Disturbing Real Mutations Found In Humans And Animals

Added: 2026-05-23

[00:00:00]You'd think Chernobyl would be a dead zone, but a lot of life is thriving [music] and changing in surprising ways.

[00:00:05]Frogs are changing color, dogs are building radiation [music] resistance, and catfish are turning into underwater tanks.

[00:00:13]>> [music] >> These are terrifying Chernobyl mutations caught on camera. What you're looking at here is a frog affected by the radiation of Chernobyl. [music] 2016, two Spanish researchers, Pablo Barahona and German Orizaola, were studying how life was bouncing back [music] in Pripyat, and they noticed something strange, black frogs. Now, obviously, dark-colored frogs on their own aren't unusual, but the type of frog they were looking [music] at, Hyla orientalis, a tree frog native to the area, is usually bright green. [music] So, what happened? Well, turns out it might be evolution caused by the radiation. The darker [music] skin isn't random. These frogs have developed higher levels of melanin, the same pigment that protects human skin from UV [music] damage. In this case, it helps block radiation from damaging the frog's cells. And it seems this shift happened fast. [music] Within a few decades, a bright green species started turning dark to survive in a nuclear zone. It's one of the clearest examples of nature adapting. Instead of dying out, these frogs [music] have adjusted their biology to deal with one of the harshest environments [music] on the planet. This is Jeremy Wade, River Monsters guy, pulling a massive catfish out of one of the cooling ponds near the Chernobyl power plant. These ponds are still radioactive. Wade mentioned the fish he caught had radiation levels about 16 times higher than normal. But, what really grabs attention is the size of these things. They're huge. People have wondered if radiation is causing these fish to mutate and grow into monsters, but it may not be the radiation that's making them giants.

[00:01:52]It's more about the environment. These ponds are closed off, meaning the catfish are at the top of the food chain, no predators, tons of food, and people even feed them sometimes. So, over time they just get bigger and bigger. They're living longer as well, [music] which adds to their size. Now, that doesn't mean they're not being affected by the radiation. They're definitely soaking it in, and scientists are still studying whether there are long-term mutations or effects we can't see from the outside. Either way though, these catfish are a real reminder of how life can keep going in places where it really shouldn't. Wolves in Chernobyl aren't just surviving, they [music] might actually be evolving. In 2014, Dr. Kara Love and her team from Princeton headed to the exclusion zone and put GPS [music] collars on several wolves to track them.

[00:02:41]These collars didn't just show where the wolves [music] were going, they also measured radiation exposure in real time. The wolves were getting hit with radiation levels up to six times [music] the legal safety limit for humans every single day. That should be deadly, but [music] instead of dying off, the wolves seem to be adapting. Blood samples showed changes [music] in their immune systems, almost like what you'd see in a person going through radiation therapy.

[00:03:08]Even [music] more interesting, parts of their DNA looked like they were evolving to resist cancer. [music] In a place where cancer risk should be through the roof, these wolves are developing ways to fight [music] it.

[00:03:19]Now, because of the situation in Ukraine and obvious safety concerns, the research [music] has slowed down. But if what they've actually found holds up, these wolves might be the key to understanding how to survive [music] in high radiation environments. Cuz we all want to do that, right? [music] Maybe even how to treat cancer in humans one day. Now, that we definitely want.

[00:03:39]Wild boars in the Chernobyl exclusion zone are basically radiation [music] sponges. Out of the animals still hanging around, these guys are carrying some of the highest levels of radioactive material in [music] in bodies, and it all comes down to what they eat. Boars dig through the soil looking for [music] roots, insects, and mushrooms, especially deer truffles. And those truffles are loaded with [music] radiation because the soil around Chernobyl is still contaminated. So, the boars eat, and the radiation builds up inside [music] them. Over time, it's had some nasty effects. People have reported sightings of boars with strange [music] growths, tumors, physical deformities.

[00:04:16]It's not like they're growing extra legs or anything out of a comic book, but their bodies clearly aren't doing great.

[00:04:22]Radiation messes with their cells and weakens their immune systems, making them more likely to get [music] sick or develop weird internal issues. But even still, they are surviving. Maybe not [music] as well as the dogs or wolves, but they've managed to reproduce and live in this environment. Some are even leaving the exclusion zone and mixing with boar populations in other parts of Europe, [music] which is kind of concerning. So, this may not be a living thing, but considering it's a glob of radioactive goo, I mean, I don't know. Maybe it is. It's known as the elephant's foot, one of the most famous concoctions to come out of the Chernobyl disaster. After reactor [music] four blew up, a bunch of nuclear fuel, metal, and concrete fused together under the plant and cooled into this massive lump of radioactive material, and it kind of looked like a deformed elephant's foot. Thus, it was dubbed the elephant's foot. This thing was first formed, [music] it was putting out so much radiation that standing near it for just a few minutes could kill you. Not exaggerating. People who had to go near it in the early days of cleanup would get a lethal dose of radiation [music] in minutes. One guy who filmed it back in the '80s was reportedly dead within a year. [music] Even now, decades later, it's still dangerous. The radiation has cooled down a bit, but not enough to really make it safe. Scientists have kept an eye on it over the years because they were worried it might keep leaking radiation or start heating up again.

[00:05:46]It's also affected the air, water, and soil around it. They call the elephant's foot a kind of man-made lava, except instead of burning you, it poisons you.

[00:05:55]And yeah, it's still sitting there deep under reactor four, slowly decaying, but still very dangerous. EV stands for this. It's sometimes referred to as the tree man disease. EV is an ultra rare genetic condition that causes uncontrollable growth of wart-like lesions all over the skin. The weird thing is these lesions are caused by certain types of HPV, the same virus that causes, you know, common warts. But almost everyone's immune system fights off HPV before it gets serious. In EV patients, their immune system doesn't work properly [music] against these HPV types. Scientists found mutations in two specific genes that seem to break the immune system's ability to control the virus, but they're not sure exactly why.

[00:06:41]Because of this, the HPV spreads unchecked, causing large, scaly lesions that can look kind of like tree bark, which is where the nickname tree man disease comes from. One of the most well-known cases was a man from Indonesia who lived with the condition for over 20 years before passing away.

[00:06:57]The lesions covered his hands, feet, and his face. Doctors don't have a cure, so treatment focuses on just removing the growths and managing infections.

[00:07:06]Diprosopus is a super rare condition where a person is born with parts of their face duplicated. This can mean anything from having two noses or two mouths to nearly just two full faces on one head. It's so rare that there have only been about 36 confirmed [music] cases of this. Scientists think this happens because of a problem with a protein called Sonic Hedgehog, not making that up, which controls how the face develops before birth. When this protein is too active, it can cause the face to split or duplicate. But exactly why this happens in some pregnancies and not in others is still a mystery. Most people born with this don't survive long because the condition usually comes with other serious problems, especially in the brain and the [music] internal organs. Sometimes the duplicated parts aren't fully formed, other times they're more complete. Doctors and researchers have studied cases over the years, but there's still no clear explanation for why it happens. It's not inherited, instead it seems to be a random error during early development. It's one of the rarest and most baffling birth anomalies recorded. Progeria is a crazy rare genetic condition where you age way faster than normal. It's caused by a mutation in a gene called LMNA, which makes a protein important for keeping cells stable. When that protein is messed up, cells get damaged faster and the body shows signs of aging early. You know, you'll have hair loss, wrinkled skin, heart problems. Kids with progeria usually look like tiny old people, even though they're actually really young.

