --> 00:21:24,266
{\an1}it can be killed instantly.

399
00:21:24,300 --> 00:21:26,766
{\an1}These are the same antibodies

400
00:21:26,800 --> 00:21:30,133
{\an1}that might one day be passed
down to the next generation.

401
00:21:30,166 --> 00:21:33,133
{\an1}-So the training early on is
the immune system says, "Okay.

402
00:21:33,166 --> 00:21:34,900
This is nothing.
We can just ignore this.

403
00:21:34,933 --> 00:21:36,766
{\an1}Ooh. This is super serious.
Red alert.

404
00:21:36,800 --> 00:21:38,600
{\an1}We really need to do something
about this."

405
00:21:38,633 --> 00:21:42,866
{\an1}And this training seems to be
really essential.

406
00:21:42,900 --> 00:21:44,866
{\an1}[ Frogs, insects chirping ]

407
00:21:44,900 --> 00:21:51,900
{\an8}♪♪

408
00:21:51,933 --> 00:21:56,600
{\an1}-Kids who spend time in nature
seem to have an advantage.

409
00:21:56,633 --> 00:22:02,600
{\an8}♪♪

410
00:22:02,633 --> 00:22:05,633
{\an1}-I'm part of an escaramuza team.

411
00:22:05,666 --> 00:22:08,500
Escaramuza --
I could describe that as, like,

412
00:22:08,533 --> 00:22:11,500
{\an1}the Mexican rodeo.

413
00:22:11,533 --> 00:22:14,133
{\an1}It's kind of like a dance
with eight girls

414
00:22:14,166 --> 00:22:17,166
{\an1}riding on top of a horse.

415
00:22:17,200 --> 00:22:19,633
{\an1}You're turning, you're spinning
within each other

416
00:22:19,666 --> 00:22:21,100
{\an1}and things like that.

417
00:22:21,133 --> 00:22:24,600
{\an8}♪♪

418
00:22:24,633 --> 00:22:27,800
{\an1}A horse isn't born
to do all this,

419
00:22:27,833 --> 00:22:29,800
{\an1}so everybody has to be
super focused

420
00:22:29,833 --> 00:22:32,266
{\an1}and have good control
of their horse.

421
00:22:32,300 --> 00:22:35,266
{\an8}♪♪

422
00:22:35,300 --> 00:22:37,933
{\an1}[ Indistinct conversations ]

423
00:22:37,966 --> 00:22:40,566
It's very rare
for me to get sick.

424
00:22:40,600 --> 00:22:42,800
{\an1}And if I do get sick,
like, with a cold,

425
00:22:42,833 --> 00:22:44,500
{\an1}it'll last one or two days.

426
00:22:44,533 --> 00:22:47,300
{\an8}♪♪

427
00:22:47,333 --> 00:22:48,966
As to my sister,

428
00:22:49,000 --> 00:22:50,933
she'll be in bed
for like two weeks.

429
00:22:50,966 --> 00:22:53,933
{\an1}You know, she's --
It hits her hard.

430
00:22:53,966 --> 00:22:57,000
{\an8}♪♪

431
00:22:57,033 --> 00:23:00,233
{\an1}-When I was in high school,
I did get sick.

432
00:23:00,266 --> 00:23:02,266
{\an1}I stayed home for like a month,

433
00:23:02,300 --> 00:23:04,766
{\an1}I think I had, like,
a respiratory virus.

434
00:23:04,800 --> 00:23:07,766
It was not fun.

435
00:23:07,800 --> 00:23:11,266
{\an1}-Kids who are not exposed
to enough germs early on

436
00:23:11,300 --> 00:23:13,133
{\an1}are really at a disadvantage

437
00:23:13,166 --> 00:23:15,433
{\an1}and are at a higher risk
for developing disease

438
00:23:15,466 --> 00:23:17,900
{\an1}because their immune system
doesn't know what to do

439
00:23:17,933 --> 00:23:19,900
{\an1}when it sees something later on.

440
00:23:19,933 --> 00:23:22,933
{\an8}♪♪

441
00:23:22,966 --> 00:23:26,500
{\an1}-As we age, the training that
happens in our immune system

442
00:23:26,533 --> 00:23:29,266
{\an1}involves a wide range
of different cells

443
00:23:29,300 --> 00:23:31,133
{\an1}with different jobs.

444
00:23:31,166 --> 00:23:35,900
{\an1}But there's one type of cell
that carries most of the weight.

445
00:23:35,933 --> 00:23:37,966
{\an8}♪♪

446
00:23:38,000 --> 00:23:42,733
{\an1}-T cells are the powerhouse
cells of our immune system.

447
00:23:42,766 --> 00:23:46,800
{\an1}They help make antibodies
against other diseases.

448
00:23:46,833 --> 00:23:48,733
{\an1}They work with signaling
to other parts

449
00:23:48,766 --> 00:23:49,966
{\an1}of the immune system.

450
00:23:50,000 --> 00:23:54,233
{\an1}They can kill cells that are bad
on their own.

451
00:23:54,266 --> 00:23:55,800
{\an1}They also can remember things --

452
00:23:55,833 --> 00:23:58,200
{\an1}so they have a memory component
to them, too --

453
00:23:58,233 --> 00:24:01,566
{\an1}to prevent future infections
or diseases.

454
00:24:01,600 --> 00:24:04,066
{\an8}♪♪

455
00:24:04,100 --> 00:24:08,433
{\an1}-Like all blood, these cells
are born in the bone marrow.

456
00:24:08,466 --> 00:24:11,700
Then they migrate
to the thymus gland.

457
00:24:11,733 --> 00:24:15,833
{\an1}It's here that T cells
go through serious training

458
00:24:15,866 --> 00:24:18,566
and they pick up
different skills.

459
00:24:18,600 --> 00:24:23,100
{\an1}Some T cells leave the thymus
as assassins.

460
00:24:23,133 --> 00:24:26,966
{\an1}Others come out as intelligence,
capable of remembering a virus

461
00:24:27,000 --> 00:24:30,833
{\an1}for fast detection
and fast execution.

462
00:24:32,266 --> 00:24:36,566
{\an1}Because of all this action,
the thymus is larger in kids,

463
00:24:36,600 --> 00:24:40,166
and it peaks
in our teenage years.

464
00:24:40,200 --> 00:24:42,600
{\an8}♪♪

465
00:24:42,633 --> 00:24:45,300
{\an1}-What I love about being here
the most

466
00:24:45,333 --> 00:24:47,233
is the bonding
with the horses...

467
00:24:47,266 --> 00:24:50,466
{\an8}♪♪

468
00:24:50,500 --> 00:24:54,300
{\an1}...grooming him, washing him...

469
00:24:55,433 --> 00:24:57,966
{\an1}...sweeping, mopping.

470
00:24:58,000 --> 00:25:01,666
{\an1}By the end of the day,
I'm extremely dirty.

471
00:25:01,700 --> 00:25:03,966
{\an1}My sweat, the horses' sweat --

472
00:25:04,000 --> 00:25:07,033
{\an1}It's a very messy job,
but I love it.

