A Mammoth Task: Scientists Are Reviving Endangered Animals, and Awakening Ethical Questions

The next big thing in cloning is 'de-extinction' - reviving endangered species by creating hybrids that fuse a threatened or extinct animal with one that is thriving.

Netta Ahituv
Netta Ahituv
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Netta Ahituv
Netta Ahituv

In the 1960s, the world population of the northern white rhinoceros ‏numbered more than 2,000. At present, there are only seven left in the world: two in the San Diego Zoo Safari Park; one in the Dvur Kralove Zoo in the Czech Republic; and four in the Ol Pejeta Conservancy in Kenya. The last birth of a northern white rhino occurred in the year 2000. Since then, none of the rhinos has shown an interest in mating, and attempts to produce offspring by means of artificial insemination have failed. Barring a miracle, within a decade no northern white rhinos will be left.

This dismal prospect has spurred some scientists to take action. Among them is Dr. Oliver Ryder, director of genetics at San Diego Zoo’s Institute for Conservation Research. Ryder readily agreed to cooperate with Dr. Inbar Friedrich Ben-Nun, an Israeli biologist doing stem-cell research as a postdoctoral fellow at the Scripps Research Institute in La Jolla, California. At Ben-Nun’s request, Ryder sent her cell samples from the rhinos at San Diego Zoo so she could take the first step on the long journey leading to the creation of a rhino in a laboratory. Using frozen skin cells from the rhinos, Ben-Nun successfully grew stem cells (which have not yet undergone differentiation into a particular type of cell, so that by biological means they can be turned into cells for a specific scientific purpose, such as reproductive cells‏).

The next stages on the path to creating a northern white rhino involve creating reproductive cells from the stem cells, inseminating them, injecting them into the womb of a surrogate female of a more common type of rhino (to avoid endangering the three remaining female northern white rhinos‏) − and waiting for the birth. The researchers believe it will be another decade before a cloned animal is born. As of now, this is the only chance our descendants will have to see a northern white rhino in the flesh.

The rhino effort is part of a global project known as “de-extinction,” which has been gaining momentum in recent years. It is also providing fertile ground for philosophical, ethical and biological discussions. Last March, a TEDx conference was held on the subject, and National Geographic devoted its April issue to de-extinction. Some researchers avoid using the c-word ‏(cloning‏) explicitly, as the idea is not to create a one-on-one individual. What the scientists are after is to generate hybrid life: a fusion between a nearly extinct animal and a more common one. Still, it is clear to everyone that this is a form of cloning, in the sense that it involves the creation of animals artificially. The first animal cloning, which took place in 1996 − the famous sheep, Dolly − sparked the imagination of many and gave rise to the thought that it would be possible to resurrect extinct animals. In 2000, for the first time, the embryo of a water buffalo – a species in danger of extinction – was implanted in the womb of a cow, but the pregnancy failed. A year later, a mouflon – an endangered species of wild sheep – was successfully cloned by Prof. Pasqualino Loi of the University of Teramo, Italy, and his lab team. Loi and his colleagues reached the birth stage of the mouflon, but it died within six months of birth.

Twelve years later, Loi is more optimistic than ever. “It’s a matter of two-three years until we succeed in achieving an adult mouflon individual,” he asserts, in a phone interview with Haaretz. “We will be able to use him for the mouflon preservation project. Imagine a thousand mouflons returning to nature and breeding naturally with one another. That would be amazing.”

Two cloning methods

There are currently two ways to clone animals. One, as in the case of the northern white rhino, is by means of stem cells that are transformed into sperm and egg cells. The other is by producing a somatic cell ‏(a nonreproductive cell‏) nucleus and injecting it into an enucleated ovary ‏(having no nucleus‏) of a surrogate-mother animal which is a relative of the endangered animal and is itself not threatened. The implanted nucleus undergoes a “reprogramming” process within the ovary and develops from the nucleus of a somatic cell into a cloned embryo. The embryo is then injected into the womb of the surrogate animal. By this method, laboratories have created embryos of buffalo, the African wild ass, wildcats, wild dogs and others.

