Malyi Lyakhovski is a tiny, remote island lodged in chilly Siberian waters. Snow-covered and ice-locked most of the year, no one lives there. Any visitors that do set foot on its sparse, treeless tundra must come well prepared; wrapped up warmly and with rifles. In winter, temperatures drop to 30 below, and there are hungry polar bears. But come they do. Every summer, when the feeble sun clings to the horizon, a unique band of hunters make their way from the Siberian mainland to the little island, but they’re not looking to make a kill. They come to scavenge the remains of animals long dead; the bodies of giant beasts that perished tens of thousands of years ago. For entombed in the permafrost are the frozen remains of the ultimate Ice Age giant, the woolly mammoth (Mammuthus primigenius).
When explorers first stumbled across Malyi Lyakhovski in the eighteenth century, they thought the island was literally made of bones and tusks. What can be said with certainty is that the archipelago and the Siberian mainland it belongs to are one massive mammoth graveyard, littered with the remains of these fallen behemoths. As our climate changes and the planet warms, the frozen north is thawing faster than ever, and mammoths, or parts of them, are being discovered with increasing frequency. Their appearance is luring keen-eyed chancers, some of whom are prepared to risk their lives in pursuit of their quarry. Mammoth-hunters have been known to scuba-dive in freezing Arctic waters, prod around inside unstable ice caves and use pressurised water jets to blast bones from crumbling cliffs. Such are the rewards that the ends, apparently, justify the means. A huge, spiralling mammoth tusk can earn its finder tens of thousands of dollars, and there are millions of bones to be found. It’s a modern-day gold rush, not in precious metal but in body parts. In a region turned ghost town after the fall of communism and the closure of Soviet-era mines and factories, mammoths provide an economic lifeline to intrepid, cash-strapped locals, and a new word has entered parlance: ‘mammontit’ – ‘to mammoth’, or to go bone hunting. But as the easy-to-reach mainland areas are picked clean, foragers are having to venture to ever more remote locations – like Malyi Lyakhovski.
It was on one such expedition in August 2012 that tusk collectors chanced upon the find of a lifetime. Standing on a wind-battered hill not far from the island’s north-east coast, they happened to look down and glimpse contours of bone peeping through the tundra. Framed against a backdrop of scraggy grasses and moss were a few fragments of skull and a shard of tusk. They stooped to take a closer look, feeling the finds gently with their gloved hands … then noticed something unmistakeable. Lying across the tusk, camouflaged against the dirty ground, was a tousled, brown trunk. Unmistakably mammoth, the curved, tentacle-like structure was covered in a matt of fur and had at its tip the tactile ‘fingers’ once used by the animal to help it feed. To find bones and tusks is not uncommon, but to find flesh and tissue is very rare. Recently exposed, the melting, semi-frozen structure had yet to decay or attract the attention of scavengers. For the hunters, it was pure gold. If the trunk had somehow managed to survive, perhaps, they reasoned, other body parts could also be found in the frozen ground. So they set to, hacking at the earth with their picks and their spades, only to find they were standing on the grave of what seemed to be an almost complete animal. What lay on the surface was just the tip of one enormous frozen mammoth Popsicle.
The weather, however, was against them. The winter winds were closing in fast. Exhuming a mammoth would take time and there was no way the hunters could excavate the body before blizzards forced them to flee the island. So they returned to the mainland empty-handed, where they pondered their next move. They could keep quiet, retrieve the corpse the following spring, then make a fortune by selling it privately. Or they could alert the local scientists at the North-Eastern Federal University (NEFU) in Yakutsk, Siberia, who were offering a more modest reward to anyone that could lead them to the remains of a well-preserved mammoth. It meant the difference between the Malyi Lyakhovski mammoth ending up in private hands or being made public through the research of the scientists and the publication of their finds. Fortunately for us, the tusk-hunters chose the latter. They alerted a man called Semyon Grigoriev, head of the university’s Mammoth Museum, who was more than a little excited. In his time, Grigoriev has handled the remains of many mammoths, but with its fleshy trunk, this one promised something really special – an unprecedented level of insight into the mammoth’s biology and life story and, more controversially, the chance to bring the animal back from the dead.
Frustratingly, Grigoriev and his team had to wait an excruciating nine months for the Arctic winter to subside before they could travel to Malyi Lyakhovski. In April 2013, they made the bumpy schlep, hundreds of miles across the snowy wastelands of northern Siberia and the frozen Laptev Sea to the remote island where the mammoth still lay. GPS coordinates lured them to the exact spot where the tusk-hunters had stood less than a year ago. They too began to chip away at the frozen ground, excavating a trench, 1.8m (6ft) deep around the frozen carcass. With the body revealed in its entirety they were able to stand back and realise the scale of their find. The mammoth was … mammoth. Looking down on it from above, they could see that the top half of the body had been gnawed at, so that it looked like a huge lump of gnarled meat. But from inside the trench, the rest of the body looked remarkably intact. Three legs, its torso, most of its head and trunk were still there. But instead of being desiccated and dry like most other mammoth bodies found before, in parts this one had flesh on its bones, skin on its flesh and fur on its skin.
But there was one more surprise in store. When the scientists prodded the creature’s belly with a pick, a dark brown liquid came oozing out. It looked like blood, but how could a mammoth, frozen in the ground for tens of thousands of years, still have blood that flowed?
A Woolly Legend
Woolly mammoths are the undisputed Kings of the Ice Age, the geological era also known as the Pleistocene. They evolved in the midst of this interminable cold spell several hundred thousand years ago, at a time when immense ice sheets covered swathes of the northern hemisphere, locking in so much water that they created cloudless blue skies. Underneath that sky lay open, fertile grassland that covered much of northern Eurasia and North America: the mammoth steppe, home to Mammuthus primigenius. Perfectly adapted to life in the freezer, with their enviably thick, lush locks, vast herds1 of mammoth grazed away to their hearts’ content.
Then, little by little, towards the end of the Pleistocene their numbers started to diminish. No one really understands why. Some blame human hunting, some climate change, others a bit of both. Whatever the reason, they disappeared from Siberia around 10,000 years ago, and from their final hiding place, a northerly island called Wrangel, as recently as 3,700 years ago – it is incredible to think that woolly mammoths were still alive at the time that Ancient Egyptians were setting up home in the Nile valley and dreaming of pyramids.