473
00:25:07,066 --> 00:25:10,166
{\an8}♪♪

474
00:25:10,200 --> 00:25:14,133
{\an1}-I see so many parallels between
the animal kingdom and us.

475
00:25:14,166 --> 00:25:16,300
And I see that
as we differentiate ourself

476
00:25:16,333 --> 00:25:17,466
more and more,

477
00:25:17,500 --> 00:25:19,833
{\an1}we're actually getting sicker
and sicker.

478
00:25:19,866 --> 00:25:24,233
{\an1}So I try to look at what's
going on in the natural world

479
00:25:24,266 --> 00:25:26,533
{\an1}and what animals do.

480
00:25:28,366 --> 00:25:30,233
{\an1}Horses take dirt baths

481
00:25:30,266 --> 00:25:32,166
because there are
ammonia-oxidizing bacteria

482
00:25:32,200 --> 00:25:33,466
in the dirt

483
00:25:33,500 --> 00:25:37,500
{\an1}that can neutralize the sweat
and help clean them.

484
00:25:37,533 --> 00:25:39,166
Getting out
and getting sweaty --

485
00:25:39,200 --> 00:25:42,000
{\an1}all the things that seem to work
so well in the animal kingdom,

486
00:25:42,033 --> 00:25:44,333
{\an1}I think work really well for us
as humans.

487
00:25:44,366 --> 00:25:51,033
{\an8}♪♪

488
00:25:51,066 --> 00:25:56,333
{\an1}-Exposure to animals can give
the young immune system a boost.

489
00:25:56,366 --> 00:25:58,733
[ Bats chirping ]

490
00:25:58,766 --> 00:26:01,066
{\an1}But it's a double-edged sword.

491
00:26:01,100 --> 00:26:02,900
{\an1}Animals are also the source

492
00:26:02,933 --> 00:26:06,700
{\an1}of some of our most
devastating diseases.

493
00:26:06,733 --> 00:26:10,100
{\an1}-Zoonotic diseases
come in many shapes and sizes,

494
00:26:10,133 --> 00:26:13,100
{\an1}and some are really,
really creepy.

495
00:26:13,133 --> 00:26:15,366
{\an1}What happens is you have
an animal host

496
00:26:15,400 --> 00:26:17,966
{\an1}and then something
that transmits it to a human.

497
00:26:18,000 --> 00:26:21,033
{\an1}It could be, like, a spider
or a mosquito.

498
00:26:21,066 --> 00:26:23,566
This represents
a huge public-health threat

499
00:26:23,600 --> 00:26:26,433
{\an1}that could get a lot worse
in the future.

500
00:26:26,466 --> 00:26:34,433
{\an1}-The bubonic plague, malaria,
swine flu, Zika, COVID-19 --

501
00:26:34,466 --> 00:26:36,500
Many of our
most lethal outbreaks

502
00:26:36,533 --> 00:26:38,766
{\an1}can be traced to wildlife.

503
00:26:40,466 --> 00:26:43,700
{\an1}And how close we live to animals
and to each other

504
00:26:43,733 --> 00:26:45,700
{\an1}plays a huge role.

505
00:26:45,733 --> 00:26:48,700
{\an1}That's something that
wasn't true for our ancestors.

506
00:26:48,733 --> 00:26:51,800
{\an1}-If you look at foraging people
or hunter-gatherers and stuff,

507
00:26:51,833 --> 00:26:55,033
{\an1}the significance of infectious
disease is relatively low.

508
00:26:55,066 --> 00:26:57,200
Today you have
a lot of individuals

509
00:26:57,233 --> 00:27:01,166
{\an1}that live in very large groups
that are in close proximity

510
00:27:01,200 --> 00:27:03,200
{\an1}and often interacting
with each other.

511
00:27:03,233 --> 00:27:06,533
{\an1}Then that
<i>does</i> 
breed conditions
for pandemic disease.

512
00:27:07,766 --> 00:27:09,633
{\an1}-As our population grows,

513
00:27:09,666 --> 00:27:12,933
{\an1}outbreaks are becoming
more frequent.

514
00:27:14,700 --> 00:27:18,433
{\an1}If hindsight is 20/20,
what can we learn from those

515
00:27:18,466 --> 00:27:24,266
{\an1}who faced past plagues
and lived to tell the tale?

516
00:27:24,300 --> 00:27:30,233
{\an8}♪♪

517
00:27:30,266 --> 00:27:34,200
{\an1}-I had a sense of being
out of my body.

518
00:27:34,233 --> 00:27:36,866
{\an1}[ Monitor beeping ]

519
00:27:36,900 --> 00:27:41,300
I was feverish,
had joint aches and pains,

520
00:27:41,333 --> 00:27:43,600
{\an1}copious vomiting and diarrhea.

521
00:27:44,633 --> 00:27:46,800
{\an1}I didn't realize how sick I felt

522
00:27:46,833 --> 00:27:51,200
{\an1}until my mother came to
the isolation center to see me

523
00:27:51,233 --> 00:27:54,533
{\an1}and she said I looked like
I was a zombie.

524
00:27:54,566 --> 00:27:57,433
{\an8}♪♪

525
00:27:57,466 --> 00:27:58,900
{\an7}My name is Adaora Okoli.

526
00:27:58,933 --> 00:28:02,766
{\an7}I'm a medical doctor entrusted
in infectious diseases,

527
00:28:02,800 --> 00:28:06,500
{\an7}and I survived Ebola in 2014.

528
00:28:06,533 --> 00:28:09,633
{\an8}♪♪

529
00:28:09,666 --> 00:28:14,966
-Viruses cause
millions of deaths every year,

530
00:28:15,000 --> 00:28:17,200
but most of them
come from diseases

531
00:28:17,233 --> 00:28:20,866
{\an1}that we are familiar with,
like the flu or HIV.

532
00:28:20,900 --> 00:28:24,533
So when a disease
that's been lurking quietly

533
00:28:24,566 --> 00:28:25,866
{\an1}in an obscure cave

534
00:28:25,900 --> 00:28:28,533
{\an1}suddenly jumps to a human
and starts to spread,

535
00:28:28,566 --> 00:28:31,000
{\an1}it's cause for alarm.

536
00:28:31,033 --> 00:28:33,633
{\an8}♪♪

537
00:28:33,666 --> 00:28:38,000
{\an7}Especially if it happens in
a place with limited resources.

538
00:28:38,033 --> 00:28:40,733
{\an1}[ Indistinct conversations,
vehicles passing ]

539
00:28:40,766 --> 00:28:44,800
{\an1}-Growing up in Nigeria,
I fell in love with medicine

540
00:28:44,833 --> 00:28:48,400
{\an1}and the idea of helping people.

541
00:28:48,433 --> 00:28:53,766
{\an1}A lot of people really didn't
have access to healthcare.

542
00:28:53,800 --> 00:28:55,700
If you were in
an emergency situation

543
00:28:55,733 --> 00:28:57,666
{\an1}and you didn't have the money
to pay,

544
00:28:57,700 --> 00:29:00,000
{\an1}you couldn't see the doctor.

545
00:29:00,033 --> 00:29:04,466
{\an1}I felt that, you know, being
a doctor would to be on the side

546
00:29:04,500 --> 00:29:07,533
{\an1}where I could be actually able
to help people.

