Ed Yong: Suicidal wasps, zombie roaches and other parasite tales

302,941 views ใƒป 2014-03-26

TED


ืื ื ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ืœืžื˜ื” ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ.

ืžืชืจื’ื: Boaz Hovav ืžื‘ืงืจ: Ido Dekkers
00:12
A herd of wildebeests, a shoal of fish,
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ืขื“ืจ ืฉืœ ื’ื ื•, ื ื—ื™ืœ ื“ื’ื™ื,
00:15
a flock of birds.
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ืœื”ืงืช ืฆื™ืคื•ืจื™ื.
00:16
Many animals gather in large groups
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ื”ืจื‘ื” ื—ื™ื•ืช ืžืชืงื‘ืฆื•ืช ื‘ืงื‘ื•ืฆื•ืช ื’ื“ื•ืœื•ืช
00:18
that are among the most wonderful spectacles
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ืฉื™ื•ืฆืจื•ืช ื—ืœืง ืžื”ืžืจืื•ืช ื”ืžื“ื”ื™ืžื™ื ื‘ื™ื•ืชืจ
00:20
in the natural world.
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ื‘ืขื•ืœื ื”ื˜ื‘ืข.
00:22
But why do these groups form?
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ืื‘ืœ ืœืžื” ื ื•ืฆืจื•ืช ื”ืœื”ืงื•ืช ื”ืœืœื•?
00:25
The common answers include things like
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ื”ืชืฉื•ื‘ื•ืช ื”ื ืคื•ืฆื•ืช ืžืชื™ื™ื—ืกื•ืช ืœืจื•ื‘
00:26
seeking safety in numbers or hunting in packs
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ืœื—ื™ืคื•ืฉ ื‘ื˜ื—ื•ืŸ ื‘ืงื‘ื•ืฆื” ื’ื“ื•ืœื” ืื• ืœืฆื™ื“ ื‘ืœื”ืงื•ืช
00:29
or gathering to mate or breed,
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ืื• ื”ืชืืกืคื•ืช ืœืฆื•ืจืš ืจื‘ื™ื™ื”,
00:32
and all of these explanations,
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ื•ื›ืœ ื”ื”ืกื‘ืจื™ื ื”ืืœื”,
00:34
while often true,
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ืœืžืจื•ืช ืฉื”ื ื ื›ื•ื ื™ื ื‘ืžืงืจื™ื ืจื‘ื™ื,
00:35
make a huge assumption about animal behavior,
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ืžื ื™ื—ื™ื ื”ื ื—ื” ืžืคืœื™ื’ื” ืื•ื“ื•ืช ื”ืชื ื”ื’ื•ืช ื‘ืขืœื™ ื”ื—ื™ื™ื,
00:38
that the animals are in control of their own actions,
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ื”ืŸ ืžื ื™ื—ื•ืช ืฉื”ื—ื™ื•ืช ืฉื•ืœื˜ื•ืช ื‘ืžืขืฉื™ื”ืŸ,
00:41
that they are in charge of their bodies.
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ืฉื”ืŸ ืฉื•ืœื˜ื•ืช ื‘ื’ื•ืคืŸ.
00:43
And that is often not the case.
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ื•ื‘ื”ืจื‘ื” ืžืงืจื™ื ื”ื“ื‘ืจ ืื™ื ื• ื ื›ื•ืŸ.
00:47
This is Artemia, a brine shrimp.
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ื–ื”ื• ื”ืืจื˜ืžื™ื”, ืกื•ื’ ืฉืœ ื—ืกื™ืœื•ืŸ.
00:50
You probably know it better as a sea monkey.
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ืื•ืœื™ ืืชื ืžื›ื™ืจื™ื ืื•ืชื ื›'ืงื•ืคื™ ื™ื'.
00:52
It's small, and it typically lives alone,
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ื”ื•ื ืงื˜ืŸ, ื•ื—ื™ ืœื‘ื“ื• ื‘ื“ืจืš ื›ืœืœ,
00:54
but it can gather in these large red swarms
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ืื‘ืœ ื”ื•ื ื™ื•ื“ืข ื’ื ืœื”ืชืงื‘ืฅ ื‘ื ื—ื™ืœื™ื ื’ื“ื•ืœื™ื ื•ืื“ื•ืžื™ื
00:57
that span for meters,
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ืฉื ืžืฉื›ื™ื ืœืื•ืจืš ืžื˜ืจื™ื,
01:00
and these form because of a parasite.
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ื•ื”ื ื ื•ืฆืจื™ื ื‘ืฉืœ ื˜ืคื™ืœ.
01:03
These shrimp are infected with a tapeworm.
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ื”ื—ืกื™ืœื•ื ื™ื ื”ืœืœื• ื ื“ื‘ืงื• ื‘ืชื•ืœืขืช ืžืขื™ื™ื ืžืกื•ื’ ืฉืจืฉื•ืจ.
01:06
A tapeworm is effectively a long, living gut
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ืฉืจืฉื•ืจ ื”ื•ื ื‘ืคื•ืขืœ ืžืขื™ ืืจื•ืš ื•ื—ื™,
01:08
with genitals at one end and a hooked mouth at the other.
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ืขื ืื‘ืจื™ ืจื‘ื™ื™ื” ื‘ืฆื“ ืื—ื“ ื•ืคื” ืขื ืฉื™ื ื™ื™ื ื“ืžื•ื™ื•ืช ืงืจืก ื‘ืฆื“ ื”ืฉื ื™.
01:11
As a freelance journalist, I sympathize.
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ื‘ืชื•ืจ ืขื™ืชื•ื ืื™ ืขืฆืžืื™, ืื ื™ ืžื–ื“ื”ื” ืื™ืชื.
01:13
(Laughter)
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(ืฆื—ื•ืง)
01:15
The tapeworm drains nutrients from Artemia's body,
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ื”ืฉืจืฉื•ืจ ืžื•ืฆืฅ ื—ื•ืžืจื™ ืžื–ื•ืŸ ืžื’ื•ืฃ ื”ืืจื˜ืžื™ื”,
01:18
but it also does other things.
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ืื‘ืœ ื”ื•ื ืขื•ืฉื” ื“ื‘ืจื™ื ื ื•ืกืคื™ื.
01:20
It castrates them,
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ื”ื•ื ืžืกืจืก ืื•ืชื,
01:22
it changes their color from transparent to bright red,
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ื”ื•ื ืžืฉื ื” ืืช ื”ืฆื‘ืข ืฉืœื”ื ืžืฉืงื•ืฃ ืœืื“ื•ื ื‘ื•ื”ืง,
01:27
it makes them live longer,
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ื”ื•ื ืžืืจื™ืš ืืช ื—ื™ื™ื”ื,
01:28
and as biologist Nicolas Rode has found,
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ื•ื›ืคื™ ืฉื”ื‘ื™ื•ืœื•ื’ ื ื™ืงื•ืœืก ืจื•ื“ ื’ื™ืœื”,
01:31
it makes them swim in groups.
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ื”ื•ื ื’ื•ืจื ืœื”ื ืœืฉื—ื•ืช ื‘ืงื‘ื•ืฆื•ืช.
01:34
Why? Because the tapeworm, like many other parasites,
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ืœืžื”? ื›ื™ ืœืฉืจืฉื•ืจ, ื›ืžื• ื˜ืคื™ืœื™ื ืจื‘ื™ื ืื—ืจื™ื,
01:37
has a complicated life cycle
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ื™ืฉ ืžื—ื–ื•ืจ ื—ื™ื™ื ืžื•ืจื›ื‘
01:39
involving many different hosts.
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ืฉืขื•ื‘ืจ ื‘ื’ื•ืคื ืฉืœ ืžืกืคืจ ืžืืจื—ื™ื ืฉื•ื ื™ื.
01:41
The shrimp are just one step on its journey.
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ื”ื—ืกื™ืœื•ืŸ ื”ื•ื ืจืง ืฆืขื“ ืื—ื“ ื‘ืžืกืข.
01:44
Its ultimate destination is this,
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ื”ื™ืขื“ ื”ืกื•ืคื™ ืฉืœ ื”ืฉืจืฉื•ืจ ื”ื•ื ื”ืคืœืžื™ื ื’ื• ื”ืžืฆื•ื™.
01:46
the greater flamingo.