[00:08:37]It's super rare, only about 400 cases have been confirmed around the world.

[00:08:41]Those born with it usually only live into their early teens and most die from heart disease. [music] There's no cure yet, but some treatments can help with symptoms and maybe slow down the aging a little. Even though scientists know the gene involved, the full picture of how this works at a molecular level is still a mystery, which makes it one of the most puzzling human mutations we know of. Next up is something called mermaid syndrome, which sounds kind of nice, [music] but it isn't. Scientifically it's known as sirenomelia. This is a rare condition where you're born with your legs fused together, looking kind of like a mermaid's tail. It's extremely uncommon and sadly it's [music] usually fatal because it comes with serious problems inside your body. You'll have missing or malformed kidneys and just lots of issues in this general area, as you can imagine. Doctors think it happens because the blood flow to the lower part of the fetus gets messed up early in pregnancy, but they don't fully understand why. Some studies say it might be caused by things [music] like maternal diabetes or exposure to certain toxins, but they're not entirely sure.

[00:09:44]Unlike conditions caused by a single gene mutation, mermaid syndrome seems to come from a mix of things, [music] but this is so rare that only a few hundred cases have ever been documented.

[00:09:55]Polycephaly means having two heads on one body. It's an extremely rare type of conjoined twins, where instead [music] of two bodies, they're just one with two separate brains. Each case is different.

[00:10:06]Sometimes both heads have control over parts of the body. Sometimes one is more dominant. How these twins share organs and nerve control varies a lot, so each case is unique, which makes it tricky [music] for doctors. Scientists know polycephaly happens when an embryo starts to split into twins, but then doesn't fully separate. What's not clear is why it stops halfway, leaving [music] two heads on one body. It's not inherited and seems to be a random developmental glitch early in pregnancy.

[00:10:34]Survival is rare because contrary to what cartoon logic would have you believe, having two brains actually [music] puts a huge strain on the body.

[00:10:42]It's It's not a good thing. There have been documented cases in both humans and animals, but very few survive for [music] long. When they do, it raises all kinds of medical and ethical questions about treatment and quality of life. Even with modern medicine, scientists still don't fully understand [music] how these twins' brains manage to coordinate the body or why the condition happens in the first [music] place. Now, right next to the Chernobyl plant is a place called the Red Forest, and it got that name for a pretty grim reason. When [music] reactor four exploded, it sent a radioactive cloud directly over this patch of forest, and within hours, [music] the pine trees turned a weird rust red color. Basically, they died almost instantly [music] from radiation exposure. That entire section of forest just collapsed. But, over the years, new trees started growing again. Not quite like before, though. Scientists [music] have found trees with bizarre growth patterns. Some have twisted trunks, stunted branches, or [music] grow at strange angles. A few have odd discolorations or split limbs that don't match [music] normal growth cycles. Even now, decades later, radiation levels in the Red Forest are some of the highest in the whole exclusion [music] zone. The forest acts like a sponge, so any rain that soaks into the [music] soil can stir up radioactive particles again.

[00:11:59]Now, beside the massive catfish cooling [music] ponds near Chernobyl, smaller fish in the rivers and lakes around Pripyat have shown some pretty unsettling traits. Researchers have talked about fish with physical deformities like missing eyes, bulging growths coming out of them, or just oddly shaped in general. The radiation that poured into the nearby waterways didn't just disappear. [music] It seeped into the water, settling in the silt, and got into the food chain. Small aquatic creatures absorbed it, and the fish that ate them absorbed even more.

[00:12:30]That kind of exposure messes with how cells divide and grow, and that's how you end up with fish that look like Blinky from The Simpsons. And then there are all the issues you can't see with the naked eye. Some fish are born sterile, others just don't live as long as they should, but there are still plenty [music] swimming around. The strange thing is that some species have adapted better than others. Mutations don't always kill them off right away.

[00:12:53]They just make the fish look off. So, while they might not be glowing like in cartoons, they're definitely not normal.

[00:13:01]This is one of the darkest and hardest to talk about. After the explosion, over 600,000 people were called in to help contain the disaster. These weren't all volunteers. Many were soldiers, firefighters, and regular workers who didn't fully understand how dangerous the job was. They were called liquidators, and their job was to clean up the mess, build the sarcophagus over the reactor, and stop the radiation [music] from spreading. There's tons of footage and photographs of these people working away in Chernobyl, completely unaware of how the radiation would affect them later on. A lot of them went in without proper protection, too. Some with just a cloth mask [music] or nothing at all, and the effects were brutal. Radiation burns, organ failure, thyroid [music] cancer, and some cases death within mere days. Some liquidators were exposed to such high doses that their bodies literally started breaking down on a cellular level. Some survivors lived for years afterward, but a lot of them did deal with long-term health issues like tumors, birth defects in their children, bone diseases. There are stories of liquidators who ended up completely isolated, physically and emotionally wrecked from what they experienced. So, when people talk about mutations, it's not just fish and frogs, it's human lives that were permanently altered. After the Chernobyl disaster, everyone had to evacuate. [music] Of course, that meant most pets, especially dogs, got left behind. Well, in the decades since, those abandoned [music] pets have multiplied into entire packs of wild dogs living in and around the exclusion [music] zone. A recent study from the University of South Carolina and the National Human Genome Research Institute looked into 302 of these dogs.

[00:14:42][music] The goal was to see how radiation may have affected them over generations, and it turns [music] out that these dogs aren't just surviving.

[00:14:51]They might actually be doing pretty well. Unlike bees and some other animals that seem to struggle with reproduction in the area, the dogs are doing just fine. They're reproducing normally, [music] raising litters, roaming free.

[00:15:03]Scientists believe they may have developed some kind of [music] resistance to the radiation. There's even early evidence showing they're less prone to cancer. Now, we're not saying they're invincible, obviously, but if these dogs really have [music] adapted to these high levels of radiation, that could mean their biology is changing [music] to handle one of the deadliest threats on Earth. It's still early days in the research, but [music] it's enough to make you stop and think. Somehow, these animals have managed to carve out a life in one of the most [music] hostile places on the planet, and that is pretty nuts. If you want straight-up visible [music] proof of mutation from Chernobyl, check out the fire bugs.

[00:15:41]These little red and black bugs are normally easy to spot because they have a really distinct [music] pattern, but in the exclusion zone, researchers started finding ones that looked all kinds of messed up. Patterns were totally off. Some bugs had their markings in the wrong spots. Others were missing parts altogether.

[00:15:57]>> [music] >> Scientists Timothy Mousseau and Anders Møller actually did a study and found that the bugs living closer to the reactor were way more likely to [music] have these deformities. They photographed tons of them and compared them to fire bugs from outside the zone, and yeah, the difference is obvious.

[00:16:13]It's not the most dramatic mutation you'll ever see, but [music] it's one of the clearest cases that got caught on camera. In February 2024, a farm in southwest Louisiana woke up to a very unusual birth. One of the cows at a farm called Bourque Farms had given birth overnight to a calf with two faces.

[00:16:31][music] From the ears back, the body looked normal, but the front of the head had four eyes, two noses, [music] and two mouths. The owners named the calf Dooface, Two-Face. Cases like this are extremely rare. According to the farm, the odds of a birth like this are estimated to be around one in 400 million. Even more surprising, the calf was alive. That almost never happens.