Gone, but not forgotten. Immortalised in cave paintings by the early humans they lived alongside, reconstructed by us from the bones and body parts they left behind, we understand more about these shaggy beasts than any other extinct prehistoric animal. If we were to choose just one animal to bring back, it had better be one we know a lot about.
Mammoths are everything that you’d want in a de-extincted animal. Vegetarian – so they won’t eat you. Iconic. Inspiring. Larger than life. Their enormous, curvy tusks could grow to over four metres (13ft) long. A thighbone could be more than a metre (3.3ft) long, and a single tooth the size of a sliced loaf. Their sheer scale almost defies imagination, so much so that we’ve been concocting stories to explain them for millennia. In the past, some thought their bones belonged to a lost race of giants, others that they were a rare breed of underground rodent, which died when exposed to the sun. Western scholars once thought the biblical flood of Genesis had swept mammoth bones to Siberia, while others believed the remains belonged to elephants that had strayed from the herds of Alexander the Great. With a central hole in its skull where the trunk would have attached, some think mammoth fossils inspired the legend of the one-eyed Cyclops. Even today, people are wary. Some locals refuse to disturb newly found mammoth remains for fear their actions will bring bad luck, like a mummy’s curse. We may think ourselves a little more mammoth-savvy these days, but there’s something about this animal that gets our imaginations running on overtime. Mammoths may be long gone, but we still incorporate them into our culture – think Manny from Ice Age, Mr Snuffleupagus from Sesame Street – and such is their stature in popular culture that their very name has become synonymous with enormity, vastness and greatness. We’ve all heard of them, we’ve all seen pictures of them. Who wouldn’t be intrigued to see one in the flesh? Bringing back a butterfly, a frog or some other smaller creature might be nice, but it would be easily overlooked, literally. A resurrected mammoth, on the other hand, would be a showstopper.
There may even be several fairly staggering economic and ecological reasons to rush forward their revival. In their day, woolly mammoths were the Alan Titchmarsh2 of the Arctic. They trundled around eating grass, trampling saplings and fertilising the ground via their nutrient-rich dung. But when they disappeared, things changed. Jacquelyn Gill from the University of Maine has analysed pollen, charcoal and spores from North American sediment cores to reveal that, over the next few thousand years, the landscape altered dramatically. Without mammoths to knock them down, temperate deciduous trees such as elm and ash sprung up next to cold-loving conifers like larch and spruce. And without mammoths to ‘mow the grass’, plant litter began to build up. Every couple of centuries, fire ripped through the forests; in time the lush grasslands of the ‘mammoth steppe’ were transformed into unproductive mossy tundra. Cue tumbleweed blowing across the page.
Today, the remains of that rich, fertile Ice Age ecosystem are locked up inside the Arctic’s frozen soil. The permafrost is thought to harbour an estimated 500 gigatonnes of sequestered organic carbon; that’s two to three times as much as occurs in all the existing rainforests combined. It’s a carbon time bomb. As our world warms, the frozen north is thawing and little by little that carbon is being released into the atmosphere as gas. It’s warming the world and computer models suggest that ice-free Arctic summers could be with us as soon as 2052, if not before.
But mammoths, some think, could help keep the Arctic cold. ‘When big animals graze, they trample the snow, which exposes the surface of the soil to cold air’, says biologist Sergey Zimov from Siberia’s Northeast Science Station. ‘This helps keep the ground frozen.’ Zimov has shown that in Siberia, soil temperatures in areas where big animals graze are, on average, several degrees colder than where grazers are absent. Recreate the mammoth steppe, with its characteristic flora and fauna, and the grazers could help keep the carbon time-bomb from blowing.
Zimov, a rollie-smoking, pony-tailed Grizzly Adams of a man with a ZZ Top-style beard, already has the project in hand, and if it all sounds a little Jurassic Park, then please allow me to elaborate … For the last 20 years, Zimov has been trying to recreate the mammoth’s original ecosystem in the shape of a nature reserve he calls Pleistocene Park. It’s situated in one of the coldest places on earth – in the Sakha Republic, northeastern Siberia, eight time-zones east of Moscow and a 4.5-hour flight away from the nearest city, Yakutsk. Zimov is filling his park not with dinosaurs, but with big imported herbivores including Yakutian horses, reindeer and moose, and with local carnivores, including wolverines and bears. These are the kinds of animals that lived there when mammoths were around. Within one season of being helicoptered in, Zimov found that his stocky Yakutian horses had turned one area of meagre, moss-filled wilderness into a lush, steppe-like grassland – promising results hinting that, with the right mix of animals, the mammoth steppe could indeed be recreated. But there is, of course, one missing ingredient. Mammoths! ‘My responsibility,’ Zimov told me, ‘is to prepare the ecosystem. I will prepare the environment for the mammoths.’ If and when the mammoths are brought back, they will have a home already waiting for them in the shape of Pleistocene Park.
Young Dreams
The first scientist to try to de-extinct the woolly mammoth was cell biologist Viktor Mikhelson from Leningrad’s Institute of Cytology, back in the 1980s. He was inspired by the discovery of a mammoth calf called Dima, found lying on its side with its trunk curled up near a tributary of the Kolyma River in northeastern Siberia. Desiccated and wrinkled, Dima was covered in straw-coloured ‘baby’ fur with tufts of darker adult hair just starting to peek through. The calf was so lifelike it almost cried out for resurrection, prompting Mikhelson to wonder if its cells could be salvaged for cloning.
It was a bold idea. At this point in time, no one had ever cloned a mammal before, much less a dead one, much less one from the last Ice Age. Mikhelson planned to take the DNA-containing nucleus from one of Dima’s cells and inject it into an elephant egg that had had its own nucleus removed. If the reconfigured egg started to develop he would then transfer the resulting embryo into the womb of a surrogate elephant mum who, if all went well, would then give birth to a cloned mammoth – Dima’s living, identical twin.
Mikhelson tried for months but never made it to first base. The thawing corpse had been left in the open for several days after it was unearthed, so had started to rot. Then, after the body was transported to Leningrad, taxidermists botched what was left of it. The carcass that nature had preserved so perfectly for thousands of years was now black, bald and full of chemicals. Mikhelson never stood a chance. If scientists were to resurrect the mammoth they’d have to find a better specimen to clone from.