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01:48
Only in a flamingo can the tapeworm reproduce,
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ืจืง ื‘ืžืขื™ ืฉืœ ื”ืคืœืžื™ื ื’ื• ื™ื›ื•ืœื™ื ื”ืฉืจืฉื•ืจื™ื ืœื”ืชืจื‘ื•ืช,
01:51
so to get there, it manipulates its shrimp hosts
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ื•ืขืœ ืžื ืช ืœื”ื’ื™ืข ืœืฉื, ื”ื•ื ื’ื•ืจื ืœื—ืกื™ืœื•ืŸ ื”ืžืืจื—
01:54
into forming these conspicuous colored swarms
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ืœื”ืชืงื‘ืฅ ื‘ื ื—ื™ืœื™ื ื‘ื•ืœื˜ื™ื ืœืขื™ืŸ
01:58
that are easier for a flamingo to spot
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ืฉืžืงืœื™ื ืขืœ ื”ืคืœืžื™ื ื’ื• ืœืืชืจ ืืช ื”ื—ืกื™ืœื•ื ื™ื ื•ืœืื›ื•ืœ ืื•ืชื,
02:00
and to devour,
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02:02
and that is the secret of the Artemia swarm.
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ื•ื–ื”ื• ื”ืกื•ื“ ืฉืœ ืœื”ืงื•ืช ื”ืืจื˜ืžื™ื”.
02:05
They aren't sociable through their own volition,
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ื”ื ืœื ื™ืฆื•ืจื™ื ื—ื‘ืจืชื™ื™ื ืžื˜ื‘ืขื,
02:07
but because they are being controlled.
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ืืœื ื‘ื’ืœืœ ืฉื”ื ื ืฉืœื˜ื™ื.
02:09
It's not safety in numbers.
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ืœื ืžื“ื•ื‘ืจ ื‘ื‘ื™ื˜ื—ื•ืŸ ืฉื ื•ื‘ืข ืžื”ื”ืชืงื‘ืฆื•ืช ื‘ืœื”ืงื”.
02:11
It's actually the exact opposite.
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ื”ื”ืคืš ื”ื•ื ื”ื ื›ื•ืŸ.
02:13
The tapeworm hijacks their brains and their bodies,
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ื”ืฉืจืฉื•ืจ ื—ื•ื˜ืฃ ืืช ืžื•ื—ื ืฉืœ ื”ื—ืกื™ืœื•ื ื™ื ื•ืืช ื’ื•ืคื,
02:16
turning them into vehicles
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ื•ื”ื•ืคืš ืื•ืชื ืœื›ืœื™ ื”ืจื›ื‘
02:17
for getting itself into a flamingo.
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ืฉื™ื•ื‘ื™ืœ ืื•ืชื• ืืœ ืžืขื™ ื”ืคืœืžื™ื ื’ื•.
02:21
And here is another example
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ื•ื”ื ื” ื“ื•ื’ืžื” ื ื•ืกืคืช
02:22
of a parasitic manipulation.
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ืฉืœ ืฉืœื™ื˜ื” ืขืœ ื™ื“ื™ ื˜ืคื™ืœ.
02:25
This is a suicidal cricket.
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ืžื“ื•ื‘ืจ ื‘ืฆืจืฆืจ ื”ืžืชืื‘ื“.
02:28
This cricket swallowed the larvae of a Gordian worm,
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ื”ืฆืจืฆืจ ื”ื–ื” ื‘ืœืข ืืช ื–ื—ืœื™ ื”ืชื•ืœืขืช ื”ื’ื•ืจื“ื™ืช,
02:31
or horsehair worm.
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ืื• ืชื•ืœืขืช ืฉืขืจ ื”ืกื•ืก.
02:33
The worm grew to adult size within it,
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ื”ืชื•ืœืขืช ื’ื“ืœื” ืœื’ื•ื“ืœื” ื”ื‘ื•ื’ืจ ื‘ืชื•ื›ื•,
02:35
but it needs to get into water in order to mate,
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ืื‘ืœ ื”ื™ื ืฆืจื™ื›ื” ืœื”ื™ื›ื ืก ืœืžื™ื ืขืœ ืžื ืช ืœื”ืชืจื‘ื•ืช,
02:38
and it does that by releasing proteins
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ื•ื”ื™ื ืขื•ืฉื” ื–ืืช ืขืœ ื™ื“ื™ ืฉื—ืจื•ืจ ื—ืœื‘ื•ื ื™ื
02:41
that addle the cricket's brain,
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ืฉืคื•ื’ืขื™ื ื‘ืžื•ื— ื”ืฆืจืฆืจ,
02:43
causing it to behave erratically.
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ื•ื’ื•ืจืžื™ื ืœื• ืœื”ืชื ื”ื’ ื‘ืื•ืคืŸ ืœื ืฆืคื•ื™.
02:45
When the cricket nears a body of water,
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ื›ืืฉืจ ื”ืฆืจืฆืจ ืžืชืงืจื‘ ืœืžืงื•ื•ื” ืžื™ื,
02:47
such as this swimming pool,
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ื›ืžื• ื‘ืจื›ืช ืฉื—ื™ื™ื”,
02:48
it jumps in and drowns,
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ื”ื•ื ืงื•ืคืฅ ืคื ื™ืžื” ื•ื˜ื•ื‘ืข,
02:51
and the worm wriggles out
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ื•ื”ืชื•ืœืขืช ืžืคืœืกืช ืืช ื“ืจื›ื” ื”ื—ื•ืฆื”
02:52
of its suicidal corpse.
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ืžื’ื•ื™ืช ื”ืฆืจืฆืจ ืฉื”ืชืื‘ื“.
02:56
Crickets are really roomy. Who knew?
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ื™ืฉ ื”ืจื‘ื” ืžืงื•ื ื‘ืชื•ืš ื”ืฆืจืฆืจ. ืžื™ ื™ื›ื•ืœ ื”ื™ื” ืœื“ืขืช?
03:00
The tapeworm and the Gordian worm are not alone.
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ื”ืฉืจืฉื•ืจ ื•ื”ืชื•ืœืขืช ื”ื’ื•ืจื“ื™ืช ืื™ื ื ืœื‘ื“.
03:03
They are part of an entire cavalcade
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ื”ื ื—ืœืง ืžืžืฆืขื“ ืฉืœื
03:05
of mind-controlling parasites,
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ืฉืœ ื˜ืคื™ืœื™ื ื”ืฉื•ืœื˜ื™ื ื‘ืžื•ื— ื”ืžืืจื—,
03:07
of fungi, viruses, and worms and insects and more
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ืฉืœ ืคื˜ืจื™ื•ืช, ื•ื™ืจื•ืกื™ื, ืชื•ืœืขื™ื, ื—ืจืงื™ื ื•ืขื•ื“
03:11
that all specialize in subverting and overriding
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ืฉื›ื•ืœื ืžืชืžื—ื™ื ื‘ืขื™ื•ื•ืช ื•ืฉืœื™ื˜ื”
03:13
the wills of their hosts.
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ื‘ืจืฆื•ื ื ืฉืœ ื”ืžืืจื—ื™ื ืฉืœื”ื.
03:16
Now, I first learned about this way of life
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ืื ื™ ืฉืžืขืชื™ ืœืจืืฉื•ื ื” ืขืœ ื”ืชื•ืคืขื” ื”ื–ื•
03:17
through David Attenborough's "Trials of Life"
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ื‘ืกื“ืจืช ื”ื˜ืœื•ื•ื™ื–ื™ื” ืฉืœ ื“ื™ื™ื•ื™ื“ ืื˜ื ื‘ื•ืจื• "ืžืกืœื•ืœื™ ื”ื—ื™ื™ื"
03:20
about 20 years ago,
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ืœืคื ื™ 20 ืฉื ื” ื‘ืขืจืš,
03:22
and then later through a wonderful book called
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ื•ืื—ืจ ื›ืš ื“ืจืš ืกืคืจ ื ืคืœื
03:23
"Parasite Rex" by my friend Carl Zimmer.
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ื‘ืฉื "ืคืจื–ื™ื˜ ืจืงืก" ืฉื›ืชื‘ ื—ื‘ืจื™ ืงืืจืœ ื–ื™ืžืจ.
03:26
And I've been writing about these creatures ever since.
