Homo floresiensis

Homo floresiensis
Temporal range: 94–13 Ka
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Skull with associated mandible.
A cast of the Homo floresiensis skull, American Museum of Natural History
Scientific classification (disputed)
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Tribe: Hominini
Genus: Homo
Species: †H. floresiensis
Binomial name
†Homo floresiensis
Brown et al., 2004
Flores in Indonesia, shown highlighted in red

Homo floresiensis ("Flores Man"; nicknamed "hobbit" and "Flo") is an extinct species widely believed to be in the genus Homo. The remains of an individual that would have stood about 3.5 feet (1.1 m) in height were discovered in 2003 on the island of Flores in Indonesia. Partial skeletons of nine individuals have been recovered, including one complete skull, referred to as "LB1".[1][2] These remains have been the subject of intense research to determine whether they represent a species distinct from modern humans. This hominin is remarkable for its small body and brain and for its survival until relatively recent times (possibly as recently as 12,000 years ago).[3] Recovered alongside the skeletal remains were stone tools from archaeological horizons ranging from 94,000 to 13,000 years ago. Some scholars suggest that the historical H. floresiensis may be connected by folk memory to ebu gogo myths prevalent on the isle of Flores.[4]

The discoverers (archaeologist Mike Morwood and colleagues) proposed that a variety of features, both primitive and derived, identify these individuals as belonging to a new species, H. floresiensis, within the taxonomic tribe of Hominini, which includes all species that are more closely related to humans than to chimpanzees.[1][3] The discoverers also proposed that H. floresiensis lived contemporaneously with modern humans on Flores.[5]

Doubts that the remains constitute a new species were soon voiced by the Indonesian anthropologist Teuku Jacob, who suggested that the skull of LB1 was a microcephalic modern human. Two studies by paleoneurologist Dean Falk and her colleagues (2005, 2007) rejected this possibility.[6][7][8] Falk et al. (2005) has been rejected by Martin et al. (2006) and Jacob et al. (2006), but defended by Morwood (2005) and Argue, Donlon et al. (2006).

Two orthopedic researches published in 2007 reported evidence to support species status for H. floresiensis. A study of three tokens of carpal (wrist) bones concluded there were similarities to the carpal bones of a chimpanzee or an early hominin such as Australopithecus and also differences from the bones of modern humans.[9][10] A study of the bones and joints of the arm, shoulder, and lower limbs also concluded that H. floresiensis was more similar to early humans and apes than modern humans.[11][12] In 2009, the publication of a cladistic analysis[13] and a study of comparative body measurements[14] provided further support for the hypothesis that H. floresiensis and Homo sapiens are separate species.

Critics of the claim for species status continue to believe that these individuals are Homo sapiens possessing pathologies of anatomy and physiology. Several hypotheses in this category have been put forward, including that the individuals were born without a functioning thyroid, resulting in a type of endemic cretinism (myxoedematous, ME),[15] and that the principal specimen LB1 suffered from Down syndrome.[16][17]

Discovery

The specimens were discovered on the Indonesian island of Flores in 2003 by a joint Australian-Indonesian team of archaeologists looking for evidence of the original human migration of Homo sapiens from Asia to Australia.[1][3] They were not expecting to find a new species, and were surprised at the recovery of a nearly complete skeleton of a hominin they dubbed LB1 because it was unearthed inside the Liang Bua Cave. Subsequent excavations recovered seven additional skeletons, dating from 38,000 to 13,000 years ago.[2] An arm bone provisionally assigned to H. floresiensis is about 74,000 years old. The specimens are not fossilized and have been described as having "the consistency of wet blotting paper"; once exposed, the bones had to be left to dry before they could be dug up.[18][19]

The cave on Flores Island where the specimens were discovered

Sophisticated stone implements of a size considered appropriate to the 3-foot-tall human are also widely present in the cave. The implements are at horizons from 95,000 to 13,000 years ago and are associated with (found in the same stratigraphic layer as) an elephant of the extinct genus Stegodon (which was widespread throughout Asia during the Quaternary), presumably the prey of LB1.[2] Homo sapiens reached the region by around 45,000 years ago.[20]

Homo floresiensis was unveiled on 28 October 2004, and was swiftly nicknamed the "Hobbit", after the fictional race popularized in J. R. R. Tolkien's book The Hobbit, and a proposed scientific name for the species was Homo hobbitus. It was initially placed in its own genus, Sundanthropus floresianus ("Sunda human from Flores"), but reviewers of the article felt that the cranium, despite its size, belonged in the genus Homo.[21]

Anatomy

The most important and obvious identifying features of H. floresiensis are its small body and small cranial capacity. Brown and Morwood also identified a number of additional, less obvious features that might distinguish LB1 from modern H. sapiens, including the form of the teeth, the absence of a chin, and the lesser angle in the head of the humerus (upper arm bone). Each of these putative distinguishing features has been heavily scrutinized by the scientific community, with different research groups reaching differing conclusions as to whether these features support the original designation of a new species,[22] or whether they identify LB1 as a severely pathological H. sapiens.[23] A 2015 study of the dental morphology of 40 teeth of H. floresiensis compared to 450 teeth of living and extinct human species, states that they had "primitive canine-premolar and advanced molar morphologies", which is unique among hominins. The dental study suggests a Homo erectus origin for Homo floresiensis.[24][25]

