Homo floresiensis
Encyclopedia
Homo floresiensis is a possible species, now extinct, in the genus Homo
. The remains were discovered in 2003 on the island of Flores
in Indonesia
. Partial skeletons of nine individuals have been recovered, including one complete cranium (skull). These remains have been the subject of intense research to determine whether they represent a species
distinct from modern humans, and the progress of this scientific controversy has been closely followed by the news media at large. 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). Recovered alongside the skeletal remains were stone tool
s from archaeological horizons
ranging from 94,000 to 13,000 years ago.
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
. Hominini currently comprises the extant species human
(the only living member of the genus Homo), bonobo
(genus Pan), and chimpanzee
(genus Pan); their ancestors; and the extinct lineages of their common ancestor. The discoverers also proposed that H. floresiensis lived contemporaneously with modern humans (Homo sapiens) on Flores
.
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. Falk et al. (2005) has been rejected by Martin et al. (2006) and Jacob et al. (2006) and defended by Morwood (2005) and Argue, Donlon et al. (2006).
Two orthopedic researches published in 2007 both 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. 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. In 2009, the publication of a cladistic analysis
and a study of comparative body measurements 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. A second hypothesis in this category is that the individuals were born without a functioning thyroid
, resulting in a type of endemic cretinism (myxoedematous
, ME).
The specimens were discovered on the Indonesian island of Flores
by a joint Australian-Indonesia
n team of archaeologists
in 2003 looking for evidence of the original human migration
of H. sapiens from Asia to Australia. 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. An arm bone provisionally assigned to H. floresiensis is about 74,000 years old. The specimens are not fossil
ized 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.
Researchers hope to find preserved mitochondrial DNA
to compare with samples from similarly unfossilised specimens of Homo neanderthalensis
and H. sapiens.
Sophisticated stone implements of a size considered appropriate to the 1-meter-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. They also shared the island with giant rats
, Komodo dragon
s, and even larger species of lizards. Homo sapiens reached the region by around 45,000 years ago.
Homo floresiensis was unveiled on 28 October, 2004, and was swiftly nicknamed the "Hobbit", after the main characters of J. R. R. Tolkien
's book The Hobbit
, made popular by Peter Jackson
's The Lord of the Rings
film trilogy (2001-2003), and a proposed scientific name for the species was Homo hobbitus. It was initially placed in its own genus, Sundanthropus floresianus ("Sunda man from Flores"), but reviewers of the article felt that the cranium, despite its size, belonged in the genus Homo.
(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, or whether they identify LB1 as a severely pathological H. sapiens. The discovery of additional partial skeletons 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. 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.
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".
LB1's height has been estimated at about 1.06 m (3.5 ft). The height of a second skeleton, LB8, has been estimated at 1.09 m (3.6 ft) based on measurements of its tibia
. 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 (4.9 ft)), Twa, Semang
(1.37 m (4.5 ft) for adult women) of the Malay Peninsula
, or the Andamanese
(1.37 m (4.5 ft) for adult women). By body mass, differences between modern pygmies and Homo floresiensis are even greater. LB1's body mass has been estimated at 25 kg (55.1 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 australopithecine
s 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. 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
.
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
, a form of speciation
which has been observed in other species on Flores also – including several species of the proboscidean genus Stegodon. (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.) This hypothesis has been criticized by Teuku Jacob and colleagues who argue that LB1 is similar to the midget humans who populate a Flores village, Rampasasa, – and who point out that size can vary substantially in pygmy populations. Contradictory evidence has emerged.
. The brain of the holotype LB1 is estimated to have had a volume of 380 cm³ (23.2 cu in), placing it at the lower range of chimpanzee
s or the extinct australopithecine
s. LB1's brain size is half that of its presumed immediate ancestor, H. erectus (980 cm³ (59.8 cu in)). The brain to body mass ratio
of LB1 lies between that of H. erectus and the great apes. 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.
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.
