Homo floresiensis ("Man of Flores") is a species in the genus Homo, remarkable for its small body, small brain, and survival until relatively recent times. It is thought to have been contemporaneous with modern humans (Homo sapiens) on the Indonesian island of Flores. One sub-fossil skeleton, dated at 18,000 years old, is largely complete. It was discovered in deposits in Liang Bua Cave on Flores in 2003. Parts of eight other individuals, all diminutive, have been recovered as well as similarly small stone tools from horizons ranging from 94,000 to 13,000 years ago. The first of these fossils was unearthed in 2003; the publication date of the original description is October 2004; and confirmation of species status is expected to appear soon, following the March 2005 publication of details of the brain of Flores Man.

Flores has been described (in the journal Nature) as "a kind of Lost World", where archaic animals, elsewhere long extinct, had evolved into giant and dwarf forms through allopatric speciation, due to its location East of the Wallace Line. The island had dwarf elephants (a species of Stegodon, a prehistoric elephant) and giant monitor lizards akin to the Komodo dragon, as well as H. floresiensis, which can be considered a species of diminutive human.

The discoverers have called members of the diminutive species "hobbits", after J.R.R. Tolkien's fictional race of roughly the same height. In the mythology of the island, there were common references to small furry people called Ebu Gogo even into the 19th century.

Discovery

The first (and so far only)^[1] specimens were discovered by a joint Australian-Indonesian team of paleoanthropologists and archaeologists looking on Flores for evidence of the original human migration of H. sapiens from Asia into Australia. They were not expecting to find a new species, and were quite surprised at the recovery of the remains of at least seven individuals of non-H. sapiens, from 38,000 to 13,000 years old, from the Liang Bua limestone cave on Flores. An arm bone, provisionally assigned to H. floresiensis, is about 74,000 years old. Also widely present in this cave are sophisticated stone implements of a size considered appropriate to the 1 m tall human: these are at horizons from 95,000 to 13,000 years and are associated with juvenile Stegodon, presumably the prey of Flores Man.

The specimens are not fossilized, but were described in a Nature news article as having "the consistency of wet blotting paper" (once exposed, the bones had to be left to dry before they could be dug up). Researchers hope to find preserved mitochondrial DNA to compare with samples from similarly unfossilised specimens of Homo neanderthalensis and H. sapiens. The likelihood of there being preserved DNA is low, as DNA degrades rapidly in warm tropical environments - sometimes in as little as a few dozen years. Also, contamination from the surrounding environment seems highly possible given the moist environment in which the specimens were found.

Small bodies

Homo erectus, thought to be the immediate ancestor of H. floresiensis, was almost the same size as modern humans. In the limited food environment on Flores, however, H. erectus is thought to have undergone strong island dwarfing, a form of speciation also seen on Flores in several species, including a dwarf Stegodon (a group of proboscideans that was widespread throughout Asia during the Quaternary), as well as being observed on other small islands. However, the "island dwarfing" theory has been subjected to some criticism from Dr Julian O'Dea's blog.

Despite the size difference, the specimens seem otherwise to resemble in their features H. erectus, known to be living in Southeast Asia at times coinciding with earlier finds of H. floresiensis. These observed similarities form the basis for the establishment of the suggested phylogenetic relationship. Despite a controversial reported finding by the same team of alleged material evidence, stone tools, of a H. erectus occupation 840,000 years ago, actual remains of H. erectus itself have not been found on Flores, much less transitional forms.

The type specimen for the species is a fairly complete skeleton and near-complete skull of a 30-year-old female, nicknamed Little Lady of Flores or Flo, about 1 m (3 ft 3 in) in height. Not only is this drastically shorter than H. erectus, it is even somewhat smaller than the three million years older ancestor australopithecines, not previously thought to have expanded beyond Africa. This tends to qualify H. floresiensis as the most "extreme" member of the extended human family. They are certainly the shortest and smallest discovered thus far.

