Will the woolly mammoth return?

Scientists are using genetic engineering and cloning to try to bring back extinct species or save endangered ones. Here’s how and why.

Will the woolly mammoth return?

Eriona Hysolli slapped at mosquitoes as she helped feed a baby moose. Not far away, shaggy Yakutian horses grazed on tall grass. It was August 2018. And Hysolli was a long way from Boston, Mass., where she worked as a genetics researcher at Harvard Medical School. She and George Church, the director of her lab, had traveled to northeastern Russia. They’d come to a nature preserve in the vast, remote region known as Siberia.

These Yakutian horses live in Pleistocene Park, a Siberian nature preserve that recreates the grassland landscape of the last ice age. The park is also home to reindeer, yaks, moose, cold-adapted sheep and goats, and many other animals. Pleistocene Park

If Hysolli let her mind wander, she could imagine a much larger animal lumbering into view — one larger than a horse, larger than a moose. This elephant-sized creature had shaggy reddish-brown fur and long, curving tusks. It was a woolly mammoth.

During the last ice age, a period known as the Pleistocene (PLYS-toh-seen), woolly mammoths and many other large plant-eating animals roamed this land. Now, of course, mammoths are extinct. But they might not stay extinct.

“We believe we can attempt to bring them back,” says Hysolli.

In 2015, Church and the organization Revive & Restore launched a Woolly Mammoth Revival project. It aims to use genetic engineering to create an animal very similar to the extinct woolly mammoth. “We call them elemoths, or cold-adapted elephants,” explains Hysolli. Others have called them mammophants or neo-elephants.

Whatever the name, bringing back some version of a woolly mammoth sounds like its coming straight out of Jurassic Park. The nature preserve Hysolli and Church visited even has a fitting name: Pleistocene Park. If they succeed in creating elemoths, the animals could live here. Explained Church in a 2019 interview with PBS, “The hope is that we will have large herds of them — if that’s what society wants.”

De-extinction engineering

Genetic engineering technology may make it possible to resurrect the traits and behaviors of an extinct animal — as long as it has a living relative. Experts call this de-extinction.

George Church poses with a woolly mammoth in a hotel lobby
On a recent trip to Siberia, George Church posed with this woolly mammoth that stood in the lobby of a hotel. He and Eriona Hysolli also found ancient mammoth remains along a river bank near Pleistocene Park.Eriona Hysolli

Ben Novak has been thinking about de-extinction since he was 14 and in eighth grade. That was when he won first place in the regional division of the Junior High North Dakota State Science and Engineering Fair. His project explored the idea of whether it would be possible to recreate the dodo bird.

This flightless bird was related to the pigeon. It went extinct in the late 1600s, about a century after Dutch sailors arrived on the only island where the bird lived. Now, Novak works at Revive & Restore, based in Sausalito, Calif. The basic goal of this conservation organization, he says, is to look at a habitat and ask: “Is there something missing here? Can we put it back?”

The woolly mammoth isn’t the only animal Novak and his team hope to restore. They are working to bring back passenger pigeons and heath hens. And they support efforts to use genetic engineering or cloning to rescue endangered species, including a type of wild horse, horseshoe crabs, coral and black-footed ferrets .

Cloning boosts endangered black-footed ferrets

Dinosaurs aren’t on their list. “Making dinosaurs is something we can’t really do,” says Novak. Sorry, T. rex. But what genetic engineering can achieve for conservation is astonishing and eye-opening. Many scientists, though, question whether bringing back extinct species is something that should be done at all. Thankfully, we have time to decide whether this is right. The science of bringing back something like a mammoth is still in its very early stages.   

Recipe for revival

Mammoths once roamed throughout most of Europe, Northern Asia and North America. Most of the mighty beasts died out around 10,000 years ago, likely due to a warming climate and human hunting. A small population survived until about 4,000 years ago on an island off the coast of Siberia. Across most of the mammoth’s former range, remains of the animals decomposed and disappeared.

In Siberia, though, cold temperatures froze and preserved many mammoth bodies. Cells inside these remains are completely dead. Scientists (so far) can’t revive and grow them. But they can read any DNA in those cells. This is called DNA sequencing. Scientists have sequenced the DNA of several woolly mammoths. (Scientists can’t do this with dinosaurs.; they died out too long ago for any DNA to have survived.)

