Scientists Sequence “Asian Unicorn” Genome To Guide Preservation Efforts

Researchers have sequenced the genome of the saola (Pseudoryx nghetinhensis) for the first time, offering new insights into the history and conservation prospects of one of the world’s rarest mammals. Also known as the Asian unicorn, the elusive antelope-like species is only known to inhabit the remote Annamite Mountains in Laos and Vietnam. It was first described by scientists in 1992, and the last confirmed sighting in the wild was in 2013.

The new study, published in Cell, was conducted by an international team of scientists from Denmark, Vietnam and other countries. It marks a milestone in conservation genomics for the species, whose population status remains uncertain. According to the International Union for Conservation of Nature (IUCN), fewer than 100 individuals likely remain, making the saola one of the most endangered mammals in the world.

Genetic data suggest ancient population split

Until now, little was known about the genetic history of the saola. In the new study, researchers extracted DNA from bone fragments housed in hunters’ households. From these materials, they generated complete genomes for 26 saolas. The analysis revealed that saola population can be divided into two genetically distinct populations, which diverged between 5,000 and 20,000 years ago.

"We were quite surprised to find that the saola is split into two populations with considerable genetic differences," said lead study author Genís Garcia Erill, who was a PhD at the University of Copenhagen when the research was conducted. He is now a postdoc at Aarhus University. 

"That was completely unknown before, and there was also no way we could have known without genetic data. It is an important result because it affects how the genetic variation in the species is distributed."

Both saola populations have experienced a long-term decline in numbers since the last Ice Age, however, the analysis reveals that each population has retained a unique set of genetic traits. 

“This means that the genetic variation lost in each population complements the other. So, if you mix them, they could compensate for what the other is missing,” says Genís Garcia Erill.

Potential for a genetic rescue strategy

The study’s models suggest that combining individuals from both genetic populations into a single captive breeding program may offer the highest chances of species recovery. According to the researchers, even a small initial group (approx. 12 individuals) could support long-term survival.

Finding 12 saolas, however, is no easy task. No live saolas have been observed in over a decade and the species’ remote habitat makes it especially difficult to track. 

“Many researchers have unsuccessfully tried to find traces of saola through methods like environmental DNA in water and even in leeches, the blood suckers inhabiting the same habitat," said study co-author Minh Duc Le, of Vietnam National University. "These techniques all rely on detecting tiny DNA fragments, and now that we know the complete saola genome, we have a much larger toolkit for detecting those fragments."

A toolkit for detection and future research

Having access to the full genome may enhance the chances of locating the remaining saolas. But this data may also hold future value even if no surviving saolas are found.

“Our results could in theory be used if we were ever to succeed in bringing the saola back through genetic de-extinction technologies, which are a hot topic right now. In that case, our new insights into saola genetic variation could make a huge difference in creating a viable population,” said study author Rasmus Heller, an associate professor at the University of Copenhagen.

“Scientists have been searching for saolas since the 1990s, and it’s only gotten harder since then, because there were more of them back then," Heller continued. "I’m not overly optimistic, I have to admit – but I really hope the saola is still out there."

Reference: Garcia-Erill G, Liu S, Le MD, et al. Genomes of critically endangered saola are shaped by population structure and purging. Cell. 2025:S0092867425003903. doi: 10.1016/j.cell.2025.03.040

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