The discovery of additional partial skeletons[2] has verified the existence of some features found in LB1, such as the lack of a chin, but Jacob and other research teams argue that these features do not distinguish LB1 from local H. sapiens morphology.[23] Lyras et al. have asserted, based on 3D-morphometrics, that the skull of LB1 differs significantly from all H. sapiens skulls, including those of small-bodied individuals and microcephalics, and is similar to the skull of Homo erectus alone.[26] Ian Tattersall argues that the species is wrongly classified as Homo floresiensis as it is far too archaic to be assigned to the genus Homo.[27]


Small bodies

The first set of remains to have been found, LB1, was chosen as the type specimen for the proposed species. LB1 is a fairly complete skeleton, including a nearly complete cranium (skull), determined to be that of a 30-year-old female. LB1 has been nicknamed the Little Lady of Flores or "Flo".[1]

LB1's height has been estimated at about 1.06 m (3 ft 6 in). The height of a second skeleton, LB8, has been estimated at 1.09 m (3 ft 7 in) based on measurements of its tibia.[2] These estimates are outside the range of normal modern human height and considerably shorter than the average adult height of even the smallest modern humans, such as the Mbenga and Mbuti (< 1.5 m (4 ft 11 in)),[28] Twa, Semang (1.37 m (4 ft 6 in) for adult women) of the Malay Peninsula,[29] or the Andamanese (1.37 m (4 ft 6 in) for adult women).[30]

By body mass, differences between modern pygmies and Homo floresiensis are even greater. LB1's body mass has been estimated at 25 kg (55 lb). This is smaller than that of not only modern H. sapiens, but also H. erectus, which Brown and colleagues have suggested is the immediate ancestor of H. floresiensis. LB1 and LB8 are also somewhat smaller than the australopithecines from three million years ago, not previously thought to have expanded beyond Africa. Thus, LB1 and LB8 may be the shortest and smallest members of the extended human family discovered thus far.

Aside from smaller body size, the specimens seem otherwise to resemble H. erectus, a species known to have been living in Southeast Asia at times coincident with earlier finds purported to be of H. floresiensis.[2] These observed similarities form the basis for the suggested phylogenetic relationship. Controversially, the same team has reported finding material evidence (stone tools) on Flores of a H. erectus occupation dating back 840,000 years ago, but not remains of H. erectus itself or transitional forms.[31]

To explain the small stature of H. floresiensis, Brown et al. have suggested that in the limited food environment on Flores, H. erectus evolved a smaller body size via insular dwarfism,[1] a form of speciation which has been observed in other species on Flores also – including several species of the proboscidean genus Stegodon, an elephant-like creature. (A dwarf stegodont species of Flores, Stegodon sondaari, went extinct by about 850,000 years ago and was replaced by another species of normal size, Stegodon florensis, which then also evolved into a dwarf form, Stegodon florensis insularis, which disappeared about 12,000 years ago.)[32][33] This hypothesis has been criticized by Teuku Jacob and colleagues[23] who argue that LB1 is similar to the pygmy peoples who populate a Flores village, Rampasasa,[34] – and who point out that size can vary substantially in pygmy populations. Contradictory evidence has emerged.[35]

Small brains

Top view of a cast of the LB1 skull.

In addition to a small body size, H. floresiensis had a remarkably small brain size. The brain of the holotype LB1 is estimated to have had a volume of 380 cm3 (23 cu in), placing it at the range of chimpanzees or the extinct australopithecines.[1][6] LB1's brain size is half that of its presumed immediate ancestor, H. erectus (980 cm3 (60 cu in)).[6] The brain-to-body mass ratio of LB1 lies between that of H. erectus and the great apes.[36] Insular dwarfism has been posited to explain the brain size reduction. Scientists at the Natural History Museum in London have found that the reduction in brain size of extinct pygmy hippopotamuses in Madagascar compared with their living relatives is greater than the reduction in body size, and similar to the reduction in brain size of H. floresiensis compared with H. erectus.[37][38]

An indicator of intelligence is the size of Brodmann's area 10, the dorsomedial prefrontal cortex, an area of the brain associated with higher cognition. LB1's region 10 is about the same size as that of modern humans, despite the much smaller overall size of the brain.[6]

Notwithstanding the small brain of H. floresiensis, the discoverers have associated it with advanced behaviors. Their cave shows evidence of the use of fire for cooking, and Stegodon bones associated with the hominins have cut marks.[2][3] The hominin specimens have also been associated with stone tools of the sophisticated Upper Paleolithic tradition typically associated with modern humans, who have nearly quadruple the brain volume (1,310–1,475 cm3 (79.9–90.0 cu in)) and 2.6 times greater body mass. Some of these tools were apparently used in the necessarily cooperative hunting of Stegodon by these hominins.[2]

Additional features

Additional features used to argue that the finds come from a population of previously unidentified hominids include the absence of a chin, the relatively low twist of the arm bones, and the thickness of the leg bones.[1][2][3] The presence of each of these features has been confirmed by independent investigators[23] but their significance has been disputed.