One way or the other, successful cloning requires three elements: the DNA of the animal that is going to be cloned; an active egg to be the recipient of the DNA; and a female to carry the egg in her womb. There are two reasons for choosing a surrogate from a close and common species: to avoid endangering the few remaining animals of the endangered species; and because scientists generally know very little about the reproductive physiology of wild species, compared to the vast knowledge that exists about the reproductive process of domestic farm animals.

The current cloning methods show an average success rate ‏(achieving a complete cell‏) of less than 5 percent. For wild animals, the success rate stands at less than 1 percent of the attempts. The situation is further compounded by funding problems. Nearly 80 percent of the available research funds in this sphere are earmarked for research on human beings, and nearly all of the rest for research on farm animals. Whatever falls into neither of these categories, such as the de-extinction project, gets the few remaining crumbs.

“We are waiting for a millionaire who loves rhinos,” Friedrich Ben-Nun says − a sarcastic quip often heard in her lab. But despite the low success rate, onerous work and budgetary shortfall, cloning − formally known as “cellular reprogramming” − continues to lure scientists, and success generates sure publicity.

Domestic cats and dogs have been involved in some of the most successful attempts to clone endangered animals. In 2008, a team from Seoul National University in South Korea successfully cloned three gray wolves – a fairly rare breed – with domestic dogs as surrogate mothers. All three wolves reached adulthood but did not succeed in reproducing.

At the Audubon Center for Research of Endangered Species in New Orleans, Dr. Martha Gomez and her colleagues cloned the African wildcat, using domestic cats as mothers. This is the most successful cloning to date of a wild carnivore − eight of the cloned animals survived until the age of 10, and one offspring was produced, now age 7.

Speaking by telephone from New Orleans, Gomez relates that she and her team are currently trying to clone a South African black-footed cat, another rare type of wildcat. “Our goal is to show that the technology is feasible and that it should be used to conserve species. I believe that the day is not far off when wildcats will return to nature,” she says.

However, the most exciting cloning fantasy is reserved for the woolly mammoth, an elephant species that probably died out around 3,000 years ago. In March 2012, scientists from Russia and South Korea announced they were cooperating in an attempt to resurrect the mammoth.

Prof. Hendrik Poinar, a molecular evolutionary geneticist and biological anthropologist from McMaster University in Hamilton, Ontario, is an expert in isolating and researching DNA proteins from fossils. At present, he is working on the DNA that was extracted from frozen mammoths that were found in the Siberian wilds. “It is impossible to replicate precisely the genome of an extinct animal,” he explains. “Although we have parts of the DNA, they are incomplete, nor do we have any way of knowing how many times each part replicated itself and in what order.”

Friedrich Ben-Nun contributes an interesting image to the discussion: “The attempt to produce DNA from a mammoth is like trying to reproduce a document that has gone through a shredder,” she says. Poinar and other scientists are filling in the gaps with the use of the closest relative of the mammoth, the Asiatic elephant. Effectively, they are aiming to create a hybrid animal that contains a genome of both a mammoth and an elephant – or, as Poinar puts it, “a mammoth in the eye of the beholder.”

Moral question

Even if everything goes well and 10 mammoths come into the world, what do we do with them? Poinar believes the mammoth can survive today in certain parts of Siberia. But how will the animals learn the necessary behavior for their survival, such as food gathering, family organization or caring for the young? Those skills are acquired through learning and imitation and are not necessarily innate. Even Poinar is aware of the absurdity.

“As much as the boy in me wants to see these fantastic creatures wandering the world, it’s difficult for me to find a logical reason for doing that.” Prof. Loi, the Italian scientist, also pours cold water on the idea of resurrecting mammoths and on the de-extinction idea as a whole. “I don’t think it will be as big and great as people imagine, because the whole process is extremely expensive and is not as attractive as finding cures for human diseases, let’s say. Nor is it truly realistic to restore different species of animals in the age of global warming.”

The possibility of bringing back what had seemed irrevocably lost generates as much criticism as it does enthusiasm. The question most commonly asked is whether the energy and resources that are being expended in the de-extinction project are not cutting into the efforts to preserve species that are still with us. As Prof. David Ehrenfeld, a biologist from Rutgers, observed in his presentation at the TEDx conference, “At this moment, brave conservationists are risking their lives to protect forest elephants from armed poachers. And we’re talking in this safe auditorium about bringing back the woolly mammoth?”

