Ophiocordyceps unilateralis is known colloquially as the "zombie ant fungi." Kartik Chandran has discovered that Ebola relies on a membrane transport protein called NPC1 to infect cells. Human and bat cells both contain NPC1 transporter proteins in their cells.
People infected with rabies become violent and belligerent. In 2014 when the COVID-19 virus was unheard of, Stacey Smith? does a classroom demonstration for Morgan Freeman in the year 2014 to demonstrate the infection rate of an air-borne virus like the flu.
Morgan Freeman says, "Enzymes are the power tools of microbiology." Jamey Marth and his lab staff work with an enzyme known as Cre recombinase. Viral vectors can deliver rescue enzymes into human DNA.
Thanks for watching. Follow for more videos.
#cosmosspacescience
#throughthewormhole
#season5
#episode6
#cosmology
#astronomy
#spacetime
#spacescience
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#zombie
People infected with rabies become violent and belligerent. In 2014 when the COVID-19 virus was unheard of, Stacey Smith? does a classroom demonstration for Morgan Freeman in the year 2014 to demonstrate the infection rate of an air-borne virus like the flu.
Morgan Freeman says, "Enzymes are the power tools of microbiology." Jamey Marth and his lab staff work with an enzyme known as Cre recombinase. Viral vectors can deliver rescue enzymes into human DNA.
Thanks for watching. Follow for more videos.
#cosmosspacescience
#throughthewormhole
#season5
#episode6
#cosmology
#astronomy
#spacetime
#spacescience
#space
#nasa
#morganfreeman
#spacedocumentary
#zombie
Category
📚
LearningTranscript
00:01It is a nightmare that has stalked us for centuries.
00:07Hordes of human beings transformed into mindless, bloodthirsty monsters,
00:13and civilization collapses.
00:18Could this nightmare become reality?
00:20Scientists have discovered parasites that turn the living into the walking dead.
00:34And new strains of deadly pathogens attack us every year.
00:40Neuroscientists are learning how to take over our minds.
00:45Will we someday lose control of our bodies and souls?
00:50Is a zombie apocalypse possible?
00:59Space.
01:01Time.
01:02Life itself.
01:06The secrets of the cosmos lie through the wormhole.
01:21According to Haitian folklore, certain priests had magical powders that could transform a corpse into a puppet.
01:33Our popular culture has turned that zombie legend into an apocalyptic nightmare.
01:41A contagious virus that turns the infected into violent monsters with rotting flesh.
01:48We are all just one bite away from joining the mindless legions of walking dead.
01:57All of these are myths, of course.
02:01But every myth has a grain of truth.
02:05Could our imaginations be telling us something about our future?
02:10A long time ago, my friends and I saw a movie that gave us nightmares.
02:21The Mummy.
02:23In that story, ancient magic made a corpse walk the earth again.
02:27Could such a mindless monster ever exist in the real world?
02:38David Hughes is an entomologist.
02:42He has a long history with the dark side of that science.
02:45When I was a kid, I had a rather personal relationship with a fungus.
02:50We didn't know exactly what it was at the beginning.
02:53And over the course of months, this fungus creeped its way across my scalp, making me half bald.
03:00David survived, but his fungus was not the worst nature has cooked up.
03:06Some funguses turn the bodies of their hosts into piles of rot and enslave their minds.
03:13David is the foremost expert on a fungus that turns its victims into the walking dead.
03:23Or, to be more accurate, the crawling dead.
03:28The fungus, like all organisms on the planet, has a scientific name.
03:32This one is called Ophiocordyceps unilateralis.
03:35But, colloquially, it's known as a zombie ant fungi.
03:37While foraging for food, an unsuspecting ant will pick up a spore of the zombie fungus.
03:44The fungus bores through the ant's body.
03:48It multiplies and infects the ant's brain, where it releases powerful, mind-controlling chemicals.
03:55The zombified ant bites the underside of a leaf and dies.
04:00Well, sort of.
04:04Death is really the starting point for the parasite.
04:08Fungi are rather interesting in that they require the host to die.
04:13And then, from its tissues, they grow and they reproduce.