It would be more than 10 years before anyone tried to resurrect the woolly mammoth again. This time it was the turn of the Japanese. At Kagoshima University, reproductive biologist Kazufumi Goto was working with wagyu, an expensive type of cattle highly prized for its marbled meat. Goto had been collecting semen from bulls then using the samples to make test-tube cattle. The idea was that, through in vitro fertilisation (IVF), a single shot from a high profile sire could be used to produce thousands of equally desirable offspring. But Goto realised the same method also worked with sperm that were dead. So, he mused, if a dead sperm from a bull could be used to create new life, why not dead sperm from a frozen mammoth?
His plan was to go to Siberia, find a mammoth, then use its sperm to fertilise an elephant egg. Unlike Mikhelson’s clone, which would be virtually pure mammoth, this animal would be half mammoth, half elephant – a hybrid, or ‘mammophant’, if you like.3 If the animal survived and was able to reproduce normally, Goto planned to breed it back with another mammophant to bump up the quota of mammoth DNA in the offspring. The process could then be repeated until an almost genetically pure mammoth had been created a couple of generations later.
The odds, however, were stacked against him. First, Goto would have to find his mammoth. For obvious reasons, the animal would need to be male, which by the law of averages ruled out 50 per cent of the frozen finds. It would also need to be an adult. Like elephants, mammoths would have become sexually mature at around 10 to 15 years of age, so finding juvenile mammoths would do little to help the cause.
Second, the adult male would have to be exceptionally well preserved. For the dead or dying beast, that would have meant being frozen quickly then covered up. Freezing something quickly means that tissue-munching bacteria have less time to get to work and the carcass is less likely to rot. Covering it up means scavengers can’t eat the body and DNA-damaging cosmic rays are less likely to ravage the cell nuclei. To achieve this, the mammoth would have to have met a fairly gruesome death, such as getting stuck in a bog then covered in snow (like Dima), or falling through the ice and drowning in a frozen lake.
But even if that happened, there was no guarantee that viable sperm could be recovered. Where humans, dogs and many other animals dangle their family jewels gratuitously outside their bodies, mammoths, like modern-day elephants, wore them discreetly, on the inside. Located deep inside their bodies their melon-sized testicles would have pumped out sperm that then matured nearby in a coiled duct system. It would have been about the last part of their dead body to freeze. Indeed, it’s been estimated that even on the coldest of nights, a six-tonne adult mammoth would still have taken several hours to freeze solid, giving bacteria ample time to get to work on its gonads. The chances of mammoth sperm being frozen quickly enough to avoid damage were as small as the sperm themselves. And that, for the record, is very, very small indeed. Assuming their reproductive biology to be similar to that of modern-day elephants, Goto and his team were looking for cells just one-tenth of a millimetre long. Looking for mammoth sperm would be like looking for the proverbial needle in a nutsack.
Even if Goto struck lucky and found viable mammoth sperm, there was no knowing for sure if the recovered cells would be able to fertilise the eggs of another species, even a closely related one. For egg and sperm to marry successfully, the strands of genetic material or chromosomes from one must align perfectly with those from the other – a feat that is possible if the two species contain an equal number of chromosomes, and problematic if they don’t. So lions and tigresses, with 38 chromosomes each, can yield fertile ‘liger’ offspring. But horses and donkeys, with 64 and 62 chromosomes respectively, tend to produce infertile mules and hinnies. Even when two closely related but different species have the same number of chromosomes, things can be tricky. African and Asian elephants, for example, have the same number of chromosomes, but there has only ever been one hybrid between the two, a male calf called Motty, born the year after Elvis died, in 1978.
For his first trip, in the summer of 1997, Goto invited along a colleague, reproductive biologist Akira Iritani, from the Department of Genetic Engineering at Kinki University, near Osaka, Japan. Iritani came with an impressive CV. In the late eighties he achieved a world first when he injected a single rabbit sperm into a single rabbit egg and made a baby rabbit. Not that rabbits need much help in this department – they breed like rabbits after all – but this was the first mammal to be produced using intracytoplasmic sperm injection, or ICSI, as it is known. Now an established technique in fertility clinics around the world, it has been used to help tens of thousands of couples have children. Iritani also wanted to make a mammoth, but he wasn’t interested in sperm. He had a different plan.
Hello Dolly
The summer before they were due to leave, something happened to boost Iritani’s spirits. On 5 July 1996, a little lamb was born on a farm in Scotland. To be sure, there were lots of lambs born that day. But this one was special. This wasn’t any old lamb. This was Dolly, who went on to become the most famous, most photographed sheep in the world. Mammalian cloning, which had been nothing more than a pipe dream for Viktor Mikhelson back in the eighties, had finally arrived. It was one small step for lamb, one giant leap for lambkind. She was named after busty ballad belter Dolly Parton because the cell used to clone her came from the mammary gland of a female sheep. Her birth was trumpeted in the world’s leading scientific journal, Nature; she stole headlines around the world, and even bagged the front cover of Time magazine. A superstar sheep who played her entire life out in front of the watchful lens of the world’s media, she could have been a demanding diva, yet Dolly was reassuringly normal to those who knew her. ‘She was a sweetie,’ says developmental biologist Michael McGrew from Scotland’s Roslin Institute, where Dolly was born. ‘She spent a lot of time with people so she became really tame.’ But Dolly was more than just a nice lamb to hang out with. Her birth heralded the arrival of a new era. Just as the Gregorian calendar can be split into bc and ad, so too the field of cloning can be divided into bc: ‘Before Cloning’, and ad: ‘After Dolly’. Before Dolly, mammals had never been cloned using DNA from an adult cell. After Dolly, that all changed.
She was important because she demonstrated, for the first time, that genes in the nucleus of a mature, adult cell can be reprogrammed into a much younger, embryonic-like state. ‘Old’ DNA could be tricked into becoming young again.
‘It was a dramatic discovery,’ says Iritani. If a sheep could be cloned, he thought, why not a mammoth? It was after all, a mammal too, albeit a very large, shaggy, dead one with a trunk. Iritani planned to pick up where Mikhelson had left off and try to de-extinct the mammoth via cloning. If only he could find an intact, viable cell then he could employ the same basic procedure used to make Dolly to fashion a baby mammoth.
