[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.64,0:00:03.20,Default,,0000,0000,0000,,A herd of wildebeests, a shoal of fish,
Dialogue: 0,0:00:03.20,0:00:04.82,Default,,0000,0000,0000,,a flock of birds.
Dialogue: 0,0:00:04.82,0:00:06.89,Default,,0000,0000,0000,,Many animals gather in large groups
Dialogue: 0,0:00:06.89,0:00:08.88,Default,,0000,0000,0000,,that are among the most wonderful spectacles
Dialogue: 0,0:00:08.88,0:00:10.60,Default,,0000,0000,0000,,in the natural world.
Dialogue: 0,0:00:10.60,0:00:13.32,Default,,0000,0000,0000,,But why do these groups form?
Dialogue: 0,0:00:13.32,0:00:14.96,Default,,0000,0000,0000,,The common answers include things like
Dialogue: 0,0:00:14.96,0:00:17.92,Default,,0000,0000,0000,,seeking safety in numbers or hunting in packs
Dialogue: 0,0:00:17.92,0:00:20.42,Default,,0000,0000,0000,,or gathering to mate or breed,
Dialogue: 0,0:00:20.42,0:00:22.09,Default,,0000,0000,0000,,and all of these explanations,
Dialogue: 0,0:00:22.09,0:00:23.32,Default,,0000,0000,0000,,while often true,
Dialogue: 0,0:00:23.32,0:00:26.37,Default,,0000,0000,0000,,make a huge assumption about animal behavior,
Dialogue: 0,0:00:26.37,0:00:29.54,Default,,0000,0000,0000,,that the animals are in control of their own actions,
Dialogue: 0,0:00:29.54,0:00:31.80,Default,,0000,0000,0000,,that they are in charge of their bodies.
Dialogue: 0,0:00:31.80,0:00:35.22,Default,,0000,0000,0000,,And that is often not the case.
Dialogue: 0,0:00:35.22,0:00:38.15,Default,,0000,0000,0000,,This is Artemia, a brine shrimp.
Dialogue: 0,0:00:38.15,0:00:40.91,Default,,0000,0000,0000,,You probably know it better as a sea monkey.
Dialogue: 0,0:00:40.91,0:00:42.91,Default,,0000,0000,0000,,It's small, and it typically lives alone,
Dialogue: 0,0:00:42.91,0:00:45.98,Default,,0000,0000,0000,,but it can gather in these large red swarms
Dialogue: 0,0:00:45.98,0:00:48.23,Default,,0000,0000,0000,,that span for meters,
Dialogue: 0,0:00:48.23,0:00:51.32,Default,,0000,0000,0000,,and these form because of a parasite.
Dialogue: 0,0:00:51.32,0:00:54.01,Default,,0000,0000,0000,,These shrimp are infected with a tapeworm.
Dialogue: 0,0:00:54.01,0:00:56.26,Default,,0000,0000,0000,,A tapeworm is effectively a long, living gut
Dialogue: 0,0:00:56.26,0:00:59.14,Default,,0000,0000,0000,,with genitals at one end and\Na hooked mouth at the other.
Dialogue: 0,0:00:59.14,0:01:01.68,Default,,0000,0000,0000,,As a freelance journalist, I sympathize.
Dialogue: 0,0:01:01.68,0:01:03.84,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:01:03.84,0:01:06.74,Default,,0000,0000,0000,,The tapeworm drains nutrients from Artemia's body,
Dialogue: 0,0:01:06.74,0:01:08.82,Default,,0000,0000,0000,,but it also does other things.
Dialogue: 0,0:01:08.82,0:01:10.44,Default,,0000,0000,0000,,It castrates them,
Dialogue: 0,0:01:10.44,0:01:15.16,Default,,0000,0000,0000,,it changes their color from transparent to bright red,
Dialogue: 0,0:01:15.16,0:01:16.67,Default,,0000,0000,0000,,it makes them live longer,
Dialogue: 0,0:01:16.67,0:01:19.03,Default,,0000,0000,0000,,and as biologist Nicolas Rode has found,
Dialogue: 0,0:01:19.03,0:01:22.39,Default,,0000,0000,0000,,it makes them swim in groups.
Dialogue: 0,0:01:22.39,0:01:25.84,Default,,0000,0000,0000,,Why? Because the tapeworm,\Nlike many other parasites,
Dialogue: 0,0:01:25.84,0:01:27.42,Default,,0000,0000,0000,,has a complicated life cycle
Dialogue: 0,0:01:27.42,0:01:29.69,Default,,0000,0000,0000,,involving many different hosts.
Dialogue: 0,0:01:29.69,0:01:32.09,Default,,0000,0000,0000,,The shrimp are just one step on its journey.
Dialogue: 0,0:01:32.09,0:01:34.70,Default,,0000,0000,0000,,Its ultimate destination is this,
Dialogue: 0,0:01:34.70,0:01:36.65,Default,,0000,0000,0000,,the greater flamingo.