Notwithstanding the small brain of H. floresiensis, the discoverers have associated it with advanced behavior
s. Their cave shows evidence of the use of fire for cooking, and Stegodon
bones associated with the hominins have cut marks. The hominin specimens have also been associated with stone tool
s of the sophisticated Upper Paleolithic
tradition typically associated with modern humans, who have nearly quadruple the brain volume (1310 cubic centimetre) and 2.6 times greater body mass. Some of these tools were apparently used in the necessarily cooperative hunting
of Stegodon
by these hominins.. This is an interesting paradox: there has been a gradual increase in brain volume as we progressed along the Human timeline of evolution (see Homininae
), starting from about 600 cm3 in Homo habilis
up to 1500 cm3 in Homo sapiens neanderthalensis. Thus, in general, there is a correlation between brain volume and intelligence. However, modern Homo sapiens have a brain volume slightly smaller (1400 cm3) than neanderthals, women have a brain volume slightly smaller than men and Homo floresiensis with a cranial capacity of about 380 cm3, considered small for a chimpanzee) and about a third that of H. erectus
, apparently used fire and made tools at least as sophisticated as those of their ancestor H.erectus. In this case, it seems that for intelligence, the structure of the brain is more important than its volume.
, and the thickness of the leg bones. The presence of each of these features has been confirmed by independent investigators but their significance has been disputed.
The forearm
and pectoral girdle of H. floresiensis have been examined by Larson et al. (2007). Modern humans have the top of the bone twisted between 145 to 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. 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 may have been able to make tools.
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 ape
s or Australopithecus
.
The feet of H. floresiensis were unusually flat and unusually long in relation with the rest of the body. As a result, when walking, it would have to bend its knee
s further back than modern people do. This forced the gait to be high stepped and the creature was not able to walk very fast. The toes had an unusual shape and the big toe
was very short.
, making it the longest lasting non-modern human, surviving long past the Neanderthal
s (H. neanderthalensis), which became extinct
about 24,000 years ago.
Because of a deep neighboring strait
, Flores remained isolated during the Wisconsin glaciation (the most recent glacial period), despite the low sea levels that united Sundaland
. 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 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.
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
. 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. 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. Gerd van den Bergh, a paleontologist working with the fossils, reported hearing of the Ebu Gogo a decade before the fossil discovery. On the island of Sumatra
, there are reports of a 1-1.5m tall humanoid, the Orang Pendek
which might be related to H. floresiensis. Henry Gee
, senior editor at Nature magazine, speculates that species like H. floresiensis might still exist in the unexplored tropical forest of Indonesia.
's National Research Centre of Archaeology, with the permission of only one of the project team's directors and kept them for three months. 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 and missing two leg bones 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" and causing the discovery team leader Morwood to remark "It's sickening, Jacob was greedy and acted totally irresponsibly". Jacob, however, denied any wrongdoing. He stated that the damages occurred during transport from Yogyakarta
back to Jakarta despite the physical evidence to the contrary that the jawbone had been broken while making a mold of bones.
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 the death of Jacob.
et al. This team concluded that the brainpan
was not that of a pygmy nor an individual with a malformed skull and brain.
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. 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. 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)).
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. Falk's team replied to the critics of their study (Falk et al. (2006)). 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.
Falk et al. (2007) offered further evidence that the claims of a microcephalic H. sapiens were not credible. 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.
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.
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.
, a genetic disorder first reported in 1966. 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. The team said 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. 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.
(ME) endemic cretinism resulting from congenital hypothyroidism
and that they were part of an affected population of H. sapiens on the island. 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. 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, 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.
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. Peter Brown declared that the remains of the pituitary fossa were very poorly preserved and no meaningful measurement was possible.
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. However, an article by Oxnard, Obendorf and Kefford rejects Groves and FitzGerald's argument and revives the cretinism hypothesis. Oxnard et al 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.
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.
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.
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.
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 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 conclusion was challenged by Robert Martin, since 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. 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. 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 species that evolved in isolation on the island.
}
}
}
Homo
Homo may refer to:*the Greek prefix ὅμο-, meaning "the same"*the Latin for man, human being*Homo, the taxonomical genus including modern humans...
. The remains were discovered in 2003 on the island of Flores
Flores
Flores is one of the Lesser Sunda Islands, an island arc with an estimated area of 14,300 km² extending east from the Java island of Indonesia. The population was 1.831.000 in the 2010 census and the largest town is Maumere. Flores is Portuguese for "flowers".Flores is located east of Sumbawa...
in Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
. Partial skeletons of nine individuals have been recovered, including one complete cranium (skull). These remains have been the subject of intense research to determine whether they represent a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
distinct from modern humans, and the progress of this scientific controversy has been closely followed by the news media at large. This hominin is remarkable for its small body and brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
and for its survival until relatively recent times (possibly as recently as 12,000 years ago). Recovered alongside the skeletal remains were stone tool
Stone tool
A stone tool is, in the most general sense, any tool made either partially or entirely out of stone. Although stone tool-dependent societies and cultures still exist today, most stone tools are associated with prehistoric, particularly Stone Age cultures that have become extinct...
s from archaeological horizons
Horizon (archaeological)
An archaeological horizon is a widely disseminated period of common art and artifacts at an archaeological site or, more usually, over a larger geographic area, and is a distinctive level in that site's or area's archaeological sequence....
ranging from 94,000 to 13,000 years ago.