The forearm and pectoral girdle of H. floresiensis have been examined by Larson et al. (2007).[11] Modern humans have the top of the bone twisted between 145 and 165 degrees to the plane of the elbow joint. For LB1, the twist was initially reported to be 110 degrees. Larson later revised this measurement to 120 degrees.[39]

This could be an advantage when arm-swinging, but it complicates activities associated with modern people, such as tool-making. As for the pectoral girdle of H. floresiensis, they studied a broken clavicle of LB1 and a shoulder blade of LB6. The clavicle was relatively short, which in combination with the shape of the shoulder blade and the low twist of the arm bone resulted in the shoulder being moved slightly forward, as if it was shrugged. Thus H. floresiensis could bend the elbow in the way modern people do and Larson concluded that it was able to make tools.[11]

Tocheri et al. (2007) examined three carpal bones believed to belong to LB1. The shapes of these bones were claimed to differ significantly from the bones of the modern human wrist and to resemble the wrist of great African apes or Australopithecus.[9]

The feet of H. floresiensis were unusually flat and unusually long in relation with the rest of the body.[40] As a result, when walking, it would have had to bend its knees further back than modern people do. This forced the gait to be high stepped and walking speed to be low.[41] The toes had an unusual shape and the big toe was very short.[42]

Recent survival

The species is thought to have survived on Flores at least until 12,000 years before present, making it the longest lasting known non-Homo Sapiens human (unless the Red Deer Cave people belonged to its own species), surviving long past the Neanderthals (H. neanderthalensis), which became extinct between 39,000 and 41,000 years ago.[43]

Because of a deep neighbouring strait, Flores remained isolated during the Wisconsin glaciation (the most recent glacial period), despite the low sea levels that united Sundaland.[44][45] 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). At this time the islands of Komodo and Flores were joined, leaving a 12-mile-wide (19 km) strait to be crossed with Komodo visible from the mainland. This idea of H. floresiensis using advanced technology and cooperation on a modern human level has prompted the discoverers to hypothesize that H. floresiensis almost certainly had language.[46]

Local geology suggests that a volcanic eruption on Flores approximately 12,000 years ago was responsible for the demise of H. floresiensis, along with other local fauna, including the elephant Stegodon.[3] Gregory Forth hypothesized that H. floresiensis may have survived longer in other parts of Flores to become the source of the Ebu Gogo stories told among the Nage people of Flores. The Ebu Gogo are said to have been small, hairy, language-poor cave dwellers on the scale of this species.[47] Believed to be present at the time of the arrival of the first Portuguese ships during the 16th century, these creatures are claimed to have existed as recently as the late 19th century.[48]

Gerd van den Bergh, a paleontologist working with the fossils, reported hearing of the Ebu Gogo a decade before the fossil discovery.[49] On the island of Sumatra, there are reports of a 1–1.5 m (3 ft 3 in–4 ft 11 in) tall humanoid, the Orang Pendek which might be related to H. floresiensis.[50] Henry Gee, senior editor at Nature magazine, speculates that species like H. floresiensis might still exist in the unexplored tropical forest of Indonesia.[51]

Scandal over specimen damage

In early December 2004, Indonesian paleoanthropologist Teuku Jacob removed most of the remains from their repository, Jakarta's National Research Centre of Archaeology, with the permission of only one of the project team's directors and kept them for three months.[52][53][54][55] Some scientists expressed the fear that important scientific evidence would be sequestered by a small group of scientists who neither allowed access by other scientists nor published their own research. Jacob returned the remains on February 23, 2005 with portions severely damaged[56] and missing two leg bones[57] to the worldwide consternation of his peers.

Reports noted the condition of the returned remains; "[including] long, deep cuts marking the lower edge of the Hobbit's jaw on both sides, said to be caused by a knife used to cut away the rubber mould"; "the chin of a second Hobbit jaw was snapped off and glued back together. Whoever was responsible misaligned the pieces and put them at an incorrect angle"; and, "The pelvis was smashed, destroying details that reveal body shape, gait and evolutionary history"[58] and causing the discovery team leader Morwood to remark "It's sickening, Jacob was greedy and acted totally irresponsibly".[56]

Jacob, however, denied any wrongdoing. He stated that the damages occurred during transport from Yogyakarta back to Jakarta[58] despite the physical evidence to the contrary that the jawbone had been broken while making a mould of bones.[56][59]

In 2005 Indonesian officials forbade access to the cave. Some news media, such as the BBC, expressed the opinion that the reason for the restriction was to protect Jacob, who was considered "Indonesia's king of palaeoanthropology", from being proven to be wrong. Scientists were allowed to return to the cave in 2007 shortly after Jacob's death.[58]

Pathological hypotheses

The proper classification of hominin remains is imperative to understanding the course of human evolution. Previous discoveries of hominin fossils, such as the Neanderthals and Pithecanthropus erectus, have sparked similar debates among the scientific community, usually challenging the accepted paradigm of human evolution and taxonomic status of our predecessors. In addition to the evolutionary implications of understanding the phylogenetic progression of humans, the International Code of Zoological Nomenclature prohibits developmentally abnormal individuals from being classified as a separate species.[60] Because of this rule, should pathology explain the appearance of the skeletal remains, then the name Homo floresiensis would be nullified and the skeletons would be classified as Homo sapiens. If the remains are representative of a new species, Homo floresiensis creates a drastic paradigm shift in our understanding of the human history of divergence, meaning that the genus Homo is "morphologically more varied and flexible in its adaptive responses than previously thought".[61]

Microcephaly hypothesis

Prior to Jacob's removal of the fossils, a CT scan was taken of the skull and a virtual endocast of the skull (i.e., a computer-generated model of the skull's interior) of H. floresiensis was produced and analyzed by Dean Falk et al. This team concluded that the brainpan was not that of a pygmy nor an individual with a malformed skull and brain.[6]

In response, Weber et al. conducted a survey the same year comparing the computer model of LB1's skull with a sample of microcephalic human skulls, concluding that the skull size of LB1 falls in the middle of the size range of the human samples and is not inconsistent with microcephaly.[62][63] Next to dispute the finding of Falk et al. (2005) were Martin et al. (2006), who objected to the failure to compare the model of LB1's skull with a typical example of adult microcephaly. Martin and his coauthors concluded that the skull was probably microcephalic, arguing that the brain is far too small to be a separate dwarf species; if it were, the 400-cubic-centimeter brain would indicate a creature only one foot in height, one-third the size of the discovered skeleton.[64] Shortly thereafter, a group of scientists from Indonesia, Australia, and the United States came to the same conclusion by examining bone and skull structure (Jacob (2006)).[23]

A cast of LB1 (left) was compared to several microcephalic skulls, amongst which is that of the microcephalic (right) used by Henneman in his attempt to present LB1 as a microcephalic. Argue (2006) and Lyras (2008) contend the opposite.

