Careful study of the "Hobbit" fossil's wrist bones supports the idea that the creature was a distinct species and not a diseased modern human, it is claimed.
Matthew Tocheri and colleagues tell Science magazine that the bones look nothing like those of Homo sapiens; they look ape-like.
The announcement in 2004 detailing the discovery of Homo floresiensis caused a sensation.
Some researchers, though, have doubted the interpretation of the find.
These individuals - including the Indonesian palaeoanthropologist Teuku Jacob - have argued that the remains are probably those of a pygmy with the brain defect known as microcephaly.
But the new analysis by Tocheri, from the Smithsonian Institution in Washington, DC, US, and co-authors will add further weight to the original assessment.
Their study shows that the wrist bones of the Hobbit are primitive and shaped differently from the bones of both modern humans and even their near-evolutionary cousins, the now extinct Neanderthals (Homo neanderthalensis).
The creature's wrist lacks a modern innovation seen in both these other human species - a wrist that distributes forces away from the base of the thumb and across the wrist for better shock-absorbing abilities.
"What was very clear from my perspective looking at the Hobbit's wrist bones is that it does not belong in the group that includes modern humans and Neanderthals. It basically has the same type of wrist that we see in [the ancient hominid] Homo habilis, that we see in Australopithecus (the famous 'Lucy' fossil) and that we see in living chimps and gorillas today," Matthew Tocheri told BBC News.
The 18,000-year-old bones of the Hobbit were unearthed on the Indonesian island of Flores, in a limestone cave at a site called Liang Bua.
Researchers found one near-complete skeleton of a female, which they designated LB1, along with the remains of at least eight other individuals.
The scientists believe these 1m-tall (3ft), small-brained people evolved a short stature to cope with the limited supply of food on the island.
The specimens were nicknamed Hobbits after the tiny creatures in JRR Tolkien's Lord of the Rings trilogy.
Subsequent detailed study of LB1's brain case and the tools found with the bones also support the position that H. floresiensis was a species distinct from modern humans.