04:17And so, at this stage, the whole ant body is completely transformed.
04:22The zombie ant fungus continues to control the dead creature's mind,
04:28keeping the insect's jaw locked onto the leaf.
04:31The fungus multiplies, building pressure inside the ant's skull until...
04:37it breaks open.
04:39Out comes a fungal stalk that sprays down deadly spores on the fungus' next victims.
04:47The cycle repeats.
04:48The fungal spores need to be shot out, launched from an area high above the foraging trail.
04:56And so, the fungus has evolved the ability to control the mind of its host.
05:03Inside their nests, ants are hygienic.
05:07But when they're out foraging, they are vulnerable to infection.
05:11David believes the fungus evolved the ability to strike the ants during this moment of weakness.
05:19The zombie ant fungus could never infect us.
05:22Our brains are too different from those of ants.
05:25But could a similar pathogen ever find its way into our mind?
05:30So, fungi have clearly evolved the ability to control the behavior of animals.
05:35Our brains are animal brains.
05:37And there's no reason, theoretically, why we couldn't have our behavior controlled.
05:42If a mind-enslaving pathogen ever strikes humanity, it will most likely jump to us from our close genetic relatives.
05:56Microbiologist Karthik Chandran studies the Ebola virus, a pathogen from our worst nightmares.
06:08Within weeks of infection, most patients leak blood from every orifice and die.
06:16Karthik is leading a team to find out how deadly viruses like Ebola evolved to infect humans.
06:23As far as we know, Ebola lives in bats.
06:29And every once in a while, this virus can break out from bats into other animals, including primates and apes and humans.
06:36Karthik is investigating how Ebola made the jump from bats to us.
06:49He's imagining what it's like to be one of the microscopic bad guys.
06:54The human body is a lot like a building where our cells are ruins.
07:02Viruses infect us by breaking and entering.
07:08So you might ask me, why does this little room in the storage facility have a lock?
07:13And so the answer is obvious, because somebody needs to go in and out.
07:16This is an attempt to secure the entrance so that only the authorized individuals can get in.
07:21And cells are the same way.
07:23You know, cells need to bring stuff in.
07:25They need to export stuff.
07:26And viruses have really evolved to exploit the sort of entry and access ways.
07:31Viruses mimic the shape of nutrients that the cell needs to survive.
07:36Just like a lockpick mimics the shape of a key.
07:42Once inside the cell, the virus inserts its malicious genetic code.
07:47The host cell becomes an enslaved factory producing countless copies of the invader.
07:56A multiplying virus can build so much pressure inside the host cell that it explodes.
08:04Ejecting millions of viral clones to infect other cells.
08:08For a virus to jump from animal to human, it has to find a piece of biological machinery shared by both the animal and the human cell.
08:22Like you often see with viruses and other parasites, they evolved to co-opt these common cellular mechanisms.
08:28And Ebola has done just that.
08:30Karatek made a groundbreaking discovery.
08:34Ebola relies on a protein called NPC1 to infect cells.
08:39NPC1 is found in both bat and human cells.
08:47Bats and humans may seem very different.
08:49But their cells use remarkably similar molecular machinery.
08:54Most viruses that infect bats can also jump to humans.
08:59All a virus has to do is find those common keys.
09:04So, I mean, I think it's a probability thing.
09:07The more closely related you are to another organism, the more likely you are to pick up a virus.
09:13A virus that turns human beings into violent, unconscious monsters already exists.
09:21Rabies.
09:23People that have rabies go through a phase where they're highly violent and deligerent and they can form at the mouth.
09:29These are changes that clearly seem to benefit the virus in terms of its ability to spread from one infected host to a naive host.
09:37A rabies infection does not spread easily from person to person.
09:45But if a virus like rabies mutated to have influenza-like properties, it could spread like wildfire.
09:52The infected would mistake it for a common cold.
10:05Until it's too late.
10:09And they fall into a mindless rage.
10:14They would become violent and attack without warning.
10:36Open wounds would benefit the virus.
10:40It would easily transmit through airborne particles.
10:50Ironically, our own vigilant immune systems could help bring this virus into existence.