Brown and Morwood countered by claiming that the skeptics had drawn incorrect conclusions about bone and skull structure and mistakenly attributed the height of H. floresiensis to microcephaly.[65] Falk's team replied to the critics of their study (Falk et al. (2006)).[36] Morphologist Jungers examined the skull and concluded that the skeleton displays "no trace of disease". Argue, Donlon, et al. (2006) rejects microcephaly and concludes that the finds are indeed a new species.[22][66]

Falk et al. (2007) offered further evidence that the claims of a microcephalic H. sapiens were not credible.[7] Virtual endocasts of an additional nine microcephalic brains and ten normal human brains were examined, and it was found that the floresiensis skulls are similar in shape to normal human brains, yet have unique features which are consistent with what one would expect in a new species. The frontal and temporal lobes of the floresiensis brain were found to be highly developed, in strong contrast to the microcephalic brain, and advanced in ways different from modern human brains. This finding also answered past criticisms that the floresiensis brain was simply too small to be capable of the intelligence required for the members of H. floresiensis to create the tools found in their proximity. Falk et al. (2007) conclude that the onus is now upon the critics that continue to claim microcephaly to produce a brain of a microcephalic that bears resemblance to the floresiensis brain.[7]

Falk's argument was supported by Lyras et al. (2008) in that 3D-morphometric features of the skulls of microcephalic H. sapiens indeed fall within the range of normal H. sapiens and that the LB1 skull falls well outside this range. This was interpreted as proving that LB1 cannot, on the basis of either brain or skull morphology, be classified as a microcephalic H. sapiens.[26]

In 2009, a study by Jungers et al. presented a statistical analysis of skull shapes of healthy modern humans, microcephalic humans, and several ancient human species, as well as H. floresiensis. They showed that the three grouped separately, with H. floresiensis among the ancient humans, providing evidence that H. floresiensis is a separate species instead of a diseased modern human.[14]

In 2013, a comparison of the LB1 endocast to a set of 100 normocephalic and 17 microcephalic endocasts by Vannucci, Baron and Holloway showed that there is a wide variation in microcephalic brain shape ratios and that in these ratios the group as such is not clearly distinct from normocephalics. The LB1 brain shape nevertheless aligns slightly better with the microcephalic sample, with the shape at the extreme edge of the normocephalic group.[67]

Laron syndrome hypothesis

The anatomist Gary D. Richards introduced a new skeptical hypothesis in June 2006: that the skeletons from Flores might be the remains of people who suffered from Laron syndrome, a genetic disorder first reported in 1966. This IGF-I deficiency is commonly caused by an exon deletion, and produces two distinct phenotypic changes in the skeleton: short stature and a small skull, which also happen to define the phenotype of H. floresiensis. The next year, a team including Laron himself published a paper arguing that the morphological features of H. floresiensis are essentially indistinguishable from those of Laron syndrome.[68] They compared the cranial and postcranial skeleton of LB1 with those of 64 Laron syndrome patients. The cohort of Laron syndrome patients exhibited statures ranging from 95 to 136 cm in adult females, and 116 to 142 cm in adult males. The estimated height for the LB1 remains places it at the lowest end of the female range. The extremely small endocranial volume of LB1 is actually smaller than anything exhibited in Laron syndrome patients. Despite this inconsistency in brain size, Hershkovitz et al. still assert there are enough characteristics shared between LB1 and the Laron syndrome patients to suggest this pathology explains the skeletal appearance.

Critics claim that to determine whether the H. floresiensis individuals had Laron syndrome would require testing their DNA for the presence of the defective genes, if samples of that DNA ever become available.[69] Critics of the hypothesis have however pointed out that despite the low stature, people suffering from Laron syndrome look nothing like the Homo floresiensis remains, particularly in the anatomy of the cranial vault.[70]

Endemic cretinism hypothesis

In 2008 Australian researchers Peter J. Obendorf, Charles E. Oxnard, and Ben J. Kefford suggested that LB1 and LB6 suffered from myxoedematous (ME) endemic cretinism resulting from congenital hypothyroidism and that they were part of an affected population of H. sapiens on the island.[15] This disease, caused by various environmental factors including iodine deficiency, is a form of dwarfism which can still be found among the local Indonesian population.[15]

Affected people, who were born without a functioning thyroid, have both small bodies and reduced brain size but their mental retardation and motor disability is not as severe as with neurological endemic cretins. According to the authors of the study, the critical environment could have been present on Flores approximately 18,000 years ago, the period to which the LB fossils are dated. They wrote that various features found on the fossils, such as enlarged pituitary fossa,[15] unusually straight and untwisted tops of the upper arm bone and relatively thick limbs, are signs of this diagnosis. The double rooted lower premolar and primitive wrist morphology can be explained in this way as well. The oral stories about strange human-like creatures may also be a record of cretinism.[15]

Falk challenged the premise of Oberndorf et al. Studying computer tomography scans of LB1's pituitary fossa, she came to the conclusion that it is not larger than usual.

