So what is the source of this great acrimony that seems to exist between the two sides in this debate over the species-hood of Ebu Gogo? At one level it is theoretical dispute: Alan Thorne and Maciej Henneberg are proponents of the "Multi-regional" hypothesis of human evolution while Peter Brown and Mike Morwood, like the majority of scientists, accept the "Out of Africa" hypothesis. But scientific differences only go so far to explaining the apparent enmity involved.

Paleoanthropology is a small field and Australian paleoanthropology is even smaller. A quick Google search will tell you that, Thorne and Brown have been sparring for years, in fact ever since Brown, a former PhD student of Thorne's, started publicly disputing his findings. Thorne had argued that Australia may have been settled by two strains of human represented by different skeleton types: one gracile and modern looking found at Lake Mungo, the other robust with primitive, almost Homo Erectus-like, features from Kow Swamp. Thorne's view is that modern Aborigines are descended from both of these groups, a unique amalgam of modern human that can only said to have originated from Australia - not Africa.

Brown disagreed, arguing that there is no evidence to suggest that there really were two groups. What was "gracile" about the Mungo "man" was due to it being female not male and what was primitive about Kow Swamp skeletons was due to a head-deforming practice which had been applied to the individuals while they were still infants (a cultural practice still observed in some parts of Australia as late as the 19th century). Skeletons found in both groups were of human beings who were modern in every respect, as modern, apparently, as the day their ancestors set foot outside of Africa.
Years later, Peter Brown analyses a new skeleton found on an Indonesia island and declares it to be from a hitherto unknown hominid species. Alan Thorne, now retired from the ANU, takes the extraordinary step of flying to Jogjakarta to visit Teuku Jacob's lab - in the knowledge that the bones were under dispute and had been made inaccessible to the researchers who found them - to confirm his already announced position, that they were those of a human being, modern in every respect except for a certain deformity. Hmmm.
Fortunately for the rest of us, the Internet has made us all instant experts on everything. So I guess it's up to us to decide who's right and who's wrong. See for yourself: the above illustration comes from supplementary material supplied for Dean Falk's paper in Science where she made virtual endocasts of the brain-cases of various skulls and compared them against Homo Floresiensis.

Ebo Gogo's brain-case is in the middle, while a modern human one is above it and a chimpanzee's is below it. To the left is the brain-case of an individual suffering microcephaly (not the variety mentioned by Alan Thorne, by the way) and to the right is one from a Homo Erectus skull.

UPDATE: a good piece on Prof Teuku Jacob and Alan Thorne's reprehensible behaviour.