10:56Once a virus infects a cell, there is sort of this hardwired immune response that makes all these new machines in the cell that can try to stop the virus from infecting.
11:11And so the virus has got to evolve so it can get around these sort of antiviral proteins.
11:15In the never-ending arms race between the virus and the host's immune system, both sides keep upping their game.
11:23As viruses mutate, they develop an array of evasive talents.
11:28In some mutations, viruses learn to become invisible.
11:31Other times, they evolve chemical tools that allow them to disable the body's infection monitors.
11:45Or, if the virus mutates just right, it can permanently evade the immune system with a decoy.
11:53Eventually, a new form of the virus will evolve that can slip past the body's defenses.
12:05And that virus, it's selected because it's the only one that's able to grow and replicate itself in these cells.
12:10And so all of a sudden, it takes over the whole population.
12:13So you go through these sort of like bursts of selection that completely change the sort of the structure of the viral population.
12:20And this can happen very quickly.
12:22As long as we rely on our immune systems to keep us healthy, new viruses will constantly evolve.
12:30But a zombie virus may also one day be created in a laboratory.
12:35We should be able to design viruses that do different things.
12:40In principle, it seems to me that if you know what buttons to push, you could make a virus that could do those things.
12:47Karthik, of course, wants to stop the zombie virus, not create one.
12:52But nothing is preventing the wrong minds from pursuing it.
12:56Is a zombie virus possible?
12:58I mean, I suppose there's really nothing in the laws of physics that says it's impossible.
13:01Although I would say that it could be some sort of combination of different viruses that we know about.
13:08A hybrid virus that turns human beings into deadly contagious monsters is not likely, but it is possible.
13:17It could come from a laboratory or could be born from the crucible of evolution.
13:23If this virus breaks out, what happens next?
13:32When you get the flu, what do you do?
13:36Go home, get in bed, and hope no one bothers you.
13:41But imagine a disease that spreads by making its victims violent.
13:45Such a disease could emerge someday.
13:50Could we keep it from becoming a global pandemic?
13:55In Ottawa, Canada, a scientist is taking on the zombie apocalypse before it happens.
14:03A scientist who always seems to have a question on his mind.
14:14I added the question mark because my name was very boring and I was getting confused with all kinds of Robert Smiths.
14:19So I thought it would be a cool thing to add to my name.
14:20And as I have my question mark, which helps me be distinguished from other Robert Smiths in my specific field of disease modeling and biomathematics.
14:33Diseases are everywhere.
14:36Robert wants to log every moment in his life when he can pick up a pathogen from an infected person.
14:43Even when the infected aren't around.
14:46If a disease is airborne, then the air that we share is obviously something that's potentially quite toxic.
14:53And the closer you are, of course, the more likely, but then other things become transmissible as well.
14:58So doorknobs and, you know, the bus handle or whatever it is that I'm touching or breathing on.
15:04Robert is using this data to build mathematical models to predict how quickly infectious diseases can spread.
15:21And with the help of his students, he's creating live human versions of those models.
15:26Just like any human community, the virus has many chances to find a new host.
15:33Okay. In these beakers, most of them are just plain water.
15:37One of them has been infected with something that's going to simulate a virus.
15:41The rules are simple.
15:43No student can take more than five steps.
15:46And go.
15:47They have 30 seconds to mix with as many other students as possible, and no one knows who has the beaker with the infection.
15:57Robert wants to see how many people patient zero can infect.
16:02Okay, now please return your beakers to the middle.
16:09At the end of the game, Robert drops a chemical into each beaker.
16:14If a student mixed with the infected, their water will turn yellow.
16:19Even though patient zero could only have direct contact with a few neighbors,
16:24those neighbors pass the disease along and about half the group ends up infected.
16:28But Robert believes the map desperately needs an update.
16:35So recently we tried to update models and we have much more powerful ways of understanding the network of connections that different people have.
16:42The old models focus on human beings and their local communities.
16:48But we now live in a global society and are on the move like never before.
16:54On an average day, approximately 22.8 million of us travel someplace far away.
17:06Robert repeats the game with the same rules.