Dialogue: 0,0:01:36.65,0:01:39.68,Default,,0000,0000,0000,,Only in a flamingo can the tapeworm reproduce,
Dialogue: 0,0:01:39.68,0:01:42.96,Default,,0000,0000,0000,,so to get there, it manipulates its shrimp hosts
Dialogue: 0,0:01:42.96,0:01:46.06,Default,,0000,0000,0000,,into forming these conspicuous colored swarms
Dialogue: 0,0:01:46.06,0:01:48.77,Default,,0000,0000,0000,,that are easier for a flamingo to spot
Dialogue: 0,0:01:48.77,0:01:50.33,Default,,0000,0000,0000,,and to devour,
Dialogue: 0,0:01:50.33,0:01:53.26,Default,,0000,0000,0000,,and that is the secret of the Artemia swarm.
Dialogue: 0,0:01:53.26,0:01:55.43,Default,,0000,0000,0000,,They aren't sociable through their own volition,
Dialogue: 0,0:01:55.43,0:01:57.50,Default,,0000,0000,0000,,but because they are being controlled.
Dialogue: 0,0:01:57.50,0:01:59.20,Default,,0000,0000,0000,,It's not safety in numbers.
Dialogue: 0,0:01:59.20,0:02:01.06,Default,,0000,0000,0000,,It's actually the exact opposite.
Dialogue: 0,0:02:01.06,0:02:04.10,Default,,0000,0000,0000,,The tapeworm hijacks their brains and their bodies,
Dialogue: 0,0:02:04.10,0:02:05.49,Default,,0000,0000,0000,,turning them into vehicles
Dialogue: 0,0:02:05.49,0:02:09.46,Default,,0000,0000,0000,,for getting itself into a flamingo.
Dialogue: 0,0:02:09.46,0:02:10.89,Default,,0000,0000,0000,,And here is another example
Dialogue: 0,0:02:10.89,0:02:13.42,Default,,0000,0000,0000,,of a parasitic manipulation.
Dialogue: 0,0:02:13.42,0:02:16.39,Default,,0000,0000,0000,,This is a suicidal cricket.
Dialogue: 0,0:02:16.39,0:02:19.70,Default,,0000,0000,0000,,This cricket swallowed the \Nlarvae of a Gordian worm,
Dialogue: 0,0:02:19.70,0:02:21.59,Default,,0000,0000,0000,,or horsehair worm.
Dialogue: 0,0:02:21.59,0:02:23.74,Default,,0000,0000,0000,,The worm grew to adult size within it,
Dialogue: 0,0:02:23.74,0:02:26.78,Default,,0000,0000,0000,,but it needs to get into water in order to mate,
Dialogue: 0,0:02:26.78,0:02:29.00,Default,,0000,0000,0000,,and it does that by releasing proteins
Dialogue: 0,0:02:29.00,0:02:31.19,Default,,0000,0000,0000,,that addle the cricket's brain,
Dialogue: 0,0:02:31.19,0:02:33.35,Default,,0000,0000,0000,,causing it to behave erratically.
Dialogue: 0,0:02:33.35,0:02:35.31,Default,,0000,0000,0000,,When the cricket nears a body of water,
Dialogue: 0,0:02:35.31,0:02:36.93,Default,,0000,0000,0000,,such as this swimming pool,
Dialogue: 0,0:02:36.93,0:02:39.18,Default,,0000,0000,0000,,it jumps in and drowns,
Dialogue: 0,0:02:39.18,0:02:40.91,Default,,0000,0000,0000,,and the worm wriggles out
Dialogue: 0,0:02:40.91,0:02:44.76,Default,,0000,0000,0000,,of its suicidal corpse.
Dialogue: 0,0:02:44.76,0:02:48.37,Default,,0000,0000,0000,,Crickets are really roomy. Who knew?
Dialogue: 0,0:02:48.37,0:02:51.58,Default,,0000,0000,0000,,The tapeworm and the Gordian worm are not alone.
Dialogue: 0,0:02:51.58,0:02:53.30,Default,,0000,0000,0000,,They are part of an entire cavalcade
Dialogue: 0,0:02:53.30,0:02:55.38,Default,,0000,0000,0000,,of mind-controlling parasites,
Dialogue: 0,0:02:55.38,0:02:59.33,Default,,0000,0000,0000,,of fungi, viruses, and worms and insects and more
Dialogue: 0,0:02:59.33,0:03:01.90,Default,,0000,0000,0000,,that all specialize in subverting and overriding
Dialogue: 0,0:03:01.90,0:03:04.11,Default,,0000,0000,0000,,the wills of their hosts.
Dialogue: 0,0:03:04.11,0:03:05.85,Default,,0000,0000,0000,,Now, I first learned about this way of life
Dialogue: 0,0:03:05.85,0:03:08.34,Default,,0000,0000,0000,,through David Attenborough's "Trials of Life"
Dialogue: 0,0:03:08.34,0:03:10.06,Default,,0000,0000,0000,,about 20 years ago,
Dialogue: 0,0:03:10.06,0:03:11.76,Default,,0000,0000,0000,,and then later through a wonderful book called
Dialogue: 0,0:03:11.76,0:03:14.44,Default,,0000,0000,0000,,"Parasite Rex" by my friend Carl Zimmer.
Dialogue: 0,0:03:14.44,0:03:16.58,Default,,0000,0000,0000,,And I've been writing about\Nthese creatures ever since.
