 Some organisms can become a mindless zombie if they are involved in certain types of relationships. There are three major types of the relationship between organisms. The first one is true love. We admit the situation when both partners clearly benefit from the relationship. Like this bee and the flower. The bee needs nectar in order to produce honey. And by flying from one flower to another, it transmits pollen to help the flower to reproduce. So both partners benefit. We admit the situation through love. And it's called mutualism. There is also one side of love when one partner benefits and another one has no real meaning. It's like a whale and small organisms that are called particles over there that live on the surface of the whale and so they get a place to live and as the whale swims they filter water and get some food. They clearly benefit from this relationship and the whale doesn't care. It's called commensurism. And then there is another type of the relationship which is not a love at all. It's when one partner constantly takes advantage of this relationship. It starts in the end all the time and you all can be there with this. Is this guy who was walking from you in school every day? Never even said thank you. Sure. But okay, it's a joke. Kids are not parasites. Or are they? I think it's a topic for another lecture. So parasites can live either inside their hosts or also outside. And so they use the energy and resources of the host to eat and reproduce. And if you think about the host, so the primary host, the main host of each parasite, it's like a house. The place where you can eat as much as you want and also reproduce as much as you want. But usually, so you would always want to come back home because you like it. But life of a parasite in most of the cases starts outside of home. And from the moment the baby parasite is born, it's on a journey. An amazing journey with adventures, challenges. It will grow. It will find some other hosts which will be intermediate hosts. Just like a temporary apartment or a vehicle that will drive itself forward in their life cycle. They will even transform, grow, evolve into some other morphological forms. And finally the mature parasite will finally come back home and of course reproduce. And then the cycle will start again. So certain parasites develop a unique ability to facilitate this process and to manipulate the behavior of intermediate hosts in order to ensure that their life cycle gets completed. And the life cycle of every parasite is an amazing, it's a thriller, it's a drama full of emotions. It's an amazing story and I'm happy to share some of the stories with you tonight. Look at this snail for example. Is it going to a disco party? We don't know. But what we do know is that it was unfortunate to eat some eggs of a parasitic worm that grew inside this snail and then invaded its eyes. And there you can say it's very poor pretending to be a delicious caterpillar. It also changes the behavior of the snail. The snail starts crowding up on a leaf or a piece of a grass because it really wants to be on a spot. It wants to get annoyed by a hungry, maybe angry bird. The bird would think, ah, delicious caterpillar. It would eat it and the worm would get back home to its primary host, a bird. Then it would multiply and with the bird's droppings the eggs of the worm will get out and then another unfortunate snail would eat it and the cycle is complete. Some parasites don't even need to be inside their host in order to manipulate their behavior. And to tell you this story I have to ask you a question. Who of you likes cockroaches? What? A couple of people there, right? Almost nobody. But why? He really means a friend, you know? Because he's got a very powerful enemy. I never liked a cockroach or a snail. This guy is a real monster. He hates cockroaches. But if he sees a cockroach it attacks him. And during the fight it stings it twice. The first time it stings it, it paralyzes the roach temporarily. So the roach cannot fight back or run away. And while it is paralyzed it stings it for the second time precisely into the brain. And there it injects a very special venom which doesn't kill the roach. Neither it seduces it. Instead it just makes the roach a very obedient slave. It can run away or fight if it wants to. It just doesn't want to. All it wants it just stands still and waits for the borders from its master. The master boss. And the boss then grabs the roach by its antenna and just hooks it home like a dog with a leash. And the roach is whatever I'm talking, you know? Because the boss had previously ticked the hole and it's guiding the roach directly into its hole. So it will lay an egg on the surface of the roach and then burricate the entrance basically burying the roach alive. And then the egg will hatch and the small larvae will suck the nutrients out of the roach and then crawl inside and feed the zombie roach which is still alive inside out. I didn't put any video, I thought it would look like that. After that the fully grown up boss emerges out of the body of the zombie roach. Don't you feel sorry for the