17:09But this time, the students are allowed to take as many steps as they wish to account for the ease with which we travel.
17:15At the end of the 30-second round, Robert tests each beaker again.
17:35Every student is infected.
17:42Robert has calculated the infection rate for a disease that doesn't yet exist.
17:48He imagines a virus that spreads easily through the air, like the flu.
17:52But unlike influenza, the disease does not make its victims want to stay home in bed.
18:00Instead, they become zombies and they take to the streets in a mindless rage.
18:06So if we actually had a zombie virus, then the mathematics predicts that we're not going to do very well.
18:15If just one person is infected with this zombie virus, Robert predicts an epidemic is inevitable.
18:23Cities would be overrun in weeks.
18:25As refugees escape, some of them inadvertently bring the disease along.
18:33Global civilization as we know it would be brought to its knees in a matter of months.
18:40We have completely eradicated only two infectious diseases, cattle plague and smallpox.
18:46Finding a cure for this hypothetical zombie virus is very unlikely.
18:53But if a zombie outbreak does happen, Robert's calculations show how humans can avoid total annihilation by getting our hands dirty.
19:06Probably the best way that we found to deal with zombies was to basically hit them hard and hit them often.
19:11So the idea is that you try and wipe the zombies out in one go.
19:16Of course, you're not going to be successful at that, so next day you try and wipe them out again using the knowledge that you learned from the last time.
19:22So we get better at it, and so then the third day we're now even better.
19:26To stop a zombie plague from becoming an apocalypse, we may only have one horrifying option.
19:33To kill every single infected person.
19:37Just one surviving zombie could trigger another epidemic.
19:44Our best hope to stop a super virus is to catch it in time.
19:50Virus hunters are scouring the microscopic world, looking for an invisible enemy that may have already made its first move.
19:59During the four years of World War One, almost 15 million people died.
20:10In the two years that followed, a single flu virus claimed three times that many lives.
20:17The virus had spread around the world before anyone detected it.
20:24There are millions of microbes out there, most of them harmless.
20:30How can we find the next deadly pandemic, perhaps a zombie virus, before it sweeps the globe?
20:40Hello? Hello?
20:53According to Ian Lipkin, the world's leading virus hunter, our civilization runs a terrible risk of global pandemic.
21:01I'm standing in the middle of Times Square, and it's completely deserted.
21:08It looks like something that you might see in a movie, but in fact, it's a real possibility.
21:13Ian is the director of the Center for Infection and Immunity at Columbia University.
21:19His team is on the front lines, hunting for deadly viruses before they become pandemics.
21:28In 2003, his lab was the first to identify the lethal SARS virus.
21:34That early discovery saved countless lives.
21:39Nature herself is continually evolving new bacteria, new viruses that are more pathogenic,
21:45that escape the antivirals, the antibacterials, the vaccines that we create to hold them in check.
21:54There are more than 10,000 trillion, trillion, trillion viruses on Earth.
22:00Pinpointing a deadly virus in a sea of its benign cousins is just about impossible.
22:06Unless you lure the virus out of hiding.
22:10When a patient falls ill somewhere in the world with an unknown virus, blood and other biological samples are often sent to Ian's lab.
22:20He then gets to work by going fishing with DNA.
22:29DNA makes for the perfect virus bait because viruses contain genetic code that binds to matching sequences of DNA.
22:37So that if that virus is present within that sample, it will be caught on the hook and I'll be able to reel it in and I'll see it.
22:48Ian can cast thousands of genetic lures into the sample.
22:53Each one is tailored to attract a known virus.
22:56Biological samples from sick patients are oceans filled with microbes that ignore the lure except for the virus that is a match for the lure's DNA sequence.
23:11The virus lines up its genetic code.
23:15A binds to T, C binds to G.
23:17Once it's hooked, the weight of the lure changes and Ian can reel in the virus.
23:27Now, if that method works, then we can get an answer very, very quickly, very inexpensively, probably in a matter of four to six hours at the outside.
23:37But viral and genetic code can evolve rapidly.
23:42Sometimes new viruses have changed so much that they no longer stick to the lure.
