Why animals extinct for thousands of years reappear alive

HostIt's a strange feeling when you find something you were sure was gone for good. Think about a set of keys you lost years ago or a toy from when you were a kid that was buried in the back of a closet. But it's much bigger when that thing is a whole living creature. We're told some animals died out with the mammoths, and then, out of nowhere, someone finds one walking around in the woods. How does a whole group of animals stay hidden for thousands of years without anyone noticing?

GuestIt happens more often than you might think. We even have a name for it. We call them Lazarus species, named after the man in the old story who came back to life. A great example is a pig-like animal called the Chacoan peccary. For a long time, the only way we knew about it was from old bones that had turned to stone. People who study fossils looked at these bones and said this animal died out over ten thousand years ago, right at the end of the last Ice Age. Then, in the nineteen seventies, some people went on a trip into a very dry, thorny forest in South America and found them. Real, living, breathing animals that looked exactly like those old bones. They had been living in those thickets for thousands of years, and the rest of the world just had no clue.

HostBut these aren't tiny bugs or mice. If it's a big animal like a pig, how do we miss them for that long? I mean, we have satellites and planes flying over everything now.

GuestWell, the view from a satellite is just a green carpet. It doesn't tell you what's moving around under the leaves. Some of these rainforests are what people call the Green Wall. You have mountains that go straight up into the clouds, and they're covered in vines so thick you have to cut your way through every single step. Just last year, people found a type of spiny creature called an echidna in the mountains of New Guinea. It looks a bit like a mix between a bird, a mole, and a hedgehog. Science hadn't seen one since the nineteen sixties. It lived on a single mountain range that's almost impossible to climb. The forest there's so dense that even the people who live nearby rarely go into the highest parts. If you're an animal and you stay in one valley that humans can't reach, you might as well be on another planet.

HostSo it's just a matter of the woods being too thick for us to walk through? It seems like we would've stumbled onto them eventually if we were really looking.

GuestThat's where the second part of the puzzle comes in. A lot of times, these animals aren't actually lost to everyone. When researchers went to find a tiny deer the size of a cat in the forests of Vietnam, they talked to the local people who lived there. The scientists showed them old drawings and asked if they had seen anything like it. The locals looked at the pictures and said, oh yeah, we see those all the time. They had their own names for them. They were in their stories. The animal wasn't gone; it was just a secret that hadn't been shared with the outside world yet. We often think if it isn't written down in a science book, it doesn't exist. But the people who live in these remote places are the real experts. They know what's moving in the shadows.

HostIt sounds like we have been a bit narrow-minded about where we look and who we ask. But even with local help, some of these creatures are really good at staying out of sight. Are they purposefully hiding from us?

GuestI don't think they're hiding on purpose, they're just very shy and the forest is very big. But we have much better ways to find them now. We use camera traps, which are small boxes we strap to trees. They sit there for months, totally quiet, and only take a picture when something moves. They don't get tired and they don't make noise like a person would. And we have this amazing new tool where we just take a cup of water from a stream or a scoop of mud. We can find tiny bits of skin or hair that an animal left behind. We check for their genetic code, or DNA, which is like a tiny instruction manual inside every living thing. We can see their signature in the water without ever actually seeing the animal itself. It's like finding a fingerprint at a crime scene.

HostSo we're basically acting like detectives, looking for those tiny clues in the dirt. Does this mean there are probably more "ghost" animals out there right now that we just haven't caught yet?

GuestThere's a very high chance of that. Every time we go into a new corner of a rainforest or use these new ways of checking the water, we find something we thought was gone. It shows us that nature is a lot tougher than we give it credit for. These animals found a way to survive through thousands of years of changes by staying in the spots we couldn't reach. Even right now, there's likely a creature we only know from dusty fossils walking through a forest somewhere, completely unaware that we think it's a ghost.

HostThe woods are much deeper than our maps make them look, and sometimes those things we think are gone are just waiting in the back of a drawer we haven't opened in a long time.