Homo floresiensis is also rather tiny compared to the modern human height and size of all peoples today. The estimated height of adult H. floresiensis is considerably shorter than the average adult height of even the physically smallest populations of modern humans, such as the African Pygmies (< 1.5 m, or 4 ft 11 in), Twa, Semang (1.37 m, or 4 ft 6 in for adult women), or Andamanese (1.37 m, or 4 ft 6 in for adult women). Mass is generally considered more biophysically significant than a one-dimensional measure of length, and by that measure, due to effects of scaling, differences are even greater. The type specimen of H. floresiensis has been estimated as perhaps about 25 kg (55 lb).

Homo floresiensis had relatively long arms, perhaps allowing this small hominid to climb to safety in the trees when needed.

Small brains

In addition to a small body size, H. floresiensis had a remarkably small brain. The type specimen, at 380 cm³ (23 in³), is at the lower range of chimpanzees or the ancient australopithecines. The brain is reduced considerably relative to this species' presumed immediate ancestor H. erectus, which at 980 cm³ (60 in³) had more than double the brain volume of its descendant species. Nonetheless, the brain to body mass ratio of H. floresiensis is comparable to that of Homo erectus, indicating the species was unlikely to differ greatly in intelligence.

Indeed, the discoverers have associated H. floresiensis with advanced behaviors. There is evidence of the use of fire for cooking. The species has also been associated with stone tools of the sophisticated Upper Paleolithic tradition typically associated with modern humans, who at 1310–1475 cm³ (80–90 in³) nearly quadruple the brain volume of H. floresiensis (with body mass increased by a factor of 2.6). Some of these tools were apparently used in the necessarily cooperative hunting of local dwarf Stegodon by this small human species.

An indicator of intelligence is the size of region 10 of the dorsomedial prefrontal cortex, which is associated with self-awareness and is about the same size as that of modern humans, despite the much smaller overall size of the brain.

Flores remained isolated during the Wisconsin glaciation (the most recent glacial period), despite the low sea levels that united much of the rest of Sundaland, because of a deep neighboring strait. This has led the discoverers of H. floresiensis to conclude that the species or its ancestors could only have reached the isolated island by water transport, perhaps arriving in bamboo rafts around 100,000 years ago (or, if they are H. erectus, then about 1 million years ago). This perceived evidence of advanced technology and cooperation on a modern human level has prompted the discoverers to hypothesize that H. floresiensis almost certainly had language. These suggestions have proved the most controversial of the discoverers' findings, despite the probable high intelligence of H. floresiensis.

Recent survival

The other remarkable aspect of the find is that this species is thought to have survived on Flores until at least as recently as 12,000 years ago. This makes it the longest-lasting non-modern human, surviving long past the Neanderthals (H. neanderthalensis) which became extinct about 29,000 years ago. Homo floresiensis certainly coexisted for a long time with modern humans, who arrived in the region 35,000–55,000 years ago, but it is unknown how they may have interacted.

Local geology suggests that a volcanic eruption on Flores was responsible for the demise of H. floresiensis in the part of the island under study at approximately 12,000 years ago, along with other local fauna, including the dwarf elephant Stegodon.

The discoverers suspect, however, that this species may have survived longer in other parts of Flores to become the source of the Ebu Gogo stories told among the local people. The Ebu Gogo are said to have been small, hairy, language-poor cave dwellers on the scale of H. floresiensis. Widely believed to be present at the time of the Dutch arrival during the 16th century, these strange creatures were apparently last spotted as recently as the late 19th century. There is also Tonga Island folklore that "small people" were living on 'Ata Island (the southernmost island of the group) at the time of the arrival of the Polynesians.

Similarly, on the island of Sumatra, there are reports of a one-metre tall humanoid, the Orang Pendek, which a number of professional scholars take seriously. Both footprints and hairs have been recovered. Scholars working on the Flores Man have noted that the Orang Pendek may also be surviving Flores men still living on Sumatra.

