1
00:00:14,605 --> 00:00:19,716
I would like to introduce you
to my favorite parasite.

2
00:00:19,716 --> 00:00:21,551
There are millions that I could choose from

3
00:00:21,551 --> 00:00:22,866
and this is it:

4
00:00:22,866 --> 00:00:24,336
it's called the jewel wasp.

5
00:00:24,336 --> 00:00:27,283
You can find it 
in parts of Africa and Asia.

6
00:00:27,283 --> 00:00:28,608
It's a little under an inch long,

7
00:00:28,608 --> 00:00:30,997
and it is a beautiful looking parasite.

8
00:00:30,997 --> 00:00:32,659
Now, you may be saying to yourself,

9
00:00:32,659 --> 00:00:34,225
"This is not a parasite.

10
00:00:34,225 --> 00:00:35,153
It's not a tapeworm,

11
00:00:35,153 --> 00:00:35,895
it's not a virus,

12
00:00:35,895 --> 00:00:38,639
how could a wasp be a parasite?"

13
00:00:38,639 --> 00:00:40,553
You are probably thinking 
about regular wasps,

14
00:00:40,553 --> 00:00:45,008
you know, the ones that build 
paper nests as their house.

15
00:00:45,008 --> 00:00:48,663
Well, the thing is that the jewel wasp

16
00:00:48,663 --> 00:00:52,721
makes its house inside 
a living cockroach.

17
00:00:54,627 --> 00:00:57,669
Here's how it happens.

18
00:00:57,669 --> 00:01:00,552
A jewel wasp is flying around, 
looking for a cockroach.

19
00:01:00,552 --> 00:01:03,719
When it sees one, it lands 
and bites on its wing.

20
00:01:03,719 --> 00:01:04,933
So, I'll be the cockroach.

21
00:01:04,933 --> 00:01:06,273
Be-wha! Bewha!

22
00:01:06,273 --> 00:01:08,352
And the cockroach starts shaking it off,

23
00:01:08,352 --> 00:01:10,671
"Get away from me!"

24
00:01:10,671 --> 00:01:14,551
The wasp very quickly starts
stinging the cockroach.

25
00:01:14,551 --> 00:01:17,045
All of a sudden, the cockroach can't move,

26
00:01:17,045 --> 00:01:18,474
for about a minute.

27
00:01:18,474 --> 00:01:21,095
And then it recovers

28
00:01:21,095 --> 00:01:22,843
and stands up.

29
00:01:22,843 --> 00:01:24,294
It could run away now,

30
00:01:24,294 --> 00:01:26,286
but it doesn't.

31
00:01:26,286 --> 00:01:28,596
It just doesn't want to.

32
00:01:28,596 --> 00:01:30,482
It just stays there.

33
00:01:30,482 --> 00:01:33,571
It's become a zombie slave.

34
00:01:35,371 --> 00:01:37,435
Again, I'm not making this up.

35
00:01:37,435 --> 00:01:38,651
The wasp goes off,

36
00:01:38,651 --> 00:01:41,266
it walks away and finds a hole

37
00:01:41,266 --> 00:01:44,155
and digs it out, makes it into a burrow.

38
00:01:44,155 --> 00:01:45,586
It walks back.

39
00:01:45,586 --> 00:01:48,268
This can take up to half an hour.

40
00:01:48,268 --> 00:01:51,181
The cockroach is still there.

41
00:01:51,181 --> 00:01:53,697
What do we do now?

42
00:01:53,697 --> 00:01:56,917
The wasps grabs onto one of the antenna,

43
00:01:56,917 --> 00:01:58,203
bites down on it,

44
00:01:58,203 --> 00:01:59,134
of the cockroach,

45
00:01:59,134 --> 00:02:01,933
and pulls the cockroach.

46
00:02:01,933 --> 00:02:04,770
And the cockroach says, "Alright,"

47
00:02:04,770 --> 00:02:07,851
and walks like a dog on a leash.

48
00:02:07,851 --> 00:02:11,765
The wasp takes it 
all the way down into the burrow.

49
00:02:11,765 --> 00:02:14,744
The cockroach says, "Nice place."

50
00:02:14,744 --> 00:02:16,331
The wasp takes care of some business

51
00:02:16,331 --> 00:02:17,933
and then goes and leaves the burrow

52
00:02:17,933 --> 00:02:19,130
and seals it shut,

53
00:02:19,130 --> 00:02:23,412
leaving the cockroach entombed 
in darkness, still alive.

54
00:02:23,412 --> 00:02:27,319
The cockroach says, "Alright, 
I'll stay here if you want."

