In the shrouded forests of the Annamite Mountains, along the border of Vietnam and Laos, lives — or perhaps once lived — one of the world’s rarest mammals. It’s a creature so rare that even its existence is a matter of debate. It has never been seen in the wild by a scientist. Only a few camera trap photos and bones were traded among hunters offer as proof that it was ever there at all.
Locals call it the saola. Scientists call it Pseudoryx nghetinhensis. And to the wider world, it’s known simply as the “Asian Unicorn.” It’s a fitting name because the animal seems to be as rare as a unicorn. But despite never actually seeing it, an international team of scientists has taken a major step toward finding and perhaps saving it: they have sequenced its genome.
“Right now, the existence of live saolas can neither be proven nor disproven,” said Nguyen Quoc Dung, a Vietnamese forest researcher who helped lead the effort. “There are some signs and indications that still give us hope.”
First described in 1993, the “Asian Unicorn” was an evolutionary enigma from the start. Despite the nickname, it doesn’t feature a horn in the middle of its head. Rather, it has two long, parallel horns and mix of goat- and cow-like features that baffled taxonomists.
In a study published in the journal Cell, researchers mapped the genomes of 26 individual saolas. They used genetic data from biological remains — mostly bones and tissue fragments collected from hunters’ households. It’s the first time scientists have been able to peer so deeply into the animal’s genetic past.
A Lineage Unlike Any Other
With the help of whole-genome sequencing, researchers have now placed the saola firmly as a sister lineage to cattle and buffalo. Their common ancestor dates back around 14 million years—giving the saola one of the most distinct evolutionary histories of any large mammal alive today. Another surprise showed that there seem to be two distinct saola populations.
“We were quite surprised to find that the saola is split into two populations with considerable genetic differences,” said Genís Garcia Erill, the lead author of the study. According to their analysis, these two groups diverged between 5,000 and 20,000 years ago.
Each population lost different pieces of genetic variation. As a result, they now complement one another. “So, if you mix them, they could compensate for what the other is missing,” said Garcia Erill.
This surprising result offers a potential conservation lifeline. When animals get close to extinction, they go through a “genetic bottleneck” where there’s not enough genetic diversity in the population. This suggests a potential source of variation. Furthermore, if scientists can locate and capture a few individuals from both lineages, they could start a captive breeding program designed to stitch the fragmented gene pool back together — giving the saola a renewed shot at long-term survival.
“Our models show the species would have a decent chance of long-term survival,” said Rasmus Heller, a geneticist at the University of Copenhagen and senior author of the study. “But it hinges on actually locating some individuals.”
An Uncertain Search and a High-Tech Toolkit
But we’re facing the same problem. No scientist has laid eyes on a live saola in decades. The last confirmed photo of one in the wild was snapped in 2013. Fewer than 100 likely remain, and they could be fully extinct. “I’m not overly optimistic, I have to admit – but I really hope the saola is still out there,” Heller said.
Still, the new genomic data may be just what conservationists need to find the unicorn again.
Efforts to track the saola have often relied on indirect methods — environmental DNA in water, or blood traces from leeches collected in the animal’s range. But those techniques are only as good as the reference genome they’re matched against.
“Now that we know the complete saola genome, we have a much larger toolkit for detecting those fragments,” said Minh Duc Le, a co-author of the study from Vietnam National University. Armed with this genetic map, future searches may be able to zero in on trace evidence of the saola’s presence more precisely than ever before.
But what if scientists fail to find any living individuals?
In this case, the saola genome could, in theory, provide the foundation for a de-extinction project, similar to efforts already underway for the woolly mammoth and the thylacine. It’s a controversial idea, but one that seems to be gaining popularity.
“Our results could in theory be used if we were ever to succeed in bringing the saola back through genetic de-extinction technologies,” said Heller. “Our new insights into saola genetic variation could make a huge difference in creating a viable population.”
Captive Breeding: Risk or Rescue?
The implications for conservation are clear. Mixing the two populations in a future captive breeding program could not only boost genetic diversity but also improve the animals’ health. Simulations showed that breeding programs with individuals from both populations had significantly higher survival odds than those relying on either group alone.
Still, the study authors offer a word of caution. “We emphasize… that our study only addresses the optimal management of the genetic resources, and it is outside the scope of our study to evaluate whether captive breeding is in fact the optimal conservation strategy for the saola.”
For now, no saola is known to survive in captivity. Some fear the animal may already be extinct in the wild. But researchers haven’t given up just yet. Genetic tools like environmental DNA and blood samples from leeches may help locate hidden individuals in the forest. These efforts are already underway.