All the researchers who were interviewed for this article maintain that these are parallel − not contradictory − efforts. They also gladly provide a moral hierarchy: first, preserve what exists, and only afterward clone. “Ethically, the most important thing is to prevent extinction; only if that is not possible should we preserve cell samples and clone,” says Dr. Amir Arav, a veterinarian and biomedical engineer.

According to Dr. Gomez, “Sociologically, it is not right to bring back animals that are totally extinct. We have to save the animals that are still here and about to disappear. Let us remember that the rare animals in the zoos get old and die, and if technology does not save them, there will be no others like them. The small amount of money that is available for animal conservation needs to go to both areas: conservation in nature and also enlarging their population by means of biotechnology. I don’t see technology as an alternative to conservation, but as a complementary aspect, and I believe that both means need to be implemented in parallel.”

Another ethical question involves which species to resurrect first. This is not a matter of urgencies, San Diego Zoo’s Dr. Ryder says, but involves giving consideration to certain criteria. “First of all, if there are cell samples from the same species; second, how familiar researchers are with the animal’s physiological reproductive system; and, finally, if a very close species exists to serve as a surrogate mother. Afterward, questions arise about raising a cloned animal and whether it is possible to return it to

And while ethical questions about theoretical mammoths are flung about, all the cloning procedures require many real animals to be sacrificed on the altar of the experiments. Hundreds of mice, frogs, cats, dogs, sheep and more have been forced to undergo invasive procedures to provide cells and information about reproduction, or to serve as surrogate mothers.

Perched on the scales of morality are the extinct animals, which suffered until they died out, and the animals of our time, which are suffering in the effort to bring them back. Asked about this, the researchers avidly defend their experiments. Gomez maintains that pain clinics cause animals immeasurably greater suffering than she causes the cats in her lab. “The cats here undergo fertility treatments, such as many women also undergo. After their role is completed, we look for a home for them,” she says.

According to Friedrich Ben-Nun, the researchers do all they can to ensure that the animals do not suffer. She also offers a broader perspective: “We need to make use of every means possible to save a species from extinction. If until now the means were to improve the living conditions of the species itself, or to move a few individuals to zoos so they can reproduce without fear of being hunted, cloning too is now part of those means.”

Frozen zoo

A biological species that becomes extinct leaves behind a large vacuum, whose scale far transcends the species’ mere absence. The most salient example of this is the coral, a primitive animal but one that is the basis for life in the oceans. If they disappear, maritime life as we know it will disappear with them. Accordingly, to ensure the success of the conservation project, and later the cloning project, several “frozen zoos” are operating − “archives” or “banks” of cells, tissues and DNA samples of animals that are extinct or are severely endangered. One of them is the San Diego Zoo Safari Park, where Dr. Ryder is the chief geneticist. It boasts the largest and most diverse collection of cells of vertebrates in the United States.

Cell storage has been underway in the San Diego facility since 1976, and the frozen archive now contains more than 8,400 samples from 800 different species. A similar national archive exists in Brazil. Founded four years ago, it houses 420 cell samples from wild animals found dead by rangers in conservation areas. One of them is the bush dog, of which only a few individuals remain.

The idea behind the Brazilian project and others like it is to preserve the genetic information of the endangered wild animals so that one day, when the technology permits, it will be possible to resurrect them with the aid of the preserved cells.

The world’s most impressive project of this kind is the Frozen Ark of Bryan Clarke, professor emeritus of genetics at Nottingham University in England. Clarke studied snails in the Far East, and just as he seemed about to achieve a breakthrough in the question of how new species are formed, the snails began to die off. Disappointed, Clarke decided to devote himself to the collection, preservation and storage of the DNA of endangered animal species.

This is a unique project, in that it was established in order to furnish raw material for future researchers, not to fulfill current scientific needs. The primary focus of Frozen Ark is on animals that are going to become extinct in the coming decades. Clarke emphasizes that he is not seeking to supply an alternative to conservation but only a supplement. Indeed, “the future” is the key term in any discussion of frozen cell banks and of cloning. The word is also used by Dr. Jeanne Loring, who heads the Scripps Research Institute, in which Friedrich Ben-Nun conducted her research. “No study without value for the future is conducted in my lab,” Loring says. At present, she adds, “We are producing stem cells from animals that will be gone in the future. We succeeded with the northern white rhinoceros and also with the Java banteng − a wild bull; with the black-footed wildcat; and with the drill, one of the world’s rarest monkeys.”