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ื•ืื ื™ ื›ื•ืชื‘ ืขืœ ื”ื™ืฆื•ืจื™ื ื”ืœืœื• ืžืื–.
03:28
Few topics in biology enthrall me more.
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ื™ืฉ ืžืขื˜ ื ื•ืฉืื™ื ื‘ื‘ื™ื•ืœื•ื’ื™ื” ืฉืžืขื ื™ื™ื ื™ื ืื•ืชื™ ื™ื•ืชืจ.
03:31
It's like the parasites have subverted my own brain.
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ืžืžืฉ ื›ืื™ืœื• ื”ื˜ืคื™ืœื™ื ื”ืฉืชืœื˜ื• ื’ื ืขืœ ืžื•ื—ื™ ืฉืœื™.
03:35
Because after all, they are always compelling
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ื›ื™ ืื—ืจื™ ื”ื›ืœ, ื”ื ืชืžื™ื“ ืžื•ืฉื›ื™ื
03:37
and they are delightfully macabre.
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ื•ืžืจืชืงื™ื ื‘ืฆื•ืจื” ืžืคื—ื™ื“ื”.
03:38
When you write about parasites,
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ื›ืืฉืจ ืืชื” ื›ื•ืชื‘ ืขืœ ื˜ืคื™ืœื™ื,
03:40
your lexicon swells with phrases like
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ืื•ืฆืจ ื”ืžื™ืœื™ื ืฉืœืš ื’ื“ืœ ืขื ื‘ื™ื˜ื•ื™ื™ื ื›ืžื•
03:42
"devoured alive" and "bursts out of its body."
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"ื ื˜ืจืฃ ื‘ืขื•ื“ื• ื—ื™" ื•"ืคื•ืจืฅ ืžืชื•ืš ื’ื•ืคื•."
03:45
(Laughter)
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(ืฆื—ื•ืง)
03:46
But there's more to it than that.
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ืื‘ืœ ื™ืฉ ืขื•ื“ ืฆื“ื“ื™ื ืœืกื™ืคื•ืจ.
03:48
I'm a writer, and fellow writers in the audience
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ืื ื™ ืกื•ืคืจ, ื•ืกื•ืคืจื™ื ืขืžื™ืชื™ื ื‘ืงื”ืœ
03:50
will know that we love stories.
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ื™ืขื™ื“ื• ืฉืื ื—ื ื• ืื•ื”ื‘ื™ื ืกื™ืคื•ืจื™ื.
03:53
Parasites invite us to resist the allure
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ื”ื˜ืคื™ืœื™ื ืžื–ืžื™ื ื™ื ืื•ืชื ื• ืœื”ืชืขืœื ืžื”ืงืกื
03:55
of obvious stories.
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ื”ื˜ืžื•ืŸ ื‘ืกื™ืคื•ืจื™ื ื”ื‘ืจื•ืจื™ื ืžืืœื™ื”ื.
03:57
Their world is one of plot twists
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ืขื•ืœืžื ืžืœื ื‘ืชืคื ื™ื•ืช ื‘ืขืœื™ืœื”
03:59
and unexpected explanations.
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ื•ื”ืกื‘ืจื™ื ื‘ืœืชื™ ืฆืคื•ื™ื™ื.
04:03
Why, for example,
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ืœืžื”, ืœื“ื•ื’ืžื”,
04:04
does this caterpillar
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ืžืชื—ื™ืœ ื”ื–ื—ืœ ื”ื–ื”
04:06
start violently thrashing about
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ืœื”ืฉืชื•ืœืœ ื‘ืื•ืคืŸ ืืœื™ื
04:08
when another insect gets close to it
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ื›ืืฉืจ ื—ืจืง ื ื•ืกืฃ ืžืชืงืจื‘ ืืœื™ื•
04:10
and those white cocoons that it seems
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ื•ืืœ ื”ืคืงืขื•ืช ื”ืœื‘ื ื•ืช ืฉื ืจืื”
04:12
to be standing guard over?
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ื›ืื™ืœื• ื”ื•ื ืฉื•ืžืจ ืขืœื™ื”ื?
04:14
Is it maybe protecting its siblings?
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ื”ืื ื”ื•ื ื“ื•ืื’ ืœืฆืืฆืื™ื•?
04:17
No.
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ืœื.
04:18
This caterpillar was attacked
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ื”ื–ื—ืœ ื”ื•ืชืงืฃ
04:20
by a parasitic wasp which laid eggs inside it.
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ืขืœ ื™ื“ื™ ืฆืจืขื” ื˜ืคื™ืœื” ืฉื”ื˜ื™ืœื” ื‘ืชื•ื›ื• ื‘ื™ืฆื™ื.
04:23
The eggs hatched and the young wasps
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ื”ื‘ื™ืฆื™ื ื‘ืงืขื• ื•ื”ืฆืจืขื•ืช ื”ืฆืขื™ืจื•ืช
04:24
devoured the caterpillar alive
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ื˜ืจืคื• ืืช ื”ื–ื—ืœ ื‘ืขื•ื“ื• ื—ื™
04:26
before bursting out of its body.
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ืœืคื ื™ ืฉืคืจืฆื• ืžืชื•ืฃ ื’ื•ืคื•.
04:27
See what I mean?
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ืจื•ืื™ื ืœืžื” ื”ืชื›ื•ื•ื ืชื™?
04:30
Now, the caterpillar didn't die.
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ืื‘ืœ, ื”ื–ื—ืœ ืœื ืžืช.
04:33
Some of the wasps seemed to stay behind
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ื—ืœืง ืžื”ืฆืจืขื•ืช ื ืฉืืจื• ืžืื—ื•ืจ
04:35
and controlled it into defending their siblings
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ื•ื’ืจืžื• ืœื• ืœื”ื’ืŸ ืขืœ ืื—ื™ื•ืชื™ื”ืŸ
04:38
which are metamorphosing
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ื‘ื–ืžืŸ ืฉื”ืŸ ืžืฉื ื•ืช ืฆื•ืจื”
04:40
into adults within those cocoons.
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ืœืฆืจืขื•ืช ื‘ื•ื’ืจื•ืช ื‘ืชื•ืš ืื•ืชืŸ ืคืงืขื•ืช.
04:42
This caterpillar is a head-banging zombie bodyguard
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ื”ื–ื—ืœ ื”ืคืš ืœืฉื•ืžืจ ื–ื•ืžื‘ื™ ืฉื—ื•ื‘ื˜ ืืช ืจืืฉื•
04:46
defending the offspring
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ืฉืžื’ืŸ ืขืœ ื”ืฆืืฆืื™ื
04:47
of the creature that killed it.
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ืฉืœ ื”ื™ืฆื•ืจ ืฉื”ืจื’ ืื•ืชื•.
04:49
(Applause)
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(ืžื—ื™ืื•ืช ื›ืคื™ื™ื)
04:53
We have a lot to get through. I only have 13 minutes. (Laughter)
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ื™ืฉ ืœื™ ื”ืžื•ืŸ ืžื” ืœื”ืกื‘ื™ืจ. ื•ืจืง 13 ื“ืงื•ืช. (ืฆื—ื•ืง)
04:57
Now, some of you are probably just
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ื—ืœืง ืžื›ื ืžื—ืคืฉื™ื ืขื›ืฉื™ื• ืงืฆืช ื ื—ืžื”
04:59
desperately clawing for some solace
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05:01
in the idea that these things are oddities
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ื‘ืขื•ื‘ื“ื” ืฉืžื“ื•ื‘ืจ ื‘ืชื•ืคืขื•ืช ืžื•ื–ืจื•ืช ื•ื ื“ื™ืจื•ืช
05:04
of the natural world, that they are outliers,
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ื‘ืขื•ืœื ื”ื—ื™, ืฉืžื“ื•ื‘ืจ ื‘ืžืงืจื™ ืงื™ืฆื•ืŸ,
05:06
and that point of view is understandable,
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ื•ื ืงื•ื“ืช ื”ืžื‘ื˜ ื”ื–ื• ืžื•ื‘ื ืช ืœื™,
05:07
because by their nature, parasites are quite small
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ื›ื™ ืžืขืฆื ื˜ื‘ืขื, ื˜ืคื™ืœื™ื ื”ื ื™ืฆื•ืจื™ื ืงื˜ื ื™ื
05:10
and they spend a lot of their time
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ื•ื”ื ืžื‘ืœื™ื ืืช ืžืจื‘ื™ืช ื–ืžื ื
05:11
inside the bodies of other things.