Over the next couple of years Iritani and Goto travelled to Siberia several times to look for mammoth tissue in the melting tundra, but the best they could find was a scruffy bit of rump that looked and smelled like a student’s bath towel. And if it wasn’t in great condition when they found it, it was even worse after Russian customs stalled its departure. Four months later when the rancid bit of bum finally arrived at Goto’s laboratory it was, perhaps predictably, a non-starter. There was no sperm for Goto’s hybridisation experiments, nor was there any DNA for cloning. To add insult to injury, they later realised that the sorry sample had probably belonged to a woolly rhino rather than a woolly mammoth. It was all a mammoth fiasco.
A Load of Old Bull
The story then goes quiet for a decade or so. Iritani hadn’t given up resurrecting the mammoth. He was just biding his time. Although Dolly had been born, in the late nineties the science of cloning was still in its infancy and the field needed time to mature. Sceptics thought (and still think) that cloning from permafrost-frozen cells was impossible. When cells are frozen for storage in the laboratory, scientists add cryoprotective ‘anti-freeze’ chemicals that prevent the cells from shattering. In this way, cryoprotected, laboratory-frozen cells can be kept in liquid nitrogen for decades, then slowly thawed and brought back to life. Mammoths, however, simply froze where they fell. With no artificial cryoprotectants to help keep their cells viable, attempts to thaw and grow mammoth cells were fully expected to fail.
But in 2011, Iritani made a bold statement. ‘Technical hurdles have been overcome,’ he told a British newspaper. ‘I think we have a reasonable chance of success and a healthy mammoth could be born in four or five years.’
Iritani’s optimism was founded on a couple of methodological advances. In 2008, Teruhiko Wakayama, then at the Riken Centre for Developmental Biology in Japan, and colleagues took cells from a mouse that had been slung in a freezer and frozen whole for 16 years, and used them to clone an entire new animal. The study is all the more remarkable because the cells that were used for cloning were far from pristine. The mouse had been frozen without any form of cryoprotection. So when the cells were thawed, none of them were even intact. The study showed that just because a frozen cell looks in bad shape, it doesn’t mean you can’t clone from it. Iritani was encouraged.
Then, a year later, a group of Japanese scientists, including Iritani, went a step further when they made clones from a prize bull called Yasufuku. During his life, Yasufuku’s sperm were collected and used to sire over 40,000 calves, but when he died (from dementia, not exhaustion) his profoundly productive testicles were removed, wrapped in tin foil and slung in a freezer at -80°C (-112°F). Whether or not it’s what he would have wanted we’ll never know for sure, but there his testicles lay for over a decade, without cryopreservatives, until Iritani and co. used cells from them to create three identical Yasufuku clones. Even in death, Yasufuku’s testicles could do the job. If you could do it for bulls, why not other large frozen animals? ‘Our results,’ the researchers said, ‘suggest the possibility of restoring extinct species, such as woolly mammoths, if live cells can be retrieved from an organ or animal that has been frozen in a freezer or in the Siberian permafrost.’ The hunt for the world’s best-preserved mammoth was on.
Iritani planned to use a modified version of Wakayama’s method to clone a mammoth, and had some promising preliminary data under his belt. In 2009, he published a paper in Proceedings of the Japan Academy, where he described the first step in the process. Iritani and his team took cells from a frozen mammoth and injected their 15,000-year-old nuclei into empty eggs. In an ideal world, Iritani would have used elephant eggs. Inside the egg, the mammoth DNA would have started to move around and organise itself into separate, stringy chromosomes. The reconstituted cell would then have started to divide. But this was not to be. Elephant eggs are hard to come by, so Iritani was forced to use mouse eggs as a proxy. It might sound far-fetched, given the obvious size difference of the two animals, but a mouse egg can easily accommodate the nucleus of a mammoth. The hope was that naturally occurring molecules inside the mouse egg might spur the mammoth DNA into action. All in all, Iritani injected more than a hundred mammoth nuclei into more than a hundred mouse eggs, but not a squeak. Perhaps, Iritani surmised, the mammoth DNA was simply too old to behave properly, or perhaps mouse eggs simply aren’t capable of reprogramming mammoth DNA. But perhaps, if tissue culture techniques could be improved and better-preserved mammoth cells found, things could be different. ‘In the elephant oocyte (egg), the mammoth nucleus might be activated,’ he told me.
Iritani is now working on specimens collected from another mummified mammoth. Yuka is an exceptionally well-preserved and complete mammoth; a 39,000-year-old strawberry blonde ‘toddler’ found lying on its back, legs in the air, in the Siberian permafrost in 2010. The body is of particular interest because it has two large cuts on its back, through which many of its bones have been removed, including its skull, spine and pelvis. There’s no way animals could have done this, so the body provides evidence of potential tampering by early humans. What’s left, however, is in pretty good shape. In 2012, Iritani travelled to Yuka’s home, the Sakha Republic Academy of Science in Yakutsk, Russia, where he signed an agreement giving him access to their mammoths, and collected samples from Yuka. It took a year of Russian bureaucracy before the samples – skin, muscle and bone with marrow – were released, but they’re now safely ensconced in Iritani’s lab at Kinki University. He’s now studying the precious samples with care, on the hunt for that one elusive, viable, intact nucleus that just might help him fulfil his dream. But Iritani and his team aren’t the only ones trying to make a mammoth. Around 500 miles away across the Sea of Japan, a controversial scientist is at the forefront of a counter-effort.
From Mutts to Mammoths
South Korean cell biologist Woo Suk Hwang is perhaps best known for a scientific scandal he has spent the last decade trying to forget. In October 2009, Hwang, who claimed to be the first to clone human embryos and create stem cell lines from them, was found guilty of fraud, embezzlement and ethical violations. For a high-profile researcher, it was a spectacular, humiliating and public fall from grace, yet through gritted teeth, dogged determination, and the emotional and financial support of many loyal fans, Hwang has quietly rebuilt his career. He now works at a shiny new laboratory that he founded on the outskirts of Seoul – the Sooam Biotech Research Foundation – where he understandably shies away from human cell research, and instead focuses on cloning big animals.
