WEBVTT 00:00:14.605 --> 00:00:19.716 I would like to introduce you to my favorite parasite. 00:00:19.716 --> 00:00:21.551 There are millions that I could choose from 00:00:21.551 --> 00:00:22.866 and this is it: 00:00:22.866 --> 00:00:24.336 it's called the jewel wasp. 00:00:24.336 --> 00:00:27.283 You can find it in parts of Africa and Asia. 00:00:27.283 --> 00:00:28.608 It's a little under an inch long, 00:00:28.608 --> 00:00:30.997 and it is a beautiful looking parasite. 00:00:30.997 --> 00:00:32.659 Now, you may be saying to yourself, 00:00:32.659 --> 00:00:34.225 "This is not a parasite. 00:00:34.225 --> 00:00:35.153 It's not a tapeworm, 00:00:35.153 --> 00:00:35.895 it's not a virus, 00:00:35.895 --> 00:00:38.639 how could a wasp be a parasite?" 00:00:38.639 --> 00:00:40.553 You are probably thinking about regular wasps, 00:00:40.553 --> 00:00:45.008 you know, the ones that build paper nests as their house. 00:00:45.008 --> 00:00:48.663 Well, the thing is that the jewel wasp 00:00:48.663 --> 00:00:52.721 makes its house inside a living cockroach. 00:00:54.627 --> 00:00:57.669 Here's how it happens. 00:00:57.669 --> 00:01:00.552 A jewel wasp is flying around, looking for a cockroach. 00:01:00.552 --> 00:01:03.719 When it sees one, it lands and bites on its wing. 00:01:03.719 --> 00:01:04.933 So, I'll be the cockroach. 00:01:04.933 --> 00:01:06.273 Be-wha! Bewha! 00:01:06.273 --> 00:01:08.352 And the cockroach starts shaking it off, 00:01:08.352 --> 00:01:10.671 "Get away from me!" 00:01:10.671 --> 00:01:14.551 The wasp very quickly starts stinging the cockroach. 00:01:14.551 --> 00:01:17.045 All of a sudden, the cockroach can't move, 00:01:17.045 --> 00:01:18.474 for about a minute. 00:01:18.474 --> 00:01:21.095 And then it recovers 00:01:21.095 --> 00:01:22.843 and stands up. 00:01:22.843 --> 00:01:24.294 It could run away now, 00:01:24.294 --> 00:01:26.286 but it doesn't. 00:01:26.286 --> 00:01:28.596 It just doesn't want to. 00:01:28.596 --> 00:01:30.482 It just stays there. 00:01:30.482 --> 00:01:33.571 It's become a zombie slave. 00:01:35.371 --> 00:01:37.435 Again, I'm not making this up. 00:01:37.435 --> 00:01:38.651 The wasp goes off, 00:01:38.651 --> 00:01:41.266 it walks away and finds a hole 00:01:41.266 --> 00:01:44.155 and digs it out, makes it into a burrow. 00:01:44.155 --> 00:01:45.586 It walks back. 00:01:45.586 --> 00:01:48.268 This can take up to half an hour. 00:01:48.268 --> 00:01:51.181 The cockroach is still there. 00:01:51.181 --> 00:01:53.697 What do we do now? 00:01:53.697 --> 00:01:56.917 The wasps grabs onto one of the antenna, 00:01:56.917 --> 00:01:58.203 bites down on it, 00:01:58.203 --> 00:01:59.134 of the cockroach, 00:01:59.134 --> 00:02:01.933 and pulls the cockroach. 00:02:01.933 --> 00:02:04.770 And the cockroach says, "Alright," 00:02:04.770 --> 00:02:07.851 and walks like a dog on a leash. 00:02:07.851 --> 00:02:11.765 The wasp takes it all the way down into the burrow. 00:02:11.765 --> 00:02:14.744 The cockroach says, "Nice place." 00:02:14.744 --> 00:02:16.331 The wasp takes care of some business 00:02:16.331 --> 00:02:17.933 and then goes and leaves the burrow 00:02:17.933 --> 00:02:19.130 and seals it shut, 00:02:19.130 --> 00:02:23.412 leaving the cockroach entombed in darkness, still alive. 00:02:23.412 --> 00:02:27.319 The cockroach says, "Alright, I'll stay here if you want." 00:02:27.319 --> 00:02:29.558 Now, I mentioned that the cockroach took care, 00:02:29.558 --> 00:02:32.278 ah, the wasp took care of a little business 00:02:32.278 --> 00:02:34.683 before it left the burrow. 