In a paper delivered to the Australasian Society for Human Biology in 2009, Colin Groves and Catharine FitzGerald compared the Flores bones with those of ten people who had had cretinism, focusing on anatomical features which are typical of the disease. They found no overlap, and stated that they had put the claim to rest.[71][72] However, an article by Oxnard, Obendorf and Kefford rejects Groves and FitzGerald's argument and revives the cretinism hypothesis.[73] Oxnard and colleagues also criticise the cladistic analysis of Argue et al. (2009), stating that it is not logically possible for the analysis to conclude that the Liang Bua remains represent a separate species and not a pathology because the cladistics analysis assumes that they do not represent a pathology.[73]

Brown (2012) compared skeletal and dental morphology in H. floresiensis with the clinical and osteological indicators of cretinism, and the traits that have been argued to be associated with ME cretinism in LB1 and LB6. He concludes that LB1 and LB6 H. floresiensis are not modern human (H. sapiens) cretins.[74]

Insular dwarfism hypothesis

The original report further claims neither growth retardation nor pituitary dwarfism could be responsible for the unique skull and short stature (however, no reason is provided); instead, Brown et al. suggest insular dwarfing of H. erectus as a result of selective pressures acting on island populations. This theory posits that the tropical rainforests present on the island tend to be a calorically impoverished environment, causing a dietary strain on hominins, especially in the absence of agriculture. Because of reduced resources, an advantage is placed on individuals who are smaller with lower energy requirements.[75] This selection can also greatly affect sensory organs such as the brain, which could explain the small endocranial volume present in H. floresiensis.

Down syndrome hypothesis

In 2014, Maciej Henneberg, a critic of the claim that H. floresiensis is a distinct species, argued in a paper published with other scholars in the Proceedings of the National Academy of Sciences[76] that LB1 suffered from Down syndrome, and that the remains of other individuals at the Flores site were merely normal H. sapiens of the Australomelanesian type. Down syndrome is one of the most common human developmental disorders, and is also exhibited in related hominoids such as the orangutan and the chimpanzee.[76] The authors write: "Our consistent hypothesis sees LB1 as a developmentally abnormal member of a recent Australomelanesian H. sapiens population, its features reflecting multiple compatible causes."[16] Colin Groves, of the Australian National University responded that the theory was "implausible" for several reasons, including the fact that abnormal features in the jaw of LB1 are shared by another specimen, LB6. Robert B. Eckhardt of Pennsylvania State University, one of the authors of the new study, rejected the criticism, stating that the study identified significant differences between the jaw of LB1 and LB6.[16] Later M. C. Westaway et al. pointed to a number of characteristics shared by both LB1 and LB6 as well as other known early humans and absent in Homo sapiens such as internal buttressing of the mandibular symphysis and lack of chin.[77]

Bone structure

Cast of the entire LB1 specimen.

The bone structure of H. floresiensis shoulders, arms[11] and wrists[9] has been described as very different from that of modern humans, and much more similar to the bone structure of chimpanzees or an early hominin. This adds support to the idea that H. floresiensis is a separate species of early human—rather than a modern human with a physical disorder.[11]

Susan G. Larson et al. analyzed the upper limb of LB1. They found that in LB1 the angle of humeral torsion is much less than in modern humans. This had been previously studied by Richards et al., who declared that it is a sign of modern pygmy populations, and T. Jacob et al., who pointed out that muscle attachments on the bone suggest LB1 had weak muscles which resulted in little development of humeral torsion. Larson et al. rejected Richards' conclusion, arguing that the humeral torsion of pygmy populations is usually similar to that of peoples of average stature. They argued that Richards et al. cited a 1972 paper which had studied a sample of six female Eastern Central African pygmies and this sample was too small to represent the whole population. Larson et al. also failed to find signs of microcephaly on the studied bones.[11]

Larson et al. also studied the relatively short clavicle and the unusual formation of the pectoral girdle. They compared their finding with the skeleton of Nariokotome Boy (variously classified as H. ergaster or H. erectus), and suggested that the pectoral girdle of H. floresiensis was a transitional stage in human shoulder evolution.[11]

While some specialists, including paleoanthropologist Russell Ciochon of the University of Iowa, supported the conclusion, others, including Eric Delson of Lehman College, City University of New York, pointed out that the recent sample of H. floresiensis individuals is too small and that Larson's research was based just on one shoulder bone.[39]

Tocheri et al. (2007) (including Morwood, Larson, and Jungers), compared three carpal bones believed to belong to LB1 with carpal bones of modern humans, some earlier hominids (that is, hominins), and African apes. They concluded that the carpals from the Liang Bua cave resembled ape carpal bones and were significantly different from the bones of H. sapiens, Homo neanderthalensis or even Homo antecessor, and that they were comparable to carpal bones of Australopithecus. The carpal bones of H. floresiensis were found to lack features that evolved with ancestors of modern humans at least about 800,000 years ago. These features are already formed during embryogenesis and therefore Tocheri et al. argue that it is improbable that the shape of H. floresiensis wrist bones could be a result of a developmental disease. This evidence also suggests that H. Florensiensis is not a modern human with an undiagnosed pathology or growth defect, but that it represents a species descended from a hominin ancestor that branched off before the last common ancestor of the clade that includes modern humans, Neandertals, and other modern hominins.[9]

