Apparantly they evolved from Homo Erectus.
And what they weren't adapted to was large volcanic erruptions, the same that wiped out the miniature elephants:
http://www.eastvalleytribune.com/index.php?sty=30692
Oh and it looks like they never co-existed with Homo Sapiens. We probably would have wiped them out much faster...
All in all an amazing find, it will be interesting to see if they can get mitochondrial dna and/or Y chromosomes.