Only two northern white rhinos remain on Earth — two females, Najin and Fatu. But all isn’t lost for the subspecies quite yet — scientists have hatched a scheme to save the rhinos and recently published their findings in a new study revealing preserved cells that could hold enough genetic diversity to seed a viable population.
The San Diego Zoo Institute for Conservation Research led the study, published this week in Genome Research, scrutinizing cryopreserved cells stored at the institute’s Frozen Zoo. They sequenced the genomes of preserved northern white rhino cells as well as southern white rhino cells for comparison. San Diego Zoo Global director of conservation genetics Oliver Ryder told The New York Times, “If it came down to the materials in the Frozen Zoo, we could turn those cells into animals.”
How might they do that? Southern white rhino females could serve as surrogate moms; Earther said this could be accomplished in several ways such as cloning or putting “northern cell line DNA into a southern rhino egg cell” — or “turning northern white rhino cell lines into stem cells and then into eggs and sperm.” The scientists didn’t want to invest a lot in such plans until they knew they had viable genetic material, and the new study reveals surprisingly high genetic diversity among the northern white rhinos, close to that of southern white rhinos, which claim a larger wild pool.
San Diego Zoo conservation geneticist Cynthia Steiner told Earther, “We know the southern white rhino was able to recover from very few individuals — between 20 and 50 individuals a century ago — to the numbers we have now, which is about 20,000. A similar recovery could be possible if we succeed with a genetic rescue of the northern white rhino.”
But should they bring the northern white rhino back from the brink? Critics say resurrecting the animals could draw attention away from others with larger chances for survival, or the resurrected northern white rhinos would probably stay in captivity instead of roaming in the wild. Save the Rhino CEO Cathy Dean told The New York Times she wishes other rhinos received as much attention, such as the critically endangered Sumatran, Javan or black rhinos.