00:02:34.683 --> 00:02:37.105 The business was laying an egg 00:02:37.105 --> 00:02:39.382 on the underside of the cockroach. 00:02:39.382 --> 00:02:40.729 The egg hatches. 00:02:40.729 --> 00:02:42.140 Out comes a wasp larva. 00:02:42.140 --> 00:02:45.792 It looks kind of like a maggot with big, nasty jaws. 00:02:45.792 --> 00:02:49.315 It chews a hole into the cockroach 00:02:49.315 --> 00:02:51.913 and starts to feed from the outside. 00:02:51.913 --> 00:02:55.352 It gets bigger, like you can see over here. 00:02:55.352 --> 00:02:56.922 And then when it gets big enough, 00:02:56.922 --> 00:03:00.457 it decides to crawl into the hole, 00:03:00.457 --> 00:03:02.215 into the cockroach. 00:03:02.215 --> 00:03:05.800 So now it's inside the still-living cockroach 00:03:05.800 --> 00:03:09.557 and the cockroach doesn't mind much. 00:03:09.557 --> 00:03:11.701 This goes on for about a month. 00:03:11.701 --> 00:03:14.293 The larva grows and grows and grows, 00:03:14.293 --> 00:03:16.678 then makes a pupa, kind of like a cocoon. 00:03:16.678 --> 00:03:18.930 Inside there it grows eyes, 00:03:18.930 --> 00:03:19.915 it grows wings, 00:03:19.915 --> 00:03:21.804 it grows legs, 00:03:21.804 --> 00:03:24.767 the cockroach is still alive, still waiting. 00:03:24.767 --> 00:03:27.142 Finally the wasp is ready to leave, 00:03:27.142 --> 00:03:30.553 and that's when the cockroach finally dies 00:03:30.553 --> 00:03:33.140 because the fullly-formed adult wasp 00:03:33.140 --> 00:03:36.595 crawls out of the cockroach's dying body. 00:03:38.193 --> 00:03:40.966 The wasp shakes itself off, 00:03:40.966 --> 00:03:42.207 climbs out of the burrow, 00:03:42.207 --> 00:03:44.349 goes and finds another wasp to mate with 00:03:44.349 --> 00:03:47.960 to start this whole, crazy cycle again. 00:03:47.960 --> 00:03:50.731 So, this is not science fiction, 00:03:50.731 --> 00:03:54.592 this happens every day, all over the world. 00:03:54.592 --> 00:03:58.343 And scientists are totally fascinated by this. 00:03:58.343 --> 00:04:01.540 They're just starting to figure out how all this happens. 00:04:01.540 --> 00:04:04.212 And, when you really start to look at the science of it, 00:04:04.212 --> 00:04:08.128 you start to kind of respect this very creepy wasp. 00:04:08.128 --> 00:04:12.079 You see, the thing is that when it attacks the cockroach, 00:04:12.079 --> 00:04:13.570 it's not just stinging wildly, 00:04:13.570 --> 00:04:18.998 it delivers two precise stings. 00:04:18.998 --> 00:04:21.060 It knows this cockroach's nervous system 00:04:21.060 --> 00:04:23.509 like you know the back of your hand. 00:04:23.509 --> 00:04:26.308 The first sting goes to that spot there, 00:04:26.308 --> 00:04:28.473 called the "walking rhythm generators," 00:04:28.473 --> 00:04:29.311 and, as you can guess, 00:04:29.311 --> 00:04:30.984 those are the neurons that send signals 00:04:30.984 --> 00:04:33.120 to the legs to move. 00:04:33.120 --> 00:04:36.025 It blocks the channels that the neurons use 00:04:36.025 --> 00:04:36.987 to send these signals. 00:04:36.987 --> 00:04:39.508 So the cockroach wants to go, it wants to run away, NOTE Paragraph 00:04:39.508 --> 00:04:42.835 but it can't because it can't move its legs. 00:04:42.835 --> 00:04:45.041 And that lasted for about a minute. 00:04:45.041 --> 00:04:49.917 This is really sophisticated pharmacology. 