55
00:02:27,319 --> 00:02:29,558
Now, I mentioned that 
the cockroach took care,

56
00:02:29,558 --> 00:02:32,278
ah, the wasp took care 
of a little business

57
00:02:32,278 --> 00:02:34,683
before it left the burrow.

58
00:02:34,683 --> 00:02:37,105
The business was laying an egg

59
00:02:37,105 --> 00:02:39,382
on the underside of the cockroach.

60
00:02:39,382 --> 00:02:40,729
The egg hatches.

61
00:02:40,729 --> 00:02:42,140
Out comes a wasp larva.

62
00:02:42,140 --> 00:02:45,792
It looks kind of like 
a maggot with big, nasty jaws.

63
00:02:45,792 --> 00:02:49,315
It chews a hole into the cockroach

64
00:02:49,315 --> 00:02:51,913
and starts to feed from the outside.

65
00:02:51,913 --> 00:02:55,352
It gets bigger, 
like you can see over here.

66
00:02:55,352 --> 00:02:56,922
And then when it gets big enough,

67
00:02:56,922 --> 00:03:00,457
it decides to crawl into the hole,

68
00:03:00,457 --> 00:03:02,215
into the cockroach.

69
00:03:02,215 --> 00:03:05,800
So now it's inside 
the still-living cockroach

70
00:03:05,800 --> 00:03:09,557
and the cockroach doesn't mind much.

71
00:03:09,557 --> 00:03:11,701
This goes on for about a month.

72
00:03:11,701 --> 00:03:14,293
The larva grows and grows and grows,

73
00:03:14,293 --> 00:03:16,678
then makes a pupa, 
kind of like a cocoon.

74
00:03:16,678 --> 00:03:18,930
Inside there it grows eyes,

75
00:03:18,930 --> 00:03:19,915
it grows wings,

76
00:03:19,915 --> 00:03:21,804
it grows legs,

77
00:03:21,804 --> 00:03:24,767
the cockroach is still alive, 
still waiting.

78
00:03:24,767 --> 00:03:27,142
Finally the wasp is ready to leave,

79
00:03:27,142 --> 00:03:30,553
and that's when the cockroach finally dies

80
00:03:30,553 --> 00:03:33,140
because the fullly-formed adult wasp

81
00:03:33,140 --> 00:03:36,595
crawls out of the cockroach's dying body.

82
00:03:38,193 --> 00:03:40,966
The wasp shakes itself off,

83
00:03:40,966 --> 00:03:42,207
climbs out of the burrow,

84
00:03:42,207 --> 00:03:44,349
goes and finds another wasp to mate with

85
00:03:44,349 --> 00:03:47,960
to start this whole, crazy cycle again.

86
00:03:47,960 --> 00:03:50,731
So, this is not science fiction,

87
00:03:50,731 --> 00:03:54,592
this happens every day, 
all over the world.

88
00:03:54,592 --> 00:03:58,343
And scientists are 
totally fascinated by this.

89
00:03:58,343 --> 00:04:01,540
They're just starting to figure out
how all this happens.

90
00:04:01,540 --> 00:04:04,212
And, when you really start 
to look at the science of it,

91
00:04:04,212 --> 00:04:08,128
you start to kind of respect 
this very creepy wasp.

92
00:04:08,128 --> 00:04:12,079
You see, the thing is that 
when it attacks the cockroach,

93
00:04:12,079 --> 00:04:13,570
it's not just stinging wildly,

94
00:04:13,570 --> 00:04:18,998
it delivers two precise stings.

95
00:04:18,998 --> 00:04:21,060
It knows this cockroach's nervous system

96
00:04:21,060 --> 00:04:23,509
like you know the back of your hand.

97
00:04:23,509 --> 00:04:26,308
The first sting goes to that spot there,

98
00:04:26,308 --> 00:04:28,473
called the "walking rhythm generators,"

99
00:04:28,473 --> 00:04:29,311
and, as you can guess,

100
00:04:29,311 --> 00:04:30,984
those are the neurons that send signals

101
00:04:30,984 --> 00:04:33,120
to the legs to move.

102
00:04:33,120 --> 00:04:36,025
It blocks the channels 
that the neurons use

103
00:04:36,025 --> 00:04:36,987
to send these signals.

104
00:04:36,987 --> 00:04:39,508
So the cockroach wants to go, 
it wants to run away,

105
00:04:39,508 --> 00:04:42,835
but it can't because 
it can't move its legs.

106
00:04:42,835 --> 00:04:45,041
And that lasted for about a minute.