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
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
of Hominini
Hominini
Hominini is the tribe of Homininae that comprises Homo, and the two species of the genus Pan , their ancestors, and the extinct lineages of their common ancestor . Members of the tribe are called hominins...
. Hominini currently comprises the extant species human
Homo (genus)
Homo is the genus that includes modern humans and species closely related to them. The genus is estimated to be about 2.3 to 2.4 million years old, evolving from australopithecine ancestors with the appearance of Homo habilis....
(the only living member of the genus Homo), bonobo
Bonobo
The bonobo , Pan paniscus, previously called the pygmy chimpanzee and less often, the dwarf or gracile chimpanzee, is a great ape and one of the two species making up the genus Pan. The other species in genus Pan is Pan troglodytes, or the common chimpanzee...
(genus Pan), and chimpanzee
Chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
(genus Pan); their ancestors; and the extinct lineages of their common ancestor. The discoverers also proposed that H. floresiensis lived contemporaneously with modern humans (Homo sapiens) on Flores
Flores
Flores is one of the Lesser Sunda Islands, an island arc with an estimated area of 14,300 km² extending east from the Java island of Indonesia. The population was 1.831.000 in the 2010 census and the largest town is Maumere. Flores is Portuguese for "flowers".Flores is located east of Sumbawa...
.
Doubts that the remains constitute a new species were soon voiced by the Indonesian anthropologist Teuku Jacob
Teuku Jacob
Teuku Jacob was an influential Indonesian paleoanthropologist. As a student of Gustav Heinrich Ralph von Koenigswald in the 1950s, Jacob discovered and studied numerous specimens of Homo erectus...
, who suggested that the skull of LB1 was a microcephalic modern human. Two studies by paleoneurologist Dean Falk
Dean Falk
Dean Falk is an American academic anthropologist who specializes in the evolution of the brain and cognition in higher primates...
and her colleagues (2005, 2007) rejected this possibility. Falk et al. (2005) has been rejected by Martin et al. (2006) and Jacob et al. (2006) and defended by Morwood (2005) and Argue, Donlon et al. (2006).
Two orthopedic researches published in 2007 both reported evidence to support species status for H. floresiensis. A study of three tokens of carpal (wrist) bones
Carpus
In tetrapods, the carpus is the sole cluster of bones in the wrist between the radius and ulna and the metacarpus. The bones of the carpus do not belong to individual fingers , whereas those of the metacarpus do. The corresponding part of the foot is the tarsus...
concluded there were similarities to the carpal bones of a chimpanzee
Chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
or an early hominin such as Australopithecus
Australopithecus
Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...
and also differences from the bones of modern humans. 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. In 2009, the publication of a cladistic analysis
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
and a study of comparative body measurements 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. A second hypothesis in this category is that the individuals were born without a functioning thyroid
Congenital hypothyroidism
Congenital hypothyroidism is a condition of thyroid hormone deficiency present at birth. Approximately 1 in 4000 newborn infants has a severe deficiency of thyroid function, while even more have mild or partial degrees. If untreated for several months after birth, severe congenital hypothyroidism...
, resulting in a type of endemic cretinism (myxoedematous
Myxedema
Myxedema describes a specific form of cutaneous and dermal edema secondary to increased deposition of connective tissue components in subcutaneous tissue as seen in various forms of hypothyroidism and Graves' disease. It is more common in women than in men...
, ME).
Discovery
Flores
Flores is one of the Lesser Sunda Islands, an island arc with an estimated area of 14,300 km² extending east from the Java island of Indonesia. The population was 1.831.000 in the 2010 census and the largest town is Maumere. Flores is Portuguese for "flowers".Flores is located east of Sumbawa...
by a joint Australian-Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
n team of archaeologists
Archaeology
Archaeology, or archeology , is the study of human society, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes...
in 2003 looking for evidence of the original human migration
Human migration
Human migration is physical movement by humans from one area to another, sometimes over long distances or in large groups. Historically this movement was nomadic, often causing significant conflict with the indigenous population and their displacement or cultural assimilation. Only a few nomadic...
of H. sapiens from Asia to Australia. 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. An arm bone provisionally assigned to H. floresiensis is about 74,000 years old. The specimens are not fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
ized and have been described as having "the consistency of wet blotting paper
Blotting paper
Blotting paper is a highly absorbent type of paper or other material. It is used to absorb an excess of liquid substances from the surface of writing paper or objects. It is also commonly used as a beauty tool to absorb excess oil from the skin.-Manufacture:Blotting paper is made from different...
