Bring Back the Northern White Rhino?

Science will soon be able to clone extinct animals. But is that the right decision?

Nola the rhino.
Nola, a northern white rhinoceros at the San Diego Zoo, died in 2015, one of the last of her subspecies.
Torill Kornfeldt

This essay is adapted from The Re-Origin of Species: A Second Chance for Extinct Animals by Torill Kornfeldt and translated by Fiona Graham, published by Scribe.

As I watched Nola, there was something about her that reminded me of my grandmother, who was fond of loose, colorful kaftans and—so it seemed to me—felt at ease, in her element, wherever she went. Though Nola was rotund and rather cumbersome, her movements were dignified and majestic, if not exactly rapid. She had no real worries in life, each sunny new day resembling the one before. She loved apples and relished a thorough back scratch. She kept the elderly male rhino nearby firmly in his place. It was clear who ruled the roost in their enclosure.

“I’ve sometimes heard the curators say that Nola doesn’t run about any longer, but I’ve seen her charge like a steam locomotive when she’s riled by her mate and determined to see him off,” said Darra Davis, the zoo education worker who was showing me around. Nola’s gentleman friend was a rhino of a different species, the southern white rhino. The main reason for his presence was to provide some company; all hope that the two might produce offspring together had long since faded.

Nola belonged to a species that has effectively died out. People are fascinated by endings, boundaries, the last of a line. Maybe that explains why I felt more moved than usual as I watched the monumental rhinoceros take a leisurely stroll. When I visited her at San Diego Zoo in Southern California in 2015, there were only four northern white rhinos (also known as northern square-lipped rhinos) left in the world. When Nola passed away in November 2015, that left three, and after Sudan, the last male, died in March, the world population of the species is down to two females, Najin and Fatu. Both seem to be unable to bear calves. No matter how often they are inseminated, no more northern white rhinos will be born by natural means.

It is mainly poaching that has killed the northern white rhinoceros, slowly but implacably. Rhino horn commands as high a price on the black market as cocaine or gold. Some horns are used in alternative medicine that has no effect; others are turned into the hafts of ornate knives or other decorative artifacts.

“This is basically about whether we believe we have a responsibility to future generations. Most people agree we have a responsibility to our children and grandchildren, and that maybe we aren’t responsible for the generations that may live tens of thousands of years in the future. But the decisions we make today will have consequences for that sort of length of time,” says Oliver Ryder in his office, a few hundred meters away from Nola. A researcher, he’s responsible for the zoo’s genetics department. Oliver is not just talking about the fact that species are dying out at an alarming rate today and that the Earth’s biodiversity is steadily shrinking. He’s also talking about how the decisions we make could make the world better and help save species. Oliver is very fond of rhinos, and has been ever since the first specimens arrived at the zoo when he was a doctoral student here. Since then he has seen one species, the southern white rhino, thrive and recover, while the other, the northern species to which Nola belonged, has disappeared.

Although the northern white rhino is already extinct in practice, that doesn’t mean all hope is lost. Here, in the zoo just outside San Diego, another, quite different kind of zoo exists, packed in plastic tubes and immersed in liquid nitrogen. Six large containers hold tens of thousands of small test tubes full of cells, eggs, sperm, and a few embryos from about a thousand species of animals. When Oliver opens one of the containers, cold vapor from the liquid nitrogen wafts out, and he needs the thick purple rubber gloves he has on to protect his hands from injury. Slowly, he lifts out the receptacle containing cells from 12 northern white rhinos. Twelve unrelated individuals may be enough to enable the species to recover. Twelve test tubes could enable new baby rhinos to rumble about once more like miniature armored vehicles. The big difference between the cells lying frozen in the zoo’s basement and the bodies conserved through taxidermy or storage in formalin in the world’s museums is that these cells are still alive.

“It’s the cells that contain life. Any attempt to revive an animal species must involve living cells. Many people are obsessed by genes. But you can’t create life from DNA alone,” says Oliver, lowering the test tubes back into their receptacle and pulling off his gloves.

If some of these cells are thawed in a dish containing a nutrient solution, they will start to grow, divide, and multiply. This makes the cells a renewable resource and means they can be kept almost indefinitely, Oliver explains. No one knows exactly how long frozen cells remain viable, but the cells frozen by scientists in 1976, when the collection began, are still in excellent condition. Each “frozen individual” is represented by eight test tubes, and each test tube contains about 10 million cells. In most cases, they’re derived from biopsies taken from living creatures, though it’s also possible to take cell samples from animals that have just died. “99.9 percent of the cells we have here in a frozen state come from individuals that are now dead, even if they were alive when we took the cell samples. These are incredibly valuable samples. This is something absolutely irreplaceable,” says Oliver.

Among the test tubes, there are species that have already become extinct. Oliver tells me about the Hawaiian poo-uli, a small gray bird with a black mask around its eyes. Scientists realized the species was threatened, and they discussed whether they should go into the forests to try and catch the last few individuals. Maybe, the scientists thought, the birds might be able to breed in captivity, so their young could be released into the wild at some point in the future. But these discussions went on for a long time. While the scientists were talking, the number of birds dwindled. By 2002, there were only three individuals left. In 2004, the last male was caught, but the scientists failed to find a female for him to mate with before his death a few months later. The body was sent to Oliver.

“It was around Christmas, and I was sitting at the microscope examining the cells when it really hit me—a sharp, intense realization that this species was gone now. I think it really affected all of us who were working on it.”

The thousand species represented here are mainly mammals, though there are quite a few birds, reptiles, and amphibians, too. Impressive though this collection is, it represents no more than a tiny fraction of all the vertebrates in existence today. For instance, scientists put the number of mammal species at more than 5,000, ranging from the rhinoceros all the way down to the tiniest bat, to say nothing of all the other types of animal in existence. As more species become threatened, the chances of filling in the gaps in the library of cells dwindle.