[00:16:55]Most animals born with this condition, known as polycephaly, are stillborn or die just after birth. The calf couldn't stand on its own at first, though, so the farmers had to support it with a sling and bottle-feed it because it couldn't nurse normally from its mother.

[00:17:10]But, both faces were actually functioning. [music] The calf could breathe through both noses, and the eyes reacted to light and movement. The two mouths even moved together, although one was slightly deformed. Fortunately, as expected, it didn't live long. It died after [music] just 26 days. In 2019, researchers surveying the Pine Barrens in New Jersey came across something they almost never see in the wild. While checking a rattlesnake den, two researchers named Dave Schneider and Dave Burkett spotted a tiny newborn snake moving [music] through the leaves.

[00:17:42]When they picked it up, they realized it had two fully formed heads on a single body. Since both the guys were named Dave, the snake quickly got the nickname Double Dave. The baby rattlesnake was only about 9 in long and just a few weeks old. This kind of mutation is called a bicephaly, which happens when what should have been identical twins don't fully separate during early development. So, the embryo develops two heads on one body. Scientists say it's basically the reptile version of conjoined twins. Animals like this almost never survive long in the wild.

[00:18:14]Each head has its own brain, so [music] they try to control the body at the same time. One head might want to move left while the other wants to go right. Not the most efficient way to hunt or avoid predators. Not to mention when it comes to actually eating, both heads may compete for the same meal. So, Dave and Dave decided to bring Double Dave into captivity where it could be studied and taken care of. In August 2019, a woman named Debbie Geddes was out fishing on Lake Champlain near the New York Vermont border when she hooked what felt like a pretty solid catch. At first, she just felt like it was a big trout, but when she finally pulled it into the boat, she immediately noticed this thing was not normal. It had two mouths, one above the other. "When we got it in the boat, I couldn't believe what I was seeing. Two mouths, and this fish was healthy and thriving," Debbie said. Photos of the trout were shared online by a local fishing group called Naughty Boys Fishing, and within days, thousands of people were sharing it and arguing about what could have caused it. Some thought it might be a genetic defect that happened while the fish was developing.

[00:19:18]Others wondered if it might have started as an injury that healed in a strange way. Even experienced fishermen who saw the photo said they'd never seen anything quite like it. Next up, we have a Guinness World Record setting cat, or cats, depending on how you look at it.

[00:19:34]Frankenlouie, or as some referred to them, Frankenlouie, which is kind of mean, but I also do kind of love that name. In 1999, a kitten was born in Massachusetts with an extremely rare condition called diprosopus, sometimes known as Janus condition. Instead of having two separate heads, the kitten had two faces on a single head. He had two mouths, two noses, and three eyes.

[00:19:57]Most cases like this end with the animal dying within a few days. Because of that, the kitten was set to be euthanized, but one veterinary nurse, Marty Stevens, decided to take the kitten home instead, see if she could keep him alive. She named one face Frank, and the other Louie. Keeping him alive took a lot of work at first.

[00:20:15]Stevens tube fed him until he was 3 months old, because she was afraid he [music] wouldn't be able to eat. Even though he had two faces, the cat only had one brain, and one esophagus, and only one of the mouths actually worked for eating. The third eye in the center of his face didn't function, and never blinked, so >> [music] >> he looked like he was constantly staring. Kind of creepy, but Frankenlouie survived far longer than anyone expected. In 2012, Guinness World Records officially recognized him as the longest living Janus cat ever recorded.

[00:20:45]He ended up living 15 years, about the normal lifespan for a house cat.

[00:20:49]In August 1995, a group of middle school students visited a small wetland near Henderson, Minnesota, as part of a school field trip. While catching frogs along the edge of the pond, they started noticing something strange. A large number of the frogs had serious deformities. Some were missing legs, others had extra ones. A few had limbs that were bent or growing out at odd angles. When scientists investigated the site, they found that half of the frogs in that pond showed some type of abnormality. That number was far higher than what biologists would normally expect to see in the wild, and that was unsettling. Being that frogs live partly in water and partly on land, they're often used by scientists as an early warning sign that something may be wrong in the environment. So, this set off a large investigation across Minnesota.

[00:21:37]Researchers surveyed wetlands around the state, examined nearly 25,000 frogs from 195 different locations. They documented deformities uh like extra limbs, partially formed legs, missing feet, and abnormal bone growth. In some wetlands, more than 60% of frogs were affected.

[00:21:56]One major cause scientists identified was a tiny parasitic worm called this.

[00:22:02]The parasite infects tadpoles while their legs are still forming. [music] When that happens, it can mess up limb development, sometimes causing frogs to grow extra legs or deformed ones. But researchers also found that parasites didn't explain every case, >> [music] >> and in some areas, the exact cause was unclear. Fibrodysplasia ossificans progressiva, or FOP if you want to get all fancy, is one of the rarest and weirdest genetic disorders. People with FOP have a mutation gene called ACVR1 that makes their body turn muscles, ligaments, and other soft tissue into bone. It's like their body starts building a second [music] skeleton, slowly just traps them in place. Imagine your muscles turning to stone over time.

[00:22:46]It's terrifying, [music] but that's kind of what happens here. The mutation causes the body's normal repair process to go totally wrong. Instead of healing injuries like normal, the body just reacts by creating bone where it shouldn't. Scientists still don't fully understand why this happens, but they know it's tied to the way cells communicate during bone growth. FOP is very rare. Only about 800 cases have ever been documented. [music] People with it usually start showing symptoms in early childhood, and it just gets worse [music] over time. There's no cure, and surgeries to remove the extra bone often just make things worse cuz as you can imagine, the body will just create more bone in response.

[00:23:25]Ectrodactyly is a rare condition where someone is born missing some of the middle fingers or toes, which makes their >> [music] >> hand or foot look like a split, so you kind of claw-like. That's why it's sometimes called lobster claw hand.

[00:23:38]Exact causes are complicated. It happens because of changes in certain genes that control how fingers and toes develop in the womb. These gene changes >> [music] >> can be different from person to person, which is why ectrodactyly can show up in a lot of ways. Some people might be missing just one finger. Others have more severe splits. The condition doesn't follow a simple pattern. That means it doesn't always get passed down in families in a clear way. Sometimes it just happens randomly during development. The gene mutations affect the process [music] where the hand or foot forms from tissue called the limb bud, causing the central digits not to develop or just [music] to fuse together. This one isn't life-threatening, though. A lot of people do live normal lives and find ways to adapt to it. Although back in the day, they would usually be put in the circus. But because the exact gene changes can vary a lot, scientists don't fully understand why [music] the condition happens or why it looks so different in different people.

[00:24:33]Hypertrichosis is a super rare condition where people grow way more hair than usual, thick hair, even on places that don't normally have it. It can show up at birth or develop later, but the form people are born with happens because of genetic mutations [music] that mess with how their hair grows. One of the earliest recorded cases was a guy named Petrus Gonsalvus from the 1500s, who had so much hair that people called him the werewolf man. The hair can cover the face, the arms, the back, sometimes just the whole body, making it look more like fur than hair. Even though it's not dangerous, it can obviously definitely make life pretty hard socially. I can only imagine how bad it must have been in the 1500s. I mean, some people would have been trying to drive a stake through his heart or burn him alive.