547
00:29:08,766 --> 00:29:10,900
{\an1}When I finished medical school,

548
00:29:10,933 --> 00:29:13,700
I started working
as a medical officer.

549
00:29:13,733 --> 00:29:16,633
{\an1}And it was during that time
that the Ebola outbreak struck

550
00:29:16,666 --> 00:29:18,166
in West Africa.

551
00:29:18,200 --> 00:29:21,100
{\an8}♪♪

552
00:29:21,133 --> 00:29:25,200
{\an1}-The Ebola virus has already
killed over 3,000 people

553
00:29:25,233 --> 00:29:26,566
{\an1}across West Africa.

554
00:29:26,600 --> 00:29:28,100
-A growing number
of health workers

555
00:29:28,133 --> 00:29:30,133
{\an1}are falling victim
of the disease,

556
00:29:30,166 --> 00:29:33,333
{\an1}adding yet more pressure to
an epidemic the WHO has called

557
00:29:33,366 --> 00:29:36,233
the most severe
acute public-health emergency

558
00:29:36,266 --> 00:29:38,266
in modern times.

559
00:29:38,300 --> 00:29:41,566
{\an1}-Although deadly outbreaks
end up being remembered

560
00:29:41,600 --> 00:29:43,266
as epic battles,

561
00:29:43,300 --> 00:29:46,966
{\an1}every major epidemic that has
brought humanity to its knees

562
00:29:47,000 --> 00:29:51,333
{\an1}can be traced back to something
imperceptibly small.

563
00:29:52,800 --> 00:29:55,333
{\an1}-There are some pathogens
which are really aggressive

564
00:29:55,366 --> 00:29:57,666
or dangerous,
and a lot of it has to do with

565
00:29:57,700 --> 00:30:00,633
{\an1}their mechanism of action
or how they attack our bodies.

566
00:30:00,666 --> 00:30:04,033
{\an8}♪♪

567
00:30:04,066 --> 00:30:07,233
{\an1}-A cell is, you know,
most simply speaking,

568
00:30:07,266 --> 00:30:10,233
{\an1}the basic unit of life.

569
00:30:10,266 --> 00:30:13,166
{\an1}It's the smallest functional
unit that life can be.

570
00:30:13,200 --> 00:30:17,433
{\an1}You could argue that viruses
are a little smaller.

571
00:30:17,466 --> 00:30:20,633
{\an1}-A virus is this little
biological agent

572
00:30:20,666 --> 00:30:25,366
{\an1}that has one central goal --
to get inside of cells,

573
00:30:25,400 --> 00:30:28,800
reproduce itself,
and then spread to another host.

574
00:30:28,833 --> 00:30:32,400
{\an1}And along the way,
it can cause a lot of damage.

575
00:30:32,433 --> 00:30:37,300
{\an1}-Viruses emerged from the ether
about 1.5 billion years ago.

576
00:30:37,333 --> 00:30:39,633
{\an8}♪♪

577
00:30:39,666 --> 00:30:42,133
And the fact that
they've been around so long

578
00:30:42,166 --> 00:30:46,266
{\an1}means they're really good
at what they do.

579
00:30:46,300 --> 00:30:48,766
{\an1}When a virus enters
a host cell...

580
00:30:48,800 --> 00:30:52,666
{\an8}♪♪

581
00:30:52,700 --> 00:30:56,733
{\an1}...it hijacks it, causing it
to spit out copy after copy

582
00:30:56,766 --> 00:30:58,700
{\an1}of new virus particles

583
00:30:58,733 --> 00:31:02,500
{\an1}that burst out of the cell
into the bloodstream.

584
00:31:02,533 --> 00:31:07,900
{\an8}♪♪

585
00:31:07,933 --> 00:31:12,000
{\an1}A virus doesn't just want to
colonize that single host.

586
00:31:12,033 --> 00:31:15,733
{\an1}It wants to spread
through populations.

587
00:31:15,766 --> 00:31:19,033
{\an1}-What made the 2014 outbreak
of Ebola widespread

588
00:31:19,066 --> 00:31:22,366
{\an1}and so dangerous is people
were contracting the disease

589
00:31:22,400 --> 00:31:23,800
{\an1}without even knowing it.

590
00:31:23,833 --> 00:31:26,633
{\an1}And by that time, there were
land crossings happening

591
00:31:26,666 --> 00:31:28,733
{\an1}between Guinea, Liberia,
Sierra Leone,

592
00:31:28,766 --> 00:31:30,766
and the disease
built a community base

593
00:31:30,800 --> 00:31:33,133
{\an1}and was spreading before
any alarms went off.

594
00:31:33,166 --> 00:31:35,133
{\an8}♪♪

595
00:31:35,166 --> 00:31:38,733
{\an1}-And that type of growth
gets out of hand quickly.

596
00:31:40,433 --> 00:31:43,700
Say you start
with one sick person.

597
00:31:43,733 --> 00:31:46,800
{\an1}If that number doubles
every three days,

598
00:31:46,833 --> 00:31:49,766
{\an1}you're gonna end up with
67 million infections

599
00:31:49,800 --> 00:31:52,300
{\an1}in under three months.

600
00:31:53,733 --> 00:31:56,733
{\an1}-On the 20th of July 2014,

601
00:31:56,766 --> 00:31:59,733
I was working in
a private hospital in Nigeria,

602
00:31:59,766 --> 00:32:03,100
{\an1}and a Liberian diplomat
was wheeled into the hospital

603
00:32:03,133 --> 00:32:06,300
{\an1}with mysterious symptoms.

604
00:32:06,333 --> 00:32:07,866
{\an1}And when I saw him in bed,

605
00:32:07,900 --> 00:32:10,533
he had his IV bag
right next to him.

606
00:32:10,566 --> 00:32:13,366
{\an1}So the first thing I did
was pick up the IV bag

607
00:32:13,400 --> 00:32:15,633
{\an1}and put it back on the stand.

608
00:32:16,600 --> 00:32:21,700
{\an1}And that might have been the
route of entry into my system.

609
00:32:21,733 --> 00:32:24,300
{\an8}♪♪

610
00:32:24,333 --> 00:32:26,933
{\an1}Twenty-four hours later,
I got a call.

611
00:32:26,966 --> 00:32:30,033
{\an1}The patient had tested positive.
He had Ebola.

612
00:32:30,066 --> 00:32:33,300
{\an1}And 24 hours after we had
the result,

613
00:32:33,333 --> 00:32:35,933
{\an1}the patient was found dead
in his bedroom.

614
00:32:37,366 --> 00:32:42,033
{\an1}At that point, the fear was more
than we could handle.

615
00:32:42,066 --> 00:32:44,700
{\an1}It could be any of us
the next day.

616
00:32:44,733 --> 00:32:47,266
{\an8}♪♪

617
00:32:47,300 --> 00:32:51,066
{\an1}-Ebola is an incredibly
infectious disease.

618
00:32:51,100 --> 00:32:53,633
{\an1}That means that in every drop
of infected fluid,

619
00:32:53,666 --> 00:32:57,133
{\an1}there are millions
of viral particles.