Dialogue: 0,0:03:16.58,0:03:19.39,Default,,0000,0000,0000,,Few topics in biology enthrall me more.
Dialogue: 0,0:03:19.39,0:03:23.10,Default,,0000,0000,0000,,It's like the parasites have subverted my own brain.
Dialogue: 0,0:03:23.10,0:03:25.71,Default,,0000,0000,0000,,Because after all, they are always compelling
Dialogue: 0,0:03:25.71,0:03:26.100,Default,,0000,0000,0000,,and they are delightfully macabre.
Dialogue: 0,0:03:26.100,0:03:28.39,Default,,0000,0000,0000,,When you write about parasites,
Dialogue: 0,0:03:28.39,0:03:30.47,Default,,0000,0000,0000,,your lexicon swells with phrases like
Dialogue: 0,0:03:30.47,0:03:33.52,Default,,0000,0000,0000,,"devoured alive" and "bursts out of its body."
Dialogue: 0,0:03:33.52,0:03:34.76,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:03:34.76,0:03:36.30,Default,,0000,0000,0000,,But there's more to it than that.
Dialogue: 0,0:03:36.30,0:03:38.40,Default,,0000,0000,0000,,I'm a writer, and fellow writers in the audience
Dialogue: 0,0:03:38.40,0:03:41.11,Default,,0000,0000,0000,,will know that we love stories.
Dialogue: 0,0:03:41.11,0:03:43.50,Default,,0000,0000,0000,,Parasites invite us to resist the allure
Dialogue: 0,0:03:43.50,0:03:45.35,Default,,0000,0000,0000,,of obvious stories.
Dialogue: 0,0:03:45.35,0:03:47.66,Default,,0000,0000,0000,,Their world is one of plot twists
Dialogue: 0,0:03:47.66,0:03:51.27,Default,,0000,0000,0000,,and unexpected explanations.
Dialogue: 0,0:03:51.27,0:03:52.76,Default,,0000,0000,0000,,Why, for example,
Dialogue: 0,0:03:52.76,0:03:54.94,Default,,0000,0000,0000,,does this caterpillar
Dialogue: 0,0:03:54.94,0:03:56.92,Default,,0000,0000,0000,,start violently thrashing about
Dialogue: 0,0:03:56.92,0:03:58.58,Default,,0000,0000,0000,,when another insect gets close to it
Dialogue: 0,0:03:58.58,0:04:00.84,Default,,0000,0000,0000,,and those white cocoons that it seems
Dialogue: 0,0:04:00.84,0:04:02.28,Default,,0000,0000,0000,,to be standing guard over?
Dialogue: 0,0:04:02.28,0:04:05.37,Default,,0000,0000,0000,,Is it maybe protecting its siblings?
Dialogue: 0,0:04:05.37,0:04:06.82,Default,,0000,0000,0000,,No.
Dialogue: 0,0:04:06.82,0:04:08.28,Default,,0000,0000,0000,,This caterpillar was attacked
Dialogue: 0,0:04:08.28,0:04:11.50,Default,,0000,0000,0000,,by a parasitic wasp which laid eggs inside it.
Dialogue: 0,0:04:11.50,0:04:12.93,Default,,0000,0000,0000,,The eggs hatched and the young wasps
Dialogue: 0,0:04:12.93,0:04:14.25,Default,,0000,0000,0000,,devoured the caterpillar alive
Dialogue: 0,0:04:14.25,0:04:15.92,Default,,0000,0000,0000,,before bursting out of its body.
Dialogue: 0,0:04:15.92,0:04:18.19,Default,,0000,0000,0000,,See what I mean?
Dialogue: 0,0:04:18.19,0:04:21.03,Default,,0000,0000,0000,,Now, the caterpillar didn't die.
Dialogue: 0,0:04:21.03,0:04:23.62,Default,,0000,0000,0000,,Some of the wasps seemed to stay behind
Dialogue: 0,0:04:23.62,0:04:26.95,Default,,0000,0000,0000,,and controlled it into defending their siblings
Dialogue: 0,0:04:26.95,0:04:28.59,Default,,0000,0000,0000,,which are metamorphosing
Dialogue: 0,0:04:28.59,0:04:30.61,Default,,0000,0000,0000,,into adults within those cocoons.
Dialogue: 0,0:04:30.61,0:04:34.15,Default,,0000,0000,0000,,This caterpillar is a head-banging \Nzombie bodyguard
Dialogue: 0,0:04:34.15,0:04:35.45,Default,,0000,0000,0000,,defending the offspring
Dialogue: 0,0:04:35.45,0:04:37.67,Default,,0000,0000,0000,,of the creature that killed it.