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ื‘ืชื•ืš ื’ื•ืคื ืฉืœ ื™ืฆื•ืจื™ื ืื—ืจื™ื.
05:14
They're easy to overlook,
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ืงืœ ืžืื“ ืœื”ืชืขืœื ืžื”ื,
05:16
but that doesn't mean that they aren't important.
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ืื‘ืœ ื–ื” ืœื ืื•ืžืจ ืฉื”ื ืœื ื—ืฉื•ื‘ื™ื.
05:18
A few years back, a man called Kevin Lafferty
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ืœืคื ื™ ืžืกืคืจ ืฉื ื™ื, ืื“ื ื‘ืฉื ืงื•ื•ื™ืŸ ืœืคืจื˜ื™
05:21
took a group of scientists into three Californian estuaries
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ื”ื•ื‘ื™ืœ ืงื‘ื•ืฆืช ืžื“ืขื ื™ื ืืœ ื”ืฉืคืš ืฉืœ ืฉืœื•ืฉื” ื ื”ืจื•ืช ื‘ืงืœื™ืคื•ืจื ื™ื”
05:24
and they pretty much weighed and dissected
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ื•ื”ื ืฉืงืœื• ื•ื ื™ืชื—ื•
05:26
and recorded everything they could find,
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ื•ืชื™ืขื“ื• ืืช ื›ืœ ืžื” ืฉื”ื ืžืฆืื• ืฉื,
05:28
and what they found
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ื•ืžื” ืฉื”ื ื’ื™ืœื•
05:29
were parasites in extreme abundance.
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ื”ื™ื™ืชื” ื›ืžื•ืช ืขืฆื•ืžื” ืฉืœ ื˜ืคื™ืœื™ื.
05:32
Especially common were trematodes,
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ื”ืกื•ื’ ื”ื ืคื•ืฅ ื”ื™ื• ืชื•ืœืขื™ื ืžืžืฉืคื—ืช ื”ื˜ืจืžื˜ื•ื“ื•ืช,
05:34
tiny worms that specialize in castrating their hosts
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ืชื•ืœืขื™ื ืงื˜ื ื•ืช ืฉืžืชืžื—ื•ืช ื‘ืกื™ืจื•ืก ื”ืžืืจื—
05:37
like this unfortunate snail.
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ื›ืžื• ื”ืฉื‘ืœื•ืœ ื”ืžืกื›ืŸ ื”ื–ื”.
05:39
Now, a single trematode is tiny, microscopic,
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ืชื•ืœืขืช ื˜ืจืžื˜ื•ื“ื” ื‘ื•ื“ื“ืช ื”ื™ื ื–ืขื™ืจื”, ืžื™ืงืจื•ืกืงื•ืคื™ืช,
05:42
but collectively they weighed as much
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ืื‘ืœ ื›ื•ืœืŸ ื™ื—ื“ ืฉืงืœื•
05:44
as all the fish in the estuaries
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ื›ืžื• ื›ืœ ื”ื“ื’ื™ื ืฉื ืžืฆืื• ื‘ืฉืคืš ื”ื ื”ืจ
05:46
and three to nine times more than all the birds.
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ื•ืคื™ 3 ืขื“ 9 ืžืžืฉืงืœ ื”ืฆื™ืคื•ืจื™ื ื‘ืื–ื•ืจ.
05:50
And remember the Gordian worm that I showed you,
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ื•ื–ื•ื›ืจื™ื ืืช ื”ืชื•ืœืขืช ื”ื’ื•ืจื“ื™ืช ืฉื”ืจืื™ืชื™ ืœื›ื,
05:52
the cricket thing?
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ื–ื• ืžื”ืฆืจืฆืจ?
05:53
One Japanese scientist called Takuya Sato
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ืžื“ืขืŸ ื™ืคื ื™ ื‘ืฉื ื˜ืงื•ื™ื” ืกืื˜ื•
05:56
found that in one stream,
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ื’ื™ืœื” ืฉื‘ื ื—ืœ ืื—ื“,
05:58
these things drive so many crickets
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ื”ืชื•ืœืขื™ื ื’ืจืžื• ืœื›ืžื•ืช ืขืฆื•ืžื” ืฉืœ ืฆืจืฆืจื™ื
06:00
and grasshoppers into the water
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ื•ื—ื’ื‘ื™ื ืœื–ื ืง ืœืžื™ื
06:01
that the drowned insects
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ื•ื”ื‘ื™ืื• ืœื›ืš ืฉื”ื—ืจืงื™ื ื”ื˜ื•ื‘ืขื™ื
06:02
make up some 60 percent of the diet of local trout.
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ื”ื™ื•ื• 60 ืื—ื•ื– ืžื”ืชื–ื•ื ื” ืฉืœ ื“ื’ื™ ื”ืคื•ืจืœ ื”ืžืงื•ืžื™ื™ื.
06:06
Manipulation is not an oddity.
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ืฉืœื™ื˜ื” ื˜ืคื™ืœื™ืช ืื™ื ื” ืชื•ืคืขื” ื ื“ื™ืจื”.
06:09
It is a critical and common part
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ื”ื™ื ื—ื™ื•ื ื™ืช ื•ื ืคื•ืฆื”
06:12
of the world around us,
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ื‘ืขื•ืœื ื”ืกื•ื‘ื‘ ืื•ืชื ื•,
06:13
and scientists have now found
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ื•ืžื“ืขื ื™ื ื’ื™ืœื• ืœืื—ืจื•ื ื”
06:15
hundreds of examples of such manipulators,
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ืžืื•ืช ื“ื•ื’ืžืื•ืช ืฉืœ ืฉืœื™ื˜ื” ื˜ืคื™ืœื™ืช,
06:17
and more excitingly, they're starting to understand
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ื•ืžื” ืฉื™ื•ืชืจ ืžืขื ื™ื™ืŸ, ื”ื ืžืชื—ื™ืœื™ื ืœื”ื‘ื™ืŸ
06:20
exactly how these creatures control their hosts.
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ื›ื™ืฆื“ ื”ื˜ืคื™ืœื™ื ืฉื•ืœื˜ื™ื ื‘ืžืืจื—ื™ื ืฉืœื”ื.
06:24
And this is one of my favorite examples.
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ื–ื• ืื—ืช ืžื”ื“ื•ื’ืžืื•ืช ื”ื—ื‘ื™ื‘ื•ืช ืขืœื™.
06:26
This is Ampulex compressa,
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ื–ื•ื”ื™ ืฆืจืขืช ื”ืืžืคื•ืœืงืก ืงื•ืžืคืจืกื”,
06:29
the emerald cockroach wasp,
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ืฆืจืขืช ืชื™ืงืŸ ื”ืื–ืžืจื’ื“,
06:31
and it is a truth universally acknowledged
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ื™ื“ื•ืข ื‘ืจื—ื‘ื™ ื”ืขื•ืœื
06:33
that an emerald cockroach wasp in possession
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ืฉืฆืจืขืช ืชื™ืงืŸ ื”ืื–ืžืจื’ื“ ืฉื‘ืจืฉื•ืชื”
06:35
of some fertilized eggs
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ื‘ื™ืฆื™ื ืžื•ืคืจื•ืช
06:37
must be in want of a cockroach.
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ืžืชื—ื™ืœื” ืœื—ืคืฉ ืชื™ืงืŸ.
06:39
When she finds one,
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ื›ืืฉืจ ื”ื™ื ืžื•ืฆืืช ืชื™ืงืŸ,
06:41
she stabs it with a stinger
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ื”ื™ื ื“ื•ืงืจืช ืื•ืชื• ื‘ืขื•ืงืฅ
06:43
that is also a sense organ.
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ืฉื”ื•ื ื’ื ืื™ื‘ืจ ื—ื™ืฉื”.
06:44
This discovery came out three weeks ago.
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ื–ื• ืชื’ืœื™ืช ืžืœืคื ื™ ืฉืœื•ืฉื” ืฉื‘ื•ืขื•ืช.
