I was just watching the cable TV show “ANIMAL PLANET”, which had a show on about the attempts to save the (endangered) Sumatran elephant. Apparently, this elephant is a subspecies of the Indian Elephant, but sufficiently different that it cannot interbreed with the Indian variety. I have two questions: the indonesian archipelago was connected to mailand Asia during the last Ice Age (ca 12,000 years ago), so it is reasonable to suppose that the elephants ranged as far south as Australia. If this is so, why are there no elephants in present day Australia? You would thing that the continent would be big enough to provide a range for them. Also, the show said that elephants inhabited the islands of Java and Borneo until historic times-were humans sufficiently advanced enough to kill them all? Finally, how could the genetic differences (between the Indian and Sumatran elephants) become so pronounced over a mere 12,00 years?
I think you might be a little confused with geography of the area. The Indnoesian Archiplelago was connected to Mainland Asia 12,000 years ago. New Guinea was connected to Australia as recently as 10,000 years ago, but there’s several hundred miles separating Indonesia and New Guinea. There are a few (a lot actually) of dinky islands in between, but it would need some pretty fancy swimming for a population of elephants to navigate all that open ocean. People only just managed to do it in canoes around 60,000 years ago, and I don’t think elephants had that sort of technology back then 
Elephants require flaming ducks to stamp upon, in order the keep thier feet flat. There being no ducks in Australia, the Australian elephant had no option but stamping duck-billed platypii, which have a much higher ignition temperature, due to its aquatic surroundings. The Australian elephants feet eventually became round, rendering them unstable (in the physical sense). Aborigine teenagers would tip them over for a prank, since no cows were available. These are the factors that led to pachydermititis, which proved fatal.
australia separated from the mainland of pangea before the emergence of placental mammals. All mammals native to australia are marsupials. 12000 years ago, during the last ice age, the ocean level dropped to the point where several land masses were connected by land bridges or at least chains of islands, allowing movement of land mammals from india to sri lanka, but the sea level didn’t drop enough to cause emergence between australia and asia or between madagascar and africa.
You will find wild camels in australia, as well as dogs and rabbits, but these were all introduced by western man after the discovery of australia by captain cook. the real reason there are no elephants in australia is that the english were not in the habit of using elephants as beasts of burden. If the indians had settled australia, the island continent would probably be chock-a-block with elephants, nothing but elephants as far as the eye can see. Plus there’s that flaming duck thing.
The line which seperates the Asian biogeographic region from the Australian is named after Alfred Wallace, the co-discoverer of the Theory of Natural Selection. He first noticed it in reference to butterfly populations in the boundary islands in the strait between New Guinea and Malaysia.
If butterflys (which have wings) could not breach the barrier, elephants (which would have had to drift up on floating logs, just like the camels) didn’t have a chance.
For the record, humans have wiped out almost every species of elephant in the world leaving only the Elephas in Asia and the Loxodonts in Africa. Since we were able to kill off all the mammoths, mastodonts, and the dwarf elephants of Malta with only “stone-age” technology, the populations of Elephas on Java and Borneo posed no problems at all.
12,000 years is sufficient time for two populations to become reproductively isolated.
Anyone else have the glorious mental picture of Steve Irwin being trampled to death by stampeding elephants?
BTW I don’t know what elephants would live on if they were introduced to Australia. The vast majority of our continent is extremely arid and it’s difficult to envisage elephants not dying out extremely rapidly here.