620
00:32:57,166 --> 00:33:00,866
{\an1}So if you come into contact
with someone who has it,

621
00:33:00,900 --> 00:33:04,400
{\an1}it takes almost nothing
to start an infection.

622
00:33:05,733 --> 00:33:10,866
{\an1}-Shortly after that, I started
to have joint aches and pain,

623
00:33:10,900 --> 00:33:13,700
{\an1}sore throat, loss of appetite.

624
00:33:13,733 --> 00:33:18,266
{\an1}Yeah, I was feverish,
I had vomiting and diarrhea.

625
00:33:18,300 --> 00:33:21,633
{\an1}And I thought, "This is it.

626
00:33:21,666 --> 00:33:23,533
{\an1}This is really it."

627
00:33:25,166 --> 00:33:28,633
{\an1}-A virus like Ebola
is extremely lethal

628
00:33:28,666 --> 00:33:31,666
because Ebola
is specifically designed

629
00:33:31,700 --> 00:33:33,033
{\an1}to evade our immune system

630
00:33:33,066 --> 00:33:35,500
{\an1}and even mess with
cell signaling in our bodies.

631
00:33:35,533 --> 00:33:38,000
{\an1}It basically can hijack a ride

632
00:33:38,033 --> 00:33:40,433
{\an1}throughout our lymphatic
and bloodstream,

633
00:33:40,466 --> 00:33:42,700
{\an1}infect our bodies,
and it's way too late

634
00:33:42,733 --> 00:33:46,266
{\an1}when our immune systems finally
pick up on what's happening.

635
00:33:48,100 --> 00:33:51,500
{\an1}-Ebola's assault is merciless.

636
00:33:51,533 --> 00:33:53,966
It attacks the
gastrointestinal tract,

637
00:33:54,000 --> 00:33:56,766
causing diarrhea
and dehydration.

638
00:33:56,800 --> 00:33:58,566
{\an1}It attacks the kidneys,

639
00:33:58,600 --> 00:34:02,100
{\an1}which make it more difficult
for the body to produce plasma.

640
00:34:02,133 --> 00:34:05,133
And finally,
the virus releases proteins

641
00:34:05,166 --> 00:34:07,600
{\an1}that damage the lining
of blood vessels,

642
00:34:07,633 --> 00:34:10,033
{\an1}which then start to leak.

643
00:34:11,166 --> 00:34:14,000
{\an1}That's why this disease has
a reputation of causing victims

644
00:34:14,033 --> 00:34:16,700
{\an1}to bleed from every orifice.

645
00:34:17,800 --> 00:34:22,133
{\an1}The blood-vessel damage leads
to a drop in blood pressure,

646
00:34:22,166 --> 00:34:25,000
{\an1}multiple organ failure
follows...

647
00:34:25,033 --> 00:34:27,600
then death.

648
00:34:27,633 --> 00:34:33,266
{\an8}♪♪

649
00:34:33,300 --> 00:34:35,866
-I was led
to the isolation center.

650
00:34:35,900 --> 00:34:39,400
{\an1}It was a dark room.

651
00:34:39,433 --> 00:34:43,266
{\an1}It was an abandoned building
that hadn't been used for years.

652
00:34:43,300 --> 00:34:45,433
{\an8}♪♪

653
00:34:45,466 --> 00:34:48,666
{\an1}Every Ebola patient has a moment
of denial

654
00:34:48,700 --> 00:34:52,100
{\an1}because nine out of ten people
who have Ebola die.

655
00:34:52,133 --> 00:34:54,566
What are the odds

656
00:34:54,600 --> 00:34:58,466
{\an1}that I would be the one
out of ten who would survive?

657
00:34:59,700 --> 00:35:02,633
{\an1}But I was using my clinical
knowledge at the time

658
00:35:02,666 --> 00:35:03,900
as a doctor.

659
00:35:03,933 --> 00:35:06,700
{\an1}What kills people is
when they lose so much fluid

660
00:35:06,733 --> 00:35:09,466
{\an1}and their system becomes
overwhelmed with the virus,

661
00:35:09,500 --> 00:35:11,433
{\an1}which has replicated.

662
00:35:11,466 --> 00:35:12,966
{\an1}That's when they die.

663
00:35:13,000 --> 00:35:14,533
{\an1}So I thought to myself,

664
00:35:14,566 --> 00:35:17,466
{\an1}"I have to really drink
this oral rehydration solution."

665
00:35:17,500 --> 00:35:20,300
{\an1}I had a bottle in my hand
every time.

666
00:35:20,333 --> 00:35:23,300
{\an1}Even when I was asleep,
I had a bottle right next to me.

667
00:35:23,333 --> 00:35:27,266
{\an1}Just in case I vomited,
I could replace my fluids.

668
00:35:27,300 --> 00:35:29,700
{\an1}I could only hope that my immune
system was strong enough

669
00:35:29,733 --> 00:35:31,333
{\an1}to fight the virus.

670
00:35:33,000 --> 00:35:38,000
{\an1}-Even on its last legs, our
immune system keeps fighting.

671
00:35:38,033 --> 00:35:42,233
T cells hone in
on Ebola-infected cells.

672
00:35:42,266 --> 00:35:45,600
{\an1}They bind to the surface
and release toxins

673
00:35:45,633 --> 00:35:49,400
{\an1}that travel through the cell's
membrane and kill them.

674
00:35:49,433 --> 00:35:52,233
{\an8}♪♪

675
00:35:52,266 --> 00:35:54,366
Other cells fire
chemical missiles

676
00:35:54,400 --> 00:35:59,100
{\an1}in the form of antibodies
to stop the virus in its tracks.

677
00:35:59,133 --> 00:36:01,533
{\an1}As the immune systems gain
the upper hand,

678
00:36:01,566 --> 00:36:04,666
{\an1}the body's systems
come back online.

679
00:36:05,900 --> 00:36:09,400
{\an1}And damaged tissue starts
to heal.

680
00:36:09,433 --> 00:36:13,700
{\an1}-Most people who survived
usually got better

681
00:36:13,733 --> 00:36:16,900
{\an1}after seven days or so,
and so it was a matter of time.

682
00:36:16,933 --> 00:36:21,300
{\an8}♪♪

683
00:36:21,333 --> 00:36:22,700
After five days,

684
00:36:22,733 --> 00:36:27,000
{\an1}I noticed that my symptoms
were starting to get better.

685
00:36:27,033 --> 00:36:31,133
{\an1}Fourteen days later,
my blood sample tested negative.

686
00:36:31,166 --> 00:36:35,066
{\an1}And that was -- It was
the happiest day of my life.

687
00:36:35,100 --> 00:36:37,100
{\an8}♪♪

688
00:36:37,133 --> 00:36:39,533
{\an1}It was like being born again.

689
00:36:39,566 --> 00:36:41,633
It was a rebirth.

690
00:36:42,400 --> 00:36:45,533
{\an8}♪♪

691
00:36:45,566 --> 00:36:47,500
{\an1}-The Ebola outbreak in 2014

692
00:36:47,533 --> 00:36:50,000
was eventually
brought under control

693
00:36:50,033 --> 00:36:53,066
{\an1}when we had international
efforts to understand

694
00:36:53,100 --> 00:36:55,600
{\an1}quarantining people
who were affected

695
00:36:55,633 --> 00:36:58,466
{\an1}and help prevent the spread
of future cases.