Dialogue: 0,0:04:37.67,0:04:41.54,Default,,0000,0000,0000,,(Applause)
Dialogue: 0,0:04:41.54,0:04:45.83,Default,,0000,0000,0000,,We have a lot to get through. \NI only have 13 minutes. (Laughter)
Dialogue: 0,0:04:45.83,0:04:47.64,Default,,0000,0000,0000,,Now, some of you are probably just
Dialogue: 0,0:04:47.64,0:04:49.86,Default,,0000,0000,0000,,desperately clawing for some solace
Dialogue: 0,0:04:49.86,0:04:52.12,Default,,0000,0000,0000,,in the idea that these things are oddities
Dialogue: 0,0:04:52.12,0:04:54.05,Default,,0000,0000,0000,,of the natural world, that they are outliers,
Dialogue: 0,0:04:54.05,0:04:55.87,Default,,0000,0000,0000,,and that point of view is understandable,
Dialogue: 0,0:04:55.87,0:04:58.25,Default,,0000,0000,0000,,because by their nature, parasites are quite small
Dialogue: 0,0:04:58.25,0:04:59.59,Default,,0000,0000,0000,,and they spend a lot of their time
Dialogue: 0,0:04:59.59,0:05:02.54,Default,,0000,0000,0000,,inside the bodies of other things.
Dialogue: 0,0:05:02.54,0:05:04.31,Default,,0000,0000,0000,,They're easy to overlook,
Dialogue: 0,0:05:04.31,0:05:06.90,Default,,0000,0000,0000,,but that doesn't mean that they aren't important.
Dialogue: 0,0:05:06.90,0:05:09.10,Default,,0000,0000,0000,,A few years back, a man called Kevin Lafferty
Dialogue: 0,0:05:09.10,0:05:12.47,Default,,0000,0000,0000,,took a group of scientists\Ninto three Californian estuaries
Dialogue: 0,0:05:12.47,0:05:14.22,Default,,0000,0000,0000,,and they pretty much weighed and dissected
Dialogue: 0,0:05:14.22,0:05:16.22,Default,,0000,0000,0000,,and recorded everything they could find,
Dialogue: 0,0:05:16.22,0:05:17.44,Default,,0000,0000,0000,,and what they found
Dialogue: 0,0:05:17.44,0:05:20.66,Default,,0000,0000,0000,,were parasites in extreme abundance.
Dialogue: 0,0:05:20.66,0:05:22.70,Default,,0000,0000,0000,,Especially common were trematodes,
Dialogue: 0,0:05:22.70,0:05:25.35,Default,,0000,0000,0000,,tiny worms that specialize in castrating their hosts
Dialogue: 0,0:05:25.35,0:05:27.90,Default,,0000,0000,0000,,like this unfortunate snail.
Dialogue: 0,0:05:27.90,0:05:30.79,Default,,0000,0000,0000,,Now, a single trematode is tiny, microscopic,
Dialogue: 0,0:05:30.79,0:05:32.59,Default,,0000,0000,0000,,but collectively they weighed as much
Dialogue: 0,0:05:32.59,0:05:34.77,Default,,0000,0000,0000,,as all the fish in the estuaries
Dialogue: 0,0:05:34.77,0:05:38.48,Default,,0000,0000,0000,,and three to nine times more than all the birds.
Dialogue: 0,0:05:38.48,0:05:40.47,Default,,0000,0000,0000,,And remember the Gordian worm that I showed you,
Dialogue: 0,0:05:40.47,0:05:41.86,Default,,0000,0000,0000,,the cricket thing?
Dialogue: 0,0:05:41.86,0:05:44.42,Default,,0000,0000,0000,,One Japanese scientist called Takuya Sato
Dialogue: 0,0:05:44.42,0:05:46.11,Default,,0000,0000,0000,,found that in one stream,
Dialogue: 0,0:05:46.11,0:05:48.08,Default,,0000,0000,0000,,these things drive so many crickets
Dialogue: 0,0:05:48.08,0:05:49.38,Default,,0000,0000,0000,,and grasshoppers into the water
Dialogue: 0,0:05:49.38,0:05:50.69,Default,,0000,0000,0000,,that the drowned insects
Dialogue: 0,0:05:50.69,0:05:54.99,Default,,0000,0000,0000,,make up some 60 percent of the diet of local trout.
Dialogue: 0,0:05:54.99,0:05:57.93,Default,,0000,0000,0000,,Manipulation is not an oddity.
Dialogue: 0,0:05:57.93,0:06:00.05,Default,,0000,0000,0000,,It is a critical and common part
Dialogue: 0,0:06:00.05,0:06:01.94,Default,,0000,0000,0000,,of the world around us,
Dialogue: 0,0:06:01.94,0:06:03.46,Default,,0000,0000,0000,,and scientists have now found
Dialogue: 0,0:06:03.46,0:06:05.94,Default,,0000,0000,0000,,hundreds of examples of such manipulators,
Dialogue: 0,0:06:05.94,0:06:08.38,Default,,0000,0000,0000,,and more excitingly, they're starting to understand
Dialogue: 0,0:06:08.38,0:06:12.44,Default,,0000,0000,0000,,exactly how these creatures control their hosts.
Dialogue: 0,0:06:12.44,0:06:14.96,Default,,0000,0000,0000,,And this is one of my favorite examples.