Eriona Hysolli collects tissue samples from mammoth remains
While in Siberia, Eriona Hysolli collected tissue samples from mammoth remains held in local museums. Here, she is taking a sample from a frozen mammoth’s trunk. Brendan Hall/Structure Films LLC

DNA is a lot like a recipe for a living thing. It contains coded instructions that tell cells how to grow and behave. “Once you know the code, you can try to recreate it in a living relative,” says Novak.

To try to recreate a mammoth, Church’s team turned to its closest living relative — the Asian elephant. The researchers started by comparing mammoth and elephant DNA. They looked for the genes most likely to match specific mammoth traits. They were especially interested in traits that helped mammoths survive in frigid weather. Those include shaggy hair, small ears, a layer of fat under the skin and blood that resists freezing.

Explainer: What is a gene bank?

The team then used DNA-editing tools to create copies of the mammoth genes. They spliced those genes into the DNA of cells collected from living Asian elephants. Now, the researchers are testing these elephant cells to see if the edits work as planned. They have gone through this process with 50 different target genes, says Hysolli. But the work hasn’t yet been published.

One problem, Hysolli explains, is that they only have access to a few types of elephant cell. They don’t have blood cells, for example, so it’s tough to check if the edit that is supposed to make blood resist freezing actually works.

an Asian elephant walking
The Asian elephant is the woolly mammoth’s closest living relative. Scientists hope to create an “elemoth” by editing the elephant’s DNA.Travel_Motion/E+/Getty Images

Cells with mammoth genes are exciting. But how do you make an entire living, breathing, trumpeting mammoth (or elemoth)? You’d need to make an embryo with the right genes, then find a living mother animal to carry the embryo in her womb. Because Asian elephants are endangered, researchers aren’t willing to put them through experimentation and possible harm in an attempt to make baby elemoths.

Instead, Church’s team hopes to develop an artificial womb. Right now, they are doing experiments with mice. Scaling up to elemoths is expected to take at least another decade.

A park for mammoths — and slowing climate impacts

Back at Pleistocene Park, the Zimov family hopes that Church’s team will succeed. But they are too busy to worry about it much. They have goats to check on, fences to mend and grasses to plant.

Sergey Zimov started this park outside of Chersky, Russia in the 1990s. He had a wild and creative idea — to restore an ancient ecosystem. Today, mosquitoes, trees, mosses, lichens and snow dominate this Siberian landscape. During the Pleistocene, however, this was a vast grassland. Woolly mammoths were just one of the many large animals that roamed here. Animals fed the grass with their droppings. They also broke apart trees and shrubs, making more room for grass.

A horse stands among grass in Siberia
Nikita Zimov says people always ask him how many animals he has at the park. That’s the wrong question, he says. The most important thing to ask is “how dense are your grasses?” He says they aren’t dense enough yet.Pleistocene Park

Nikita Zimov remembers watching his father release Yakutian horses into the park when he was just a little boy. Now, Nikita helps run the park. Around 150 animals live here, including horses, moose, reindeer, bison and yaks. In 2021, Nikita introduced small herds of Bactrian camels and cold-adapted goats to the park.

The park might be a nice tourist attraction, especially if it ever has woolly mammoths or elemoths. But showing off animals is not the Zimovs’ main goal. They are trying to save the world.

Beneath the Arctic soil, a layer of ground stays frozen all year long. This is permafrost. Lots of plant matter is trapped inside it. As Earth’s climate warms, the permafrost can melt. Then what’s trapped inside will rot, releasing greenhouse gases into the air. “It will make climate change quite severe,” says Nikita Zimov.

A grassland habitat filled with large animals, though, could change the fate of that permafrost. In most of Siberia today, thick snow covers the ground in winter. That blanket stops cold winter air from reaching deep underground. After the snow melts, the blanket is gone. High summer heat bakes the ground. So the permafrost warms a lot during hot summers, but it doesn’t cool very much during cold winters.

Large animals trample and dig through snow to munch on grass trapped underneath. They destroy the blanket. This allows frigid winter air to reach the ground, keeping the permafrost beneath chilly. (As a bonus, during summer thick grass also traps a lot of carbon dioxide, a greenhouse gas, from the air.)

Nikita Zimov holds two baby goats
Nikita Zimov holds two baby goats born during a journey in May 2021 to deliver new animals to Pleistocene Park. The goats were especially rambunctious during the trip, he says. “Each time we fed them, they were jumping on each other’s heads and bumping with their horns.”Pleistocene Park

Sergey, Nikita and a team of researchers tested this idea. They took measurements of snow depth and soil temperatures inside and outside of Pleistocene Park. In winter, snow inside the park was half as deep as it was outside. The soil was also colder by about 2 degrees Celsius (3.5 degrees Fahrenheit).