Hwang has spent the last two decades making cloning look easy. In 2005, he produced the world’s first-ever cloned dog, a goofy black-and-tan Afghan hound called Snuppy4 . It took Hwang and his team two and a half years (or 19 dog-years) to produce the pooch, but since then he’s honed his methods, knuckled down and cloned more than 500 dogs.5 Many are copies of beloved pets, but he’s also cloned several dozen working dogs for the Korean National Police Service, not to mention cows, pigs and coyotes. Who better, then, to bring back the woolly mammoth? In 2012, Sooam entered into an agreement with the keepers of the exquisitely preserved Malyi Lyakhovski mammoth at the NEFU’s Mammoth Museum. Under the banner of the Mammoth Resurrection Project, the Koreans would supply their cloning expertise if the Russians handed over the best mammoth tissue they could find. ‘It’s a very exciting experience for us,’ says Sooam scientist Insung Hwang (no relation to Woo Suk). ‘Sooam have lots of experience cloning large animals and the Russians have a lot of mammoths. It’s the perfect partnership.’
And so it was, in March 2014, after the Malyi Lyakhovski mammoth – or ‘that bloody mammoth’ as I like to call it – travelled all the way from its frozen resting-place to the NEFU in Yakutsk, that Hwang and an all-star cast of mammoth experts took part in one of the most bizarre spectacles of recent times – a CSI-style autopsy of an Ice Age mammoth. The dirty, slate grey carcass lay on an enormous slab, weirdly juxtaposed against the sterile, white-tiled laboratory, while the scientists, dressed in full forensic garb, jostled one another for samples. Under the watchful eye of two TV crews they prodded, poked, measured, photographed, drilled, sawed and plundered the slowly thawing carcass. No part of its anatomy was left untouched. If the scientists were to make the most of this remarkable animal, they would need to act quickly before decay set in.
They could tell from the curvature of the animal’s tusks, its nipples and its internal plumbing that the Malyi Lyakhovski mammoth was female. From her tusks, scanned in 3D at the local hospital, they could tell also that she had lived a long and productive life. Mammoth tusks grew throughout their lives, leaving a series of growth rings from which it is possible to deduce not just their age but snippets of their life story. The tusks of adult females, for example, would have grown more slowly when the animal was pregnant or lactating. This mammoth, tests revealed, had given birth to eight calves; seven of these survived past weaning, and one died while still dependent on its mother’s milk. Then, after 30 years of childcare, the pattern of growth rings changed again, most likely when the Malyi Lyakhovski mammoth rose to become the matriarch of her herd. After reaching the pinnacle of mammoth society, however, life became difficult. Mammoths, we know, had just four teeth – two in the upper jaw and two in the lower. With rows of ridges, these molars were great for grinding plants, but when the grooves wore down the teeth fell out. New ones would grow in their place, but when the sixth and final set came loose, it was game over for the gummy beast. When she died in her fifties, the Malyi Lyakhovski mammoth was down to her last few gnashers, themselves far from pristine. In her stomach and liver the scientists found a number of hard, round stones, which they think are either gallstones or actual stones that she swallowed accidentally. Then, one unseasonably warm day towards the end of the last Ice Age, she came across a boggy pool and leaned down to take what would be her last drink. Her forelimbs became stuck in the mud and no amount of struggle could free her. Teeth marks on her bones and the grizzly state of her gnarled upper body tell us that the Malyi Lyakhovski mammoth was eaten alive. A prolific mother and mammoth of great status, she met with a brutal and gory end.
But her story, of course, doesn’t end there. ‘It’s amazing that her body is with us at all,’ says Roy Weber from Denmark’s Aarhus University, who attended the autopsy. ‘She must have fallen into the bog on the one day in 40,000 years that it wasn’t frozen. Then it stayed frozen ever since.’ It’s this continuous, uninterrupted, long period of freezing that means the mammoth is still with us today and the autopsy could happen at all. ‘It looked like an animal that had died two or three weeks ago, not one that had been dead for tens of thousands of years,’ he says.
When researchers cut into the mammoth’s body, they found that parts of it were still remarkably fresh. ‘The muscle looked like beef steak from the supermarket,’ says Weber. And when samples of the apparently ‘liquid blood’ were tested, they were found to contain traces of haem.6 The find hints that the fluid is perhaps some dilute, degraded version of mammoth blood, but why the ‘blood’ remained liquid when the rest of the mammoth froze remains a mystery until the liquid has been fully analysed. The most likely explanation, says Weber, is that the substance is a mix of sediments and breakdown products from blood and other tissues, which could have lowered the liquid’s freezing point, and that natural anti-freeze molecules produced by bacteria inside the mammoth could have helped prevent the substance from turning solid.
For the South Koreans, however, it was all good news. Mature mammalian red blood cells don’t contain nuclei so can’t be used for cloning, but the seemingly fresh flesh raised hopes that cells suitable for cloning might be found. ‘Other well-preserved mammoths have been found but it could be that the bleeding mammoth proves better at the cellular level,’ says Insung Hwang. During the autopsy, Russian scientists examined tissue samples from the mammoth and were enthused to spot what look like muscle cells, but it’s one thing to spot the outline of a cell on a microscope slide and quite another to find a cell whose DNA is sufficiently intact to be used for cloning. Another problem is the omnipresent Russian red tape; samples due for export are all too often delayed, meaning that precious time and potentially precious cells are lost long before they ever make it to the shiny, new labs at Sooam in South Korea.
With this in mind, Hwang and colleagues decided to move the mountain to Mohammed … or, at least, the lab to the mammoth. The South Koreans have funded the set-up of a purpose-built laboratory in Yakutsk itself, and because a woolly project deserves a woolly name they’ve called their new facility the International Centre for the Collective Use of Molecular Palaeontology for the Study of Cells of Prehistoric Animals, or the ICCUMPSCPA for short. Russian scientists have gone to South Korea to learn how to clone large mammals, and the plan is that as fresh tissue is found it will be studied in situ on Russian soil, where researchers will have the know-how and kit to initiate a cloning attempt.