696
00:36:58,500 --> 00:37:02,566
{\an1}-And that's because what
we think of as Ebola's strength

697
00:37:02,600 --> 00:37:05,533
{\an1}is actually its weakness.

698
00:37:05,566 --> 00:37:08,166
{\an1}It's so deadly that victims die

699
00:37:08,200 --> 00:37:12,133
{\an1}before infecting enough people
for it to spread widely.

700
00:37:12,166 --> 00:37:14,300
{\an8}♪♪

701
00:37:14,333 --> 00:37:16,100
{\an1}The thing about viruses

702
00:37:16,133 --> 00:37:19,366
{\an1}is that they actually want you
to stay alive.

703
00:37:19,400 --> 00:37:20,700
{\an1}[ Monitor beeping ]

704
00:37:20,733 --> 00:37:24,733
{\an1}A virus like COVID-19
is ultimately more lethal

705
00:37:24,766 --> 00:37:27,133
{\an1}because its victims stay alive
long enough

706
00:37:27,166 --> 00:37:29,533
{\an1}for it to spread like wildfire.

707
00:37:29,566 --> 00:37:31,533
[ Flatline ]

708
00:37:31,566 --> 00:37:33,266
{\an8}♪♪

709
00:37:33,300 --> 00:37:38,933
{\an1}But the really terrifying
pandemic is likely yet to come.

710
00:37:40,333 --> 00:37:41,933
{\an1}-It's starting to seem as though

711
00:37:41,966 --> 00:37:44,166
{\an1}we're having emergencies
after emergencies

712
00:37:44,200 --> 00:37:47,733
and we are seeing
the same things replicate,

713
00:37:47,766 --> 00:37:50,100
{\an1}the same things happen.

714
00:37:51,100 --> 00:37:52,700
{\an1}Viruses do not wait.

715
00:37:52,733 --> 00:37:54,700
{\an8}♪♪

716
00:37:54,733 --> 00:37:56,866
-In the future,
we could see a virus

717
00:37:56,900 --> 00:38:02,600
{\an1}that is as lethal as Ebola
and as contagious as COVID-10.

718
00:38:02,633 --> 00:38:05,433
[ Bell clanging ]

719
00:38:05,466 --> 00:38:07,300
{\an8}For Dr. Okoli,

720
00:38:07,333 --> 00:38:10,400
{\an7}her firsthand experience
with the horror of Ebola

721
00:38:10,433 --> 00:38:12,366
{\an7}caused her to shift focus

722
00:38:12,400 --> 00:38:15,633
{\an8}towards fighting
future epidemics.

723
00:38:15,666 --> 00:38:19,333
{\an1}-Since surviving Ebola,
I came to New Orleans

724
00:38:19,366 --> 00:38:23,000
{\an1}training in internal medicine
at Tulane University.

725
00:38:24,066 --> 00:38:26,100
{\an1}Hi. Good afternoon.
-Hi.

726
00:38:26,133 --> 00:38:27,933
-I'm Dr. Okoli.

727
00:38:27,966 --> 00:38:29,666
{\an1}What brings you to the hospital
today?

728
00:38:29,700 --> 00:38:31,166
{\an1}-I've been having a dry cough,

729
00:38:31,200 --> 00:38:32,966
{\an1}and it's been coming in
at night.

730
00:38:33,000 --> 00:38:35,933
{\an1}-I have shifted my focus
towards infectious disease

731
00:38:35,966 --> 00:38:38,200
{\an1}and global health advocacy...

732
00:38:39,500 --> 00:38:42,400
{\an1}...specifically looking at how
we can reduce the burden

733
00:38:42,433 --> 00:38:45,033
{\an1}of infectious diseases
in low-income communities.

734
00:38:45,066 --> 00:38:46,766
{\an1}We're in an age now

735
00:38:46,800 --> 00:38:50,666
{\an1}where viruses do not respect
geographical locations,

736
00:38:50,700 --> 00:38:54,466
{\an1}they do not respect race,
they don't respect age.

737
00:38:54,500 --> 00:38:56,766
{\an8}♪♪

738
00:38:56,800 --> 00:39:00,333
{\an1}We're in a world and a time
when people are mobile,

739
00:39:00,366 --> 00:39:02,566
{\an1}and all it takes is one person
to hop into a plane

740
00:39:02,600 --> 00:39:06,166
{\an1}and fly thousands of miles away.

741
00:39:06,200 --> 00:39:10,533
{\an8}♪♪

742
00:39:10,566 --> 00:39:13,533
{\an1}It's no longer them and us.

743
00:39:14,966 --> 00:39:17,666
{\an1}We're all in this together.

744
00:39:19,633 --> 00:39:21,600
{\an8}♪♪

745
00:39:21,633 --> 00:39:25,333
{\an1}-The destruction from an
epidemic can have ripple effects

746
00:39:25,366 --> 00:39:28,466
across continents
and generations.

747
00:39:28,500 --> 00:39:31,933
{\an1}But given how many bugs
are floating around in nature,

748
00:39:31,966 --> 00:39:35,166
these events
are still pretty rare.

749
00:39:35,200 --> 00:39:37,900
In fact,
there's a lot more danger

750
00:39:37,933 --> 00:39:42,366
{\an1}potentially lurking
within our own cells.

751
00:39:42,400 --> 00:39:45,866
{\an1}-Something that's just starting
to become understood

752
00:39:45,900 --> 00:39:50,866
{\an1}is why does the immune system
sometimes attack our own bodies

753
00:39:50,900 --> 00:39:54,300
{\an1}instead of threats
that come from outside?

754
00:39:54,333 --> 00:39:56,266
{\an1}Why is it that our immune system

755
00:39:56,300 --> 00:40:00,866
is not good
at recognizing cancer?

756
00:40:00,900 --> 00:40:04,066
{\an1}Why do our own cells
sometimes go off script?

757
00:40:05,933 --> 00:40:08,933
{\an1}-The immune system has to
constantly strike a balance

758
00:40:08,966 --> 00:40:10,766
{\an1}between killing intruders

759
00:40:10,800 --> 00:40:14,233
{\an1}without damaging the body
in the process.

760
00:40:14,266 --> 00:40:17,566
{\an1}And when the threat
comes from our own cells,

761
00:40:17,600 --> 00:40:20,100
{\an1}that job gets even harder.

762
00:40:21,500 --> 00:40:23,700
{\an1}So now the cutting edge
of immune science

763
00:40:23,733 --> 00:40:26,366
{\an1}is a quest to understand
how we can harness

764
00:40:26,400 --> 00:40:28,700
{\an1}the power of the immune system

765
00:40:28,733 --> 00:40:32,933
{\an1}when it's our own bodies
who are the enemy.

766
00:40:32,966 --> 00:40:37,500
{\an8}♪♪

767
00:40:37,533 --> 00:40:40,633
{\an1}-The only thing I remember
is going into the hospital,

768
00:40:40,666 --> 00:40:43,200
{\an1}them putting me to sleep,
and then waking up

769
00:40:43,233 --> 00:40:47,533
{\an1}to needles and tubes
and machines all around me.