Thanks to his work on the frozen cells, he lives with a constant awareness of the presence and finality of death. “Our goal has never been to establish a mausoleum; we want to help preserve these species. I don’t think anyone realized what potential there was in the cells when we started. But later on came the research that proved it’s possible to produce living creatures from skin cells.”

That was one of the greatest scientific breakthroughs of the new millennium. In 2006, a Japanese researcher, Shinya Yamanaka, showed he could take ordinary skin cells from mice and transform them into stem cells. The fact that stem cells can be obtained in this way has aroused tremendous hope in medical research circles. In theory, such cells would make it possible to grow new organs from a patient’s own cells, or to repair injury or damage. It would also be feasible to transform the skin cells in Oliver’s cold store into new living creatures.

Jeanne Loring has a wonderful voice, deep and smoky, with a husky quality accentuated by the fact that she has a cold when I meet her. She is a professor of neurobiology and the head of the Center for Regenerative Medicine at the Scripps Research Institute, also based in San Diego. Her main occupation is medical research. One of her major research areas involves using stem cells to cure Parkinson’s disease. Trying to save the northern white rhino in cooperation with Oliver is a side project.

“If I had a million dollars and had to choose between investing them in conserving habitat for threatened species or in genetic research into those species, I’m assuming it’s a lot more important to conserve habitat and protect animals against poaching. But the northern white rhino is a species that’s going to die out, and we need to make a decision about whether we’re going to try to rescue them, and to what lengths we would go to rescue them. There’s no alternative,” she says.

Some years back, members of her team started trying to convert some of the frozen cells into skin cells. There was absolutely no guarantee of success; if anything, the reverse was true. At the time, the only species in which the technique had been successful were mice and humans. It was pretty complicated, says Jeanne, but finally they managed to transform ordinary cells from the rhino into stem cells. Jeanne hopes that one day they will take all 12 of the lab’s frozen rhino samples and apply the same process to them. The next logical step would be to try to get the stem cells to develop into embryos, thereby creating clones of rhinos that once lived. But Jeanne plans to take things a step further; she wants to apply a new method and transform the cells into sperm and unfertilized ova. If that were successful, it would be a major scientific breakthrough.

“There’s simply no reason to think that you can’t get something to work, just because it’s never been done before.”

Several research teams are trying to develop ways of transforming stem cells into ova or sperm (gametes). If this succeeded, it would, for instance, make it easier in some cases for childless people who want a family to have biological children of their own. Once the method has been developed—whether by Jeanne or by someone else—she wants to apply it to the frozen cells. Then the plan is to combine ova and sperm in every imaginable permutation, thereby maximizing the genetic variation of the first generation of new rhinos.

The resultant rhino embryos would be implanted in surrogate mothers, using standard IVF treatment. These mothers would be southern white rhino females, closely related to the northern white rhino but not endangered. “The great thing about this technique is that we can also apply it to frozen cells from dead animals. We don’t have to have living animals,” says Jeanne.

Jeanne doesn’t want to guess how long it could take for the first new northern white rhinoceros to be born. Oliver thinks the main thing is for their work to continue. “Personally, my attitude is that we have to do everything we can to save the species living today. As for the northern white rhino, I think we should give it a try. We have the tools, and I don’t like giving up and saying it’s impossible.”

Those tools are getting sharper. New research has shown that the northern and southern white rhino are more related to each other than researchers previously thought, which means that the chances of successful surrogacy are even higher. In July 2018, there were also some trials with hybrids between the two species. Using frozen sperm from the northern white rhino and eggs form the southern, researchers created embryos and have hopes for a successful birth within a handful of years. All of this suggests that the possibility of bringing this species back is constantly getting closer.

We are already manipulating nature in so many ways, says Oliver. He looks quite tired and down as we carry on talking about where these new techniques could lead. It’s not only about how we kill off species, but also about how we shape nature. “The notion that there is a Garden of Eden somewhere, nature unaffected by human beings, is no longer possible. That isn’t how nature works any longer. In the end, it’s us who design nature. Our influence is huge, and it’s going to get even more dominant and invasive. It’s going to happen in ways we can’t even really imagine or understand today,” he says. That sounds terrifying to me. It is not a world I want to live in. But Oliver also sees potential in such a future. He says we humans need to start scenario-thinking about our role, about how we should exercise our stewardship of the natural world. If we were to do that, we could use our enormous influence to make the world better instead.

“Today we are a force that destroys biodiversity and brings species to extinction. But we could become the first species in biological history to consciously expand biodiversity,” he says.

While I stood watching Nola eating in the enclosure, it seemed like a no-brainer to agree. If it’s in the scientists’ power to save this species, I want it done. The northern white rhinoceros is already an extinct species in practice. Yet from another perspective, it is a species that will never disappear. As long as nothing happens to the containers full of liquid nitrogen, the cells from the 12 individuals will remain where they are, a promise for the future.

The big question that gradually takes shape in my head is whether this is an empty promise. Maybe one can say that since the cells are still alive, the animals have not died either. Yet something has been lost. To claim otherwise would be absurd. It may be possible for new rhinos to replace the old ones, but they wouldn’t be identical. On the other hand, the rhinos running around in Africa 50 years ago weren’t the same as those that lived 100,000 years ago. Does that matter? The Frozen Zoo will be an attempt to stop the clock, to preserve nature as it is now. But why should nature as it is now be of any greater value than the natural world of 10,000 years ago, or the species that will exist 10,000 years from now? Right now, I have no idea, but my stomach knots up at the thought of Nola’s death, at the idea that everything that is unique in her and her species will cease to exist. The feeling that this should not happen is stronger than the philosophical quibbles in my mind.