Should extinct animals be resurrected?

In central Kenya, three of the world's four remaining North African white rhinos live here, and they stubbornly refuse to breed. Since 2009, conservationists have been trying to "cage" these rhinos together, but to no avail. Today, the only male northern white rhinoceros is nearly 43 years old and too old to reproduce, making the extinction of this subspecies inevitable, only a matter of time.

Meanwhile, in San Diego, California, scientists are trying to revive their populations. At the Scripps Research Institute, regenerative medicine researcher Jeanne Loring has found a way to get multipotential stem cells - cells that can develop into any type of cell - from rhino skin. She and colleagues are studying how to culture such stem cells into rhino egg cells and sperm cells. If successful, they have the opportunity to save this subspecies from the brink of extinction by producing new individual rhinoceroses through in vitro fertilization.

The northern white rhinoceros is not the only species that has come close to artificial recovery. For species that have become completely extinct, scientists have had to resort to animal and plant cells kept in cryogenic repositories (such as the American Museum of Natural History's cold storage center). Other researchers use artificial hybridization, crossing an endangered species with another similar species, thus preserving some of the characteristics of that species.

Through these methods, biologists may soon be able to bring extinct species back into our sight. This is an exciting development, but it is indeed an unnatural way to preserve nature. Some scientists and conservationists also question whether resurrecting extinct animals can truly protect the planet's endangered species.

Wilderness without the wild

Many of the arguments about resurrecting extinct species have been repeated for a long time, and conservationists and scientists have faced the same objections for decades when using more traditional methods. When the cost of saving a species is too high - tens of millions of dollars to save the African fetal toad, for example - it is argued that the forces of natural selection cannot be defied by humans. If an animal cannot adapt to a changing world, it should be eliminated. For some scientists who consider themselves "absolute Darwinists," this logic also applies to species that have been driven to desperate measures by humans, such as the white rhinoceros and the Pinta Island tortoise. "Humans themselves are part of nature," so the logic applies, says Joanna Radin, a historian of science at Yale University, "so it's all about survival of the fittest."

If scientists choose to save a species, that doesn't mean that species will flourish. When conservationists release once-endangered American cranes into the wild, for example, the birds can no longer migrate without a human pilot in an airplane to guide them. If Jenny Lorraine succeeds in breeding North African white rhinos, she won't be able to release them back into the wild either - poachers will kill them. "Unless we can make room on Earth for other species, it will be futile to resurrect as many animals as possible," writes M.R. O'Connor in her book, Resurrection Science. "There is not much room left for them on Earth."

So, where will these resurrected animals survive? Zoos. Jenny Lorraine describes her work as "Jurassic Park without the horror," in part because her new experiment might just end up being a living museum. If animals can't survive in the wild, does it make sense to keep them? Says one environmental ethicist, "A tiger in a zoo is no longer a real tiger because it can't do what it's supposed to do."

Jenny Lorraine also realizes that resurrecting an animal that has been deprived of its natural home can hardly be called an ideal solution. "I don't want to save an animal that can only continue to exist in a zoo," she says, "but it's probably better than nothing."

The fear of species loss is why scientists are preserving the cells of endangered animals in what amounts to a "primordial zoo" (a San Diego institution calls itself the "Frozen Zoo"). These "DNA banks" are being used as safes, and scientists don't know what to do with the preserved samples - from clouded leopards in the Himalayas to corals on the Great Barrier Reef - yet. what to do with them. "In a sense, keeping the animals frozen is a concession that we are not yet sure how to save them," O'Connor writes.

What will happen to these preserved cells after the animals become extinct is still up for debate. If stem cells are induced to transform into sperm and eggs, as Jenny Lorraine tried with the white rhinoceros, then scientists could create new animals in the lab. Alternatively, they could try to transfer specific DNA from extinct animals into extant species that share certain characteristics (one scientist hopes to resurrect the mammoth by making a similar attempt with elephant cells).

However, if we focus single-mindedly on preserving DNA, it may lead to the demise of the true spirituality of the animal. O'Connor notes, "No one would argue that preserved human DNA preserves the things that make us human." For example, in an attempt to resurrect the extinct Galapagos subspecies of the Pinta Island tortoise, scientists have tried to inbreed some other tortoises with some of the subspecies' DNA, a process that has been going on for a century, and one of the offspring may have all of the Pinta Island tortoise's DNA. whether this tortoise is the same kind of tortoise it once was, I'm sure many people have different opinions. "It's a bit of a paradox, to say the least," O'Connor says, "the more we get involved and try to save species, they tend to become less and less wild."

Human self-recrimination

Perhaps humans have a moral obligation to save some extinct species. For Jenny Lorraine, white rhinos are good candidates for resurrection, not only because they are an important symbol of Africa's large beasts, but because of the reasons for their extinction. "The rhinos went extinct from a very direct process - people killed them for their horns," Lorraine said, "and I think we have a responsibility to save these animals, which we killed in the wild environment."

The attempt to save the white rhinoceros, however, may have another impetus: human selfishness. 50 years ago, scientists succeeded in cloning the carp, now a vulnerable species. Using this technique to bring back the carp's population, however, does not sound as attractive as saving the white rhino from the brink of extinction. It is estimated that the rate of extinction of species on Earth due to human activity is 100 times faster than the rate in its natural state. Yet only those species that gain popularity in people's hearts - or make them feel particularly guilty - will get a chance to be saved. "I'm not going to save mosquitoes," Lorraine says, "trust me."

In this way, saving extinct species is more of a self-satisfied animal-care label. Resurrecting extinct animals shows that we desperately need to do something, but it's for the sake of humans, not the animals. For animals that are already extinct, it no longer makes sense whether they are resurrected or not.