guy now? Don't you feel sorry for the guy now? But these are all warrants, insects, I mean who cares really? What about bigger animals? There is another story about the bigger animals. But before I tell this, I actually need to make a little announcement. The thing is I've been in a sort of a relationship for a while and I thought since I'm here on this stage today it's a good opportunity for me to confess my feelings. And publicly I say that I'm in love and actually it's a bit stressful so I would appreciate a little bit of your support. Be in love, in love. Be in love! He tried to take you away. It all started when Boris got slightly sick. He had a parasitic infection. I actually think the Boris of the Parasite himself because when he eats, sleeps and plays around. But at the time it was serious. He got infected with a real monster. Ducks of plasma go into him. A single cell which was on Parasite that wanted to leave and multiply inside the guts of the Parasite. This Parasite is very, very... but what's important here is that it can only sexually reproduce inside the guts of different feline species. A romantic place, right? So Boris wasn't really happy about it. So he decided to get rid of the Parasite. So he went to the bathroom and from there the Parasite escaped and quickly spread all around the nature. Condemnated grass, water, come into him, it was everywhere. But as it can only sexually reproduce inside the intestines of different cats' niches it really wanted to come back for my comparison. So he waited for the Boris's mortal enemy to appear. The Mr. Mouse. Once it got inside the mouse it needed to convince him to go find Boris. And for that it developed a very, very evil plan. It migrated in the brain of Mr. Mouse and forced neurons to produce dopamine. The molecule which is responsible for the release of joy, excitement and reward. So Mr. Mouse became very happy and reminded. But still he didn't want to go find Boris because mice have innate fear of predators. If they smell a cat's urine they bite and they're out of the way. And I understand this. It's okay. But the Parasite accumulated in a special region of the brain which is called amygdala. This region controls fear and excitement. So if it accumulated there it totally messed it up. Instead of being afraid Mr. Mouse became very, very, very pissed. All he wanted is to run into Boris and make sweet, sweet love. Just like that. Mr. Mouse ran there. Love became deadly. And that's another example of Parasite's control behavior with their intervention costs in order to ensure their life cycle gets completed. But what if Parasite didn't get inside the mouse? What if he gets inside the mouse? Well, in fact, one-third of the world's population and all of you included, of all one-third, is positive for the exemplars. I don't want to say that U.A. has full ones. Okay? Anyway, if you did it's fine. Right? But probably you got it under complete or under-stressed meal or while working in your garden as a Parasite can terminate soil easily. Our immune system is able to protect us. With real danger these are the pregnant women because if you get infected with the Parasite for the first time in your life during pregnancy that can be a very serious danger for babies. There are no drugs here. Please, if you're pregnant and you have a cat go to the doctor and do some tests please avoid changing the cat's literature. Stay away from this as far as you can. Guys, we have to deal with this shit. But Parasite may remain in our brain. At the end of the day, I mean, our brain is not very different from the mouse brain. I know it sounds upsetting but it actually gives hope to so many people who think about it. As a factor, here there is some scientific evidence showing that if you're positive for txoplasma you're more likely to be involved in car accidents and also there is a correlation between being positive for txoplasma and exhibiting aggressive and reckless behavior and also connection with development of mental illness. And now you're probably thinking okay cat's mental illness now it explains all the crazy cat ladies, right? Don't jump into confusion that fast. Still it's not fully understood. But even if Parasites make us love cats how can we resist? And for me, it is totally fine but I ask you to remember one thing Boris is mine. So there is not Parasite which does control our behavior and it's a fact. And if txoplasma is, I mean one third of the world is positive for txoplasma so for this Parasite it's way more. And I guarantee you that most of you it's not everybody are in contact with this Parasite. Some people are more susceptible some people are less. I know that I'm super infected and uncontrolled. And... Yeah. So this Parasite is a smartphone and a social media. You're just walking like a zombie like-like-like, document-document you're sitting on the toilet in the morning, in the evening, all the time. There's nothing we can do about it, right? It's just a fact. But we can, however, turn this Parasitic relationship into mutualistic. And the best, it's not the only way to do that, is to share it's like it's fine.