This conclusion was challenged by Robert Martin (after Jacob's death the leading proponent of the microcephaly hypothesis) and Alan Thorne. Martin noted that no research has been done on wrists of microcephalic people.[10] Thorne maintained that the differences were small and that similar variation could occur with living modern humans. He also pointed out that the carpal bones had been found scattered in the cave and it was not certain that they all belonged to the same individual.[78] Project leader Morwood countered that there were also other features, such as the stature, body proportions, brain size, shoulder, pelvis, jaw, and teeth which suggested that H. floresiensis is a separate hominin species that evolved in isolation on the island.[79][80]

Opposition of multiregionalists

Supporters of H. floresiensis such as Chris Stringer and Dean Falk attribute opposition partly to the fact that the existence of the species challenges the theories of multiregionalists, who believe that Homo sapiens was the only living species of hominin, evolving simultaneously in different regions, at the time when the Flores individuals were alive. Early multiregionalist critics included Alan Thorne and Maciej Henneberg.[81][82]

DNA extraction

In around 2006, two teams attempted to extract DNA from a tooth discovered in 2003, but both teams were unsuccessful. It has been suggested that this happened because the dentine was targeted; new research suggests that the cementum has higher concentrations of DNA. Moreover, the heat generated by the high speed of the drill bit may have denatured the DNA.[83]

"Hobbit" nickname and the Tolkien Estate

In October 2012, a New Zealand scientist due to give a public lecture on Homo floresiensis was told by the Tolkien Estate that he was not allowed to use the word "hobbit" (the title of J.R.R. Tolkien's book The Hobbit) in promoting the lecture.[84]

In 2012, the American studio The Asylum, which produces low-budget "mockbuster" films,[85] planned to release a movie entitled Age of the Hobbits depicting a "peace-loving" community of H. floresiensis "enslaved by the Java Men, a race of flesh-eating dragon-riders."[86] The film was intended to piggyback on the success of Peter Jackson's film The Hobbit: An Unexpected Journey.[87] The film was blocked from release due to a legal dispute about using the word "hobbit."[87] The Asylum argued that the film did not violate the Tolkien copyright because the film was about H. floresiensis, "uniformly referred to as 'Hobbits' in the scientific community."[86] The film was later retitled Clash of the Empires.