06:47
She stabs it with a stinger that is a sense organ
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ื”ืฆืจืขื” ื“ื•ืงืจืช ืืช ื”ืชื™ืงืŸ ืขื ื”ืขื•ืงืฅ ืฉื”ื•ื ืื™ื‘ืจ ื—ื™ืฉื”
06:49
equipped with small sensory bumps
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ืขื ื‘ืœื™ื˜ื•ืช ืชื—ื•ืฉื” ืงื˜ื ื•ืช
06:51
that allow her to feel the distinctive texture
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ืฉืžืืคืฉืจื•ืช ืœื” ืœื–ื”ื•ืช ืืช ื”ืžืจืงื ื”ื™ื™ื—ื•ื“ื™
06:54
of a roach's brain.
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ืฉืœ ืžื•ื— ื”ืชื™ืงืŸ.
06:56
So like a person blindly rooting about in a bag,
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ืžืžืฉ ื›ืžื• ืื“ื ืฉืžื—ืคืฉ ื—ืคืฆื™ื ื‘ืชื•ืš ื”ืชื™ืง ืฉืœื•,
06:59
she finds the brain, and she injects it with venom
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ื”ื™ื ืžื•ืฆืืช ืืช ื”ืžื•ื—, ื•ืžื–ืจื™ืงื” ืคื ื™ืžื” ืืจืก
07:01
into two very specific clusters of neurons.
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ืืœ ืฉืชื™ ืงื‘ื•ืฆื•ืช ืขืฆื‘ื™ื ื™ื™ื—ื•ื“ื™ื•ืช.
07:05
Israeli scientists Frederic Libersat and Ram Gal
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ื”ืžื“ืขื ื™ื ื”ื™ืฉืจืืœื™ื ืคืจื“ืจื™ืง ืœื‘ืจืกื˜ ื•ืจื ื’ืœ
07:08
found that the venom is a very specific chemical weapon.
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ื’ื™ืœื• ืฉื”ืืจืก ื”ื•ื ื ืฉืง ื›ื™ืžื™ ืžื“ื•ื™ืง ืžืื“.
07:12
It doesn't kill the roach, nor does it sedate it.
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ื”ื•ื ืœื ื”ื•ืจื’ ืืช ื”ืชื™ืงืŸ, ื”ื•ื ืœื ืžื˜ืฉื˜ืฉ ืื•ืชื•.
07:15
The roach could walk away
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ื”ืชื™ืงืŸ ื™ื›ื•ืœ ืœื”ืžืฉื™ืš ืœืœื›ืช
07:17
or fly or run if it chose to,
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ืื• ืœืขื•ืฃ ืื• ืœืจื•ืฅ ืื ื™ืจืฆื”,
07:20
but it doesn't choose to,
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ืื‘ืœ ื”ื•ื ืœื ืจื•ืฆื”,
07:22
because the venom nixes its motivation to walk,
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ื›ื™ ื”ืืจืก ืžืฉืชืง ืืช ืจืฆื•ื ื• ืฉืœ ื”ืชื™ืงืŸ ืœืœื›ืช,
07:25
and only that.
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ื•ื–ื”ื•.
07:26
The wasp basically un-checks the escape-from-danger box
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ื”ืฆืจืขื” ืคืฉื•ื˜ ืžื‘ื˜ืœืช ืืช ืคืงื•ื“ืช ื”'ืœื‘ืจื•ื— ืžืกื›ื ื”'
07:30
in the roach's operating system,
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ื‘ืžืขืจื›ืช ื”ื”ืคืขืœื” ืฉืœ ื”ืชื™ืงืŸ,
07:32
allowing her to lead her helpless victim
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ื•ื›ืš ื”ื™ื ื™ื›ื•ืœื” ืœื”ื•ื‘ื™ืœ ืืช ืงื•ืจื‘ื ื” ื—ืกืจ ื”ื™ืฉืข
07:35
back to her lair by its antennae
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ืืœ ื”ืžืื•ืจื” ืฉืœื” ื›ืืฉืจ ื”ื™ื ืžื›ื•ื•ื ืช ืืช ืžื—ื•ืฉื™ื•
07:37
like a person walking a dog.
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ืžืžืฉ ื›ืžื• ืื“ื ืฉืžื•ืœื™ืš ืืช ื›ืœื‘ื•.
07:40
And once there, she lays an egg on it,
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ื›ืฉื”ื ืžื’ื™ืขื™ื ืœืžืื•ืจื”, ื”ืฆืจืขื” ืžื˜ื™ืœื” ืืช ื‘ื™ืฆื™ื” ื‘ืชื™ืงืŸ,
07:41
egg hatches, devoured alive, bursts out of body,
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ื”ื‘ื™ืฆื™ื ื‘ื•ืงืขื•ืช, ื”ืชื™ืงืŸ ื ื˜ืจืฃ ืžื‘ืคื ื™ื, ื”ืฆืจืขื•ืช ืคื•ืจืฆื•ืช ืžื’ื•ืคื•,
07:44
yadda yadda yadda, you know the drill.
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ื™ื“ื” ื™ื“ื” ื™ื“ื”, ืืชื ืžื›ื™ืจื™ื ืืช ื”ื”ืžืฉืš.
07:46
(Laughter) (Applause)
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(ืฆื—ื•ืง) (ืžื—ื™ืื•ืช ื›ืคื™ื™ื)
07:49
Now I would argue that, once stung,
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ื ื™ืชืŸ ืœื˜ืขื•ืŸ, ืฉืื—ืจื™ ื”ืขืงื™ืฆื”,
07:52
the cockroach isn't a roach anymore.
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ื”ืชื™ืงืŸ ืื™ื ื• ืชื™ืงืŸ ื™ื•ืชืจ.
07:54
It's more of an extension of the wasp,
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ื”ื•ื ื”ื•ืคืš ืœื”ื™ื•ืช ืกื•ื’ ืฉืœ ืื™ื‘ืจ ืฉืœ ื”ืฆืจืขื”,
07:56
just like the cricket was an extension of the Gordian worm.
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ืžืžืฉ ื›ืžื• ืฉื”ืฆืจืฆืจ ื”ื•ืคืš ืœืื™ื‘ืจ ืฉืœ ื”ืชื•ืœืขืช ื”ื’ื•ืจื“ื™ืช.
07:59
These hosts won't get to survive or reproduce.
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ื‘ืขืœื™ ื”ื—ื™ื™ื ื”ืžืืจื—ื™ื ืœื ื™ื–ื›ื• ืœื”ื™ืฉืืจ ื‘ื—ื™ื™ื ืื• ืœื”ืชืจื‘ื•ืช.
08:02
They have as much control over their own fates
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ื”ืฉืœื™ื˜ื” ืฉืœื”ื ืขืœ ื’ื•ืจืœื ื“ื•ืžื” ืœืžื™ื“ืช ื”ืฉืœื™ื˜ื” ื”ืขืฆืžื™ืช ืฉืœ ื”ืžื›ื•ื ื™ืช ืฉืœื™.
08:04
as my car.
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08:06
Once the parasites get in,
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ื‘ืจื’ืข ืฉื”ื˜ืคื™ืœ ื—ื•ื“ืจ ืคื ื™ืžื”,
08:07
the hosts don't get a say.
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ื”ืžืืจื— ืžืื‘ื“ ืืช ื–ื›ื•ืช ื”ื‘ื—ื™ืจื” ืฉืœื•.
08:10
Now humans, of course,
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ื‘ื ื™ ืื“ื, ื›ืžื•ื‘ืŸ,
08:11
are no stranger to manipulation.
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ืžื›ื™ืจื™ื ื”ื™ื˜ื‘ ืืช ื ื•ืฉื ื”ืžื ื™ืคื•ืœืฆื™ื•ืช ื•ื”ืฉืœื™ื˜ื”.
08:13
We take drugs to shift the chemistries of our brains
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ืื ื—ื ื• ืžืฉืชืžืฉื™ื ื‘ืชืจื•ืคื•ืช ืฉื’ื•ืจืžื•ืช ืœืฉื™ื ื•ื™ื™ื ื›ื™ืžื™ื™ื ื‘ืžื•ื—ื ื•
08:15
and to change our moods,
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ื•ืžืฉืคื™ืขื™ื ืขืœ ืžืฆื‘ ืจื•ื—ื ื•,
08:17
and what are arguments or advertising or big ideas
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ื•ืื™ืš ื ื’ื“ื™ืจ ื˜ื™ืขื•ื ื™ื ืื• ืคืจืกื•ืžื•ืช ืื• ืจืขื™ื•ื ื•ืช ื“ื’ื•ืœื™ื
08:21
if not an attempt to influence someone else's mind?