23:47In that case, Ian switches to another technique.
23:51Grab all the DNA he can.
23:54I have a net.
23:56This is essentially a DNA sequence.
23:58When we don't know precisely what we're looking for,
24:00we use a high-throughput sequencer that allows us to characterize all of the genetic material to be present within a sample.
24:08We pull everything in and then we compare that with a database of all known sequences.
24:14That allows us to identify anything which is potentially a microbial agent.
24:19Ian and his team then grow colonies of the isolated virus
24:23and attempt either to identify a drug that can fight the infection or to develop a vaccine.
24:31We and our colleagues can begin testing drugs for efficacy.
24:36Drugs that will be able to prevent this agent from reproducing itself.
24:40And then ultimately, because drugs are frequently too expensive,
24:45we try to collaborate with people who know how to develop vaccines.
24:48No matter how quickly they identify new viruses, however,
24:53there will always be a lag time between detection and treatment.
24:57A time when the virus can spread.
25:00The major time lag is not at the level of the laboratory.
25:04It's really in the field.
25:06It's recognizing the appearance of something as new.
25:10Then that has to percolate through the ether until it reaches people like us.
25:15Ian's team could prevent millions if not billions of us from succumbing to a highly infectious disease.
25:24But if a virus evolves that is sufficiently different from the viruses we know today,
25:30Ian's team will not be able to fish it out.
25:35In humanity's war on viruses, we need a new strategy.
25:39We can hunt viruses down and we can try to vaccinate ourselves against them.
25:48But once they infect us, we are at their mercy.
25:53What if we turn a virus into a zombie that works for us and make it kill a zombie virus?
26:03Modern medicine has conquered many diseases in the past century.
26:11Viruses, however, remain elusive targets.
26:16Because they hijack the vital genetic machinery of our cells, killing them is tricky.
26:22The solution may require a pair of these.
26:29Shrunk down to the size of our DNA.
26:37Viruses are party crashes.
26:40They do everything possible to blend in with healthy cells.
26:43All the while relentlessly infecting the invited guests.
26:49For severe infections, our best medical treatments today are crude.
26:54They work by chopping up the harmful invaders.
26:58Party's over.
27:01And all the healthy cells in their vicinity.
27:05But a new treatment that only goes after the bad guys could be right around the corner.
27:14As the director of the Center for Nanomedicine at UC Santa Barbara,
27:19Jamie Marth thinks it should be possible to make an antiviral drug
27:24out of a class of chemicals that we all have in our stomachs.
27:28The food that I have on this plate right now is what I need to keep me alive and mostly healthy.
27:39But for my body to use this material, it has to convert it into different forms.
27:46And it does that by using small natural machines called enzymes.
27:51Enzymes are the power tools of microbiology.
27:54In the stomach, they break apart our food into digestible forms.
28:01Jamie and his colleagues are working with an enzyme called CRE recombinase.
28:07This enzyme has a remarkable utility.
28:11It can cut out any section of DNA and neatly staple back together the two adjoining genetic pieces.
28:19It's allowed us to do things that we haven't been able to do before.
28:24To remove specific genes from specific cells at different times.
28:32Inside every cell in our body, there is a forest of DNA.
28:38Viruses sneak foreign genes into this forest and hijack our cellular machinery.
28:43A drug based on Jamie's CRE recombinase enzyme could chop down viral infections at their root.
28:53By weeding out their DNA.
28:58The enzyme needs to find a specific sequence of 34 genetic letters at either end of the cut.
29:04And that sequence can be customized.
29:08So once you know the genetic sequence of a virus, you can program CRE recombinase to latch onto the first and last parts of its DNA code.
29:18This represents viral DNA, DNA that's foreign to the cell and has integrated itself into the genome.
29:28An enzyme like the CRE recombinase is capable of removing this precisely from the cell's genome.
29:35It does this with precision.
29:37And then what the enzyme will do is it will stitch back together the ends of the normal DNA so that the cell is effectively cured of the disease.
29:56Jamie is laying the groundwork for what could be a cure for all infectious viruses.
30:01HIV, AIDS, influenza, even the common cold will all only exist in history books.