"; once exposed, the bones had to be left to dry before they could be dug up.
Researchers hope to find preserved mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
to compare with samples from similarly unfossilised specimens of Homo neanderthalensis
Neanderthal
The Neanderthal is an extinct member of the Homo genus known from Pleistocene specimens found in Europe and parts of western and central Asia...
and H. sapiens.
Sophisticated stone implements of a size considered appropriate to the 1-meter-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
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
layer as) an elephant of the extinct genus Stegodon
Stegodon
Stegodon , is a genus of the extinct subfamily Stegodontinae of the order Proboscidea. It was assigned to the family Elephantidae , but has also been placed in Stegodontidae . Stegodonts were present from 11.6 mya to 4,100 years ago...
(which was widespread throughout Asia during the Quaternary
Quaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
), presumably the prey of LB1. They also shared the island with giant rats
Flores Giant Rat
The Flores Giant Rat is a rodent of the family Muridae that occurs on the island of Flores in Indonesia. It is found in primary, secondary and disturbed forest over a wide range of elevations...
, Komodo dragon
Komodo dragon
The Komodo dragon , also known as the Komodo monitor, is a large species of lizard found in the Indonesian islands of Komodo, Rinca, Flores, Gili Motang and Gili Dasami. A member of the monitor lizard family , it is the largest living species of lizard, growing to a maximum length of in rare cases...
s, and even larger species of lizards. Homo sapiens reached the region by around 45,000 years ago.
Homo floresiensis was unveiled on 28 October, 2004, and was swiftly nicknamed the "Hobbit", after the main characters of J. R. R. Tolkien
J. R. R. Tolkien
John Ronald Reuel Tolkien, CBE was an English writer, poet, philologist, and university professor, best known as the author of the classic high fantasy works The Hobbit, The Lord of the Rings, and The Silmarillion.Tolkien was Rawlinson and Bosworth Professor of Anglo-Saxon at Pembroke College,...
's book The Hobbit
The Hobbit
The Hobbit, or There and Back Again, better known by its abbreviated title The Hobbit, is a fantasy novel and children's book by J. R. R. Tolkien. It was published on 21 September 1937 to wide critical acclaim, being nominated for the Carnegie Medal and awarded a prize from the New York Herald...
, made popular by Peter Jackson
Peter Jackson
Sir Peter Robert Jackson, KNZM is a New Zealand film director, producer, actor, and screenwriter, known for his The Lord of the Rings film trilogy , adapted from the novel by J. R. R...
's The Lord of the Rings
The Lord of the Rings
The Lord of the Rings is a high fantasy epic written by English philologist and University of Oxford professor J. R. R. Tolkien. The story began as a sequel to Tolkien's earlier, less complex children's fantasy novel The Hobbit , but eventually developed into a much larger work. It was written in...
film trilogy (2001-2003), and a proposed scientific name for the species was Homo hobbitus. It was initially placed in its own genus, Sundanthropus floresianus ("Sunda man from Flores"), but reviewers of the article felt that the cranium, despite its size, belonged in the genus Homo.
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 humerusHumerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
(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, or whether they identify LB1 as a severely pathological H. sapiens. The discovery of additional partial skeletons 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. 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
Homo erectus
Homo erectus is an extinct species of hominid that lived from the end of the Pliocene epoch to the later Pleistocene, about . The species originated in Africa and spread as far as India, China and Java. There is still disagreement on the subject of the classification, ancestry, and progeny of H...
alone.
Small bodies
The first set of remains to have been found, LB1, was chosen as the type specimenHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
for the proposed species. LB1 is a fairly complete skeleton
Human skeleton
The human skeleton consists of both fused and individual bones supported and supplemented by ligaments, tendons, muscles and cartilage. It serves as a scaffold which supports organs, anchors muscles, and protects organs such as the brain, lungs and heart....