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ืื ืœื ื›ื ื™ืกื™ื•ืŸ ืœื”ืฉืคื™ืข ืขืœ ืžื—ืฉื‘ื•ืชื™ื• ืฉืœ ืžื™ืฉื”ื• ืื—ืจ?
08:24
But our attempts at doing this
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ืื‘ืœ ื ื™ืกื™ื•ื ื•ืช ื”ื”ืฉืคืขื” ืฉืœื ื•
08:26
are crude and blundering compared
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ื”ื ื’ืกื™ื ื•ื›ื•ืฉืœื™ื ื‘ื”ืฉื•ื•ืื”
08:28
to the fine-grained specificity of the parasites.
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ืœื™ื›ื•ืœื•ืช ื”ื”ืฉืคืขื” ื”ืžืฉื•ื›ืœืœื•ืช ืฉืœ ื”ื˜ืคื™ืœื™ื.
08:31
Don Draper only wishes he was as elegant
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ื“ื•ืŸ ื“ืจื™ื™ืคืจ ื”ื™ื” ืžืช ืœื”ื™ื•ืช ืืœื’ื ื˜ื™
08:33
and precise as the emerald cockroach wasp.
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ื•ืžื“ื•ื™ืง ื›ืžื• ืฆืจืขืช ืชื™ืงืŸ ื”ืื–ืžืจื’ื“.
08:38
Now, I think this is part of what makes parasites
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ืœื˜ืขืžื™, ื–ื” ื—ืœืง ืžืžื” ืฉื”ื•ืคืš ืืช ื”ื˜ืคื™ืœื™ื
08:42
so sinister and so compelling.
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ืœื›ืœ ื›ืš ืžืจื•ืฉืขื™ื ื•ื›ืœ ื›ืš ืžืจืชืงื™ื.
08:45
We place such a premium on our free will
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ืื ื—ื ื• ืžื—ืฉื™ื‘ื™ื ืžืื“ ืืช ื–ื›ื•ืช ื”ื‘ื—ื™ืจื” ื”ื—ื•ืคืฉื™ืช ืฉืœื ื•
08:47
and our independence
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ื•ื”ืขืฆืžืื•ืช ืฉืœื ื•
08:48
that the prospect of losing those qualities
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ื•ื”ืืคืฉืจื•ืช ืœืื‘ื“ ืืช ื”ื™ื›ื•ืœื•ืช ื”ืœืœื•
08:50
to forces unseen
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ืœื˜ื•ื‘ืช ื›ื•ื—ื•ืช ื‘ืœืชื™ ื ืจืื™ื
08:51
informs many of our deepest societal fears.
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ืžืขื•ืจืจื•ืช ื‘ื ื• ืคื—ื“ื™ื ื•ื—ืจื“ื•ืช ื‘ืจืžื” ื”ื—ื‘ืจืชื™ืช.
08:54
Orwellian dystopias and shadowy cabals
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ื”ืขื•ืœืžื•ืช ื”ืžืคื—ื™ื“ื™ื ืฉืชื™ืืจ ื’'ื•ืจื’' ืื•ืจื•ื•ืœ, ืชื›ื›ื™ื ืืคืœื™ื
08:57
and mind-controlling supervillains --
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ื•ื ื‘ืœื™ื ื”ืฉื•ืœื˜ื™ื ื‘ืžื•ื— --
08:59
these are tropes that fill our darkest fiction,
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ืืœื• ื“ื™ืžื•ื™ื™ื ืฉืžืžืœืื™ื ืืช ืกื™ืคื•ืจื™ ื”ืื™ืžื” ืฉืœื ื•,
09:02
but in nature, they happen all the time.
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ืื‘ืœ ื‘ื˜ื‘ืข, ื”ื ืžืชืจื—ืฉื™ื ื›ืœ ื”ื–ืžืŸ.
09:07
Which leads me to an obvious
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ืžื” ืฉืžื•ื‘ื™ืœ ืื•ืชื™ ืœืฉืืœื” ื‘ืจื•ืจื”
09:09
and disquieting question:
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ื•ืžื“ืื™ื’ื”:
09:11
Are there dark, sinister parasites
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ื”ืื ื™ืฉ ื˜ืคื™ืœื™ื ืืคืœื™ื
09:13
that are influencing our behavior
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ืฉืžืฉืคื™ืขื™ื ืขืœ ื”ืชื ื”ื’ื•ืชื ื•
09:15
without us knowing about it,
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ื‘ืœื™ ืฉื ื“ืข,
09:17
besides the NSA?
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ืคืจื˜ ืœืกื•ื›ื ื•ืช ื”- NSA?
09:20
If there are any โ€”
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ืื ื™ืฉ ื›ืืœื” --
09:21
(Laughter) (Applause)
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(ืฆื—ื•ืง)(ืžื—ื™ืื•ืช ื›ืคื™ื™ื)
09:25
I've got a red dot on my forehead now, don't I?
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ื™ืฉ ืœื™ ื ืงื•ื“ืช ืœื™ื™ื–ืจ ืื“ื•ืžื” ืขืœ ื”ืžืฆื— ืขื›ืฉื™ื•, ื ื›ื•ืŸ?
09:27
(Laughter)
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(ืฆื—ื•ืง)
09:30
If there are any, this is a good candidate for them.
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ืื ื™ืฉ ื›ืืœื”, ื–ื”ื• ืžื•ืขืžื“ ื˜ื•ื‘ ืœื”ื™ื•ืช ืื—ื“ ืžื”ื.
09:33
This is Toxoplasma gondii, or Toxo, for short,
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ื–ื”ื• ื”ื˜ืคื™ืœ ื˜ื•ืงืกื•ืคืœื–ืžื” ื’ื•ื ื“ื™, ืื• ื˜ื•ืงืกื• ื‘ืงื™ืฆื•ืจ,
09:36
because the terrifying creature
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ืžืฉื•ื ืฉืœื™ืฆื•ืจื™ื ืžืคื—ื™ื“ื™ื
09:37
always deserves a cute nickname.
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ืชืžื™ื“ ืžื’ื™ืข ื›ื™ื ื•ื™ ื—ืžื•ื“.
09:40
Toxo infects mammals,
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ื˜ื•ืงืกื• ืžื“ื‘ื™ืง ื™ื•ื ืงื™ื,
09:42
a wide variety of mammals,
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ืžื’ื•ื•ืŸ ืจื—ื‘ ืฉืœ ื™ื•ื ืงื™ื,
09:43
but it can only sexually reproduce in a cat.
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ืื‘ืœ ื”ื•ื ืžืชืจื‘ื” ืจื‘ื™ื™ื” ืžื™ื ื™ืช ืจืง ื‘ื—ืชื•ืœื™ื.
09:47
And scientists like Joanne Webster have shown that
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ื•ืžื“ืขื ื™ื ื›ืžื• ื’'ื•ืืŸ ื•ื•ื‘ืกื˜ืจ ื”ื•ื›ื™ื—ื•
09:49
if Toxo gets into a rat or a mouse,
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ืฉืื ื˜ื•ืงืกื• ื—ื•ื“ืจ ืืœ ืชื•ืš ืขื›ื‘ืจื•ืฉ ืื• ืขื›ื‘ืจ,
09:52
it turns the rodent into a cat-seeking missile.
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ื”ื•ื ื”ื•ืคืš ืืช ื”ืžื›ืจืกื ืœื˜ื™ืœ ืฉืžื—ืคืฉ ื—ืชื•ืœื™ื.
09:55
If the infected rat smells the delightful odor
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ืื ื”ืขื›ื‘ืจื•ืฉ ื”ื ื’ื•ืข ืžืจื™ื— ืืช ื”ืจื™ื— ื”ื ืคืœื
09:58
of cat piss,
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ืฉืœ ืฉืชืŸ ื—ืชื•ืœื™ื,
09:59
it runs towards the source of the smell
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ื”ื•ื ืจืฅ ืืœ ืขื‘ืจ ืžืงื•ืจ ื”ืจื™ื—
10:02
rather than the more sensible direction of away.