Dialogue: 0,0:06:14.96,0:06:17.42,Default,,0000,0000,0000,,This is Ampulex compressa,
Dialogue: 0,0:06:17.42,0:06:19.64,Default,,0000,0000,0000,,the emerald cockroach wasp,
Dialogue: 0,0:06:19.64,0:06:21.94,Default,,0000,0000,0000,,and it is a truth universally acknowledged
Dialogue: 0,0:06:21.94,0:06:23.58,Default,,0000,0000,0000,,that an emerald cockroach wasp in possession
Dialogue: 0,0:06:23.58,0:06:25.38,Default,,0000,0000,0000,,of some fertilized eggs
Dialogue: 0,0:06:25.38,0:06:27.84,Default,,0000,0000,0000,,must be in want of a cockroach.
Dialogue: 0,0:06:27.84,0:06:29.04,Default,,0000,0000,0000,,When she finds one,
Dialogue: 0,0:06:29.04,0:06:31.25,Default,,0000,0000,0000,,she stabs it with a stinger
Dialogue: 0,0:06:31.25,0:06:32.70,Default,,0000,0000,0000,,that is also a sense organ.
Dialogue: 0,0:06:32.70,0:06:35.37,Default,,0000,0000,0000,,This discovery came out three weeks ago.
Dialogue: 0,0:06:35.37,0:06:37.68,Default,,0000,0000,0000,,She stabs it with a stinger that is a sense organ
Dialogue: 0,0:06:37.68,0:06:39.47,Default,,0000,0000,0000,,equipped with small sensory bumps
Dialogue: 0,0:06:39.47,0:06:42.03,Default,,0000,0000,0000,,that allow her to feel the distinctive texture
Dialogue: 0,0:06:42.03,0:06:44.13,Default,,0000,0000,0000,,of a roach's brain.
Dialogue: 0,0:06:44.13,0:06:47.17,Default,,0000,0000,0000,,So like a person blindly rooting about in a bag,
Dialogue: 0,0:06:47.17,0:06:49.65,Default,,0000,0000,0000,,she finds the brain, and she injects it with venom
Dialogue: 0,0:06:49.65,0:06:53.85,Default,,0000,0000,0000,,into two very specific clusters of neurons.
Dialogue: 0,0:06:53.85,0:06:56.94,Default,,0000,0000,0000,,Israeli scientists Frederic Libersat and Ram Gal
Dialogue: 0,0:06:56.94,0:07:00.66,Default,,0000,0000,0000,,found that the venom is a\Nvery specific chemical weapon.
Dialogue: 0,0:07:00.66,0:07:03.20,Default,,0000,0000,0000,,It doesn't kill the roach, nor does it sedate it.
Dialogue: 0,0:07:03.20,0:07:05.33,Default,,0000,0000,0000,,The roach could walk away
Dialogue: 0,0:07:05.33,0:07:08.36,Default,,0000,0000,0000,,or fly or run if it chose to,
Dialogue: 0,0:07:08.36,0:07:10.23,Default,,0000,0000,0000,,but it doesn't choose to,
Dialogue: 0,0:07:10.23,0:07:13.61,Default,,0000,0000,0000,,because the venom nixes its motivation to walk,
Dialogue: 0,0:07:13.61,0:07:14.72,Default,,0000,0000,0000,,and only that.
Dialogue: 0,0:07:14.72,0:07:18.43,Default,,0000,0000,0000,,The wasp basically un-checks\Nthe escape-from-danger box
Dialogue: 0,0:07:18.43,0:07:20.27,Default,,0000,0000,0000,,in the roach's operating system,
Dialogue: 0,0:07:20.27,0:07:23.50,Default,,0000,0000,0000,,allowing her to lead her helpless victim
Dialogue: 0,0:07:23.50,0:07:25.62,Default,,0000,0000,0000,,back to her lair by its antennae
Dialogue: 0,0:07:25.62,0:07:28.25,Default,,0000,0000,0000,,like a person walking a dog.
Dialogue: 0,0:07:28.25,0:07:29.93,Default,,0000,0000,0000,,And once there, she lays an egg on it,
Dialogue: 0,0:07:29.93,0:07:32.21,Default,,0000,0000,0000,,egg hatches, devoured alive, bursts out of body,
Dialogue: 0,0:07:32.21,0:07:34.40,Default,,0000,0000,0000,,yadda yadda yadda, you know the drill.
Dialogue: 0,0:07:34.40,0:07:37.63,Default,,0000,0000,0000,,(Laughter) (Applause)
Dialogue: 0,0:07:37.63,0:07:40.51,Default,,0000,0000,0000,,Now I would argue that, once stung,
Dialogue: 0,0:07:40.51,0:07:42.51,Default,,0000,0000,0000,,the cockroach isn't a roach anymore.
Dialogue: 0,0:07:42.51,0:07:44.86,Default,,0000,0000,0000,,It's more of an extension of the wasp,
Dialogue: 0,0:07:44.86,0:07:47.70,Default,,0000,0000,0000,,just like the cricket was an\Nextension of the Gordian worm.
Dialogue: 0,0:07:47.72,0:07:50.52,Default,,0000,0000,0000,,These hosts won't get to survive or reproduce.
Dialogue: 0,0:07:50.52,0:07:52.32,Default,,0000,0000,0000,,They have as much control over their own fates
Dialogue: 0,0:07:52.32,0:07:54.10,Default,,0000,0000,0000,,as my car.