770
00:40:48,866 --> 00:40:51,233
{\an1}I just remember my mom crying
on the side of the bed

771
00:40:51,266 --> 00:40:53,600
and saying, like,
"You have cancer."

772
00:40:53,633 --> 00:40:55,800
{\an8}♪♪

773
00:40:55,833 --> 00:40:59,200
{\an1}And to an 8-year-old, I wasn't
really sure what cancer is.

774
00:41:01,033 --> 00:41:03,133
{\an7}My name is Milton Wright.

775
00:41:03,166 --> 00:41:07,633
{\an7}I'm 26 years old, and I'm
a three-time cancer survivor.

776
00:41:09,233 --> 00:41:11,333
{\an1}I'm an active person.

777
00:41:11,366 --> 00:41:14,033
{\an1}I am usually boxing
or kickboxing

778
00:41:14,066 --> 00:41:16,633
{\an1}or going out for jogs.

779
00:41:16,666 --> 00:41:19,133
And growing up,

780
00:41:19,166 --> 00:41:22,466
{\an1}I just ran around all day
around the neighborhood,

781
00:41:22,500 --> 00:41:24,733
playing football.

782
00:41:24,766 --> 00:41:26,733
{\an1}When I was about 8,

783
00:41:26,766 --> 00:41:29,466
{\an1}I just started having
intensive pains.

784
00:41:29,500 --> 00:41:33,466
{\an8}♪♪

785
00:41:33,500 --> 00:41:36,633
{\an1}And I just wasn't able to walk
anymore,

786
00:41:36,666 --> 00:41:38,366
{\an1}wasn't eating, wasn't drinking.

787
00:41:38,400 --> 00:41:40,900
{\an1}My weight was down
to my 2-year-old little sister

788
00:41:40,933 --> 00:41:41,900
when I was 8.

789
00:41:41,933 --> 00:41:44,333
{\an1}Obviously something was way off.

790
00:41:44,366 --> 00:41:48,966
{\an8}♪♪

791
00:41:49,000 --> 00:41:51,666
{\an1}I was diagnosed with leukemia,

792
00:41:51,700 --> 00:41:54,066
{\an1}a cancer that forms
in the bone marrow

793
00:41:54,100 --> 00:41:56,866
and spreads out
through your blood,

794
00:41:56,900 --> 00:41:59,966
{\an1}destroying your cells
in your body.

795
00:42:00,000 --> 00:42:02,466
{\an8}♪♪

796
00:42:02,500 --> 00:42:05,466
{\an1}-Our DNA is really
just a molecule.

797
00:42:06,600 --> 00:42:08,000
It's not perfect.

798
00:42:08,033 --> 00:42:11,000
{\an1}It's prone to getting damaged
over time.

799
00:42:11,033 --> 00:42:14,800
{\an8}♪♪

800
00:42:14,833 --> 00:42:17,800
{\an1}And if the DNA in our cells
get damaged,

801
00:42:17,833 --> 00:42:22,300
{\an1}then they lose their ability
to perfectly divide.

802
00:42:22,333 --> 00:42:24,800
{\an8}♪♪

803
00:42:24,833 --> 00:42:27,466
-Our cells come
with an internal clock...

804
00:42:27,500 --> 00:42:29,866
[ Clock ticking ]

805
00:42:29,900 --> 00:42:33,866
{\an1}...that tells them
when to divide and grow

806
00:42:33,900 --> 00:42:36,533
{\an1}and when to slow down and die.

807
00:42:36,566 --> 00:42:39,466
{\an8}♪♪

808
00:42:39,500 --> 00:42:42,633
But occasionally
a switch gets flipped

809
00:42:42,666 --> 00:42:45,566
{\an1}that says, "Keep dividing.
Don't stop."

810
00:42:47,000 --> 00:42:49,666
{\an1}When cells don't die as planned,

811
00:42:49,700 --> 00:42:52,966
they crowd out
and kill healthy cells...

812
00:42:53,000 --> 00:42:57,900
{\an1}disrupting the body's
complex balance.

813
00:42:57,933 --> 00:43:00,900
{\an8}♪♪

814
00:43:00,933 --> 00:43:05,066
{\an1}When that happens, it's
the immune system that steps in.

815
00:43:05,100 --> 00:43:07,300
{\an8}♪♪

816
00:43:07,333 --> 00:43:10,066
In fact,
every day, your immune system

817
00:43:10,100 --> 00:43:13,800
{\an1}snuffs out the spark of cancer
without you ever knowing it.

818
00:43:15,633 --> 00:43:18,566
{\an1}The irony of leukemia --
the sad irony --

819
00:43:18,600 --> 00:43:23,100
{\an1}is that sometimes these
cancer-fighting cells go rogue.

820
00:43:23,133 --> 00:43:26,200
{\an8}♪♪

821
00:43:26,233 --> 00:43:28,566
White blood cells
in the bone marrow

822
00:43:28,600 --> 00:43:32,333
{\an1}start to divide unceasingly,
disrupting blood production

823
00:43:32,366 --> 00:43:35,333
and causing
a system-wide breakdown.

824
00:43:37,733 --> 00:43:40,000
{\an1}-They ended up immediately
putting me

825
00:43:40,033 --> 00:43:43,033
{\an1}into a three-and-a-half-year
chemotherapy treatment.

826
00:43:45,533 --> 00:43:50,866
{\an1}Chemotherapy is gonna break the
body down no matter who you are.

827
00:43:50,900 --> 00:43:53,866
It doesn't matter
if you're built like Mike Tyson.

828
00:43:53,900 --> 00:43:55,366
{\an1}Like, it -- it doesn't matter.

829
00:43:55,400 --> 00:43:58,500
{\an8}♪♪

830
00:43:58,533 --> 00:44:01,900
{\an1}It can get to a point
where the chemo itself

831
00:44:01,933 --> 00:44:03,533
{\an1}is worse than the cancer.

832
00:44:03,566 --> 00:44:05,833
{\an8}♪♪

833
00:44:05,866 --> 00:44:07,333
{\an1}-I'm Rebecca Gardner.

834
00:44:07,366 --> 00:44:09,833
{\an7}I'm an associate professor
at the University of Washington

835
00:44:09,866 --> 00:44:11,033
{\an7}and a pediatric oncologist.

836
00:44:11,066 --> 00:44:13,700
Historically,
the way we've treated cancer

837
00:44:13,733 --> 00:44:15,933
{\an1}is we have developed
chemotherapies,

838
00:44:15,966 --> 00:44:18,633
{\an1}which target cells
that are growing quickly.

839
00:44:18,666 --> 00:44:20,600
They're effective
at treating cancer,

840
00:44:20,633 --> 00:44:23,366
{\an1}but they're not specific,
meaning that they will target

841
00:44:23,400 --> 00:44:25,133
{\an1}a lot of your healthy tissues
as well.

842
00:44:25,166 --> 00:44:28,000
{\an1}And in kids, that's a big issue
because a lot of their cells

843
00:44:28,033 --> 00:44:30,166
{\an1}are growing quickly.