[00:25:18]Scientists still aren't totally sure why the mutation makes the hair grow so much hair, why it picks certain body parts to cover. There are only a few hundred confirmed cases around the world, so it's super [music] rare. Marfan syndrome is a genetic condition that affects connective tissues, so all the stuff that holds your body together, like skin, bones, and organs. People with Marfan usually have really long limbs and fingers, plus super flexible joints.

[00:25:42]Sometimes their hearts are affected as well because the blood vessels This happens because of a mutation in a gene called FBN1, which controls a protein called fibrillin-1. This protein gives strength and stretchiness to tissues, so when fibrillin-1 doesn't work right, the body parts it supports just get weaker and stretch out more than they should.

[00:26:01]Some people with this condition might barely notice it, others need serious medical care to protect their heart and lungs. With the right treatment and monitoring, most people with this live full active lives. Scientists have learned a lot about this one, but they're still studying how to prevent the serious issues that it can cause.

[00:26:18]Imagine never feeling pain. I bet some people would wish for this, but but for people with congenital insensitivity to pain or CIP, it's actually a big problem. This rare genetic condition means their nerves don't send pain signals to the brain properly, so they don't notice when they're hurt. And because of this, they often injure themselves without realizing it.

[00:26:39]>> [music] >> Might burn their skin, get infections.

[00:26:42]There have been cases of people with this condition breaking their bones and not knowing. CIP happens [music] because of mutations in certain genes that interfere with how nerve cells send pain messages to the brain. Scientists study it closely because understanding this condition, I mean, it's not only going to help people with CIP, but they could also develop new pain treatments for everyone else. The tricky part is, since pain is the body's way of protecting itself, not feeling it means these people have to be extra careful all the time. In 1966, a gorilla was captured in a forest in Equatorial Guinea that looked completely different from any other gorilla anyone had seen. It had pure white fur, pale skin, and light blue eyes. The gorilla was named Snowflake, and he's still the only known albino gorilla ever documented. [music] Albino animals like Snowflake are born without normal amounts of melanin. Of course, [music] genetic testing later showed Snowflake's albinism came from a mutation in a gene he inherited from both parents. Because of this lack of pigment though, Snowflake was unusually sensitive to sunlight and prone to health [music] issues. Unfortunately, this made him more vulnerable to skin cancer, which eventually caused his death in 2003. Snowflake spent most of his life at the Barcelona Zoo, where he became a huge attraction. Albino gorillas are so rare, scientists said this case was one in a million. After most woolly mammoths disappeared from the mainland, a tiny group survived on Wrangel Island in the Arctic for thousands of years. When scientists looked at their DNA, they found a lot of problems. These last mammoths had tons of harmful mutations building up over generations because the population was so small and isolated. Some of the mutations affected their fur, making it kind of satin-like instead of the thick wool we usually picture. Being so cut off, the mammoths couldn't get rid of these genetic problems, and over time it added up, making [music] them weaker, less capable of dealing with sicknesses and changes in the weather. Scientists think this pile up of bad mutations probably helped push the last Wrangel Island [music] mammoths to extinction about 4,000 years ago. Just recently in Brazil, paleontologists came across a strange fossil jaw bone in a riverbed.

[00:28:53]First, they thought it was just a deformed bone that had been pressed weirdly by rock, but they found eight more just like it. That's when they realized they'd found a whole new species. They named it [music] Tanika Amakola, and the fossils date back about 275 million years, long before dinosaurs ruled the planet. [music] Its jaw was nothing like what you'd expect. Instead of teeth pointing up or down like normal animals, the main teeth pointed out to the sides. Even the part of the jaw that would face the tongue was [music] twisted upward and covered in rows of tiny grinding teeth called denticles. The lead scientist who studied it, Jason Pardo, said the jaw has this weird twist that drove them crazy trying to figure out. He spent years wondering if it was a deformation until they realized every jaw had the same twist. Scientists think it used its jaw more like a grinder than a slicer, maybe chomping on plants or small bits of food in the water. They haven't found anything beyond the jaws yet, so things like what its body looked like are still a bit of a mystery.

[00:29:57]In 2011, a fisherman in the Gulf of California caught a pregnant dusky shark. When the shark was cut open, several embryos were found inside. Most of them looked normal. One of them clearly didn't. The embryo, which was about 22 inches long, had a single eye sitting right in the center of its head.

[00:30:14]When photos of it started getting shared around online, people thought it had to be a hoax. I mean, just look at this thing. It looks like a muppet. But marine biologists who looked at the specimen said the photos were real.

[00:30:26]Condition is called cyclopia, which happens when the front part of the brain doesn't split into two halves the way it normally does during early development.

[00:30:34]And because of that, the face never forms two eye sockets. The embryo ends up with one central eye instead.

[00:30:40]Researchers also noticed something interesting about the eye itself. It had actually developed optical tissue, so it had formed the way a regular eye would.

[00:30:49]Even so, sharks with this condition almost never survive. Cyclopia usually comes with severe brain problems, as you can probably imagine, and so it probably wouldn't have lived long [music] if it had actually been born. In May 2025, a team called Rattlesnake Solutions was called to a backyard in Scottsdale, Arizona to pick up what they thought would be a pretty normal western diamondback rattlesnake. Instead, it got one that looked quite different. Instead of the standard crisscross diamond pattern these snakes are named for, this one was covered in round, curvy spots that looked more like a leopard's coat.

[00:31:22][music] When the team shared the photos of the snake on social media, they were just as amazed as everyone who saw the pics. In their words, [music] "In the many thousands of diamondbacks we've seen over the years, this is a first." That's wild when you think about, I mean, how many rattlesnakes uh they encounter every year. They didn't think it was a hybrid with another species either. The prevailing [music] theory is that it's just a pattern mutation, a fluke genetic change that gave the snake the unusual spots. But, according to the group's owner, Brian Hughes, this kind of thing is insanely rare. He said that over the past 25 years, only three snakes with a similar pattern mutation have ever been seen.

[00:31:59]This one, another near the same area in 2016, and the first about 20 years ago.

[00:32:04]After the Chernobyl disaster, one of the first obvious signs of mutation was in the local bird populations. Researchers started noticing barn swallows with bright white patches, a condition called partial albinism, which is rare under normal circumstances. Along with the odd coloring, though, some birds had twisted beaks, deformed toes, and strangely shaped tail feathers. These weren't just small defects, either. Some of the beak deformities made it almost impossible for the birds to feed properly.

[00:32:33]According to studies published in journals like Biological Conservation, these mutations were especially common within the highly contaminated areas closest to the reactor. The bird survival rates were much lower than normal, too. A lot of the albino swallows didn't make it through their first year. Scientists figure the radiation damaged their DNA leading to these visible abnormalities.

[00:32:55]Interestingly, the frequency of these mutations actually gives researchers clues about how dangerous certain areas still are today. High numbers of mutated swallows usually means higher residual radiation levels. Even now, generations later, you could still find birds around Chernobyl with unusual [music] markings or growth defects. Inside Chernobyl, scientists discovered something totally unexpected. Some species of fungi show a phenomenon called radiotropism, where instead of growing toward lights like normal plants, these fungi actually grow toward radioactive material.