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ื‘ืžืงื•ื ืœื ื”ื•ื’ ื‘ื”ื™ื’ื™ื•ืŸ ื•ืœื‘ืจื•ื— ืžื”ืื–ื•ืจ.
10:06
The cat eats the rat. Toxo gets to have sex.
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ื”ื—ืชื•ืœ ื˜ื•ืจืฃ ืืช ื”ืขื›ื‘ืจื•ืฉ. ื”ื˜ื•ืงืกื• ืžืชืจื‘ื”.
10:08
It's a classic tale of Eat, Prey, Love.
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ืžื“ื•ื‘ืจ ื‘ืกื™ืคื•ืจ ื”ืงืœืืกื™ ืฉืœ ืœืื›ื•ืœ, ืœืฆื•ื“, ืœืื”ื•ื‘.
10:11
(Laughter) (Applause)
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(ืฆื—ื•ืง) (ืžื—ื™ืื•ืช ื›ืคื™ื™ื)
10:19
You're very charitable, generous people.
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ืืชื ืžืžืฉ ืฆื“ื™ืงื™ื, ืื ืฉื™ื ื ื“ื™ื‘ื™ื.
10:22
Hi, Elizabeth, I loved your talk.
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ื”ื™ื™, ืืœื™ื–ื‘ืช, ืื”ื‘ืชื™ ืืช ื”ื”ืจืฆืื” ืฉืœืš.
10:25
How does the parasite control its host
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ืื™ืš ืฉื•ืœื˜ ื”ื˜ืคื™ืœ ื‘ืžืืจื—?
10:28
in this way?
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10:29
We don't really know.
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ืื ื—ื ื• ืœื ื™ื•ื“ืขื™ื ื‘ื“ื™ื•ืง.
10:31
We know that Toxo releases an enzyme
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ืื ื—ื ื• ื™ื•ื“ืขื™ื ืฉื˜ื•ืงืกื• ืžืคืจื™ืฉ ืื ื–ื™ืžื™ื
10:32
that makes dopamine, a substance involved
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ืฉืžื™ื™ืฆืจื™ื ื“ื•ืคืžื™ืŸ, ื”ื•ืจืžื•ืŸ ืฉืžืขื•ืจื‘
10:34
in reward and motivation.
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ื‘ืชื—ื•ืฉืช ืกื™ืคื•ืง ื•ืžื•ื˜ื™ื‘ืฆื™ื”.
10:36
We know it targets certain parts of a rodent's brain,
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ืื ื—ื ื• ื™ื•ื“ืขื™ื ืฉื”ื•ื ืคืขื™ืœ ื‘ืื–ื•ืจื™ื ืกืคืฆื™ืคื™ื™ื ื‘ืžื•ื—ื ืฉืœ ื”ืžื›ืจืกืžื™ื,
10:39
including those involved in sexual arousal.
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ื•ื‘ื”ื ื”ืื–ื•ืจื™ื ื”ืžืขื•ืจื‘ื™ื ื‘ืขื•ืจืจื•ืช ืžื™ื ื™ืช.
10:41
But how those puzzle pieces fit together
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ืื‘ืœ ืื™ืš ืžืกื“ืจื™ื ืืช ื—ืœืงื™ ื”ืคืื–ืœ
10:43
is not immediately clear.
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ืขื“ื™ื™ืŸ ืœื ื‘ืจื•ืจ ืœื ื•.
10:45
What is clear is that this thing
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ืžื” ืฉื‘ืจื•ืจ ืœื ื• ื”ื•ื ืฉื”ื˜ืคื™ืœ
10:47
is a single cell.
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ื”ื•ื ื™ืฆื•ืจ ื—ื“ ืชืื™.
10:49
This has no nervous system.
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ืื™ืŸ ืœื• ืžืขืจื›ืช ืขืฆื‘ื™ื.
10:50
It has no consciousness.
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ืื™ืŸ ืœื• ืžื•ื“ืขื•ืช.
10:51
It doesn't even have a body.
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ืื™ืŸ ืœื• ื’ื•ืฃ.
10:53
But it's manipulating a mammal?
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ืื‘ืœ ื”ื•ื ืฉื•ืœื˜ ื‘ื™ื•ื ืง?
10:55
We are mammals.
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ืื ื—ื ื• ื™ื•ื ืงื™ื.
10:57
We are more intelligent than a mere rat, to be sure,
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ืื ื—ื ื• ื™ื•ืชืจ ืื™ื ื˜ืœื™ื’ื ื˜ื™ื ืžืขื›ื‘ืจื•ืฉ ืคืฉื•ื˜, ื–ื” ื‘ื˜ื•ื—,
10:59
but our brains have the same basic structure,
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ืื‘ืœ ื”ืžื•ื— ืฉืœื ื• ื‘ื ื•ื™ ื‘ืื•ืคืŸ ื“ื•ืžื”,
11:02
the same types of cells,
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ืื•ืชื ืกื•ื’ื™ ืชืื™ื,
11:03
the same chemicals running through them,
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ืื•ืชื ื›ื™ืžื™ืงืœื™ื ืžื•ืขื‘ืจื™ื ื‘ื™ืŸ ื”ืชืื™ื,
11:05
and the same parasites.
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ื•ืื•ืชื ื˜ืคื™ืœื™ื.
11:07
Estimates vary a lot, but some figures suggest
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ื”ื”ืขืจื›ื•ืช ืžืฉืชื ื•ืช, ืื‘ืœ ื—ืœืง ืžื”ื—ื•ืงืจื™ื ืžืขืจื™ื›ื™ื
11:09
that one in three people around the world
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ืฉืœืื“ื ืื—ื“ ืžื›ืœ ืฉืœื•ืฉื” ืื ืฉื™ื ื‘ืขื•ืœื
11:12
have Toxo in their brains.
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ื™ืฉ ื˜ื•ืงืกื• ื‘ืžื•ื—.
11:13
Now typically, this doesn't lead to any overt illness.
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ื‘ื“ืจืš ื›ืœืœ, ื”ื•ื ืœื ืžื•ื‘ื™ืœ ืœื”ื•ืคืขืช ืžื—ืœื”.
11:17
The parasite holds up in a dormant state
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ื”ื˜ืคื™ืœ ืžืชืงื™ื™ื ื‘ืžืฆื‘ ืจื“ื•ื
11:19
for a long period of time.
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ืœืžืฉืš ืชืงื•ืคืช ื–ืžืŸ ืืจื•ื›ื”.
11:21
But there's some evidence that those people
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ืื‘ืœ ื™ืฉื ืŸ ืขื“ื•ื™ื•ืช ื”ืžืจืื•ืช ืฉื”ืื ืฉื™ื ื”ื ื’ื•ืขื™ื
11:23
who are carriers score slightly differently
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ืฉื”ื ืจืง ื ืฉืื™ื, ืžืฉื™ื’ื™ื ืชื•ืฆืื•ืช ืฉื•ื ื•ืช ื‘ืžืงืฆืช
11:26
on personality questionnaires than other people,
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ื‘ืžื‘ื—ื ื™ ืื™ืฉื™ื•ืช ื‘ื”ืฉื•ื•ืื” ืœืื ืฉื™ื ืื—ืจื™ื,
11:29
that they have a slightly higher risk of car accidents,
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ืฉื”ื ื ืžืฆืื™ื ื‘ืกื™ื›ื•ืŸ ืžืขื˜ ื’ื‘ื•ื” ื™ื•ืชืจ ืœืžืขื•ืจื‘ื•ืช ื‘ืชืื•ื ื•ืช ื“ืจื›ื™ื,
11:31
and there's some evidence that people with schizophrenia
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ื•ื™ืฉ ื’ื ืขื“ื•ื™ื•ืช ืœื›ืš ืฉืื ืฉื™ื ื”ื—ื•ืœื™ื ื‘ืกื›ื™ื–ื•ืจืคื ื™ื”
11:34
are more likely to be infected.
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ื ื•ื˜ื™ื ืœืฉืืช ืืช ื”ื˜ืคื™ืœ ื‘ืฉื›ื™ื—ื•ืช ื’ื‘ื•ื”ื” ื™ื•ืชืจ.