So let’s just take a breather and recap. The race is on to bring back the woolly mammoth. Two different teams of scientists – one from South Korea, the other from Japan, both of which know a lot about cloning – are collaborating with two different Russian research institutions – who have lots of mammoths. The Japanese have ginger toddler Yuka, while the South Koreans have ‘that bloody mammoth’. Both groups hope to extract nuclei from the dead mammoths’ cells and then use them for cloning. Both are optimistic. They have to be. To take on a project of this vision and magnitude necessitates a ‘glass half-full’ disposition, but there are plenty of sceptics who think the projects are doomed to fail. The chances, they say, of finding a mammoth cell with a viable, intact nucleus are so remote as to be almost impossible. ‘I have an antique porcelain vase on my mantelpiece,’ says physiologist Kevin Campbell from the University of Manitoba in Winnipeg, Canada, who has studied mammoth molecules. ‘It looks beautiful but I don’t put water in it because it leaks. It’s the same with mammoth cells.’ Even a cell that looks good down the microscope is likely to be damaged and its contents long since leaked away. Just as well, then, that there’s a third horse in this race.
Edit an Elephant
Harvard University’s George Church is also trying to revive the woolly mammoth, and if anyone can do it, I believe he can. My conviction is based on two reasons. First, as I have discussed already, Church is one of the most intelligent, innovative, brilliant geneticists that there is. He has a string of high-profile scientific achievements under his belt and the most sophisticated gene-editing technology available at his fingertips. Second – and here’s the deal breaker – he looks a lot like God. Church has a beard of biblical proportions, the likes of which wouldn’t look out of place in a Michelangelo fresco. If I’m to put my trust in one man, it’s got to be the one who would look most at home on the ceiling of the Sistine Chapel. His plan is to use genome editing to make something that, to all intents and purposes, will look and act like a woolly mammoth – a big, hairy elephant that loves the cold and can live in the Arctic.
In their time, woolly mammoths evolved many adaptations to cope with the extreme cold. On the outside, they were famously woolly. Their skin was pitted with numerous sebaceous glands that helped waterproof the fur by keeping it oiled. They had little ears and tails to minimise heat loss, and a spare tyre so thick it would make a sumo wrestler look dainty. But there were also changes on the inside. In 2010, Kevin Campbell and colleagues demonstrated that woolly mammoths carried an odd version of the haemoglobin gene. By inserting this mammoth gene into a bacterial cell, they persuaded the bacteria to make mammoth haemoglobin and were able to show that this Pleistocene molecule was particularly good at offloading oxygen at low temperatures. This would have helped mammoths to conserve energy and cope with the cold. ‘It’s genuine, authentic haemoglobin,’ says Campbell. ‘It’s no different to what you’d get if you went back in time and took a blood sample from a real, living mammoth.’ He hadn’t quite de-extincted the mammoth, but he had de-extincted one of its proteins.
Then in 2015, two groups published high-quality versions of the mammoth genome. One group, led by Vincent Lynch from the University of Chicago, compared the woolly mammoth genome to that of the Asian elephant, the woolly mammoth’s closest living relative, with which it shared a common ancestor just six million years ago. Although the vast majority of the nucleotides were identical, the researchers found 1.4 million DNA letters that were different and which in turn altered the sequence of more than 1,600 protein-coding genes. Some of these genes were involved in hair growth and colour, some in sensing temperature, while others helped regulate the internal body clock, a possible adaptation to life in a place where the summer sun sometimes never sets.
Together these genetic idiosyncrasies provide a road map for anyone seeking to resurrect the woolly mammoth. Much as a would-be Neanderthal-maker could theoretically take a human cell and edit it to become Neanderthal-like, Church plans to take an elephant cell and alter its genome so that it becomes mammoth-like. ‘But just because there are millions of differences [between the mammoth and elephant genomes], it doesn’t mean it’s a daunting task,’ he says. Far from it. To fulfil his goal of making a ‘mammoth-like’ creature, he doesn’t need to edit all of the million or so uniquely mammoth sequences into an elephant cell. Instead, he plans to alter only the most salient of these genetic differences.
He’s using a technique called CRISPR (pronounced ‘crisper’). This new method enables genomes to be edited with pinpoint accuracy. In the old days, researchers could add genes into cells but there was no saying where in the genome the new additions would end up, raising fears they might disrupt cell growth-related sequences and cause cancer. CRISPR, in contrast, is seen as a safer option because it can be used to edit the genome at precise locations.
CRISPR stands for ‘Clustered Regularly Interspaced Short Palindromic Repeats’. As the fiendishly fashioned name suggests, these DNA sequences are clustered together, regularly spaced and repeat in palindromic order; drab as a fool, aloof as a bard, some of the DNA letters read the same forwards as backwards. They’re found naturally in some bacteria where they help fight off viruses. Co-opted for use in the lab, the system has been likened to a pair of molecular scissors being guided by a satnav. The satnav is a specially designed guide molecule made of the DNA-like molecule RNA, which directs the scissors, and an enzyme called Cas9, to snip the genome at the exact desired spot.
The technology was propelled into the spotlight in 2012, when Jennifer Doudna at the University of California, Berkeley, and Emmanuelle Charpentier, now at the Helmholtz Centre for Infection Research in Braunschweig, Germany, co-authored a paper showing how they could use the system to cut the double-stranded genome at any place they wanted. Then a year later, George Church and colleagues showed that the system could be used not just to cut but also to edit the genomes of human cells, a milestone in the CRISPR story. CRISPR, we now know, can be used to add, delete or alter anything from single nucleotides up to whole genes. With the technique being relatively cheap and easy to use, CRISPR has since been adopted by hundreds of laboratories all over the world, which are using it to help understand how genes influence health and disease, to design and develop new therapies, and to do lots of other clever stuff. But it’s also been shown to work in other species … including elephants.