[00:33:32]According to research shared by the National Institutes of Health, these fungi use melanin, the same pigment [music] that gives human skin its color, to absorb radiation and turn it into energy. Almost like photosynthesis, but you know, instead of using sunlight, they're using deadly gamma rays. So, not only can these fungi handle huge doses of radiation that would kill most living things, they actually prefer it. Samples were even brought up to the International Space Station to see how they would react to cosmic radiation.

[00:34:01]And again, they were just fine. One of the areas sites in Chernobyl is the Red Forest, a place where pine trees absorbed so much radiation that they turned rusty red before dying. But some trees didn't just die, they mutated.

[00:34:15]According to the BBC, researchers noticed that a lot of pine trees developed strange needles. Instead of fanning out like normal, their needles were clumped together in these thick tangled bunches. In some cases, the trees looked almost like natural bonsai, stunted, twisted, sometimes missing their tops completely. Normally, pines grow in a clean, upward-pointing shape, but radiation damage scrambled their growth patterns. Mutations affected how cells divided and how these trees structured their branches and leaves.

[00:34:47]Some trees stayed abnormally small even decades later. Others grew in these chaotic, knotted shapes. Scientists say the Red Forest today is one of the most radioactive outdoor places on Earth, so it makes sense that the trees would be kind of messed up. While a lot of animals around Chernobyl died off after the meltdown, some species, like the bank vole, a small rodent, adapted pretty well. According to a study in Nature Communications, these rodents show clear signs of genetic damage.

[00:35:18]Their DNA has more breaks and mutations compared to voles living outside the zone. But, instead of dying out, a lot of them have somehow developed to better repair their DNA. It's not that the radiation didn't mess them up. It absolutely did. Researchers just found evidence of abnormalities. What's crazy, though, is that these voles are still surviving in one of the most contaminated parts of the world. Some scientists think natural selection favored ones that could fix their damaged DNA better, allowing them to pass those traits on. Rotifers, microscopic animals that live in freshwater, have been studied in Chernobyl's contaminated ponds.

[00:35:56]According to Frontiers in Microbiology, researchers found that rotifers from the exclusion zone can survive much higher doses of radiation than ones outside it.

[00:36:06]Instead of just dying from DNA damage like you'd expect, these rotifers seem to have upgraded at a cellular level.

[00:36:13]They developed better systems of repairing their DNA and possibly even in ways to protect it from radiation damage in the first place. Rotifers are already known for surviving crazy conditions like being frozen solid or dried out for years, but Chernobyl pushed them even further. These little guys adapted in a way that scientists are still trying to fully understand. And now, some researchers are looking into whether the rotifers' abilities could help humans or other animals deal with radiation better one day. Right after the Chernobyl explosion, researchers started noticing that insects were showing some changes.

[00:36:51]Beetles and grasshoppers with missing parts became pretty common. The worst mutations showed up in areas closest to the reactor, where radiation levels were just off the charts, of course. Insects would hatch with warped or missing body parts that made it almost impossible for them to survive. Wings would come out crumpled. Antenna, which insects need to sense their environment, would be stubs or just completely gone. Some beetles had legs growing in the wrong places or extra limbs. Scientists were able to connect the number and severity of deformities directly to how much radiation the insects were exposed to.

[00:37:29]The first few years after the disaster saw the worst of it, obviously. Over time, the number of severe mutations dropped, mostly because the most damaged insects didn't survive to reproduce. In April of 2023, Australian farmers at a small hobby farm in Queensland noticed one of their hens had not two, not three, but four legs. Two extra limbs dangled awkwardly from her rear. And now, what's really interesting about this case is that the other chickens noticed this, and they did not like it.

[00:38:01]They bullied her. They pecked at the extra legs, pecked so hard that feathers fell out and a wound formed. The chicken had polymelia, a rare birth defect where extra limbs form. Usually, when an embryo starts as a twin and then reabsorbs, but leaves parts behind. And looking at this chicken, you can see that these are full legs. They're not just these little stumps that barely look like legs. They're functional. The local farmer eventually re-homed the four-legged hen to someone willing to [music] take care of her separately.

[00:38:34]Otherwise, the rest of the flock would have tormented her probably to death. In the late '90s, people started finding frogs with freakish mutations all across North America, like legs growing out of their faces or two extra limbs near their chest. One kid in Minnesota came across a five-legged bullfrog in 1996.

[00:38:54]And stories kept rolling [music] in from states like Wisconsin and even into Quebec, Canada. Wasn't a cartoonish anomaly. [music] These deformities were very real. There were misshapen eyes as well, appendages sprouting in weird spots, and sometimes even had mixed reproductive [music] bits. Researchers weren't sure what was going on here, but eventually they landed on this messy cocktail of causes: parasites burrowing into tadpoles, chemicals seeping into ponds, UV lights messing with embryos, [music] and just predators biting off limbs that then regrew in wonky ways. They called it a sign something was going wrong with the environment. Over time, they narrowed it down to four main issues, [music] but no single culprit explains every case. These frogs are still popping up today, just thankfully not in huge numbers, but every once in a while someone pulls a limbless tadpole or a frog with an eye [music] in its shoulder out of a pond. In 2020, a homeowner in Florida was surprised when her daughter brought a tiny snake into the house. The cat had [music] caught it. Small, but still shocked her cuz it had two fully formed heads on its body. Each head moving independently with its own tongue, eyes, even competing for control when they ate. Wildlife officials named [music] him Dos and said it was a southern black racer. This kind of mutation called bicephaly happens when an embryo splits and then stops, [music] basically creating an identical twin that doesn't fully separate. The snake was taken in by Florida Fish and Wildlife experts who said this snake could survive in human care, but that chances in nature would be slim. Snakes like this can't dodge predators as easy, they can't grab food as easy. I mean, they can't even agree with each other.

[00:40:43]One head might go left, the other [music] one to go right. It's just an absolute nightmare. So, while a two-headed snake sounds pretty dangerous, you'd actually have an easier time dealing with two heads [music] than one. Next up is the Dracula fish, a tiny see-through freshwater fish discovered in Myanmar in 2007. [music] It's just 1.7 cm long. The males have these creepy fang-like bones protruding from their jaws. Not scales or teeth, but actual bone structures that jut out in front like vampire fangs. [music] Scientists say billions of years ago its ancestors lost real teeth, but this lineage reversed [music] course and grew bone fangs. Again, evolution in reverse, pretty cool. These fangs are used by males in fights. They jab [music] at each other in territorial squabbles. The fish is translucent, almost larva-like, >> [music] >> and has far fewer bones than normal fish. Most of its body is cartilage, which just makes its fangs stand out even more. Scientists still don't know how or why this exact setup came about.

[00:41:45]Fangs regrowing in a species millions of years after losing them is pretty wild, [music] and since it's only been found in one small stream, it's just kind of a freak show of nature that may never [music] exist anywhere else. After the Chernobyl disaster, a group of wild chevalski's horses, an endangered species, was introduced into the exclusion zone in the late '90s. These horses actually started doing pretty well in the abandoned human-free landscape, but not everything was normal. Researchers noticed that some of the horses were being born with these strange physical defects, like shortened, scruffy manes, and unusually stubby tails. The deformities weren't as extreme as some other animals, but there was still a lot of concern about whether radiation exposure had messed with the horses' development. Normally, Przewalski's horses have thick, upright manes and long tails, which help protect them from insects and the elements, but these Chernobyl ones looked rougher.