30:16And the delivery vehicle for this life-saving drug is the last thing you would expect.
30:23Another virus.
30:24We could reprogram that virus so that once that virus binds and goes inside the cell, instead of releasing a disease-causing payload, it will instead release a cargo that allows us to cure those cells.
30:44Our best weapon against a virus that turns humans into zombies could be a virus that we turn into our zombie slaying.
30:52This harmful virus would be stripped of its disease payload and instead be filled with reprogrammed CRE recombinase enzymes, which can search throughout our entire bodies and only eliminate the unwanted invaders.
31:14But finding a universal cure for viruses may not save us from a world filled with zombies.
31:19A zombie takeover is already underway in a lab in North Carolina, where living creatures are turned into zombie drones at the press of a button.
31:31If I told you to run off a cliff, you wouldn't do it, would you?
31:40But what if I took control of the neurons in your brain and made your legs run straight off the edge?
31:48Turning a conscious person into a mindless zombie may only be a matter of finding and controlling the right circuits in the brain.
31:57How do you get a living mind to completely surrender its will?
32:11Electrical engineer Alper Bosgert thinks we've been doing it for centuries by domesticating wild animals.
32:18The horses open themselves to our control thanks to this mutual beneficial relation that we have with them and it took a long time for us to be able to train them basically to condition them with different rewards or punishments.
32:34Alper looks at animals as electrical circuits.
32:39As a horse moves, its brain sends an elaborate series of commands to its muscles through the electrical wiring of its nerve cells.
32:48But convincing a horse to make these complex movements only requires a simple input.
32:53So when the rider wants the horse to go to left, she just pulls the reins to left and the horse starts going in that direction.
33:04And when she wants it to go right, she just pulls it to right and we see that the horse is going on the right.
33:10Then when she wants it to go forward, she just provides a gentle kick with her heels and the horse knows that it needs to go forward and it does it.
33:19The horse obeys because of its training, but Alper thinks he can get the same results in other creatures without conditioning by replacing mechanical commands with electrical signals sent directly to the brain.
33:37I have a set of dominostones here representing a neural network like in any brain.
33:44A brain is a set of electrical relay networks.
33:47It is composed of excitable cells called neurons.
33:51When neurons become electrically excited, they pass a signal on to their neighbors, which in turn pass the signal along.
33:58Alper only needs to stimulate one neuron and the entire neural circuit will activate, resulting in a complex bodily action.
34:15It's a principle that should work in any brain, but Alper is starting with a simple mind, the cockroach.
34:22Alper implanted electrodes into the sockets where a roach's antenna connect to its brain.
34:32When he sends an electronic pulse to the neurons inside, the roach becomes a zombie.
34:41It goes wherever the electronic pulse tells it to go and it even turns on a dime.
34:48So when we stimulate the right antenna of the insect, the insect thinks that there is an obstacle in front of it and it tries to make a left turn.
34:59And when we stimulate the left antenna, it tries to make a right turn.
35:03Alper thinks his zombie bugs will one day save lives.
35:13He envisions cockroach cyborgs, outfitted with cameras and GPS chips so they can locate survivors under collapsed buildings.
35:21But his breakthrough could be the beginning of a world where no mind is safe.
35:28Theoretically, even a human could be zombified.
35:34We know how neurons work and we can communicate with them.
35:39When we stimulate the insect, it is the same stimulation principle that is used in deep brain stimulation patients with Parkinson's disease.
35:50So these are all the same principles.
35:53It's relatively easy with cockroaches to make them follow our command signals.
35:58But with higher organisms, with vertebrates, it is much complicated, although it's not impossible.
36:05Technology may soon exist that in the wrong hands could turn us into zombies.
36:13If our minds are taken over, will we even know it?
36:16A zombie apocalypse may already be happening today.
36:22In fact, this neuroscientist thinks we're already 98% zombie.
36:31In fiction, the nightmare of a zombie apocalypse is constantly taking on new forms.
36:39But they all have a common theme.
36:41The infected don't even know they are zombies.
36:47If right now we were zombies in the midst of an apocalypse, would we even know it?