844
00:44:32,233 --> 00:44:34,100
{\an1}And so chemotherapy
can have devastating

845
00:44:34,133 --> 00:44:36,166
{\an1}long-term consequences.

846
00:44:36,200 --> 00:44:39,866
{\an8}♪♪

847
00:44:39,900 --> 00:44:42,633
{\an1}-After finally being
in the clear, when I was 12,

848
00:44:42,666 --> 00:44:46,466
{\an1}you get back to normal life
as much as possible.

849
00:44:47,700 --> 00:44:51,233
{\an1}But then I relapsed
when I was 15 years old.

850
00:44:53,233 --> 00:44:56,500
{\an1}And I relapsed again
when I was about 20 years old.

851
00:44:56,533 --> 00:45:01,133
{\an8}♪♪

852
00:45:01,166 --> 00:45:05,533
{\an1}A third time is pretty much
like...that's it.

853
00:45:07,266 --> 00:45:09,733
{\an1}You're not gonna make it.

854
00:45:09,766 --> 00:45:12,366
{\an1}After all that happened,
the doctor came back in,

855
00:45:12,400 --> 00:45:14,466
and she was like,
"We have this study

856
00:45:14,500 --> 00:45:18,900
{\an1}where we use your immune system
to fight off the cancer."

857
00:45:18,933 --> 00:45:21,800
{\an8}♪♪

858
00:45:21,833 --> 00:45:24,800
{\an1}-The concept of immunotherapy
sounds very sci-fi.

859
00:45:24,833 --> 00:45:27,766
{\an1}At the heart of it,
it's a very simple idea.

860
00:45:28,766 --> 00:45:31,400
{\an1}Our immune system is designed
to protect us.

861
00:45:31,433 --> 00:45:35,200
{\an8}♪♪

862
00:45:35,233 --> 00:45:38,066
{\an1}The issue is that cancer usually
comes from your own body,

863
00:45:38,100 --> 00:45:41,700
{\an1}and so your immune system is not
educated to recognize it as bad.

864
00:45:41,733 --> 00:45:45,333
{\an1}So immunotherapy is really
exploiting your immune system

865
00:45:45,366 --> 00:45:48,166
{\an1}to recognize your cancer cells
as being bad.

866
00:45:49,700 --> 00:45:52,033
{\an1}-Cancer is a cellular disease,

867
00:45:52,066 --> 00:45:56,666
{\an1}and each of those cells have
their own intelligence.

868
00:45:56,700 --> 00:45:59,333
{\an8}♪♪

869
00:45:59,366 --> 00:46:01,933
{\an1}Interacting with our bodies
on that level,

870
00:46:01,966 --> 00:46:06,733
as ecosystems
composed of trillions of cells,

871
00:46:06,766 --> 00:46:11,733
{\an1}I think can open up
a whole new way to view health

872
00:46:11,766 --> 00:46:15,100
and disease
that is much more nuanced.

873
00:46:15,133 --> 00:46:18,133
{\an8}♪♪

874
00:46:18,166 --> 00:46:19,333
-A century ago,

875
00:46:19,366 --> 00:46:21,466
{\an1}scientists realized
they could treat cancer

876
00:46:21,500 --> 00:46:24,666
{\an1}by intentionally triggering
their patient's immune system,

877
00:46:24,700 --> 00:46:28,433
{\an1}like by injecting them
with a bacteria or a virus.

878
00:46:28,466 --> 00:46:32,800
{\an8}♪♪

879
00:46:32,833 --> 00:46:36,233
{\an1}Now gene-editing technology
is allowing us

880
00:46:36,266 --> 00:46:40,000
{\an1}to educate the immune system
on the level of DNA

881
00:46:40,033 --> 00:46:43,133
{\an1}to target cancer with a new
and extreme precision.

882
00:46:45,133 --> 00:46:48,100
{\an1}-We felt like Milton was a good
candidate for this treatment

883
00:46:48,133 --> 00:46:50,700
{\an1}because he'd gotten chemotherapy
a couple times

884
00:46:50,733 --> 00:46:52,966
and each time,
his leukemia came back.

885
00:46:53,000 --> 00:46:55,133
{\an8}♪♪

886
00:46:55,166 --> 00:46:57,733
{\an1}Any time a treatment is new,
you're guarded.

887
00:46:57,766 --> 00:47:00,733
{\an1}You think, "Well, even though
all of this stuff looks good,

888
00:47:00,766 --> 00:47:03,133
{\an1}we're just not sure
if it's actually gonna work."

889
00:47:03,166 --> 00:47:05,766
{\an8}♪♪

890
00:47:05,800 --> 00:47:09,000
{\an1}But Milton was like, "Okay.
Sounds good. Where do I sign?"

891
00:47:09,033 --> 00:47:11,500
{\an8}♪♪

892
00:47:11,533 --> 00:47:13,033
{\an1}-You kind of go in blind,

893
00:47:13,066 --> 00:47:16,966
{\an1}but it's that or, you know,
nothing, so...

894
00:47:17,000 --> 00:47:21,800
{\an8}♪♪

895
00:47:21,833 --> 00:47:24,300
-In Seattle,
he was the second patient

896
00:47:24,333 --> 00:47:26,400
{\an1}that we had ever done this for.

897
00:47:26,433 --> 00:47:29,366
{\an8}♪♪

898
00:47:29,400 --> 00:47:31,466
{\an1}-Milton's immunotherapy began

899
00:47:31,500 --> 00:47:35,066
with his T cells
being extracted from his blood.

900
00:47:36,266 --> 00:47:39,833
{\an1}The DNA of the cells
was then edited.

901
00:47:39,866 --> 00:47:42,633
{\an1}Imagine it's like changing
someone's eyes

902
00:47:42,666 --> 00:47:44,866
{\an1}from blue to brown.

903
00:47:44,900 --> 00:47:47,700
{\an1}In this case, they changed
the surface of the T cells

904
00:47:47,733 --> 00:47:50,633
{\an1}so that the cancer cells
would recognize them,

905
00:47:50,666 --> 00:47:53,233
{\an1}bind to them, and be killed.

906
00:47:53,266 --> 00:47:56,033
{\an8}♪♪

907
00:47:56,066 --> 00:47:58,633
{\an1}The mutated T cells
were then injected

908
00:47:58,666 --> 00:48:02,766
{\an1}back into Milton's bloodstream
and unleashed.

909
00:48:02,800 --> 00:48:08,566
{\an8}♪♪

910
00:48:08,600 --> 00:48:10,700
{\an1}-A couple days after that,

911
00:48:10,733 --> 00:48:13,633
I started getting
flu-like symptoms.

912
00:48:13,666 --> 00:48:15,200
{\an1}They were like, "Yes!"

913
00:48:15,233 --> 00:48:17,733
{\an8}♪♪

914
00:48:17,766 --> 00:48:20,033
{\an1}-To confirm the immunotherapy
is working,

915
00:48:20,066 --> 00:48:25,133
{\an1}doctors look for fevers,
aches, and nausea.

916
00:48:25,166 --> 00:48:28,066
{\an1}These symptoms are caused
by chemical signals

917
00:48:28,100 --> 00:48:31,200
{\an1}the immune system sends
to rally the troops.