[00:42:44]There's still debate about whether the radiation is the direct cause, or if it's more [music] about poor nutrition in the contaminated environment, but either way, the odd physical changes were real. Not everything in Chernobyl shrank or mutated into weird, broken [music] shapes. Some plants actually grew bigger. Certain species of moss, mushrooms, and ferns in the exclusion zone started showing signs of gigantism after the disaster. According to the Journal of Environmental Radioactivity, radiation seems to have messed with the genes that control how these plants grow. Instead of growing normally, some plants ended up with these oversized leaves or [music] unusually thick stems.

[00:43:23]It's believed that the radiation disrupted the normal signals that tell plants [music] when to stop growing, leading to these bizarre, almost monster-like versions. [music] In some parts of the Red Forest, ferns grew much larger than expected, and certain mushrooms popped up freakishly big.

[00:43:40]Scientists think this is because mutations either removed natural growth limits or somehow activated dormant genetic traits. Of course, just because a plant is bigger, though, doesn't mean it's healthier. A lot of these oversized plants had heavy radioactive contamination. Research has shown that birds living in the most radioactive areas around Chernobyl had brains that were about 15% smaller than birds from clean areas. Researchers think that radiation exposure during development damaged cells in their brain, either killing them off or stopping them from forming properly. They found that younger birds had it worse than adults, meaning that radiation was having a serious effect during the earliest stages of life. And those birds with smaller brains, unsurprisingly, had lower survival rates. What you're looking at here is the only known photograph of a creature known as the Blackbird of Chernobyl. In early April of 1986, people living around the Chernobyl nuclear power plant started reporting something strange. Witnesses described seeing this huge, dark creature, like a man but without a head.

[00:44:47]It had massive wings and glowing red eyes. Locals started calling it the Blackbird of Chernobyl. Sightings of this thing kept piling up right up until the morning of April 26th, when reactor four exploded. That disaster unleashed a radioactive cloud that spread across parts of the Soviet [music] Union, Europe, and North America. The area around Chernobyl was just devastated.

[00:45:09]Over 300,000 people had to evacuate.

[00:45:11]Still considered the worst nuclear accident in human history. In the chaos after the explosion though, Soviet helicopters dumped sand, lead, and other materials onto the burning reactor trying to smother the fire.

[00:45:23]Firefighters, not realizing they were dealing with a radioactive inferno, rushed in often without proper protection. [music] A lot of them would die soon after the radiation poisoning, including Lieutenant Vladimir Pravik >> [music] >> who passed away just weeks later. But some of those firefighters who survived long enough to talk, well, they reported seeing this massive, dark, [music] winged creature flying through the radioactive smoke above reactor four.

[00:45:47]After the meltdown, sightings of the Blackbird stopped completely. Some people believed that the Blackbird of Chernobyl was the same kind of entity as the Mothman, the creature seen in Point Pleasant, West Virginia, before the Silver Bridge collapsed in 1967. Both creatures had similar appearances, giant wings, red eyes, and in both cases, there were also reports of nightmares and strange threatening phone calls before disaster struck. Another theory is that people might have actually been seeing a black stork, but the black stork only has a 6-ft wingspan, not 20.

[00:46:22]And that bird doesn't explain the terrifying dreams and phone calls that witnesses talked about. Whatever the blackbird really was though, it hasn't been seen again since Chernobyl. Whether it's a warning, a bad omen, or just mass hysteria, no one really knows. But if it ever shows up again, history says something very bad might not be far behind. In September of 2024, a farm in Kentucky welcomed a calf that looked like some sort of bizarre Frankenstein creation. It had two fully formed heads on one body. Each had its own eyes, snout, and neck, [music] but they shared a single body and internal organs like a heart and lungs. The little calf also had other issues, a cleft [music] palate, twisted spine, underdeveloped rectum, and weird jointed legs. Farmers said the odds of something like this happening are around 1 in 400 [music] million. I'm not sure how they find that number, but apparently that's the case.

[00:47:18]And unfortunately, the calf didn't make it past its first [music] day. Honestly, as bad as this might sound, I think that's a good thing. I mean, not only would it have had a poor quality of life, but you really want to see this [music] thing walking around. Casey Tarter, one of the farmers, is also an agricultural student at Western [music] Kentucky University. She mentioned the two-headed calf in class, saying they decided to use it as a learning opportunity. They took detailed photos, they examined its oddly fused organs, and used the data to teach about developmental issues in mammals. [music] In March of 2018, in Shaoyang, China, a farmer found a calf with six legs. Well, there were two normal legs at the front and then four [music] weirdly dangling limbs from its belly. The calf had trouble moving because of the extra limbs, but other than that, it was doing okay and quickly became a local attraction. People from the area started visiting the farm just to take pictures with the calf. This isn't the first time something like this happened in China.

[00:48:19]Back in 2014, another six-legged cow was [music] born in Shandong. This one had two extra legs growing out of its neck.

[00:48:26]The farmer, Zhang Gongjun, who helped deliver the calf, said, "I've raised the mother for 5 years and seen her through four births, and I've never [music] seen anything like this before." Once his friends shared photos of the cow online, people started showing up. Zhang said, "I get crowds of people here every day and all kinds [music] of camera crews from TV stations." According to a 2002 study, cases like this are very rare.

[00:48:50]Only around four in every 100,000 [music] cattle are born with extra limbs. In August of 2019, an angler named Debbie Geddes pulled a trout out of Lake Champlain, which had two mouths. One where it should be and another just below it. Her photo went viral with people calling it the catch of a lifetime, but scientists don't actually think this was a genetic mutation. They think it could have been caused by an injury that healed oddly, creating what looks like a second mouth. One researcher from Harvard said, "This sort of deformity can happen when soft tissues heal in strange [music] ways, not because of DNA changes." But, that's just one theory. Nobody really knows what the deal was with this fish. Geddes released it back into [music] the water.

[00:49:38]In October of 2021, a rare two-headed turtle, later named Mary-Kate [music] and Ashley, hatched in Cape Cod, Massachusetts. It was a diamondback terrapin that hatched with a rare condition [music] that caused it to have two heads and six legs all sharing one shell. Bird's Eye Cape Wildlife [music] Center posted a photo of it on Facebook along with the caption, "This is a condition called the bicephaly. It's a rare anomaly that can occur [music] from both genetic and environmental factors that influence an embryo during development." [music] Even though animals with this condition usually don't make it very long, the staff felt pretty hopeful. [music] The turtles continued to be, quote, bright and active and were eating, swimming, and gaining weight each day. Mary-Kate and Ashley were discovered [music] in a protected nesting spot. Researchers noticed that while they shared a shell, they each had their own spine [music] and digestive system and seemed to team up to move around. In 2023, during heavy monsoon rains in India, farmers found a 5-ft albino cobra slithering through their home. Unlike some pale snakes, though, this one lacked the dark pigmentation entirely, so it [music] actually kind of glowed pale pink in the rain. Albino cobras are almost unheard of because without pigment, their skin is very sensitive to sun and their vision usually suffers. This [music] snake was venomous, fully grown, yet somehow it managed to avoid predators and humans until it found shelter in this person's home. Wildlife rescue teams safely captured it and the cobra was taken to a wildlife rehabilitation center. Her vet said its survival was slim, but improved with care. But while albino animals pop up here and there, an adult albino venomous snake is shockingly rare, apparently. In 2023, conservationists in Western Australia came across this bright blue frog with white spots, totally different from your average green tree frog. Field researchers at night heard some rustling and wandered over to see it perched near the workshop. The frog lacked the yellow pigment thanks to a genetic mutation, leaving only the blue tone behind. It's so rare that Jodi Rowley, a biologist who studied tens of thousands of these frogs, said she'd never seen anything like it in her entire career. Scientists don't know if this blue frog will survive, find a mate, or have a shot at passing its color on, but regardless, a reminder that while genetics can still surprise us. One group of people can naturally stay underwater far longer than almost anyone else. The Bajau of Southeast Asia live their lives on the ocean and rely heavily on deep diving.