Dialogue: 0,0:07:54.10,0:07:55.60,Default,,0000,0000,0000,,Once the parasites get in,
Dialogue: 0,0:07:55.60,0:07:58.17,Default,,0000,0000,0000,,the hosts don't get a say.
Dialogue: 0,0:07:58.17,0:07:59.48,Default,,0000,0000,0000,,Now humans, of course,
Dialogue: 0,0:07:59.48,0:08:01.51,Default,,0000,0000,0000,,are no stranger to manipulation.
Dialogue: 0,0:08:01.51,0:08:03.87,Default,,0000,0000,0000,,We take drugs to shift the chemistries of our brains
Dialogue: 0,0:08:03.87,0:08:05.00,Default,,0000,0000,0000,,and to change our moods,
Dialogue: 0,0:08:05.00,0:08:09.02,Default,,0000,0000,0000,,and what are arguments or advertising or big ideas
Dialogue: 0,0:08:09.02,0:08:12.73,Default,,0000,0000,0000,,if not an attempt to influence someone else's mind?
Dialogue: 0,0:08:12.73,0:08:14.25,Default,,0000,0000,0000,,But our attempts at doing this
Dialogue: 0,0:08:14.25,0:08:16.03,Default,,0000,0000,0000,,are crude and blundering compared
Dialogue: 0,0:08:16.03,0:08:19.13,Default,,0000,0000,0000,,to the fine-grained specificity of the parasites.
Dialogue: 0,0:08:19.13,0:08:21.52,Default,,0000,0000,0000,,Don Draper only wishes he was as elegant
Dialogue: 0,0:08:21.52,0:08:26.48,Default,,0000,0000,0000,,and precise as the emerald cockroach wasp.
Dialogue: 0,0:08:26.48,0:08:30.22,Default,,0000,0000,0000,,Now, I think this is part of what makes parasites
Dialogue: 0,0:08:30.22,0:08:33.00,Default,,0000,0000,0000,,so sinister and so compelling.
Dialogue: 0,0:08:33.00,0:08:35.63,Default,,0000,0000,0000,,We place such a premium on our free will
Dialogue: 0,0:08:35.63,0:08:36.89,Default,,0000,0000,0000,,and our independence
Dialogue: 0,0:08:36.89,0:08:38.47,Default,,0000,0000,0000,,that the prospect of losing those qualities
Dialogue: 0,0:08:38.47,0:08:39.75,Default,,0000,0000,0000,,to forces unseen
Dialogue: 0,0:08:39.75,0:08:42.92,Default,,0000,0000,0000,,informs many of our deepest societal fears.
Dialogue: 0,0:08:42.92,0:08:45.37,Default,,0000,0000,0000,,Orwellian dystopias and shadowy cabals
Dialogue: 0,0:08:45.37,0:08:47.22,Default,,0000,0000,0000,,and mind-controlling supervillains --
Dialogue: 0,0:08:47.22,0:08:50.25,Default,,0000,0000,0000,,these are tropes that fill our darkest fiction,
Dialogue: 0,0:08:50.25,0:08:55.05,Default,,0000,0000,0000,,but in nature, they happen all the time.
Dialogue: 0,0:08:55.05,0:08:57.68,Default,,0000,0000,0000,,Which leads me to an obvious
Dialogue: 0,0:08:57.68,0:08:59.98,Default,,0000,0000,0000,,and disquieting question:
Dialogue: 0,0:08:59.98,0:09:01.70,Default,,0000,0000,0000,,Are there dark, sinister parasites
Dialogue: 0,0:09:01.70,0:09:03.66,Default,,0000,0000,0000,,that are influencing our behavior
Dialogue: 0,0:09:03.66,0:09:05.23,Default,,0000,0000,0000,,without us knowing about it,
Dialogue: 0,0:09:05.23,0:09:08.05,Default,,0000,0000,0000,,besides the NSA?
Dialogue: 0,0:09:08.05,0:09:09.36,Default,,0000,0000,0000,,If there are any —
Dialogue: 0,0:09:09.36,0:09:13.33,Default,,0000,0000,0000,,(Laughter) (Applause)
Dialogue: 0,0:09:13.33,0:09:15.65,Default,,0000,0000,0000,,I've got a red dot on my forehead now, don't I?
Dialogue: 0,0:09:15.65,0:09:18.18,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:09:18.18,0:09:21.13,Default,,0000,0000,0000,,If there are any, this is a good candidate for them.
Dialogue: 0,0:09:21.13,0:09:24.41,Default,,0000,0000,0000,,This is Toxoplasma gondii, or Toxo, for short,
Dialogue: 0,0:09:24.41,0:09:25.100,Default,,0000,0000,0000,,because the terrifying creature
Dialogue: 0,0:09:25.100,0:09:28.21,Default,,0000,0000,0000,,always deserves a cute nickname.
Dialogue: 0,0:09:28.21,0:09:30.49,Default,,0000,0000,0000,,Toxo infects mammals,
Dialogue: 0,0:09:30.49,0:09:31.97,Default,,0000,0000,0000,,a wide variety of mammals,
Dialogue: 0,0:09:31.97,0:09:35.05,Default,,0000,0000,0000,,but it can only sexually reproduce in a cat.