918
00:48:32,833 --> 00:48:34,533
{\an1}Inside Milton's body,

919
00:48:34,566 --> 00:48:38,066
{\an1}his reprogrammed immune cells
were on the offensive,

920
00:48:38,100 --> 00:48:42,266
attaching to
and killing his leukemia.

921
00:48:44,166 --> 00:48:45,766
{\an1}-I think it took three months.

922
00:48:45,800 --> 00:48:47,400
{\an1}Then just one day they came in.

923
00:48:47,433 --> 00:48:50,400
{\an1}They were like, "Good news.
It's gone."

924
00:48:52,200 --> 00:48:54,700
They were like,
"You're officially cancer-free."

925
00:48:54,733 --> 00:48:58,866
{\an8}♪♪

926
00:48:58,900 --> 00:49:01,033
{\an1}-You look at Milton,

927
00:49:01,066 --> 00:49:04,766
{\an1}who had really been failed
by chemotherapy.

928
00:49:04,800 --> 00:49:06,866
We came up with
this new therapy,

929
00:49:06,900 --> 00:49:08,433
{\an1}and we were able to do it.

930
00:49:08,466 --> 00:49:11,000
{\an1}We were able to get him
into remission.

931
00:49:12,200 --> 00:49:13,766
Hey, hey!
-Hi again.

932
00:49:13,800 --> 00:49:16,700
{\an1}I'm surprised you're out
of work, out of the office.

933
00:49:16,733 --> 00:49:18,866
-I know.
It's amazing.

934
00:49:18,900 --> 00:49:21,266
{\an1}-What has it been,
like six years now, right?

935
00:49:21,300 --> 00:49:22,666
-Yeah.

936
00:49:22,700 --> 00:49:24,466
{\an1}-I'm very thankful for her.

937
00:49:24,500 --> 00:49:28,500
{\an1}'Cause if it wasn't for her,
you know, I would...

938
00:49:28,533 --> 00:49:30,033
{\an1}I would be six feet under.

939
00:49:30,066 --> 00:49:32,633
{\an1}I was taking like 110 pills
a day or something.

940
00:49:32,666 --> 00:49:34,866
-I know.
Right?

941
00:49:34,900 --> 00:49:36,366
{\an1}You don't take any medicines
now.

942
00:49:36,400 --> 00:49:37,566
-No.
-And just think.

943
00:49:37,600 --> 00:49:40,700
{\an1}When you walk by somebody,
they have no idea.

944
00:49:40,733 --> 00:49:44,700
{\an1}Right now about half the people
who respond stay in remission.

945
00:49:44,733 --> 00:49:47,066
{\an1}Our hope is we try to stay
one step ahead of everybody.

946
00:49:47,100 --> 00:49:48,866
So, like, "Okay.
This is your trial now.

947
00:49:48,900 --> 00:49:52,300
{\an1}But if this one doesn't work
for you, we have this next one."

948
00:49:53,833 --> 00:49:56,600
{\an1}-It feels good knowing
that I can give back

949
00:49:56,633 --> 00:50:00,200
{\an1}to what the nurses and doctors
gave to me, which was life.

950
00:50:00,233 --> 00:50:03,866
{\an8}♪♪

951
00:50:03,900 --> 00:50:07,933
{\an1}I'm actually working at
Seattle Children's Hospital now.

952
00:50:07,966 --> 00:50:11,833
{\an1}So I did a full 360,
from being a patient

953
00:50:11,866 --> 00:50:16,933
{\an1}to now I work with those same
patients that I once was.

954
00:50:16,966 --> 00:50:22,166
{\an8}♪♪

955
00:50:22,200 --> 00:50:23,533
{\an1}-We've learned so much

956
00:50:23,566 --> 00:50:26,500
{\an1}that we're actually able to use
the immune system

957
00:50:26,533 --> 00:50:27,766
to treat cancer.

958
00:50:27,800 --> 00:50:29,800
{\an1}And I think when you look
into the future,

959
00:50:29,833 --> 00:50:32,166
{\an1}that's what the future
of oncology is gonna be.

960
00:50:32,200 --> 00:50:34,900
{\an1}It's not gonna be chemotherapy
and radiation.

961
00:50:34,933 --> 00:50:37,200
It's gonna be
very precision medicine.

962
00:50:37,233 --> 00:50:39,333
{\an1}It's gonna be immunotherapy.

963
00:50:39,366 --> 00:50:41,266
{\an8}♪♪

964
00:50:41,300 --> 00:50:43,800
-To know that you
can have something

965
00:50:43,833 --> 00:50:48,333
{\an1}that is not foreign
to your body protect you

966
00:50:48,366 --> 00:50:51,333
{\an1}and defeat the cancer cells
inside you

967
00:50:51,366 --> 00:50:53,700
{\an1}just feels empowering.

968
00:50:53,733 --> 00:51:01,366
{\an8}♪♪

969
00:51:01,400 --> 00:51:05,366
{\an1}-Look at what humans have gone
through throughout history...

970
00:51:05,400 --> 00:51:09,566
{\an1}from famine, natural disasters,
disease.

971
00:51:09,600 --> 00:51:12,100
{\an8}♪♪

972
00:51:12,133 --> 00:51:15,500
{\an1}We have this incredible ability
to adapt to our circumstances

973
00:51:15,533 --> 00:51:18,700
{\an1}and persevere as a species.

974
00:51:18,733 --> 00:51:20,833
{\an1}I think we're incredibly
resilient.

975
00:51:20,866 --> 00:51:23,733
{\an8}♪♪

976
00:51:23,766 --> 00:51:25,900
{\an1}-Our ability to survive

977
00:51:25,933 --> 00:51:29,533
{\an1}goes back to the limitless
potential of this system.

978
00:51:29,566 --> 00:51:31,666
{\an8}♪♪

979
00:51:31,700 --> 00:51:37,433
{\an1}-I've developed a really
intuitive sense of trust

980
00:51:37,466 --> 00:51:39,200
{\an1}that the cells know what to do.

981
00:51:41,066 --> 00:51:44,333
{\an1}But we have the potential
to amplify

982
00:51:44,366 --> 00:51:47,333
{\an1}our body's natural ability
to heal...

983
00:51:47,366 --> 00:51:49,333
{\an8}♪♪

984
00:51:49,366 --> 00:51:53,433
{\an1}...to move past repair
of the body

985
00:51:53,466 --> 00:51:58,600
{\an1}and think about the next level,
which is true healing.

986
00:51:58,633 --> 00:52:02,866
{\an8}♪♪

987
00:52:04,166 --> 00:52:09,566
{\an8}♪♪

988
00:52:09,600 --> 00:52:15,766
{\an8}♪♪

989
00:52:15,800 --> 00:52:18,600
{\an8}-To order "Human:
The World Within" on DVD,

990
00:52:18,633 --> 00:52:20,766
{\an8}visit shopPBS.org

991
00:52:20,800 --> 00:52:23,066
{\an7}or call 1-800-PLAY-PBS.

992
00:52:23,100 --> 00:52:32,600
{\an8}♪♪