From six million-year-old Orrorin tugenensis to Australia's 40,000 year-old Mungo Man, it seems that controversy swirls around almost every new skeleton that falls out of the human family closet.

If Debbie Argue's cladistic analysis of the morphology of diminutive Homo floresiensis is on the mark, the two million-year-old australopithecine roots of the human family tree threw up a little sucker that persisted into very recent times.

Some critics have argued that the "hobbits" are pathological, microcephalic modern Homo sapiens, but the consistent size and morphology of the partial fossils during the 6000-year period from 18,000 years to 12,000 years ago argues otherwise.

The cave floor sediments yielded small stone tools dating from 94,000 to 13,000 years ago, a period encompassing the time of its occupation by "hobbits", and supporting claims that they represent a new and distinct species of Homo.

In their folklore, the nearby Nage people of Flores describe encounters with tiny pot-bellied, hairy humans around a metre tall, with prominent ears, called ebu gogo, who conversed with each other in murmurs, and parroted words spoken to them. Ebu gogo means "grandmother who eats anything" - they were apparently gluttons.

If the tales are true, ebu gogo were extant when Portuguese colonists arrived 400 years ago, and may have persisted until the later Dutch occupation until about 100 years ago - a possibility that fuelled the media sensation surrounding the hobbits' discovery.

While the hobbits have been formally accorded the status of a distinct species, not everyone is convinced.

How likely is it that another species of Homo persisted for at least 15,000 years after the last Neanderthals went extinct in Europe, despite living in the direct migratory path of waves of island-hopping modern H. sapiens who for at least 42,000 years had been using Flores as a stepping stone to Timor, en route to colonising Australia, New Guinea and the Pacific?

Dr Peter Obendorf and Dr Ben Kefford, of RMIT University's School of Applied Science, and Professor Emeritus Charles Oxnard, of the Centre for Forensic Science at the University of Western Australia, have issued another challenge to the hobbits' newfound species status.

In a paper in Proceedings of the Royal Society BL Biological Science, they revisit the hypothesis that hobbits are simply pathological modern H. sapiens. They offer an environmental explanation for the recurrence, over 6000 years, of a set of physical traits including diminutive stature, microcephaly and apparently primitive skeletal features.

The paper provoked a storm of controversy when it was published earlier this year. Professor Colin Groves from the School of Archaeology and Anthropology at the ANU said he was sorry to see serious scientists involved in such a "travesty" and that many of the claims were sheer speculation and some flew in the face of the evidence.

Professor Peter Brown from the University of New England, who was part of the team that discovered H. floresiensis, said the conclusions in the paper were not supported by the facts. "The authors have not examined the original fossil, have little or no experience with fossil hominids and depend upon data obtained by others," he said.

But others, such as Professor Maciej Henneberg from the University of Adelaide, who first proposed that the hobbits were not a new species but a pathological modern human, said the paper was a welcome addition to the debate.