Under the banner of the ‘Mammoth Restoration Project’, Church and colleagues have already used CRISPR to edit the genes for mammoth haemoglobin into the nucleus of an elephant cell. Then, when he’s satisfied that the elephant cell can read the new instructions and make bona fide mammoth haemoglobin, he’ll turn his attention to other key mammoth traits, like fur and fat. To give his animal the required shaggy coat, he’ll probably have to alter around half a dozen different genes; mammoth fur was, after all, anything but ordinary. Where the coarse, outer hairs on their flanks and belly grew up to a metre (3.3ft) long, the finer, curly under-wool was much more closely cropped. He’ll also be able to engineer coat colour. Mammoths, we know, carried a particular version of a gene called Mc1r that influences skin and hair colour. But depending on the exact sequence he chooses to use, Church could make hairy elephants that range in colour from strawberry blonde to deep auburn. Church tells me he is plumping for ginger. ‘There would have been mammoths with light ginger hair,’ he says. So why not?! And because he is aiming to recreate features that would help his animal to survive in the Arctic, rather than an exact genetic copy of the mammoth, he’s not averse to the idea of adding in genes from other species too. One option would be to plagiarise DNA from another shaggy-coated Arctic mammal, the musk ox (Ovibos moschatus). ‘Then there are woolly humans,’ says Church. People with hypertrichosis or ‘Werewolf Syndrome’, for example, are completely covered in hair. Courted as circus sideshow freaks in times gone by, it’s now known that some sufferers owe their fate to a particular genetic mutation. Cut and paste that into the elephant genome and it may be possible to generate one seriously hairy beast. As I write this now, Church has ‘mammoth-ified’ over a dozen different positions in the elephant genome, but that’s the easy part. The next stage of the process, making an embryo that develops normally, is far more challenging.
An Elephant in the Room
The problem is that all of the various mammoth-making methods being discussed at some point hit the same two stumbling blocks. They all involve using elephants and elephant eggs, neither of which are easy to come by.
The first problem, then, is to find a female elephant that is ovulating. An adult female releases just one egg every four months, but a few weeks before this happens, she lets slip some pheromone-laden mucus from her vagina, which signals her fertility to pachyderms near and far. Close by, her immediate family amplify this sexual signal via the ‘mating pandemonium’. Herd members charge around chaotically, trumpeting and screaming, advertising the female’s readiness for sex to anyone that wants to know. It’s a bit like Newcastle on a Saturday night. The resident bull, who may be tens of miles away, picks up on these not-so-subtle cues and rushes to be near her, so that they can mate as soon as she ovulates. The result: in the wild, at least, there are almost no fertile females that aren’t already pregnant.
Best then to focus efforts on captive elephants, but even then there are problems. Female elephants endure the longest pregnancy of any mammal – 22 months – then spend roughly the same amount of time nursing their calves. So because mammals tend not to ovulate while they are pregnant or producing milk, this means it could be four or five years from one egg being released to another being available. This limits the potential pool of eggs for mammoth restoration.
But suppose an ovulating female is found. The next step would be to collect the egg, a procedure that involves navigating the complex system of internal plumbing that exists between an elephant’s ovaries and the outside world. Where humans have but the smallest of gaps between daylight and the entrance to the vagina, elephants have an enormous, metre-long tube called the vestibule. The vestibule is not, as its name might suggest, a space for hanging up coats, nor do male elephants have to knock before they enter. It’s simply a quirk of elephant biology – where humans have but the smallest of gaps between daylight and the entrance to the vagina, elephants have this additional waiting room. Bull elephants may have the largest penis of any land mammal (over a metre long when erect) but the vestibule is as close to the vagina as the wayward, bendy member ever gets. Because of this, an elephant’s hymen, the membrane that covers the entrance to the vagina, isn’t physically damaged during sex. Instead, sperm have to wriggle through a tiny hole in the hymen to reach the vagina and beyond, and when a baby elephant is born and the hymen is ruptured, it just grows back. To retrieve an egg, a would-be mammoth-maker would need to guide a surgical instrument to places an elephant penis has never been: up the vestibule, through the hymen, straight on at the vagina, to infinity and beyond. It’s a tricky manoeuvre, but it has been done. A team of specialist veterinarians led by Thomas Hildebrandt from the Leibniz Institute for Zoo and Wildlife Research in Berlin (of whom much more in Chapter 8) has refined the technique, and managed to harvest elephant eggs.
The next step, then, is to use those eggs to make a mammoth. Embryonic development needs to be kick-started in a petri dish. But no one has ever made an elephant embryo in the lab, much less a mammoth one. Cloning, the method most often mooted, is notoriously inefficient. When researchers were trying to de-extinct the bucardo, they used over 500 goat eggs to make over 500 cloned embryos, most of which stalled in the culture dish. The best of the bunch – a couple of hundred – were then implanted into over 50 different surrogate goats, of which only seven became pregnant.
But if the odds weren’t great for the bucardo, they’ll be even worse for the woolly mammoth. The bucardo cloning experiments sought to reprogramme DNA from healthy adult skin cells, frozen carefully with protective chemicals. But if Ice Age tissue is to be used to make a mammoth, then the cells and any DNA in them will be far from perfect, lengthening the odds of success even further. Even if the DNA is decent, crafted perhaps through gene editing, there’s no way of knowing if an elephant egg can reprogramme mammoth DNA. And if the bucardo researchers had to make hundreds of cloned embryos in order to generate one live birth, then a mammoth-maker would probably need to make thousands. The little bundles of dividing cells would then need to be transplanted into the womb of a surrogate, but here again we sail in unchartered territory.
No one has ever transplanted an embryo back into a female elephant. To do this, the embryo would need to be guided up the vestibule, through the hymen, straight on at the vagina, keep going at the cervix, then perform an emergency stop at the uterus. It’s a torturous, twisty, two-metre (6.6ft) journey. The plucky vet would need either the arms of Mr Tickle or an eye-watering endoscope, but there could be another route. Sooam researchers plan to return their mammoth embryos not via the vestibule but up the rectum. A laparoscopic device would then be used to punch a hole in the intestinal wall and set the embryo down close to the womb. It’s a reproductive shortcut, devised for rhinos, that shaves over a metre off the embryo’s journey. If Option A is like taking the ring road, then Option B is like going cross country, through a field full of manure. Even then, the chances that the little embryo would survive are slim. No one knows how a mammoth or genetically modified elephant embryo will fair inside the uterus of an elephant. But we do know that when the embryo of one species is placed inside the uterus of another, things tend not to go well. Team Bucardo, remember, transplanted embryos into 50 different surrogates, of which only seven became pregnant, but six of those pregnancies failed and the one cloned bucardo that was born died in the arms of the vet who delivered her. Experience from the bucardo project, and from attempts to clone other endangered species, suggests that if researchers try to make mammoth embryos and have them develop inside the wombs of surrogate elephants, there will be many, many failures before even coming close to success. The surrogates will be placed under enormous stress, guinea pigs for experimental procedures that have yet to be tested.