[00:52:23]When researchers studied them, they found a hereditary mutation in a gene that enlarges their spleens by up to 50% Larger spleens store more oxygenated red blood cells, and when they dive, that oxygen is released into their bloodstream, letting them stay underwater for minutes at a time. This mutation appears almost only in this group of people, not in neighboring populations, not in similar coastal groups. A real modern example of human adaptation shaped by isolation and lifestyle.

[00:52:56]During an extreme drought in the Amazon, people started seeing dolphins turning unusually bright pink. Pink river dolphins normally have a soft rosy color, but in Lake Tefé during the 2023 heatwave, researchers documented dolphins with intense full-body pink coloration. The mutation appears linked to heat stress and blood vessel expansion near their skin. Younger dolphins showed the effect the strongest, suggesting a developmental trigger. Some dolphins eventually faded back to normal colors, others stayed bright. It is one of the clearest examples of environmental pressure creating rapid visible changes in an isolated species.

[00:53:41]Most people struggle to at high altitude. Tibetans thrive there because of a mutation almost no one else has, a gene called EPAS1 inherited from ancient human ancestors.

[00:53:55]It prevents blood from thickening at low oxygen levels. This lets Tibetans live at altitudes that would leave most people dizzy or sick. The mutation is incredibly common in the region, but extremely rare outside of it. It is one of the strongest known cases of inherited human adaptation preserved because of the harsh and isolated environment of the Tibetan Plateau. In a remote region of Kazakhstan, generations of families began noticing the same disturbing pattern. Birth defects, growth abnormalities, and unusually high rates of rare cancers. There was a test site that was the Soviet Union's main nuclear testing zone for decades.

[00:54:37]Between 1949 and 1989, more than 400 nuclear tests took place there. Some were underground, but many were atmospheric sending radioactive material drifting straight into surrounding villages. Decades later, researchers discovered something alarming. People in these remote villages showed genetic mutations passed down through multiple generations. Some mutations affected bone development, others altered immune function, some increased susceptibility to diseases not normally seen in the region. And these people here never evacuated. Many did not even know that they were living in fallout. So, the mutations accumulated slowly and spread within families. There's nothing supernatural about it. It is simply the long-lasting biological impact of radiation exposure combined with extreme geographic isolation. Inside Central American mangroves lives a fish that does not need a partner to reproduce.

[00:55:35]The mangrove killifish can self-fertilize, producing offspring that are nearly perfect genetic clones. It evolved this ability because the swamp pools it lives in frequently become isolated or temporarily uninhabitable.

[00:55:50]When a pool dries or becomes cut off, a single killifish can repopulate the area once conditions improve. Very few vertebrates on Earth can do this. It is one of the strangest real reproductive mutations ever documented. A two-headed brown trout was found in a creek in southern Idaho, and it wasn't the only deformed fish in the area. Scientists found more trout with facial deformities, twisted fins, and defective eggs, and it all pointed to one thing, selenium pollution. Selenium is a metal that shows up naturally in the environment, but when it builds up from things like mining or coal burning, it becomes toxic. In this case, the pollution was traced back to operations run by J.R. Simplot, a massive agribusiness company that processes food and chemicals. They funded a study to look into the deformities, and while the report claimed that the selenium levels were safe, others strongly disagreed.

[00:56:45]Joseph Skorupa, a wildlife biologist with the U.S. Fish and Wildlife Service, said the study was biased and quote highly questionable. He pointed out that it completely skipped over the effects on birds and reptiles and seriously downplayed the deformity rates in fish.

[00:57:01]Meanwhile, in Tennessee, politicians started pushing bills to deregulate selenium altogether. See, the coal industry has a stake in this, too.

[00:57:10]What's happening in one Idaho creek is just one part of a much bigger picture.

[00:57:15]There's this fish called the Clear Lake hitch that only lives in Clear Lake, California, and some of them have developed a mutation known as pug-headedness, [music] which you can probably perform a pretty clear image of in your head. They end up with steep, almost boxy foreheads, bulging eyes, and an underdeveloped upper jaw. Basically, the top half of the mouth doesn't grow right, so it ends up shorter than the bottom, making the whole face [music] look warped.

[00:57:41]Scientists think this is thanks to pollution, mainly from pesticides and mercury that have built up in the lake over time. The hitch used to be everywhere in this area. They were a big part of the diet for indigenous tribes like the Pomo, and back in the day you could see massive runs every spring.

[00:57:57]These days, even in a good year, only a few thousand show up to spawn. Some years, barely any. Out in the middle of the Mojave Desert, there's this tiny deep pool called Devil's Hole. It looks like just a weird blue hole in the ground surrounded by dry rocks, but it's actually a deep water-filled crack in the earth, kind of like a natural well.

[00:58:18]And inside this tiny pool lives one of the rarest fish in the world, the Devil's Hole pupfish. These fish are tiny, smaller than your pinky finger, and they've been living here for thousands of years. The water is warm, nearly 90°, and has very little oxygen.

[00:58:33]The fish need that exact setup to survive. It's a very specific environment, but they have adapted perfectly until recently. Right now, there are only about 75 of these fish left, and scientists are worried. Their genes are a mess. Scientists have found what's called genetic load. Basically, these fish are drowning in bad DNA, and there's no way for natural selection to clean it out. This leads to what's called an extinction vortex, where the genetic problems [music] make it even harder to survive. Back in the '70s, conservationists built backup tanks to protect the pupfish in case the wild ones died out. But, at one of these tanks, some pupfish from a nearby but different species snuck in. Their babies mixed with the DNA and grew way faster and healthier, even sprouting extra fins. The hybrids exploded in number, which showed biologist Andy Martin that introducing new genes was probably the solution here. Martin thinks the Devil's Hole Pupfish could be saved if they bring in a few of these cousins from a spring just a few miles away. But some conservationists hate this idea. To them, it's not really saving this specific species of fish >> [music] >> if you're changing their DNA. Nano silver, it sounds like an anime attack.

[00:59:49]But this is a real particle causing mutations in fish. Silver nanoparticles, tiny particles smaller than viruses, are used in over 200 consumer products because they kill bacteria on contact.

[01:00:02]Scientists are now worried these little particles might be messing with the environment and wildlife. When silver nanoparticles wash down drains, they end up in rivers, lakes. Darren Ferguson, a researcher at the University of Utah, tested these particles on zebrafish embryos in the lab and found some pretty scary mutations. Some of them became, quote, extremely distorted, almost [music] making a number nine or a comma instead of a linear fish, he said. The particles caused deformities in eyes, tails, and most disturbingly, their hearts. And here's something pretty scary. Zebrafish actually have organs kind of similar to ours, so this could hint at risks for people, too.

