May not be extinct after all. Borneo pygmy elephants may be descendants of Javan elephants given as gifts between rulers and gone native.
Wow, thanks for that. Love elephant news: they are such smart beasts of burden,have worked hard for us humans, and we are now understanding their complexity.
These guys are so small. What is their heritage?
Missed the edit window; better question:Why did these elephants go diminutive, with a race that is generally mammoth by definition?
“Pygmy” is misused. They are 2.5 meters tall vs 3.0 meters for your basic Asian elephant. I believe that is shoulder height rather than head height.
An elephant news link
And the place I visit and harp about here on the SDMB. 
What elelle said. Good elephant news always makes me happy.
I think the most important question here, is can we breed the pygmy elephants to pot-bellied pigs, and thus achieve pot-bellied elephants? Clearly, using the big guys was a pipe dream, but now that we have a solid population of pygmies…
Island biogeography. Animals tend to shrink when living on small islands (over generations) due to scarce resources, such that the smaller individuals can better survive. There were races of pygmy elephants on several Mediterranean islands until about 3-4,000 years ago, even smaller than these IIRC. Wiki article
Go elephants!
Thanks for that, John. An ace answer, and expanded my elephant knowledge,always a good thing in this sweet world!
These aren’t terribly small; 2.5 meters vs 3 meters for you Basic Asian Elephant. What size were these Mediterranean guys?
The Wiki article states a mass of 200 kg, about twice a full grown human male.
One wonders if the Borneo elephants are continuing to evolve to a smaller size. If so, it seems that it would take a while for this to be a useful adaptation. A lack of food would be a rather immediate obstacle.
For comparison, Miss Betts (scroll to the bottom of the page) weighs 500 pounds (227 Kg), and one of the keepers said on visitors day, “…it’s all muscle. It took six of us to get that little lady down here.”
(263 Lbs was her birth weight. Shes was four months old at the time of the “six of us” comment.)
I notice that the wiki article mentions the pygmy mammoth formerly inhabiting our local Channel Islands. Heh, pygmy mammoths, sort of like jumbo shrimp.