Scientists sifting through artifacts and skeletal remains in a damp cave on a remote Indonesian island have found new evidence that a race of tiny, primitive "Hobbit"-like human ancestors lived there as recently as 12,000 years ago.

The Australian-led team unearthed a lower jawbone and other bones from as many as nine individuals at the Liang Bua cave on the island of Flores. All the bones are from human ancestors who stood 3 feet tall and lived between 18,000 and 12,000 years ago.

The controversial Flores site, first reported a year ago, has left paleontologists puzzling over how such ostensibly primitive beings -- with 25-cubic-inch brains similar in size to those of human ancestors 3 million years old -- could make sophisticated tools, master fire, and kill, butcher and cook small elephants with the skill of modern humans.

"We've presented the evidence," team leader Michael J. Morwood said in a telephone interview from Australia. "We have a lot of tools, and they're very sophisticated. People can make up their own minds."

Morwood, an archaeologist from Australia's University of New England, suggested that the newest findings -- bones from many individuals dated over a long period of time -- dispelled the skeptics' view that tiny, archaic humans such as the inhabitants of Flores were, in fact, modern humans with some form of dwarfism.

Primatologist Robert Martin of Chicago's Field Museum, a leading critic, acknowledged that having a second jawbone 3,000 years younger than that of the original fossil "makes it more difficult" to argue that microcephaly -- small-headed dwarfism -- would persist for 100 generations.

He also called it "interesting" that the second jawbone, like that of the original fossil, had no chin, another characteristic of archaic humans. Modern humans are the only primates, past or present, who have chins.

But archaeologist James Phillips, a Martin colleague from the University of Illinois at Chicago and the Field Museum, said that regardless of physical characteristics or bone dates, there is "simply no way on this earth that a [25-cubic-inch-brain] individual could have made the sophisticated artifacts that are claimed to have been found."

The Morwood team's report yesterday in the online version of the journal Nature followed by almost exactly a year the original paper announcing the celebrated discovery of Homo floresiensis, a tiny archaic human that had survived on Flores long after Neanderthals, the last human ancestors, had gone extinct about 30,000 years ago, and well after modern humans had spread throughout the world.

Evidence of sophisticated toolmaking and the ability to hunt and prepare game soon earned the original fossil -- of a 30-year-old woman -- the nickname Hobbit, after the tiny but able characters in the J.R.R. Tolkien fantasies.

At first researchers suggested that the diminutive hunters were the products of "island dwarfing": the tendency of large creatures living on isolated islands with few predators to grow smaller to adapt to limited resources, while small animals grow larger to be able to compete.

Ancient Flores also had pygmy elephants as well as large Komodo dragon lizards and giant rats. The Morwood team suggested that the Hobbit was a reduced-size evolutionary adaptation of Homo erectus, an early human ancestor that arrived on Flores about 800,000 years ago.

Still, "no erectus ever made the tools" from Liang Bua, Phillips said in a telephone interview. In fact, paleontologists agreed that no species apart from modern Homo sapiens -- with an 85-cubic-inch braincase -- was capable of making the blade tools and points found with the Hobbit remains. This gave rise to the theory that the Hobbit was a modern human with dwarfism.

But in a second paper earlier this year, researchers said the Hobbit's brain, while only the size of a grapefruit, had relatively large temporal lobes, like those of modern humans, and a highly convoluted frontal lobe, another modern characteristic. This research was vigorously attacked by Phillips and Martin.

Morwood acknowledged that skull size, along with the Hobbit's extra-long arms, suggested a physical size and shape much more like those of australopithecines, ancient hominids from Africa, rather than the more sophisticated erectus. His team is examining the possibility that floresiensis was "the evolved version of an earlier homo."

"What was the ancestral population?" Morwood asked. "We don't know."

The skull of Homo floresiensis, found on the Indonesian island of Flores, is much smaller than that of a modern human.