See also

Human evolution

Notes

  1. 1 2 3 4 5 6 7 Brown et al. 2004
  2. 1 2 3 4 5 6 7 8 9 Morwood, Brown et al. 2005
  3. 1 2 3 4 5 6 Morwood, Soejono et al. 2004
  4. ↑ Gregory Forth, Hominids, hairy hominoids and the science of humanity, Anthropology Today, Vol. 21 No. 3 (June 2005), pp. 13-17; John D. Hawks, Stalking the wild ebu gogo (June 24, 2005).
  5. ↑ McKie, Robin (February 21, 2010). "How a hobbit is rewriting the history of the human race". The Guardian. Retrieved February 23, 2010.
  6. 1 2 3 4 5 Falk et al. 2005
  7. 1 2 3 Falk et al. 2007
  8. ↑ FSU News 2007
  9. 1 2 3 4 Tocheri et al. 2007
  10. 1 2 New Scientist 2007-09-20
  11. 1 2 3 4 5 6 7 Larson et al. 2007 (preprint online)
  12. ↑ Guardian 2007-09-21
  13. ↑ Argue, Morwood et al. 2009
  14. 1 2 Jungers and Baab 2009
  15. 1 2 3 4 5 Obendorf et al. 2008
  16. 1 2 3 "Did the 'Hobbit' have Down syndrome?".
  17. ↑ ""Hobbit" Specimen Likely Down Syndrome - The Skeptics Guide to the Universe".
  18. ↑ Dalton, 2004
  19. ↑ Morwood and van Oosterzee 2007
  20. ↑ Smithsonian July 2008
  21. ↑ Aiello, Leslie C. (2010). "Five years of Homo floresiensis". American Journal of Physical Anthropology 142 (2): 167–179. doi:10.1002/ajpa.21255. PMID 20229502. Archived from the original on 2011-09-29.
  22. 1 2 Argue, Donlon et al. 2006
  23. 1 2 3 4 5 Jacob et al. 2006
  24. ↑ Kaifu, Yousuke; Kono, Reiko T.; Sutikna, Thomas; Saptomo, Emanuel Wahyu; Jatmiko, .; Due Awe, Rokus (18 November 2015). Bae, Christopher, ed. "Unique Dental Morphology of Homo floresiensis and Its Evolutionary Implications". PLOS ONE 10 (11): e0141614. doi:10.1371/journal.pone.0141614.
  25. ↑ "Dental analysis suggests Homo floresiensis was a separate species from modern man". phys.org. Retrieved 2015-11-21.
  26. 1 2 Lyras et al. 2008
  27. ↑ Tattersall, 2015, p. 194
  28. ↑ Encyclopædia Britannica Online. Pygmy.
  29. ↑ Fix 1995
  30. ↑ "Weber ch. 5". Andaman.org. Retrieved 2011-10-01.
  31. ↑ Morwood et al., 1998
  32. ↑ Morwood and van Oosterzee 2007: 8, 169
  33. ↑ Van Den Bergh, G. D.; Rokhus Due Awe; Morwood, M. J.; Sutikna, T.; Jatmiko; Wahyu Saptomo, E. (May 2008). "The youngest Stegodon remains in Southeast Asia from the Late Pleistocene archaeological site Liang Bua, Flores, Indonesia". Quaternary International 182 (1): 16–48. Bibcode:2008QuInt.182...16V. doi:10.1016/j.quaint.2007.02.001. Retrieved 2011-11-27.
  34. ↑ Elegant, Simon (2005-04-30). "Science: Bones of Contention". Time (Rampasasa). Retrieved 16 January 2011.
  35. ↑ Tran, Mark (7 May 2009). "Indonesian 'hobbits' were distinct human species, say researchers". London: guardian.co.uk. Retrieved 24 February 2010.
  36. 1 2 Falk et al. 2006
  37. ↑ Weston et al. 2009
  38. ↑ "Hippo's island life helps explain dwarf hobbit". Natural History Museum. 2009-05-07. Retrieved 2011-10-01.
  39. 1 2 "Science Magazine" (PDF). 2006-05-19. Retrieved 2011-10-01.
  40. ↑ Jungers et al. 2008
  41. ↑ Blaszczyk, Maria B., and Christopher L. Vaughan. 2007. "Re-interpreting the evidence for bipedality in Homo floresiensis : research letter." South African Journal Of Science no. 9: 409.
  42. ↑ New Scientist 2008
  43. ↑ "BBC News - New dates rewrite Neanderthal story". BBC News.
  44. ↑ "Homo erectus the sailor seaman". Patagoniamonsters.blogspot.com. 2011-01-18. Retrieved 2011-10-01.
  45. ↑ http://www.greenstone.org/greenstone3/sites/nzdl/collect/hdl/archives/HASH0181.dir/80197e01.gif
  46. ↑ Science Daily 2004-10-28
  47. ↑ Forth 2005
  48. ↑ Telegraph 2004-11-02
  49. ↑ Sereno, M.I. (2005). "Language Origins Without the Semantic Urge" (PDF). Cognitive Science Online 3.1: 1–12.
  50. ↑ Nature 2004-10-27
  51. ↑ "'Hobbit' joins human family tree". BBC News. October 27, 2004.
  52. ↑ Morwood and van Oosterzee 2007: ch. 9
  53. ↑ New Zealand Herald 2004-11-30
  54. ↑ New Scientist 2004-12-11
  55. ↑ Times Online 2004-12-03
  56. 1 2 3 Sydney Morning Herald 2005-03-05
  57. ↑ Scientist 2005-02-28
  58. 1 2 3 BBC News 2007-01-25
  59. ↑ Morwood and van Oosterzee 2007: ch. 9, p. 230-231
  60. ↑ Ride, W.D.L. (1999). "International Code for Zoological Nomenclature".
  61. ↑ Brown, P. (2004). "A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia". Nature 431: 1055–1061. doi:10.1038/nature02999. PMID 15514638.
  62. ↑ Weber et al. 2005-10-14
  63. ↑ Spiegel 2006-09-01
  64. ↑ Los Angeles Times 2006-05-20
  65. ↑ New York Times 2006-08-21
  66. ↑ USA Today 2006-07-16
  67. ↑ R.C. Vannucci et al. 2013, Frontal Brain Expansion During Development Using MRI and Endocasts: Relation to Microcephaly and Homo floresiensis, The Anatomical Record vol. 296, p. 630-637
  68. ↑ Hershkovitz, I. (2011). "Comparative skeletal features between Homo floresiensis and patients with primary growth hormone insensitivity (Laron syndrome)". American Journal of Physical Anthropology 134 (2): 198–208. doi:10.1002/ajpa.20655. PMID 17596857.
  69. ↑ Science News 2006
  70. ↑ Falk, D. & al. (2009): LB1's virtual endocast, microcephalyand hominin brain evolution. Journal of Human Evolution Nov. ed, pp 597-607
  71. ↑ Groves and Fitzgerald, 2010.
  72. ↑ New Scientist, 26 June 2010, p. 17
  73. 1 2 Oxnard, C.; Obendorf, P.J.; Kefford, B.B.; Obendorf; Kefford (2010). "Post-cranial skeletons of hypothyroid cretins show a similar anatomical mosaic as Homo floresiensis". PLoS ONE 5 (9): e13018. Bibcode:2010PLoSO...513018O. doi:10.1371/journal.pone.0013018.
  74. ↑ Brown, Peter. (2012). LB1 and LB6 Homo floresiensis are not modern human (Homo sapiens) cretins. "Journal of Human Evolution", 62:2, pp. 201-224. http://www.sciencedirect.com/science/article/pii/S0047248411002223
  75. ↑ Lomolino, M.V. (1985). "Body size of mammals on islands: The island rule reexamined". The American Naturalist 125: 310–316. doi:10.1086/284343.
  76. 1 2 Henneberg, Maciej; Eckhardt, Robert B.; Chavanaves, Sakdapong; Hsü, Kenneth J. (August 5, 2014), "Evolved developmental homeostasis disturbed in LB1 from Flores, Indonesia, denotes Down syndrome and not diagnostic traits of the invalid species Homo floresiensis", Proceedings of the National Academy of Sciences of the United States of America 111 (31): 11967–11972, doi:10.1073/pnas.1407382111
  77. ↑ Westaway, Michel Carrington; Durband, Arthur C. C; Groves, Colin P.; Collard, Mark (February 17, 2015). "Mandibular evidence supports Homo floresiensis as a distinct species". Proceedings of the National Academy of Sciences 112 (7): E604–E605. doi:10.1073/pnas.1418997112. Retrieved February 27, 2015.
  78. ↑ Anna Salleh. (21 September 2007). "Wrist gives hobbit theory the flick". ABC.net.au. Retrieved 2012-09-14.
  79. ↑ Hobbit origins pushed back Nature 464, 335 2010
  80. ↑ Hominins on Flores, Indonesia, by one million years ago Nature 464, 748-752 2010
  81. ↑ Stringer 2011, pp. 81-82
  82. ↑ Falk, 2011, pp. 96-98
  83. ↑ Cheryl Jones. "Researchers to drill for hobbit history : Nature News". Nature.com. Retrieved 2011-10-01.
  84. ↑ Lee, Julian (24 October 2012). "Hobbit makers ban uni from using ‘hobbit’". 3 News NZ.
  85. ↑ Somma, Brandon (2013-01-04). "Masters of the Mockbuster:What The Asylum Is All About". The Artifice.
  86. 1 2 "The Hobbit producers sue 'mockbuster' film company". BBC. 2012-11-08. Retrieved 2012-11-10.
  87. 1 2 Fritz, Ben (December 10, 2012). "'Hobbit' knockoff release blocked by judge". Los Angeles Times. Retrieved December 11, 2012.

