A mammoth question: Should we revive extinct species?

One of the last two Northern White Rhinos in the world, at Ol Pejeta in Kenya. Photo: Gioia Forster/dpa

By Gioia Forster, Christian Thiele and Christina Horsten

Every year, hundreds of species become extinct - and humans are usually to blame. Some researchers think they could reverse the losses with the help of modern technology. But not everyone is on board with the idea.

Nairobi/New York (dpa) - The death last year of Sudan the rhinoceros in Kenya made news around the world. He was a celebrity in the animal world, the last male northern white rhino on Earth.

With his death, the subspecies almost went extinct. But science could help save it; there are still two females alive and frozen sperm available. Using modern technology, scientists in Berlin are working to create a baby northern white rhino.

To enhance the world's biodiversity, some researchers are going one step further: they would like to revive animals that in some cases died out thousands of years ago. At Harvard and in Santa Cruz, researchers are trying to bring the woolly mammoth and the passenger pigeon back to life. 

But scientists are very much at odds: Does this still qualify as wildlife conservation? Are we interfering too much with nature?

At one time, northern white rhinos roamed eastern and central Africa in large numbers; then, poachers killed them off. The fate of the subspecies now lies in a Petri dish. Researchers at the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin want to inseminate eggs from the last females in Kenya with sperm from the dead male in a laboratory.

A female from the closely related southern white rhino subspecies could carry the baby.

The procedures are still being tested, says Steven Seet from the IZW. Eggs have been taken from southern white rhinos in zoos and inseminated with sperm from the northern white rhino. The hybrid embryo was then implanted into a female southern white rhino. The transfer was successful, but it is not yet clear if the embryo has attached to the uterus.

Six thousand kilometres away, in a laboratory at Harvard University in the US city of Boston, work is underway to resurrect an animal that died out 10,000 years ago: the woolly mammoth.

Leading the project is George Church, a superstar among geneticists.

The animal is not being cloned since the genetic material of the mammoth that has been found is not sufficient. Instead, Church and his team are extracting certain DNA sections from the mammoth genome and inserting them into elephant cells. They are using new technologies such as the CRISPR-Cas9 molecular scissors, which can be used to precisely cut DNA.

Strictly speaking, it is not a mammoth that is being created, but a completely new animal.

"We're trying to make an elephant that is resistant to the cold and to poaching," Church says. You could for instance decrease the size of the animal's tusks to lower the poaching risk. But first results that will resemble elephants are not expected for at least another four years.

On the US West Coast, meanwhile, Ben Novak wants to use similar methods to resurrect the passenger pigeon. It used to fly in huge flocks over the United States, but became extinct at the end of the 19th century. 

It will probably be another five to 10 years before the first chicks hatch, according to the researcher at the University of California in Santa Cruz.

"Some time after 2025 is possible, but more likely closer to 2030," Novak says.

The only animal subspecies that has so far actually been revived is the Pyrenean ibex. The last animal died in 2000, but before his death a cell sample was removed and frozen for cloning. The cloned fawn - carried by another kind of ibex - survived for only a few minutes after its caesarean birth.

Advocates for de-extinction - the revival of extinct animal species - insist that their work is not about making headlines.

"We want to bring biotech to conservation ... to create a more bio-diverse, bio-abundant world," says Ryan Phelan, the head of the organization Revive and Restore, which supports projects like those of the mammoth and passenger pigeon.

But many scientists disapprove.

"This is a waste of time," says evolutionary biologist Stuart Pimm from Duke University in the US city of Durham.

To save species from extinction, you have to solve the actual problem, he says: the conflict between human and animal. The research being done by Church and others leads to dangerous negligence, in Pimm's view.

He argues that if killing off and then reviving a species were an option, there would be no need to care about conservation any more.

Pimm also cannot help but wonder: "What would we do with a woolly mammoth?"

Church already has an answer to that question. He wants to settle the mammoth elephant in Siberia. This way, a giant, barely inhabited area would be used to create an ecosystem for a new species.

And "we could help slow down climate change," he says. The mammoths would stomp down the snow and help prevent the ground from thawing. This would in turn lead to fewer greenhouse gases such as carbon dioxide and methane making their way into the atmosphere.

Nikita Zimov is eagerly awaiting the newcomers. The Russian scientist is in charge of a vast nature reserve in eastern Siberia, which is meant to one day again feature grassland - as was the case during the last ice age, when mammoths roamed the region.

If successful, Church has promised to send the first mammoth to Pleistocene Park, Zimov says.

But a single animal will not make much difference in the fight against climate change. Zimov says many, many more are needed: "To have meaningful impact on the climate, I would say thousands - hundreds of thousands."

Published by the German Press Agency (dpa).