00:04:49.917 --> 00:04:51.996 We actually use the same method, 00:04:51.996 --> 00:04:53.266 a drug called Ivermectin, 00:04:53.266 --> 00:04:54.227 to cure river blindness, 00:04:54.227 --> 00:04:55.496 which is caused by a parasitic worm 00:04:55.496 --> 00:04:57.600 that gets into your eye. 00:04:57.600 --> 00:05:00.734 If you take Ivermectin, you paralyze the worm 00:05:00.734 --> 00:05:03.071 using the same strategy. 00:05:03.071 --> 00:05:05.150 Now, we discovered this in the 1970s, 00:05:05.150 --> 00:05:08.331 the wasp has been doing this for millions of years. 00:05:09.500 --> 00:05:11.546 Then comes the second sting. 00:05:11.546 --> 00:05:14.974 Now the second sting actually hits two places along the way. 00:05:14.974 --> 00:05:18.057 And to try to imagine how this can happen, 00:05:18.057 --> 00:05:22.172 I want you to picture yourself with a friend 00:05:22.172 --> 00:05:25.790 who's got a very long, very, very scary looking needle. 00:05:25.790 --> 00:05:26.571 And your friend, 00:05:26.571 --> 00:05:28.090 or at least you thought he was your friend, 00:05:28.090 --> 00:05:31.314 sticks it in your neck, 00:05:31.314 --> 00:05:33.288 goes into your skull, 00:05:33.288 --> 00:05:35.672 stops off at one part of your brain 00:05:35.672 --> 00:05:38.787 and injects some drugs, 00:05:38.787 --> 00:05:40.986 then keeps going in your brain 00:05:40.986 --> 00:05:43.621 and injects some more. 00:05:43.621 --> 00:05:45.186 These are two particular spots, 00:05:45.186 --> 00:05:46.196 marked here, "SEG", 00:05:46.196 --> 00:05:50.313 and you can see the tip of it in the brain, marked "Br". 00:05:50.313 --> 00:05:55.749 Now, we can do this, but it's really hard for us. 00:05:55.749 --> 00:05:57.997 It's called stereotactic drug delivery. 00:05:57.997 --> 00:06:00.522 You have to put a patient in a big metal frame 00:06:00.522 --> 00:06:01.642 to hold them still, 00:06:01.642 --> 00:06:03.803 you need CAT Scans to know where you're going, 00:06:03.803 --> 00:06:05.094 so you look at the picture and say, 00:06:05.094 --> 00:06:07.305 "Are we going the right way?" 00:06:07.305 --> 00:06:10.542 The jewel wasp has sensors on its stinger 00:06:10.542 --> 00:06:14.489 and scientists think that it can actually feel its way 00:06:14.489 --> 00:06:17.092 through the cockroach's brain until it gets 00:06:17.092 --> 00:06:19.876 to the exact, right place, 00:06:19.876 --> 00:06:22.703 and then penetrates an individual neuron 00:06:22.703 --> 00:06:25.244 and then delivers the goods. 00:06:25.244 --> 00:06:29.389 So, this is quite amazing stuff, 00:06:29.389 --> 00:06:31.440 and what seems to happen then 00:06:31.440 --> 00:06:36.772 is that the wasp is taking away the control 00:06:36.772 --> 00:06:39.214 that the cockroach has over its own body. 00:06:39.214 --> 00:06:42.124 It's taking away the cockroach's free will. 00:06:42.124 --> 00:06:43.688 We didn't really appreciate that cockroaches 00:06:43.688 --> 00:06:46.657 have free will until this wasp showed us. 00:06:46.657 --> 00:06:50.343 And, we have no idea how it's doing this, 00:06:50.343 --> 00:06:52.443 we don't know yet what the venom has in it 00:06:52.443 --> 00:06:53.926 and we don't know which circuits 00:06:53.926 --> 00:06:56.380 it's hitting in the cockroach's brain, 00:06:56.380 --> 00:06:58.278 and I think that's why this is, 00:06:58.278 --> 00:07:00.208 most of all, my favorite parasite 00:07:00.208 --> 00:07:03.194 because we have so much left to learn from it. 00:07:03.194 --> 00:07:05.323 Thank you very much.