The researchers predict that filling the Arctic with large animals will help keep around 80 percent of the permafrost frozen, at least until the year 2100. Only 43 percent would remain frozen if the Arctic’s ecosystem doesn’t change, their research predicts. (These types of predictions can vary quite a lot based on how researchers assume climate change will progress). Their findings appeared last year in Scientific Reports.

At just 20 square kilometers (around 7 square miles), Pleistocene Park has a long way to go. To make a difference, millions of animals must roam over millions of square kilometers. It’s a lofty goal. But the Zimov family believes in it whole-heartedly. They don’t need elemoths to make the idea work. But these animals would speed the process, says Nikita. He likens replacing forest with grassland to a war. Horses and reindeer make great soldiers in this war. But mammoths, he says, are like tanks. “You can conquer much bigger territory with tanks.”

Considering the consequences

Hysolli wants elemoths in Pleistocene Park not just for the climate but also as a way to improve Earth’s biodiversity. “I am an environmentalist and an animal lover at the same time,” she says. Humans aren’t using most of the space in the Arctic. In many ways, it’s a perfect place for elemoths and other cold-adapted animals to live and thrive.    

Novak also pursues de-extinction because he believes it will make the world a better place. “We live in a very impoverished world compared to what it used to be,” he says. He means that Earth is home to fewer species today than in the past. Habitat destruction, climate change and other human-caused problems threaten or endanger numerous species. Many have already gone extinct.

an illustration of a passenger pigeon
This sketch is of the extinct passenger pigeon is from A History of British Birds by Francis Orpen Morris. This was once the most common bird in North America. Some scientists are now working to bring this bird back.duncan1890/DigitalVision Vectors/Getty Images

One of those creatures is the passenger pigeon. This is the species Novak most desires to see restored. In the late 19th century in North America, these birds gathered in flocks of as many as 2 billion birds. “A person could see a flock of birds that blotted out the sun,” says Novak. But humans hunted passenger pigeons to extinction. The last, named Martha, died in captivity in 1914. Hunting likely also contributed to the downfall of the mammoth. Stewart Brand, co-founder of Revive & Restore, has argued that since humans destroyed these species, we may now have a responsibility to try to bring them back. 

Not everyone agrees. Restoring any species —  mammoth, bird or something else — would take a lot of time, effort and money. And there are already many existing species that need help if they are to be saved from extinction. Many conservation scientists argue that we should help these species first, before turning our attention to ones that are long gone.

Effort and money aren’t the only problems. Experts also wonder how the first generation of new animals will be raised. Woolly mammoths were very social. They learned a lot from their parents. If the first elemoth lacks a family, “have you created a poor creature who is lonely and has no role models?” wonders Lynn Rothschild. She is a molecular biologist affiliated with Brown University. That’s in Providence, R.I. Rothschild has debated the question of de-extinction. She thinks the idea is incredibly cool but hopes that people will think it through carefully.

As the Jurassic Park movies warn, humans may not be able to control the living things they introduce nor predict their behavior. They could end up harming existing ecosystems or species. There’s also no guarantee these animals will be able to thrive in the world that exists today.

“I worry about introducing a species that went extinct. We’re bringing them back into a world they’ve never seen,” says Samantha Wisely. She is a genetics expert who studies conservation at the University of Florida in Gainesville. If mammoths or passenger pigeons were to end up going extinct a second time, that would be doubly tragic.

De-extinction should only be done with “a lot of thought and protection of the animals and ecosystems,” adds Molly Hardesty-Moore. She is an ecologist at the University of California, Santa Barbara. In her opinion, we should only seek to restore species that we know will thrive and help to heal existing ecosystems.

What do you think? Genetic engineering has given humans incredible power to transform life on Earth. How can we use this technology to make Earth a better place for us as well as for the animals who share this planet?

Kathryn Hulick, a regular contributor to Science News for Students since 2013, has covered everything from acne and video games to ghosts and robotics. This, her 60th piece, was inspired by her new book: Welcome to the Future: Robot Friends, Fusion Energy, Pet Dinosaurs, and More. (Quarto, October 26, 2021, 128 pages).

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Cloning boosts endangered black-footed ferrets

A cloned ferret named Elizabeth Ann brings genetic diversity to a species that nearly went extinct in the 1980s.

Cloning boosts endangered black-footed ferrets

On December 10, 2020, a new baby black-footed ferret came into the world. Her species is one of the most endangered in North America. Named Elizabeth Ann, she quickly grew up into a chattering, tumbling, nipping ball of energy. This little girl doesn’t know it, but she could be key to saving her species.