And it’s now that the very large elephant in the corner of the room, the one that’s been sitting quietly throughout the whole of this chapter, stands up, waves a flag that says ‘OVER HERE’ and starts to loudly trumpet its displeasure.
Asian elephants are the woolly mammoth’s closest living relatives, so it is to them we must turn for eggs and surrogacy skills. But Asian elephants are endangered. Their numbers have been reduced by half over just three generations, yet we continue to hunt them and trash their habitat. These are not laboratory animals. They are not experimental tools. A living, breathing mammoth might well be a marvellous thing, but at what cost?
Scientists are, of course, trying to think of ways around these problems. Maybe researchers could collect eggs from elephants that have died naturally or been culled. Maybe eggs could be created artificially in the laboratory (see Chapter 9), or clever tweaks to the cloning process could increase the chances of success. Perhaps, thinking much further ahead, one day we could do away with the need for surrogate animals altogether and grow embryos in the lab in some sort of artificial womb. But if, as the old saying goes, ifs and ands were pots and pans, there’d be no work for tinkers’ hands.
Woolly Thinking
But suppose for a minute that someone does manage to make a mammoth. What happens next is the sad part. If – and it’s a big if – a healthy baby mammoth is born, it runs the risk of being very lonely indeed. We can surmise from mass mammoth graves and from fossilised footprints that mammoths once lived in large, extended families. Like modern-day elephants, these groups were probably matriarch-led, and largely female. Herd members would have communicated with one another via low frequency noises and it’s reasonable to assume that, just like elephants, woolly mammoth mothers would have had close relationships with their calves. But would a woolly mammoth calf recognise its elephant mum? Would it know to suckle? How about the mother? Would a modern elephant mum caress her hairy newborn with her tactile trunk, or reject it as an aberration? And if she did decide to care for a Pleistocene misfit, how could she possibly teach it to act like a mammoth rather than an elephant? If the goal is to repopulate Siberia with mammoths, how would the twenty-first-century lookalikes learn to survive in the cold when their female role models are sun-loving? The degree to which mammoth behaviour is innate and/or learned is a very woolly area. With so much at stake, it’s inevitable the first de-extincted woolly mammoth would be born and raised in captivity where the environment could be carefully controlled. But then other woolly mammoths would follow. They’d have to. It’s not just a mix of genders that is required, but a mixture of genes. Without genetic diversity to buffer against disease and environmental change, the new animals wouldn’t stand a chance. If the new mammoths were to hail from just one or two genetic founders, over time they’d end up as inbred as the royal family, albeit arguably with smaller ears. The goal, then, would be to release herds of mammoths back into the wild. But how many to release and where? Here again, predictions are vague.
By matching the chemical isotopes in tooth enamel with those in the soil, researchers calculate that some mammoth species roamed up to 300 miles a year, so they would need a lot of space. Modern elephants eat up to 200kg (450lb) of food per day, so the mammoths would also need a lot of fodder. If the aim is to restock Siberia with woolly mammoths then we have to question whether the reserves being prepared for them are big enough. Pleistocene Park, the brainchild of Sergey Zimov, covers around 160km2 (60 square miles) while a second, more southerly nature reserve created closer to Moscow is 50 times smaller. Sure they could roam elsewhere. Not many people live in the High Arctic. But if a key goal is to keep mammoths in such numbers that they can help keep the Arctic frozen and its sequestered carbon tucked away, then it’s time for some joined-up thinking. Even if all the technical hurdles involved in making a mammoth were overcome tomorrow (which they won’t be), it would still take well over half a century to generate anything like a single viable herd … by which time, if current predictions are to be believed, the Arctic ice could already be gone. ‘The mammoths would arrive too late to do any good,’ says climate engineer Hugh Hunt from Cambridge University. With no ice to reflect the sunlight back into space, the world will continue to warm. The tundra will melt and the carbon time bomb that it’s holding will explode. ‘We need to be looking at refreezing the North Pole in the next 10 to 20 years,’ he says, ‘after that it will be too late.’ If we’re looking to the woolly mammoth to save us from global warming we need to think again. Although the image of a mammoth in pants and a cape is visually appealing, mammoths are simply not the climate-change superheroes that some would paint them to be.
Were I to choose one animal to bring back to life, would it be the woolly mammoth? Sure, I’d like to see one. I’d cough up the cash for a thermal onesie, a brandy-filled hip flask and an airfare to Siberia in order to marvel at the wonders of a fully stocked Pleistocene Park, but only if the mammoths could be made without harming the pachyderms we already have. I don’t want mammoths back at the expense of the elephant. I don’t want high-risk, potentially harmful procedures practised on a species so loved, so precious, so very much in need of our protection. There will, perhaps, come a time when science and technological progress will triumph over my objections, in which case, so much the better. But for now, at least, the woolly mammoth is off my list.
NOTES
1 I’m presuming that ‘herd’ is the correct collective noun for mammoths. If early modern humans or Neanderthals ever possessed such a word it has been lost in the mists of time. Perhaps a ‘ball’ of woolly mammoths would be better.
2 For those who don’t know, Alan Titchmarsh is a legendary British gardener and national treasure. I’m not suggesting that he eats grass, tramples saplings or shits in his own back garden. But he does sculpt landscapes with his green fingers. It’s also hotly tipped that when Prince Philip pops his clogs, the Queen may well marry Titchmarsh and let him put raised beds in the grounds of Buckingham Palace.
3 Or indeed, ‘elemoth’.
4 ‘Snuppy’ is short for ‘Seoul National University puppy’, but with the animal now fully grown, perhaps his name should be changed to ‘Seoul National University dog’, or ‘Snug’ for short.
5 Advice from Sooam’s website: ‘When your dog has passed away DO NOT place the cadaver inside the freezer. Then, patiently follow these steps: (1) Wrap the entire body with wet bathing towels. (2) Place it in the fridge (not the freezer) to keep it cool. Do not forget it is in there, or you’ll have a nasty shock when you go for the milk … (OK, I added the last bit in, but it’s a valuable piece of advice.) Please take into account that you have approximately five days to successfully extract and secure live cells.’
6 A constituent of the oxygen-transporting haemoglobin molecule found in vertebrate red blood cells.