[01:00:42]Scientists still don't know exactly what this means for us or the planet long-term, but the Environmental Protection Agency said the same special properties that make nanoscale materials useful are also properties that may cause some nanoscale materials to pose potential risks.

[01:01:02]Researchers deep in the Bornean rainforest found indigenous families with bright blue eyes and no European ancestry at all. Genetic testing showed the Dayak groups do not have the same blue eye mutation found in Europeans.

[01:01:18]They developed an entirely separate mutation that created the same trait through a completely different genetic path. This rare case of convergent evolution stayed preserved because the communities were extremely isolated for generations. Wolves living inside the Chernobyl exclusion zone are bigger and genetically different from wolves outside the region. Scientists found mutations related to immune response and DNA repair, which helped them tolerate constant low-dose radiation. Wolf populations inside the zone are also estimated to be dramatically higher than outside it.

[01:01:56]The mutations were not engineered. They were developed naturally as the wolves adapted to an environment with no humans and persistent radiation exposure. A small coastal region in Japan saw an outbreak of severe developmental disorders caused by industrial pollution. From the 1930s to the 1960s, [music] mercury-contaminated wastewater was dumped into Minamata Bay. When pregnant ate contaminated fish, the mercury disrupted fetal brain development.

[01:02:25]Babies were born with a syndrome now known as congenital Minamata disease.

[01:02:30]This was a developmental mutation, not a genetic one. It changed how the brain formed in utero, caused entirely by environmental exposure in a geographically isolated [music] community. In one of the most remote mountain regions of Siberia, researchers found sheep with unusually dense [music] skull bones. The isolated snow sheep of the Putorana Plateau showed mutations affecting bone development. Their skulls and horn bases were noticeably thicker than normal, [music] likely an adaptation to harsh cold and heavy predation pressure. Because the herd was cut off from other populations, the mutation strengthened over time instead of being [music] diluted. In one remote region of South America, an entire population developed a mutation that allows them to survive something that should be deadly. [music] In parts of northern Argentina and the Atacama region, local drinking water naturally contains high levels of arsenic, some of the highest on Earth. But instead of widespread poisoning, researchers discovered something unexpected. People in this isolated area carry a rare mutation in the gene AS3MT, which dramatically increases the body's ability to detoxify arsenic. For most humans, arsenic builds up in the body and causes organ damage. For this population, the toxin is processed and expelled far more efficiently. The mutation is thought to have developed over thousands of years of exposure to the contaminated water supply. What makes it truly strange is how localized it is. Populations just a few hundred miles away do not have this protection.

[01:04:06]It is one of the strongest real examples of humans evolving resistance to a natural poison.

[01:04:16]In California's Kesterson Reservoir, a big environmental problem popped up because of selenium pollution. Selenium is a naturally occurring element, but when it builds up too much, it becomes toxic. In Kesterson, the water got contaminated with high selenium levels, mainly from irrigation [music] runoff.

[01:04:34]The fish there, especially embryos, started coming out with serious deformities. Some had messed up eyes or were just missing them completely. There were deformities in their fins, the brain. Scientists call this cluster of problems Kesterson syndrome, and it's not limited to fish because the birds eating them also suffered. Birds [music] have been found with deformed beaks, legs, and wings. In Oneida Lake, New York, walleye fish started appearing with tumors. This comes from exposure to chlorinated wastewater effluent. That's water discharged from treatment plants containing chlorine byproducts. So, these chemicals don't break down easily and can build up in the lake. These tumors are obviously a sign that pollution in the lakes has [music] carcinogenic effects, meaning it can cause cancer. Walleye are especially important, too, cuz they're popular for fishing. So, this is worrying not only scientists, but fishermen and the communities who depend on the lake. Back in the '70s, a coal-fired power plant in North Carolina started dumping wastewater full of selenium into Belleville's Lake. Over time, it completely wrecked the fish population.

[01:05:39]By the early 2000, the number of fish species in the lake dropped from 24 down to just six. Most of the fish couldn't reproduce anymore. One study found that 19 of the original 20 species couldn't produce any surviving offspring. Only smaller fish that ate plankton, like mosquito fish, managed to stick around.

[01:05:57]They weren't affected as badly by the selenium buildup. Eventually, the plant stopped dumping the waste into the lake in 1986. Levels of selenium in the water dropped way down, and they even restocked the lake with sport fish like bass and bluegill, but even 10 years later, the fish were still having trouble reproducing. That's because selenium sinks to the lake bed and slowly leaks back into the food chain, especially if storms stir up the sediment. To make things even worse, some illegally introduced Alabama bass in 2011. They started outcompeting the native bass, especially largemouth. Now, state officials are trying to get rid of them by removing catch limits, but the damage is already being done. In the Great Lakes, especially Lake Ontario and Lake Michigan, scientists have seen lake trout hatching with strange deformities.

[01:06:45]They found fish with weird faces, swollen yolk sacs, which are the little sacs attached [music] to fish embryos that hold the nutrients they need to grow, and they have bloated areas around the heart, symptoms known as blue sac disease. It's caused by exposure to dioxins and toxic [music] chemicals that build up in the water over years from things like industrial waste, pesticides. These toxins settle in the sediment, but work their way up the food chain. Fish at the top, like lake trout, get hit hardest cuz they eat smaller contaminated fish. The damage mostly shows up in the embryos, so it's affecting [music] reproduction more than anything else. Many of the baby fish just don't survive. These deformities were first spotted decades ago, and they're still showing up in areas where dioxin levels are high. Even though regulations have cut down on the amount of dioxins going into the lakes, the old contamination is still there. Now, we've talked about all the bad stuff going on with fish, but what about some interesting adaptations? Well, Atlantic tomcod in the Hudson River developed a mutation that lets them survive in waters full of toxins. For decades, the river was basically a chemical dumping ground. Chemicals that usually kill or will seriously harm fish, but scientists have noticed that tomcod have developed a genetic mutation that changed how they process pollutants. Normally, these chemicals get into a fish's cells and start causing damage, but this mutation messes with the pathway the pollutants [music] usually use. Instead, the fish store the toxins in their fat, basically locking them away where they can't cause a whole lot of harm. This trait didn't show up everywhere, it's specific to tomcod that live in polluted water. The downside, though, is that these fish are now heavily specialized to survive in dirty, polluted water. If the environment changes again, even if it's for the better, they might not adapt fast enough. And they're still concerned about predators eating them and taking in those same toxins [music] up the food chain, including people who eat the fish. Killifish are tiny, colorful fish found along the East Coast, often in places no other fish would want to be, like New Jersey's Newark Bay or Virginia's Elizabeth River, where there's a lot of toxic waste. These areas are loaded with dioxins and heavy metals, but somehow killifish are doing pretty well, all things considered.

[01:09:04]Turns out they've evolved an insane resistance, up to 8,000 times more than normal. Researchers collected hundreds of killifish from different polluted sites and [music] sequenced their genomes. And what they found was that each population had developed similar mutations in the same genes that basically turned off the normal response to these toxins. This kind of resistance is only possible because killifish have super high genetic diversity. For other species that don't have that kind of variation, adapting like this isn't really an option. Again though, they're still food for birds and bigger fish, so there's still a lot of worry as to how all that stored up pollution could affect the rest of the food chain.

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