The elephants are around a fifth smaller than the average Asian elephant, but around the same size as those in Malaysia. Sainam51/Shutterstock
The Bornean elephant has always been something of an enigma, but now what is the highest dosage of prozac seems we might be a step closer to understanding just where they came from.
Smaller in size than most Asian elephants (and thus sometimes known as pygmy elephants as a result), they only live in a small region of forest in northeastern Borneo. Curiously, the animals are not found anywhere else on the island, and it's thought that historically their range has been fairly limited.
This has given rise to a popular theory that the diminutive elephants are not actually native to Borneo, but are a remnant feral population of pachyderms that originate from captive elephants kept by the Sultan of Sulu, who was frequently gifted the beasts by neighboring Sultans during the 17th century. The story goes that some of these elephants escaped and founded the isolated population we see today. Their passive nature and behavior has been used to support this.
There is, however, a problem with this theory. Genetic tests of the animals showed that their DNA is significantly different from Malaysian elephants, even though the creatures are similar in size.
One study estimated that the last common ancestor between the Malayan and Bornean elephant existed some 300,000 years ago. This suggests that when the sea level was lower, some of the animals crossed a land bridge and have been isolated ever since. The problem with this is that despite the supposed long history of elephants in Borneo, not a single elephant fossil has yet been found, despite those from other forest animals like the orangutan turning up.
To try and shed some light on this confusing history, a group of researchers decided to combine genetic data with computational modeling and run a number of different scenarios to track the demographic history of the animals.
"We compared the results from these models with the existing genetic data, and used statistical techniques to identify the scenario that best explained the current genetic diversity of the elephant population in Borneo," explains Lounès Chikhi, who led the research published in statement.
The results suggest that both established theories might be wrong. They found that the most likely scenario was that the elephants colonized the island between 11,400 and 18,300 years ago, corresponding with when the sea levels were a lot lower.
"We cannot exclude more complex scenarios, but a historical human introduction seems very improbable, and so does a very ancient arrival," says Reeta Sharm, first co-author of the paper.
By settling the debate about whether or not the elephants are native, the researchers hope they can influence increased protection for the animals, of which there are only around 2,000 left in the wild.