Dialogue: 0,0:09:35.05,0:09:37.81,Default,,0000,0000,0000,,And scientists like Joanne Webster have shown that
Dialogue: 0,0:09:37.81,0:09:40.00,Default,,0000,0000,0000,,if Toxo gets into a rat or a mouse,
Dialogue: 0,0:09:40.00,0:09:43.47,Default,,0000,0000,0000,,it turns the rodent into a cat-seeking missile.
Dialogue: 0,0:09:43.47,0:09:46.55,Default,,0000,0000,0000,,If the infected rat smells the delightful odor
Dialogue: 0,0:09:46.55,0:09:47.77,Default,,0000,0000,0000,,of cat piss,
Dialogue: 0,0:09:47.77,0:09:50.49,Default,,0000,0000,0000,,it runs towards the source of the smell
Dialogue: 0,0:09:50.49,0:09:54.41,Default,,0000,0000,0000,,rather than the more sensible direction of away.
Dialogue: 0,0:09:54.41,0:09:56.95,Default,,0000,0000,0000,,The cat eats the rat. Toxo gets to have sex.
Dialogue: 0,0:09:56.95,0:09:59.82,Default,,0000,0000,0000,,It's a classic tale of Eat, Prey, Love.
Dialogue: 0,0:09:59.82,0:10:04.49,Default,,0000,0000,0000,,(Laughter) (Applause)
Dialogue: 0,0:10:07.51,0:10:10.71,Default,,0000,0000,0000,,You're very charitable, generous people.
Dialogue: 0,0:10:10.71,0:10:13.30,Default,,0000,0000,0000,,Hi, Elizabeth, I loved your talk.
Dialogue: 0,0:10:13.30,0:10:16.67,Default,,0000,0000,0000,,How does the parasite control its host
Dialogue: 0,0:10:16.67,0:10:17.87,Default,,0000,0000,0000,,in this way?
Dialogue: 0,0:10:17.87,0:10:19.20,Default,,0000,0000,0000,,We don't really know.
Dialogue: 0,0:10:19.20,0:10:20.88,Default,,0000,0000,0000,,We know that Toxo releases an enzyme
Dialogue: 0,0:10:20.88,0:10:22.88,Default,,0000,0000,0000,,that makes dopamine, a substance involved
Dialogue: 0,0:10:22.88,0:10:24.69,Default,,0000,0000,0000,,in reward and motivation.
Dialogue: 0,0:10:24.69,0:10:27.12,Default,,0000,0000,0000,,We know it targets certain parts of a rodent's brain,
Dialogue: 0,0:10:27.12,0:10:29.59,Default,,0000,0000,0000,,including those involved in sexual arousal.
Dialogue: 0,0:10:29.59,0:10:31.79,Default,,0000,0000,0000,,But how those puzzle pieces fit together
Dialogue: 0,0:10:31.79,0:10:33.63,Default,,0000,0000,0000,,is not immediately clear.
Dialogue: 0,0:10:33.63,0:10:35.93,Default,,0000,0000,0000,,What is clear is that this thing
Dialogue: 0,0:10:35.93,0:10:37.32,Default,,0000,0000,0000,,is a single cell.
Dialogue: 0,0:10:37.32,0:10:38.69,Default,,0000,0000,0000,,This has no nervous system.
Dialogue: 0,0:10:38.69,0:10:39.82,Default,,0000,0000,0000,,It has no consciousness.
Dialogue: 0,0:10:39.82,0:10:41.12,Default,,0000,0000,0000,,It doesn't even have a body.
Dialogue: 0,0:10:41.12,0:10:43.75,Default,,0000,0000,0000,,But it's manipulating a mammal?
Dialogue: 0,0:10:43.75,0:10:45.17,Default,,0000,0000,0000,,We are mammals.
Dialogue: 0,0:10:45.17,0:10:47.61,Default,,0000,0000,0000,,We are more intelligent than a mere rat, to be sure,
Dialogue: 0,0:10:47.61,0:10:50.13,Default,,0000,0000,0000,,but our brains have the same basic structure,
Dialogue: 0,0:10:50.13,0:10:51.52,Default,,0000,0000,0000,,the same types of cells,
Dialogue: 0,0:10:51.52,0:10:53.11,Default,,0000,0000,0000,,the same chemicals running through them,
Dialogue: 0,0:10:53.11,0:10:55.43,Default,,0000,0000,0000,,and the same parasites.
Dialogue: 0,0:10:55.43,0:10:57.78,Default,,0000,0000,0000,,Estimates vary a lot, but some figures suggest
Dialogue: 0,0:10:57.78,0:11:00.14,Default,,0000,0000,0000,,that one in three people around the world
Dialogue: 0,0:11:00.14,0:11:01.85,Default,,0000,0000,0000,,have Toxo in their brains.
Dialogue: 0,0:11:01.85,0:11:05.34,Default,,0000,0000,0000,,Now typically, this doesn't lead to any overt illness.
Dialogue: 0,0:11:05.34,0:11:07.22,Default,,0000,0000,0000,,The parasite holds up in a dormant state
Dialogue: 0,0:11:07.22,0:11:09.40,Default,,0000,0000,0000,,for a long period of time.