References

Further reading

  • Goldenberg, Linda (2007). Little People and a Lost World: An Anthropological Mystery. Minneapolis, Minnesota: Twenty-First Century Books. p. 112. ISBN 978-0-8225-5983-2. OCLC 62330789. 
  • Henneberg, Maciej; Schofield, John (2008). The Hobbit Trap: Money, Fame, Science and the Discovery of a 'New Species'. Kent Town: Wakefield Press. p. 159. ISBN 978-1-86254-791-9. 
  • Trueman, J. W. H. (2010). "A new cladistic analysis of Homo floresiensis". Journal of Human Evolution 59 (2): 223–226. doi:10.1016/j.jhevol.2010.01.013. PMID 20494404. 
  • Brumm, A.; Jensen, G. M.; Van Den Bergh, G. D.; Morwood, M. J.; Kurniawan, I.; Aziz, F.; Storey, M. (2010). "Hominins on Flores, Indonesia, by one million years ago". Nature 464 (7289): 748–752. Bibcode:2010Natur.464..748B. doi:10.1038/nature08844. PMID 20237472. 
  • Jungers, W. L.; Harcourt-Smith, W. E. H.; Wunderlich, R. E.; Tocheri, M. W.; Larson, S. G.; Sutikna, T.; Due, R. A.; Morwood, M. J. (2009). "The foot of Homo floresiensis". Nature 459 (7243): 81–84. doi:10.1038/nature07989. PMID 19424155. 
  • Gordon, A. D.; Nevell, L.; Wood, B. (2008). "The Homo floresiensis cranium (LB1): Size, scaling, and early Homo affinities". Proceedings of the National Academy of Sciences 105 (12): 4650–4655. doi:10.1073/pnas.0710041105. 
  • Vannucci, R. C.; Barron, T. F.; Holloway, R. L. (2011). "Craniometric ratios of microcephaly and LB1, Homo floresiensis, using MRI and endocasts". Proceedings of the National Academy of Sciences 108 (34): 14043–14048. doi:10.1073/pnas.1105585108. 
  • Argue, D.; Morwood, M.; Sutikna, T.; Jatmiko; Saptomo, E. W. (2010). "A Reply to Trueman's "A new cladistic analysis of Homo floresiensis."". Journal of Human Evolution 59 (2): 227–230. doi:10.1016/j.jhevol.2010.05.004. 
  • Holliday, T. W.; Franciscus, R. G. (2009). "Body size and its consequences: Allometry and the lower limb length of Liang Bua 1 (Homo floresiensis)". Journal of Human Evolution 57 (3): 223–228. doi:10.1016/j.jhevol.2009.04.007. PMID 19674770. 
  • Lieberman, D. E. (2009). "Palaeoanthropology: Homo floresiensis from head to toe". Nature 459 (7243): 41–42. doi:10.1038/459041a. PMID 19424142. 
  • Montgomery, S. H.; Capellini, I.; Barton, R. A.; Mundy, N. I. (2010). "Reconstructing the ups and downs of primate brain evolution: Implications for adaptive hypotheses and Homo floresiensis". BMC Biology 8: 9. doi:10.1186/1741-7007-8-9. PMC 2825212. PMID 20105283. 
  • Larson, S. G.; Jungers, W. L.; Tocheri, M. W.; Orr, C. M.; Morwood, M. J.; Sutikna, T.; Awe, R. D.; Djubiantono, T. (2009). "Descriptions of the upper limb skeleton of Homo floresiensis". Journal of Human Evolution 57 (5): 555–570. doi:10.1016/j.jhevol.2008.06.007. PMID 19056103. 
  • Kaifu, Y.; Baba, H.; Sutikna, T.; Morwood, M. J.; Kubo, D.; Saptomo, E. W.; Jatmiko; Awe, A.; Djubiantono, T. (2011). "Craniofacial morphology of Homo floresiensis: Description, taxonomic affinities, and evolutionary implication". Journal of Human Evolution 61 (6): 644–682. doi:10.1016/j.jhevol.2011.08.008. PMID 22036083. 
  • "What is the Hobbit?" A review of the state of debate regarding the status of H. Floresiensis, circa 2006, from the open access journal Public Library of Science, Biology
  • Henneberg, M.; Eckhardt, R. B.; Chavanaves, S.; Hsu, K. J. (2014). "Evolved developmental homeostasis disturbed in LB1 from Flores, Indonesia, denotes Down syndrome and not diagnostic traits of the invalid species Homo floresiensis". Proceedings of the National Academy of Sciences 111 (33): 11967–11972. doi:10.1073/pnas.1407382111. 

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