Significance

The discovery is widely considered the most important of its kind in recent history, and came as a surprise to the anthropological community. The new species challenges many of the ideas of the discipline.

Homo floresiensis is so different in form from other members of genus Homo that it forces the recognition of a new, undreamt-of variability in the genus, and provides evidence against linear evolution.

No doubt, this discovery provides more fuel for the perennial debate over the out-of-Africa or multiregional models of speciation of modern humans (despite H. floresiensis not itself being an ancestor of modern humans). Already, further arguments have been made on either side.

The discoverers of H. floresiensis fully expect to find the remains of other, equally divergent Homo species on other isolated islands of Southeast Asia, and think it possible, if not quite "likely", that some lost Homo species could be found still living in some unexplored corner of jungle.

Henry Gee, a senior editor of the journal Nature, has agreed, saying, "Of course it could explain all kinds of legends of the little people. They are almost certainly extinct, but it is possible that there are creatures like this around today. Large mammals are still being found. I don't think the likelihood of finding a new species of human alive is any less than finding a new species of antelope, and that has happened" [1].

Gee has also written that "The discovery that Homo floresiensis survived until so very recently, in geological terms, makes it more likely that stories of other mythical, human-like creatures such as Yetis are founded on grains of truth....Now, cryptozoology, the study of such fabulous creatures, can come in from the cold" [2].

An alternative suggestion is that Homo floresiensis was actually a rainforest-adapted type of modern Homo sapiens, like Pygmies and Negritos, only of a more extreme type. [3][4]

Reaction

When the first skull (that of 'Flo') was found, the first assumption was that it was a child. When it turned out to be a grown individual (closed fontanelles and worn teeth), it was thought to be microcephalic, but that theory has been refuted by a subsequent detailed scan of the skull. And comparisons with modern human achondroplasiacs (about 1.2 m, or 3 ft 11 in) or other dwarfs, are also flawed, as these people are not generally proportionally smaller than other humans, only short-limbed.

Professor Teuku Jacob, chief paleontologist of the Indonesian Gadjah Mada University and other scientists reportedly disagree with the placement of the new finds into a new species of Homo, stating instead, "It is a sub-species of Homo sapiens classified under the Austrolomelanesid race". He contends that the find is from a 25–30 year-old omnivorous subspecies of H. sapiens, and not a 30-year-old female of a new species. He is convinced that the small skull is that of a mentally defective modern human, probably a Pygmy, suffering from the genetic disorder microcephaly or nanocephaly (now discounted). Similar dismissive arguments were made regarding the discovery of Neanderthals in 1856. Neanderthals were also considered examples of diseased or mentally deficient modern humans, but this was proven incorrect.

Some scientists reportedly believe the skeleton found may be of a male and not a female.

When interviewed on the Australian television program Lateline, Professor Roberts reportedly conceded that the skeleton may be that of a male rather than a female but he strenuously maintained the fossil is of a new species. A paper published in Science disputes the microcephaly theory.

Access controversy

In late November and early December 2004, in an apparent arrangement with discoverer Radien Soejono, Professor Jacob borrowed most of the remains from Soejono's institution, Jakarta's National Research Centre of Archaeology, for his own research (apparently without the permission of the Centre's directors [5], [6], [7], [8]). Some expressed fears that, like the Dead Sea Scrolls, important scientific evidence would be sequestered by a small group of scientists who neither allowed access by other scientists nor published their own research. However, Jacob returned the remains to the Centre, except for two leg bones, on 23 February, 2005 [9].

Scan of skull supports distinct species designation

In 2005, a computer-generated model of the skull of Homo floresiensis provided further support that the controversial specimens from Indonesia do indeed represent a new species.

The study of the creature's brainpan shows that it was neither a pygmy nor an individual with a malformed skull and brain, as some critics contend. This lends support to the discovery team's assertion that the metre-tall specimen belongs to a species distinct from Homo erectus.