Evolution and taxonomy of Asian elephants

Museum researchers are studying the morphology of Borneo elephants, an interesting population that is genetically distinct from all other living elephant populations.

There are currently three recognised subspecies of Asian elephant, Elephas maximus:

• E. m. maximus of Sri Lanka and southern India
• E. m. sumatrensis of Sumatra
• E. m. indicus throughout the rest of the range

The physical differences between them are a matter of degree and are expressed as gradual changes across the range:

• Elephants from Sri Lanka:
  • are the largest
  • have the darkest skin colour
  • have the largest ears
  • are most prone to pink depigmentation of the skin on the face, trunk and ears
• Elephants from Sumatra:
  • are the smallest
  • are lightest in colour
  • are least prone to depigmentation

Fossil comparisons

In collaboration with colleagues in the UK, Israel and elsewhere, we have investigated the evolutionary origin of the Asian elephant through a comparison of fossils from northern India/Pakistan and the Middle East, many of them in the Museum collections.

Fossils from Bethlehem, excavated in the 1930s, are probably more than three million years old and may represent the earliest record of the mammoth/Asian elephant lineage out of Africa.

Our current focus is on historical populations of Asian elephants that lived in the Near East, far to the west of the species’ current range in the Indian subcontinent and south-east Asia.

We studied skulls and skeletons of elephant excavated in an area of south-east Turkey, and dated them by radiocarbon to the Bronze Age, around 1500 BC. DNA analysis of the bones (the first ancient DNA from this species) showed them not to be genetically distinct from living Asian elephants, even though they had previously been named as a distinct subspecies.

The bones show no trace of human activity, so we consider this to be a wild-living population, rather than one brought from the East for domestic use, although this is a subject of debate.

Further back in time, remains of Elephas hysudricus, the species considered ancestral to the living species Elephas maximus, have been identified from sites in Jordan and Israel, some of them as late as 300,000 years ago (half the age of the latest fossils from India), suggesting the origin of the living species was quite recent.

Type specimen

Finally, in collaboration with colleagues in the UK, Denmark, Italy, and elsewhere, we have properly defined, for the first time since Linnaeus named the species in 1758, a type specimen (lectotype) for the Asian elephant Elephas maximus.

About Borneo elephants

The elephants of north-east Borneo present an interesting case. Genetically distinct from all other living populations, they may have been isolated there for hundreds of thousands of years, since Borneo was connected to the mainland during the ice ages.

However, there is circumstantial evidence that people imported them from Java a long time ago. Since elephants are extinct on Java, the Borneo population may represent the last surviving relict of the 'Javanese' subspecies.

Borneo elephants have been described as a separate subspecies, Elephas maximus borneensis. They are said to be pygmies, perhaps an example of 'island dwarfing'.

A Natural History Museum-led expedition in 2008 investigated this claim by measuring the height of elephants in the field using a laser rangefinder technique.  

Our results suggest that Borneo elephants are not significantly smaller than those of mainland south-east Asia. Our research on their status continues.