Kimberly Fraser is an education specialist at the National Black-footed Ferret Conservation Center in Wellington, Colo. And she knows Elizabeth Ann well. “She loves getting in tubes and boxes and paper bags. I would say she’s very happy,” Fraser says.

Elizabeth Ann is a clone who brings much-needed genetic diversity to her endangered species. In the coming years, her handlers hope that she will have babies of her own and will spread her special genes through the black-footed ferret population. USFWS National Black-footed Ferret Conservation Center

What makes this little ferret special is that she is a clone. She’s a genetic copy of an animal that died decades ago.

More than five million black-footed ferrets once lived on the great plains of North America. They were cunning hunters that preyed almost entirely on prairie dogs. When European settlers moved to the area and built farms, they destroyed these animals’ habitats. They also poisoned and killed prairie dogs, leaving many black-footed ferrets without food. A plague also spread through the populations of both species. In 1979, experts declared the black-footed ferret extinct.

But then, in 1981, there was “an electrifying announcement,” recalls Oliver Ryder. A farmer in Wyoming had discovered a small community of wild black-footed ferrets! Ryder, now a genetics expert at San Diego Zoo Wildlife Alliance in California, was elated. Conservationists captured the wild ferrets and began a captive-breeding program. They hoped to save the species.

Ryder had the foresight to ask for cell samples from several of the animals that were captured. “It will be useful for reasons we don’t know,” he recalls saying. For each animal, he received a little glass vial containing a tiny piece of skin. The cells from this skin were preserved in a way that makes it possible to revive and grow them.

Back then, he couldn’t have imagined how very useful these preserved cells would turn out to be.

Rebuilding a population

The captive-breeding program was challenging. The plague still threatened prairie dogs and ferrets. Over time, though, scientists have been able to reintroduce wild ferrets to parts of Wyoming, Montana, South Dakota, Arizona, Mexico and elsewhere. Scientists also developed a vaccine for the plague. The wild population now numbers around 350, with around 300 more still living in captivity.

A cloned ferret named Elizabeth Ann is bringing genetic diversity to a species that nearly went extinct.

However, only seven of that original captured ferret population had pups that survived to have babies of their own. That meant every black-footed ferret in the world was closely related. They all had very similar genes. With each generation, offspring were more likely to have genetic problems. They needed genetic diversity to survive, says Samantha Wisely. She is a genetics expert who studies conservation at the University of Florida in Gainesville.

Enter Elizabeth Ann. She is a clone of Willa, one of the ferrets whose cells Ryder preserved back in 1986. Until 2020, Willa had no living descendants. So her genes were quite different from the rest of the species. Elizabeth Ann’s birth was “a leap of hope” for the species, says Fraser. Wisely was also excited. “I was over the moon,” she says.

a diagram shows the process for cloning Elizabeth Ann the black-footed ferret
Elizabeth Ann’s genetic information was copied from one black-footed ferret. Here is how the cloning process worked. A domestic ferret acted as a surrogate mother for Elizabeth Ann.Journal of Heredity

In the cloning process, scientists removed the entire nucleus, or middle, from Willa’s cells. This nucleus contains genes that are akin to a recipe for creating an animal identical to Willa. Researchers also took egg cells from a domestic ferret and removed their nuclei. Then they transferred Willa’s nuclei into these egg cells. The egg cells began to divide, becoming embryos. The researchers then put the embryos into another domestic ferret. This ferret carried the babies until they were born.

The only embryo to survive the entire process was Elizabeth Ann. Her birth showed that it is possible for DNA from a creature that died many years earlier to live again — and potentially boost an entire species.

Meanwhile, Ryder continues to collect cells from as many animal species as possible. He thinks this work is important because, “We love the world we live in and we want to protect it.”

The collection he works on is called the Frozen Zoo. It has samples from more than 1,100 different animal species so far. Almost all are mammals, birds, reptiles and amphibians. But at least 13,000 of these types of animals are threatened or endangered with extinction. He hopes that researchers will donate cells from as many of these species as possible. And then maybe someday, someone will use those cells to save another species.

Genetics researcher Oliver Ryder holds up a test tube sample of animal cells
Genetics researcher Oliver Ryder holds a sample of animal cells that were donated to the Frozen Zoo in San Diego, Calif. Cells like these can allow genetic engineers to rescue an endangered species. Someday, they may even resurrect extinct ones. San Diego Zoo Wildlife Alliance
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