Though the northern and southern white rhinos are formally classified as subspecies, some biologists have argued that, having diverged from each other a million years ago, they deserve full species status.
The latest evidence suggests that while they are genetically distinct, they interbred (and thus shared genes) as recently as 14,000 years ago, when grasslands expanded to bring their ranges together, before retreating once again.
Southern white rhinos outnumber all other rhino species combined. The northern white, which once ranged across the central African grasslands, is arguably the most endangered mammal on the planet – only two females survive.
Any disappointment that we don’t have an extra rhino species may be assuaged to some extent by the bolstered hopes for preserving what’s left of the northern gene pool through hybridisation with southerns.
Main image: southern white rhino © Getty Images