, including a nearly complete cranium (skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
), determined to be that of a 30-year-old female. LB1 has been nicknamed the Little Lady of Flores or "Flo".
LB1's height has been estimated at about 1.06 m (3.5 ft). The height of a second skeleton, LB8, has been estimated at 1.09 m (3.6 ft) based on measurements of its tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
. These estimates are outside the range of normal modern human height
Human height
Human height is the distance from the bottom of the feet to the top of the head in a human body standing erect.When populations share genetic background and environmental factors, average height is frequently characteristic within the group...
and considerably shorter than the average adult height of even the smallest modern humans, such as the Mbenga
Mbenga people
The Mbenga people, Bambenga, are the western pygmies of Cameroon and Gabon: the,*Aka ,*Baka ,*Gyele,*Kola , and*Bongo....
and Mbuti
Mbuti
Mbuti or Bambuti are one of several indigenous pygmy groups in the Congo region of Africa. Their languages belong to the Central Sudanic and also to Bantu languages.-Overview:...
(< 1.5 m (4.9 ft)), Twa, Semang
Semang
The Semang are a Negrito ethnic group of the Malay Peninsula. Lowland Semang tribes are also known as Sakai, although this term is considered to be derogatory by the Semang people. They are probably the indigenous peoples of this area. They have been recorded to have lived here since before the...
(1.37 m (4.5 ft) for adult women) of the Malay Peninsula
Malay Peninsula
The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...
, or the Andamanese
Andamanese
The Andamanese people are the various aboriginal inhabitants of the Andaman Islands, which is the northern district of the Andaman and Nicobar Islands union territory of India, located in the southeastern part of the Bay of Bengal. They include the Great Andamanese, Jarawa, Onge, Sentinelese, and...
(1.37 m (4.5 ft) for adult women). By body mass, differences between modern pygmies and Homo floresiensis are even greater. LB1's body mass has been estimated at 25 kg (55.1 lb). This is smaller than that of not only modern H. sapiens, but also H. erectus
Homo erectus
Homo erectus is an extinct species of hominid that lived from the end of the Pliocene epoch to the later Pleistocene, about . The species originated in Africa and spread as far as India, China and Java. There is still disagreement on the subject of the classification, ancestry, and progeny of H...
, which Brown and colleagues have suggested is the immediate ancestor of H. floresiensis. LB1 and LB8 are also somewhat smaller than the australopithecine
Australopithecus
Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...
s 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
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
at times coincident with earlier finds purported to be of H. floresiensis. These observed similarities
Homology (biology)
Homology forms the basis of organization for comparative biology. In 1843, Richard Owen defined homology as "the same organ in different animals under every variety of form and function". Organs as different as a bat's wing, a seal's flipper, a cat's paw and a human hand have a common underlying...
form the basis for the suggested phylogenetic relationship
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
. 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
Transitional fossil
A transitional fossil is any fossilized remains of a lifeform that exhibits characteristics of two distinct taxonomic groups. A transitional fossil is the fossil of an organism near the branching point where major individual lineages diverge...
.
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
Insular dwarfism
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of the reduction in size of large animals – typically mammals – when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf...
, a form of speciation
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
which has been observed in other species on Flores also – including several species of the proboscidean genus Stegodon. (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.) This hypothesis has been criticized by Teuku Jacob and colleagues who argue that LB1 is similar to the midget humans who populate a Flores village, Rampasasa, – and who point out that size can vary substantially in pygmy populations. Contradictory evidence has emerged.
Small brains
In addition to a small body size, H. floresiensis had a remarkably small brainHuman brain
The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...
. The brain of the holotype LB1 is estimated to have had a volume of 380 cm³ (23.2 cu in), placing it at the lower range of chimpanzee
Chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
s or the extinct australopithecine
Australopithecine
The term australopithecine refers generally to any species in the related genera Australopithecus or Paranthropus. These species occurred in the Plio-Pleistocene era, and were bipedal and dentally similar to humans, but with a brain size not much larger than modern apes, lacking the...
s. LB1's brain size is half that of its presumed immediate ancestor, H. erectus (980 cm³ (59.8 cu in)). The brain to body mass ratio
Brain to body mass ratio
Brain-to-body mass ratio, also known as the brain to body weight ratio, is the ratio of brain weight to body weight, which is hypothesised to be a rough estimate of the intelligence of an animal. A more complex measurement, encephalization quotient, takes into account allometric effects of widely...
of LB1 lies between that of H. erectus and the great apes. Insular dwarfism
Insular dwarfism
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of the reduction in size of large animals – typically mammals – when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf...
has been posited to explain the brain size reduction. Scientists at the Natural History Museum
Natural History Museum
The Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...