The drill’s closeness to human beings made it the most intriguing candidate for cloning to date. Dr. Arav has developed a method to preserve animal cells without the need for complicated machinery and expensive maintenance. Under his method, the tissues taken from animals can be converted into powder, which can be stored for very long periods at room temperature. This method is widely used internationally for animal cells, and even for human eggs.

The last leopard in Israel, a desert denizen named Mashiach ‏(Messiah‏), also now exists in the form of powder, after Dr. Arav received its blood from the veterinarians who pronounced the big cat dead. According to Arav, it will be possible to produce between 50,000 and 70,000 leopards from the cells in his possession. In almost every case in which members of endangered animal species are put to sleep in Israel, a DNA sample is taken for preservation and to provide the information, or the sample itself, to local researchers or zoos abroad.

Many reproductive organs of zoo animals that have died are also sent out for research purposes, says Nili Avni-Magen, the chief zoologist and head veterinarian of the Jerusalem Biblical Zoo. “It is our obligation to preserve DNA, because there are species that have become extinct, and we are so sorry that we don’t know more about them. Naturally, though, most of our resources and energy go into conserving animals just before they are about to become extinct,” she says.

According to Dr. Arav, the African wild ass – forebear of the donkey – should become a symbol of the restoration of extinct animals in Israel, like the panda for the Chinese and the condor for the Californians. “This animal is mentioned in the Bible [as the arud], is very beautiful and easily identifiable. There are only 10 individuals left in the world. In another decade there will be none.” Arav is preserving cells of the African wild ass in the hope that someone will undertake the project of cloning them.

“People who are alive today have a rare opportunity to preserve species and protect them from extinction,” he declares, adding, “It is our responsibility, as we brought about their disappearance.”

Israel does not have a state-managed frozen zoo, but there is a bank of samples, which are being collected independently by Dr. Gila Kahila Bar-Gal, from the School of Veterinary Medicine of the Hebrew University’s Faculty of Agriculture. She has collected more than 7,000 samples of Israeli wild mammals and is now also beginning to collect samples of local reptiles and birds.

“This is the largest and most representative collection of samples from wild animals in Israel,” she notes. Asked whether she is in favor of restoring extinct animals to Israel, she replies that it is a complex issue. “There used to be elephants, hippopotami and tigers here. Where will we return them to? Even if we clone them and release them into the existing habitats, the conflict between humanity – which caused their extinction – and the animals still exists. Take the fallow deer that were restored to the Tzoran Creek area here. They integrated into their environment successfully, but most of them were killed in train accidents or devoured by stray dogs. So what’s the point?”

A few facts about extinct and endangered animals

* As far as is known, there are about 1.5 million species of animals in the world today. Experts conjecture that in the course of history there were 20 times more species.

* As of January 2013, the U.S. Fish and Wildlife Service has listed 2,054 species worldwide as being endangered or threatened.

* There are about 3,500 nature conservation parks across the world, which cover three percent of the planet’s land surface.

* An animal species down on its luck is classified as being in one of six stages: “Extinct,” “extinct in nature,” “in critical danger,” “endangered,” “sensitive” and “threatened.”

* A species is declared extinct if no individual from it has been reported seen for five years. It is estimated that there are twice as many extinct
species as are officially recognized.

* Fifty percent of the endangered species live in the rain forests. The largest of these forests, the Amazon, has lost 17 percent of its area in the past century due to human activity.

* Bodies of sweet water, which are home to more than 100,000 species of animals and plants, are considered the most threatened habitat, due to human development, pollution and global warming.

‏(Sources: National Wildlife Federation, IUCN, World Wildlife Fund‏)

A northern white rhino (left, accompanied by a southern white rhino) at the Dvur Kralove Zoo in the Czech Republic. One of only seven left in the world.Credit: AP
A mammoth.Credit: Getty Images
Dr. Oliver Ryder.Credit: San Diego Zoo Safari Park
Dr. Inbar Friedrich Ben-Nun.Credit: Golan Ben-Nun



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