Sudan, the last remaining male northern white rhino, has died in captivity at the Ol Pejeta Conservancy in Kenya.
He was 45 years old—elderly for a rhino—and his unexpected death may have been a result of infections and other health problems. Two northern white rhinos remain: Najin, Sudan’s daughter, and Fatu, Sudan’s granddaughter.
Northern white rhinos are a subspecies of southern white rhino, though some researchers argue they should be considered their own species. They’re hairier, smaller, and have different dental structures.
The population of northern white rhinos has been decreasing since 1960 when about 2,000 rhinos were living on the grasslands of east and central Africa. By 2008, researchers couldn’t find any. War, habitat loss, and poaching for their horns contributed to the subspecies’ extinction in the wild.
The only northern white rhinos left were located in zoos around the world-including Sudan, who was captured in 1975. Here’s Rachel Nuwer for The New York Times:
“Sudan is an extreme symbol of human disregard for nature,” said Jan Stejskal, director of international projects at the Dvur Kralove Zoo in the Czech Republic, where Sudan spent most of his life. “He survived extinction of his kind in the wild only thanks to living in a zoo.”
The possibility of losing these creatures has led to a team of scientists from five different continents to band together and develop reproductive technologies that may save the subspecies. They intent to use classic reproduction techniques and innovative stem-cell technologies.
These scientists hope to fertilize northern white rhino eggs in vitro and then implant embryos in surrogate southern white rhinos. White rhino sperm is available from males unrelated to Najin and Fatu, but even if they were to get pregnant, they’re unable to carry the calf to full term. Additionally, they would lack genetic diversity.
In vitro fertilization is common for humans and livestock, but it’s never been performed successfully on a rhino. Researchers have accomplished to extract eggs from southern white rhinos and expect to use a similar procedure on Najin and Fatu. They hope to combine these eggs with frozen cell cultures-which will be created into sperm cells-from 12 northern white rhinos. In theory, this will become an embryo.
Still, this procedure could take up to 15 years to accomplish. At which point, it may be too late to save the northern white rhino. However, scientists hope this technique could save other species—especially since all rhino species are under threat of extinction.