11:36
Now, I think this evidence is still inconclusive,
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ืื ื™ ื—ื•ืฉื‘ ืฉื”ืขื“ื•ื™ื•ืช ื”ืœืœื• ืœื ืžืืคืฉืจื•ืช ืœื”ืกื™ืง ืžืกืงื ื•ืช,
11:39
and even among Toxo researchers,
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ื•ืืคื™ืœื• ื—ื•ืงืจื™ ื”ื˜ื•ืงืกื•,
11:40
opinion is divided as to whether the parasite
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ื—ืœื•ืงื™ื ื‘ื“ืขืชื ืœื’ื‘ื™ ื”ืฉืืœื” ืื ืœื˜ืคื™ืœ
11:43
is truly influencing our behavior.
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ื™ืฉ ื”ืฉืคืขื” ืžืžืฉื™ืช ืขืœ ื”ืชื ื”ื’ื•ืชื ื•.
11:45
But given the widespread nature of such manipulations,
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ืื•ืœื ื‘ื”ืชื—ืฉื‘ ื‘ืžื’ื•ื•ืŸ ื”ืขืฆื•ื ืฉืœ ื”ืžื ื™ืคื•ืœืฆื™ื•ืช,
11:48
it would be completely implausible
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ื™ื”ื™ื” ื–ื” ื‘ืœืชื™ ืกื‘ื™ืจ ืœื”ื ื™ื—
11:50
for humans to be the only species
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ืฉื‘ื ื™ ื”ืื“ื ื”ื ื”ืžื™ืŸ ื”ื™ื—ื™ื“
11:51
that weren't similarly affected.
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ืฉืื™ื ื• ืžื•ืฉืคืข ืžื˜ืคื™ืœื™ื.
11:54
And I think that this capacity to constantly
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ื•ืื ื™ ืกื‘ื•ืจ ืฉื”ื™ื›ื•ืœืช ืœืขื•ื•ืช
11:59
subvert our way of thinking about the world
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ืืช ืžื—ืฉื‘ื•ืชื™ื ื• ืื•ื“ื•ืช ื”ืขื•ืœื
12:02
makes parasites amazing.
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ื”ื•ืคื›ืช ืืช ื”ื˜ืคื™ืœื™ื ืœืžื“ื”ื™ืžื™ื.
12:03
They're constantly inviting us to look at the natural world sideways,
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ื”ื ืชืžื™ื“ ืžื–ืžื™ื ื™ื ืื•ืชื ื• ืœื”ื‘ื™ื˜ ื‘ืขื•ืœื ื”ื˜ื‘ืข ืฉืกื‘ื™ื‘ื ื•,
12:06
and to ask if the behaviors we're seeing,
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ื•ืœืชื”ื•ืช ืื ื”ื”ืชื ื”ื’ื•ืช ืฉืื ื• ืจื•ืื™ื,
12:09
whether they're simple and obvious
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ื‘ื™ืŸ ืื ื”ืŸ ืคืฉื•ื˜ื•ืช ื•ื‘ืจื•ืจื•ืช
12:10
or baffling and puzzling,
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ืื• ืžื‘ื™ื›ื•ืช ื•ืžื‘ืœื‘ืœื•ืช,
12:12
are not the results of individuals
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ืื™ื ืŸ ืชื•ืฆืื” ืฉืœ ืื ืฉื™ื ื‘ื•ื“ื“ื™ื
12:14
acting through their own accord
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ื”ืคื•ืขืœื™ื ืขืœ ื“ืขืช ืขืฆืžื
12:15
but because they are being bent
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ืืœื ืžืฉื•ื ืฉื”ื ืžื•ืฉืคืขื™ื
12:17
to the control of something else.
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ืžืฉืœื™ื˜ืชื• ืฉืœ ืžืฉื”ื• ืื—ืจ.
12:20
And while that idea may be disquieting,
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ื•ื‘ืฉืขื” ืฉื”ืจืขื™ื•ืŸ ื”ื–ื” ืžืขื•ืจืจ ื‘ื ื• ื—ื•ืกืจ ืฉืงื˜,
12:22
and while parasites' habits may be very grisly,
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ื•ื‘ื–ืžืŸ ืฉื”ืจื’ืœื™ ื”ื—ื™ื™ื ืฉืœ ื”ื˜ืคื™ืœื™ื ื ื•ื˜ื™ื ืœื”ื™ื•ืช ืžื—ืจื™ื“ื™ื,
12:25
I think that ability to surprise us
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ืื ื™ ื—ื•ืฉื‘ ืฉื”ื™ื›ื•ืœืช ืœื”ืคืชื™ืข ืื•ืชื ื•
12:27
makes them as wonderful and as charismatic
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ื”ื•ืคื›ืช ืืช ื”ื˜ืคื™ืœื™ื ืœื ืคืœืื™ื ื•ื›ืจื™ื–ืžื˜ื™ื™ื
12:30
as any panda or butterfly or dolphin.
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ื›ืžื• ื›ืœ ื“ื‘ ืคื ื“ื”, ืคืจืคืจ ืื• ื“ื•ืœืคื™ืŸ.
12:33
At the end of "On the Origin of Species,"
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ื‘ืกื™ื•ื ื”ืกืคืจ "ืžื•ืฆื ื”ืžื™ื ื™ื",
12:35
Charles Darwin writes about the grandeur of life,
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ืฆ'ืืจืœืก ื“ืืจื•ื™ืŸ ื›ื•ืชื‘ ืขืœ ื”ื’ื“ื•ืœื” ืฉื‘ื—ื™ื™ื,
12:38
and of endless forms most beautiful
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ื•ืขืœ ืจื™ื‘ื•ื™ ื”ืฆื•ืจื•ืช ื”ื™ืคื”ืคื™ื•ืช
12:41
and most wonderful,
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ื•ื”ื ืคืœืื•ืช,
12:43
and I like to think he could easily have been talking
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ื•ืื ื™ ื—ื•ืฉื‘ ืฉื”ื•ื ื™ื›ื•ืœ ื”ื™ื” ื‘ืงืœื•ืช ืœื“ื‘ืจ
12:45
about a tapeworm that makes shrimp sociable
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ืขืœ ื”ืฉืจืฉื•ืจ ืฉื’ื•ืจื ืœื—ืกื™ืœื•ื ื™ื ืœื”ืชืืกืฃ ื‘ื—ื‘ื•ืจื•ืช
12:48
or a wasp that takes cockroaches for walks.
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ืื• ืขืœ ื”ืฆืจืขื” ืฉืžื•ืฆื™ืื” ืืช ื”ืชื™ืงืŸ ืœื˜ื™ื•ืœ.
12:52
But perhaps, that's just a parasite talking.
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ืื‘ืœ ืื•ืœื™, ื–ื” ื”ื˜ืคื™ืœ ืฉื‘ืžื•ื—ื™ ืฉืžื“ื‘ืจ.
12:55
Thank you.
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ืชื•ื“ื” ืœื›ื.
12:56
(Applause)
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(ืžื—ื™ืื•ืช ื›ืคื™ื™ื)
ืขืœ ืืชืจ ื–ื”

ืืชืจ ื–ื” ื™ืฆื™ื’ ื‘ืคื ื™ื›ื ืกืจื˜ื•ื ื™ YouTube ื”ืžื•ืขื™ืœื™ื ืœืœื™ืžื•ื“ ืื ื’ืœื™ืช. ืชื•ื›ืœื• ืœืจืื•ืช ืฉื™ืขื•ืจื™ ืื ื’ืœื™ืช ื”ืžื•ืขื‘ืจื™ื ืขืœ ื™ื“ื™ ืžื•ืจื™ื ืžื”ืฉื•ืจื” ื”ืจืืฉื•ื ื” ืžืจื—ื‘ื™ ื”ืขื•ืœื. ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ื”ืžื•ืฆื’ื•ืช ื‘ื›ืœ ื“ืฃ ื•ื™ื“ืื• ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ ืžืฉื. ื”ื›ืชื•ื‘ื™ื•ืช ื’ื•ืœืœื•ืช ื‘ืกื ื›ืจื•ืŸ ืขื ื”ืคืขืœืช ื”ื•ื•ื™ื“ืื•. ืื ื™ืฉ ืœืš ื”ืขืจื•ืช ืื• ื‘ืงืฉื•ืช, ืื ื ืฆื•ืจ ืื™ืชื ื• ืงืฉืจ ื‘ืืžืฆืขื•ืช ื˜ื•ืคืก ื™ืฆื™ืจืช ืงืฉืจ ื–ื”.

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