Scientists Reveal Why Sumatran Rhinoceros Has Been Close To Extinction For Thousands Of Years

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The Sumatran rhinoceros is one of the rarest animals in the world, with statistics showing that there might be less than 100 of their kind remaining in the world. And while environmentalists are very much aware that their numbers have been way down for quite some time, a new study has revealed that this rhino species’ decline may have started much sooner than once thought.

In a new study published this week in the journal Current Biology, a multinational team of researchers sequenced the entire Sumatran rhino genome, taking the sample from the Cincinnati Zoo’s male rhino Ipuh, who lived in the zoo for over two decades before his 2013 death. This marked the first time scientists were able to analyze such data in full, according to a report from Newsweek.

Based on the researchers’ findings, the Sumatran rhinoceros’ troubles might have started during the Pleistocene era, which was described by study author Herman Mays Jr., a professor at Marshall University, as a “roller-coaster ride.” This period, which spanned from 2.6 million to 11,700 years ago, saw the populations of Sumatran rhinos and other large mammals reach their peak. But as the period drew to an end, populations of these animals began to decline, with the Sumatran rhino’s numbers from about 9,000 years ago estimated at just 700.

“The population bottomed out and never showed signs of recovery,” Mays explained in a statement.

In order to get an idea of the Sumatran rhinoceros’ past history, the researchers used a technique called pairwise sequentially Markovian coalescent, or PSMC, which takes an individual of the species’ genome sequence, then estimates the demographics of that species over thousands of generations. After gathering PSMC data from Ipuh’s genome, the researchers then combined those results with climate data to see if weather events may have played a part in the Sumatran rhino’s decline.


Once all the data was analyzed, the researchers concluded that climate change compromised the Sumatran rhinoceros’ habitat in the Southeast Asian biogeographical region of Sundaland. According to the researchers, weather events toward the end of the Pleistocene period caused Sundaland to be submerged, resulting in the fragmentation of the species, which in turn led to their decline.

Although the Sumatran rhinoceros is not one of those endangered species whose decline was mainly brought about by man-made causes, the researchers noted that humans also played a part in further whittling down the species’ numbers. According to Newsweek, deforestation and hunting both contributed to the Sumatran rhino’s “quick” decline, as humans began to settle on the land.

“The Sumatran rhinoceros species is hanging on by a thread,” said researcher Terri Roth, of the Center for Conservation and Research of Endangered Wildlife at the Cincinnati Zoo and Botanical Garden.

“We need to do more to save it.”

At the present, there are varying estimates for the world’s Sumatran rhinoceros population. A report from BBC News stated that there might be less than 250 individuals remaining in the wild, while Newsweek’s report cited data from the World Wildlife Fund for Nature, which suggests that there are less than 100 Sumatran rhinos remaining in the world as of 2017. A new report from Channel News Asia also suggests that Iman, the last female Sumatran rhino in Malaysia, is suffering from serious health issues, which could further underscore the need to keep the species alive.

UPDATE [12/17/2017]: New information on Iman, Malaysia’s last female Sumatran rhino.