There are two northern white rhinos left on Earth. Can a controversial approach save them?

A global consortium of scientists racing to save the northern white rhinoceros—two females shy of extinction—are now enlisting help from U.S. biotech company Colossal, known for attempting to resurrect extinct species such as the woolly mammoth, the dodo, and the Tasmanian tiger.

Thomas Hildebrandt, leader of the BioRescue consortium and an expert in wildlife reproduction based at Leibniz-Institute of Zoo and Wildlife Research in Berlin, says he was initially reluctant to work with Colossal.

“I don’t like this idea to recreate the mammoths and call it a conservation project,” he says. However, he’s come to realize that the tools developed by Colossal might be instrumental in the pursuit to rewild a healthy northern white rhino population.

“We want to save a keystone species, which played a very crucial role in a complex ecosystem in Central Africa,” Hildebrandt says. “We still have time to bring the rhinos back, and we strongly hope to achieve the first reintroduction of the northern white rhino in 10 to 20 years.”

Colossal founder and CEO Ben Lamm says the company’s involvement illustrates how its $225 million dollar investment in “de-extinction” can also boost conservation of living species before they vanish. (Read about the controversial quest to bring back the Tasmanian tiger.)

“The vast majority of conservation is focused on preserving land, stopping poaching.… but when you get down to the point that you’ve only got two females, you have to do more advanced technologies,” Lamm says.

He’s hopeful that their “whole de-extinction toolkit can be used by conservation groups and governments all around the world to save species.”

The 11^th hour

White rhinos, native to sub-Saharan Africa, are divided into two subspecies—southern and northern.

Poachers kill rhinos for their horns, which are then sold on the black market for traditional medicine and carvings, decimating the animals’ populations. By the late 1800s, only about 20 southern white rhinos were left. A century later, conservation efforts have boosted their numbers to about 16,000 rhinos in eastern and southern Africa. The northern white rhino, however, became extinct in the wild in 2008, leaving only a handful of survivors in zoos. (Read more about efforts to protect rhinos from poaching.)

In 2009, the last four breeding northern white rhinos—two females and two males—were flown from the Dvůr Králové Zoo in Czechia to a new home at Kenya’s Ol Pejeta Conservancy, a nonprofit at the foot of Mount Kenya. Some conservationists believed that the rhinos might be more likely to breed in their natural environment. Under the watchful protection of 24/7 armed guards, the animals did mate, but the females did not become pregnant. In 2013, one of the males, Suni, died suddenly from a heart attack. Soon after, Hildebrandt made a disappointing discovery while examining female Najin and her daughter Fatu: Both of them suffered from ailments that would prevent them from ever having a successful pregnancy.

Another tragedy struck in 2018, when Ol Pejeta had to make the wrenching decision to euthanize Sudan—at 45 years old, the world’s last male northern white rhino—after a leg infection and age-related illness became so severe, he could no longer stand.

Last hope

By then, it had become clear that in vitro fertilization would be the only hope to save the species, says Samuel Mutisya, Ol Pejeta’s head of conservation.

On August 22, 2019, Hildebrandt and a team of veterinarians successfully collected eggs from Najin and Fatu—the first time the procedure was ever performed in northern white rhinos.

Those eggs were speedily transported to Aventea, a private laboratory in Italy specializing in animal reproduction, where founding scientist Cesare Galli artificially inseminated them with frozen sperm collected from male northern white rhinos before they died in zoos. Since then, additional egg collections have helped Galli create 29 northern white rhino embryos. 

The BioRescue team aims to soon implant one of those embryos into a southern white rhino surrogate mother, with the goal of producing a healthy calf by 2025. This offspring would be considered genetically a northern white rhino. (Read about Ami Vitale’s work photographing the last northern white rhinos.)

“We have to produce a baby quite soon because we also want to save the social heritage—the language and behavior—of the last two northern white rhinos. They can’t learn that from the southern white rhinos,” says Hildebrandt.

How de-extinction works

So where does Colossal come in? Their genomic technology is key. For its woolly mammoth de-extinction effort, for instance, the company is working to add genes for mammoth traits, like cold tolerance and shaggy fur, into elephant DNA.

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The hope is to eventually produce embryos of those mammoth-like elephants that can be implanted into living elephant surrogate mothers. (Read: Should we bring back extinct animals?)

By comparison, the rhino project is what Lamm calls “genetic rescue.” Rather than piecing together a species, they’re mining DNA from museum specimens of northern white rhinos from around Africa to determine what genetic diversity was lost from the population.

The next step would be using gene-editing tools to reintroduce genetic diversity into the cells used to create embryos, which can help protect a future herd against disease and other threats.

“It’s a slow game,” James says. “But as we develop these technologies, we can scale up the population more quickly…. In our lifetime, we will see northern rhinos back in their range states.”

No silver bullet

 Some critics argue that such extreme measures to save a species from the edge—or bring them back from the beyond—takes time, attention, and resources away from other endangered animals that can be saved conventionally, and for far less money. (Read more about Pimm’s case against reviving extinct animals.)

Stuart Pimm, a Duke University expert on wildlife extinction and conservation management, is a strong opponent of de-extinction because he worries that it’s “giving people the excuse to allow species to go extinct and then say we can keep them alive in a test tube.”

Though he’s more sympathetic to the effort to save the northern white rhino, he still has concerns: “Even if this technology works, how are we going to put those animals back into the wild? We lost the northern rhino because we destroyed its habitats and because rhinos were poached.”

Colossal’s James says their work with northern white rhinos, or any other endangered species in the future, is not a “silver bullet” solution for preventing extinctions. “We provide a very integral innovative tool,” he says, “but it has to be married directly to traditional conservation work.”

Pimm agrees it would be a tragedy to lose the northern white rhino.

“Two rhinos fighting is one of the most extraordinary wildlife spectacles I’ve ever seen. They are so amazingly big, and they’re fast, and they go after each other with an intensity that’s unbelievable. You feel as if the Earth is shaking under your feet.”