37:00Neuroscientist Scott Grafton believes that in sports like golf, it pays to be a zombie.
37:08I was watching this tournament where Fuzzy Zoller was winning.
37:12The announcer runs up to him and says, Fuzzy, how did you do it? How did you win?
37:17He says, well, I've been brain dead all week.
37:22After enough practice, a good swing is automatic.
37:28In fact, nearly everything that our bodies do requires little, if any, thought.
37:33Almost all of our actions are actually unconscious.
37:38We can pretend we access our muscles.
37:41You know, when I hold a golf club, I can grip it, and then I can think,
37:45OK, flex this muscle, extend this muscle, turn my shoulders, turn my waist, and so forth.
37:51But actually I have very, very poor access to those muscles.
37:59It's much easier to visualize what you'd like to have.
38:03And the swing just takes care of itself.
38:06Our brains are goal-oriented.
38:12We think of an end result, and our bodies mindlessly follow a program to achieve it.
38:18For Scott, this is evidence that our willpower is not as strong as we think.
38:23On a good day, I think we're about 97% zombie, and on a bad day, 98% zombie.
38:33And the rest of the 2% or 3% is us having actually willful control over our daily activities.
38:38Scott is running an experiment to momentarily rob his subject, Misty, of the other 2%.
38:49He uses a technique called transcranial magnetic stimulation, or TMS,
38:56to induce a harmless electrical current in her brain.
38:59TMS is a method for very briefly turning off a small part of your brain.
39:08So it's a copper coil that goes against the skull, and you induce a current through that,
39:15and during that time you essentially have a virtual lesion in your brain.
39:20Scott calibrates the device by stimulating the neurons that control her right hand.
39:25He then moves the device to focus on her parietal cortex.
39:33This region of the brain is believed to be responsible for making sure that our actions match our intentions,
39:41like trying to touch an illuminated dot.
39:44In the first round of Scott's experiment, there is no TMS pulse.
39:50As soon as their hand starts moving, we jump that second light to the right.
39:55A few inches.
39:57And their hand quickly corrects for that jump.
40:01And it smoothly goes over and pursues that new location.
40:06But in the second round, right as Misty's finger moves, Scott zaps her parietal cortex.
40:13She doesn't feel the pulse, but loses the ability to consciously correct her action for a brief moment.
40:20They react essentially as a zombie and go to the original location, that second light, and they're unable to correct themselves on the fly.
40:30So when we turn off the parietal lobe, we're essentially making a person a full zombie for just a second or so.
40:36And during that time, they're just carrying out a movement that they no longer can control.
40:42Scott believes we evolved to be 98% zombie so that the intellectual parts of our brains could be freed up from thinking about the menial tasks that take up most of our time.
40:54For all of its evolutionary advantages, the intelligent human brain may come with a cost.
41:02I think we're a hair's breadth away from a zombie apocalypse in the sense that most of what we do, we can accomplish without thinking about it.
41:10Just think about how many willful choices you've made in the last week.
41:15It's probably maybe one or two.
41:18Everything else you did was essentially automatic behavior.
41:21So if now you think of something that takes away that last 2%, you're already prepared to live as a zombie.
41:28By the time we reach adulthood, most of our daily lives are spent engaging in activities that require little conscious thought.
41:38If we were to lose our ability to make conscious decisions, life just might continue as normal.
41:45Certainly we wouldn't recognize it in ourselves.
41:48And the scary thing is whether you could recognize it in anyone else.
41:52If there was a zombie apocalypse, I don't think it would be like World War Z.
41:57I think we would be plain old normal human beings, except we'd be a little bit different.
42:02We'd be more like Invasion of the Body Snatchers.
42:05Where we're ourselves, but we're not ourselves anymore.
42:08We humans love our free will.
42:21As bizarre as it may seem, it is entirely possible that a microscopic parasite, or technology run wild, could take away the free will we cherish so dearly.
42:33All of this talk of zombie apocalypse raises one final question.
42:40Why do we enjoy scaring ourselves half to death?
42:45Maybe that's what we need to do in order to prepare for the worst.
42:50I'm not scared, because science is our best defense.
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