The elephants of Borneo have achieved scientific fame by being recognised as a new subspecies.
By Alex Kirby
BBC News Online environment correspondent
WWF, the global environment campaign, says DNA sampling and analysis of the animals' dung has proved the case.
Borneo's elephants are different
The animals are appreciably different from other elephants on the Asian mainland.
Scientists believe they must have been on the island for many thousands of years.
The DNA sampling was carried out by the Sabah wildlife department and WWF-Malaysia.
Samples of dung from across Borneo were collected and sent to Columbia University's department of ecology, evolution and environmental biology in the US for assessment and comparison with other elephants from across Asia and Sumatra.
Borneo's so-called "pygmy" elephants are said to be smaller, tamer and better-tempered compared with their cousins on mainland Asia and Sumatra.
The DNA evidence shows Borneo's elephants were isolated about 300,000 years ago from their relatives elsewhere in Asia.
Trapped by the waves
During that time they grew smaller, with relatively larger ears, longer tails and straighter tusks. Their genetic distinctiveness makes them one of the highest priority populations for conservation.
"This discovery is fantastic news. It was thought these elephants had been introduced to Borneo by the British East India Company as gifts to the Sultan of Sulu in the 17th Century," said Stuart Chapman, head of WWF's species programme.
The new subspecies is a conservation priority
"But this proves they were already there - remnants of a larger population that once roamed Borneo and were trapped on the island after sea levels rose and severed the link with Sumatra."
Mr Chapman told BBC News Online: "Asian elephants are 10 times more endangered than those in Africa - there are only about 35,000 of them in the wild, spread over 10 countries.
"There are thought to be from 500 to 2,000 of the Borneo elephants. The crux of the genetic survey is that it ratchets up the need for direct action to conserve them.
"They've adapted to their local environment, and they have unique characteristics, so they're essential for maintaining the diversity of the species in Asia.
"In Borneo the main threat is habitat loss, particularly for cash crops like oil palm and other crops which can attract the elephants.
"They're not helped by their lack of aggression. When someone approaches they don't charge but often back away, almost apologetically, and that increases their vulnerability."
Images courtesy of WWF-Malaysia.