107
00:04:45,041 --> 00:04:49,917
This is really sophisticated pharmacology.

108
00:04:49,917 --> 00:04:51,996
We actually use the same method,

109
00:04:51,996 --> 00:04:53,266
a drug called Ivermectin,

110
00:04:53,266 --> 00:04:54,227
to cure river blindness,

111
00:04:54,227 --> 00:04:55,496
which is caused by a parasitic worm

112
00:04:55,496 --> 00:04:57,600
that gets into your eye.

113
00:04:57,600 --> 00:05:00,734
If you take Ivermectin, 
you paralyze the worm

114
00:05:00,734 --> 00:05:03,071
using the same strategy.

115
00:05:03,071 --> 00:05:05,150
Now, we discovered this in the 1970s,

116
00:05:05,150 --> 00:05:08,331
the wasp has been doing this for millions of years.

117
00:05:09,500 --> 00:05:11,546
Then comes the second sting.

118
00:05:11,546 --> 00:05:14,974
Now the second sting actually hits two places along the way.

119
00:05:14,974 --> 00:05:18,057
And to try to imagine how this can happen,

120
00:05:18,057 --> 00:05:22,172
I want you to picture yourself with a friend

121
00:05:22,172 --> 00:05:25,790
who's got a very long, very, very scary looking needle.

122
00:05:25,790 --> 00:05:26,571
And your friend,

123
00:05:26,571 --> 00:05:28,090
or at least you thought he was your friend,

124
00:05:28,090 --> 00:05:31,314
sticks it in your neck,

125
00:05:31,314 --> 00:05:33,288
goes into your skull,

126
00:05:33,288 --> 00:05:35,672
stops off at one part of your brain

127
00:05:35,672 --> 00:05:38,787
and injects some drugs,

128
00:05:38,787 --> 00:05:40,986
then keeps going in your brain

129
00:05:40,986 --> 00:05:43,621
and injects some more.

130
00:05:43,621 --> 00:05:45,186
These are two particular spots,

131
00:05:45,186 --> 00:05:46,196
marked here, "SEG",

132
00:05:46,196 --> 00:05:50,313
and you can see the tip of it in the brain, marked "Br".

133
00:05:50,313 --> 00:05:55,749
Now, we can do this, but it's really hard for us.

134
00:05:55,749 --> 00:05:57,997
It's called stereotactic drug delivery.

135
00:05:57,997 --> 00:06:00,522
You have to put a patient in a big metal frame

136
00:06:00,522 --> 00:06:01,642
to hold them still,

137
00:06:01,642 --> 00:06:03,803
you need CAT Scans to know where you're going,

138
00:06:03,803 --> 00:06:05,094
so you look at the picture and say,

139
00:06:05,094 --> 00:06:07,305
"Are we going the right way?"

140
00:06:07,305 --> 00:06:10,542
The jewel wasp has sensors on its stinger

141
00:06:10,542 --> 00:06:14,489
and scientists think that it can actually feel its way

142
00:06:14,489 --> 00:06:17,092
through the cockroach's brain until it gets

143
00:06:17,092 --> 00:06:19,876
to the exact, right place,

144
00:06:19,876 --> 00:06:22,703
and then penetrates an individual neuron

145
00:06:22,703 --> 00:06:25,244
and then delivers the goods.

146
00:06:25,244 --> 00:06:29,389
So, this is quite amazing stuff,

147
00:06:29,389 --> 00:06:31,440
and what seems to happen then

148
00:06:31,440 --> 00:06:36,772
is that the wasp is taking away the control

149
00:06:36,772 --> 00:06:39,214
that the cockroach has over its own body.

150
00:06:39,214 --> 00:06:42,124
It's taking away the cockroach's free will.

151
00:06:42,124 --> 00:06:43,688
We didn't really appreciate that cockroaches

152
00:06:43,688 --> 00:06:46,657
have free will until this wasp showed us.

153
00:06:46,657 --> 00:06:50,343
And, we have no idea how it's doing this,

154
00:06:50,343 --> 00:06:52,443
we don't know yet what the venom has in it

155
00:06:52,443 --> 00:06:53,926
and we don't know which circuits

156
00:06:53,926 --> 00:06:56,380
it's hitting in the cockroach's brain,

157
00:06:56,380 --> 00:06:58,278
and I think that's why this is,

158
00:06:58,278 --> 00:07:00,208
most of all, my favorite parasite

159
00:07:00,208 --> 00:07:03,194
because we have so much left to learn from it.

160
00:07:03,194 --> 00:07:05,323
Thank you very much.