Dialogue: 0,0:11:09.40,0:11:11.44,Default,,0000,0000,0000,,But there's some evidence that those people
Dialogue: 0,0:11:11.44,0:11:14.47,Default,,0000,0000,0000,,who are carriers score slightly differently
Dialogue: 0,0:11:14.47,0:11:17.20,Default,,0000,0000,0000,,on personality questionnaires than other people,
Dialogue: 0,0:11:17.20,0:11:19.69,Default,,0000,0000,0000,,that they have a slightly \Nhigher risk of car accidents,
Dialogue: 0,0:11:19.69,0:11:22.29,Default,,0000,0000,0000,,and there's some evidence\Nthat people with schizophrenia
Dialogue: 0,0:11:22.29,0:11:24.84,Default,,0000,0000,0000,,are more likely to be infected.
Dialogue: 0,0:11:24.84,0:11:27.02,Default,,0000,0000,0000,,Now, I think this evidence is still inconclusive,
Dialogue: 0,0:11:27.02,0:11:28.93,Default,,0000,0000,0000,,and even among Toxo researchers,
Dialogue: 0,0:11:28.93,0:11:31.37,Default,,0000,0000,0000,,opinion is divided as to whether the parasite
Dialogue: 0,0:11:31.37,0:11:33.75,Default,,0000,0000,0000,,is truly influencing our behavior.
Dialogue: 0,0:11:33.75,0:11:36.41,Default,,0000,0000,0000,,But given the widespread\Nnature of such manipulations,
Dialogue: 0,0:11:36.41,0:11:38.26,Default,,0000,0000,0000,,it would be completely implausible
Dialogue: 0,0:11:38.26,0:11:39.91,Default,,0000,0000,0000,,for humans to be the only species
Dialogue: 0,0:11:39.91,0:11:42.85,Default,,0000,0000,0000,,that weren't similarly affected.
Dialogue: 0,0:11:42.85,0:11:47.25,Default,,0000,0000,0000,,And I think that this capacity to constantly
Dialogue: 0,0:11:47.25,0:11:50.11,Default,,0000,0000,0000,,subvert our way of thinking about the world
Dialogue: 0,0:11:50.11,0:11:51.66,Default,,0000,0000,0000,,makes parasites amazing.
Dialogue: 0,0:11:51.66,0:11:54.87,Default,,0000,0000,0000,,They're constantly inviting us to\Nlook at the natural world sideways,
Dialogue: 0,0:11:54.87,0:11:57.04,Default,,0000,0000,0000,,and to ask if the behaviors we're seeing,
Dialogue: 0,0:11:57.04,0:11:58.53,Default,,0000,0000,0000,,whether they're simple and obvious
Dialogue: 0,0:11:58.53,0:12:00.06,Default,,0000,0000,0000,,or baffling and puzzling,
Dialogue: 0,0:12:00.06,0:12:02.15,Default,,0000,0000,0000,,are not the results of individuals
Dialogue: 0,0:12:02.15,0:12:03.100,Default,,0000,0000,0000,,acting through their own accord
Dialogue: 0,0:12:03.100,0:12:05.81,Default,,0000,0000,0000,,but because they are being bent
Dialogue: 0,0:12:05.81,0:12:08.48,Default,,0000,0000,0000,,to the control of something else.
Dialogue: 0,0:12:08.48,0:12:10.52,Default,,0000,0000,0000,,And while that idea may be disquieting,
Dialogue: 0,0:12:10.52,0:12:13.44,Default,,0000,0000,0000,,and while parasites' habits may be very grisly,
Dialogue: 0,0:12:13.44,0:12:15.23,Default,,0000,0000,0000,,I think that ability to surprise us
Dialogue: 0,0:12:15.23,0:12:18.41,Default,,0000,0000,0000,,makes them as wonderful and as charismatic
Dialogue: 0,0:12:18.41,0:12:21.77,Default,,0000,0000,0000,,as any panda or butterfly or dolphin.
Dialogue: 0,0:12:21.77,0:12:23.99,Default,,0000,0000,0000,,At the end of "On the Origin of Species,"
Dialogue: 0,0:12:23.99,0:12:26.98,Default,,0000,0000,0000,,Charles Darwin writes about the grandeur of life,
Dialogue: 0,0:12:26.98,0:12:29.63,Default,,0000,0000,0000,,and of endless forms most beautiful
Dialogue: 0,0:12:29.63,0:12:31.06,Default,,0000,0000,0000,,and most wonderful,
Dialogue: 0,0:12:31.06,0:12:33.64,Default,,0000,0000,0000,,and I like to think he could easily have been talking
Dialogue: 0,0:12:33.64,0:12:36.82,Default,,0000,0000,0000,,about a tapeworm that makes shrimp sociable
Dialogue: 0,0:12:36.82,0:12:40.07,Default,,0000,0000,0000,,or a wasp that takes cockroaches for walks.
Dialogue: 0,0:12:40.07,0:12:43.22,Default,,0000,0000,0000,,But perhaps, that's just a parasite talking.
Dialogue: 0,0:12:43.22,0:12:44.95,Default,,0000,0000,0000,,Thank you.
Dialogue: 0,0:12:44.95,0:12:48.95,Default,,0000,0000,0000,,(Applause)