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.
An indicator of intelligence is the size of Brodmann's area 10
Brodmann area 10
Brodmann area 10, or BA10 is the frontopolar part of the frontal cortex in the human brain. BA10 was originally defined in terms of cytoarchitectonic traits in autopsy brains; modern functional imaging research cannot directly identify these boundaries and the terms anterior prefrontal, rostral...
, the dorsomedial prefrontal cortex
Prefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...
, an area of the brain associated with higher cognition
Cognition
In science, cognition refers to mental processes. These processes include attention, remembering, producing and understanding language, solving problems, and making decisions. Cognition is studied in various disciplines such as psychology, philosophy, linguistics, and computer science...
. LB1's region 10 is about the same size as that of modern humans, despite the much smaller overall size of the brain.
Notwithstanding the small brain of H. floresiensis, the discoverers have associated it with advanced behavior
Human behavior
Human behavior refers to the range of behaviors exhibited by humans and which are influenced by culture, attitudes, emotions, values, ethics, authority, rapport, hypnosis, persuasion, coercion and/or genetics....
s. Their cave shows evidence of the use of fire for cooking, and Stegodon
Stegodon
Stegodon , is a genus of the extinct subfamily Stegodontinae of the order Proboscidea. It was assigned to the family Elephantidae , but has also been placed in Stegodontidae . Stegodonts were present from 11.6 mya to 4,100 years ago...
bones associated with the hominins have cut marks. The hominin specimens have also been associated with stone tool
Stone tool
A stone tool is, in the most general sense, any tool made either partially or entirely out of stone. Although stone tool-dependent societies and cultures still exist today, most stone tools are associated with prehistoric, particularly Stone Age cultures that have become extinct...
s of the sophisticated Upper Paleolithic
Upper Paleolithic
The Upper Paleolithic is the third and last subdivision of the Paleolithic or Old Stone Age as it is understood in Europe, Africa and Asia. Very broadly it dates to between 40,000 and 10,000 years ago, roughly coinciding with the appearance of behavioral modernity and before the advent of...
tradition typically associated with modern humans, who have nearly quadruple the brain volume (1310 cubic centimetre) and 2.6 times greater body mass. Some of these tools were apparently used in the necessarily cooperative hunting
Hunting
Hunting is the practice of pursuing any living thing, usually wildlife, for food, recreation, or trade. In present-day use, the term refers to lawful hunting, as distinguished from poaching, which is the killing, trapping or capture of the hunted species contrary to applicable law...
of Stegodon
Stegodon
Stegodon , is a genus of the extinct subfamily Stegodontinae of the order Proboscidea. It was assigned to the family Elephantidae , but has also been placed in Stegodontidae . Stegodonts were present from 11.6 mya to 4,100 years ago...
by these hominins.. This is an interesting paradox: there has been a gradual increase in brain volume as we progressed along the Human timeline of evolution (see Homininae
Homininae
Homininae is a subfamily of Hominidae, which includes humans, gorillas and chimpanzees, and some extinct relatives; it comprises all those hominids, such as Australopithecus, that arose after the split from orangutans . Our family tree, which has 3 main branches leading to chimpanzees, humans and...
), starting from about 600 cm3 in Homo habilis
Homo habilis
Homo habilis is a species of the genus Homo, which lived from approximately at the beginning of the Pleistocene period. The discovery and description of this species is credited to both Mary and Louis Leakey, who found fossils in Tanzania, East Africa, between 1962 and 1964. Homo habilis Homo...
up to 1500 cm3 in Homo sapiens neanderthalensis. Thus, in general, there is a correlation between brain volume and intelligence. However, modern Homo sapiens have a brain volume slightly smaller (1400 cm3) than neanderthals, women have a brain volume slightly smaller than men and Homo floresiensis with a cranial capacity of about 380 cm3, considered small for a chimpanzee) and about a third that of H. erectus
H. erectus
H. erectus may refer to:* Homo erectus, an extinct hominid species* Hippocampus erectus, a seahorse species from the Western Atlantic-See also:* H. erecta * Erectus...
, apparently used fire and made tools at least as sophisticated as those of their ancestor H.erectus. In this case, it seems that for intelligence, the structure of the brain is more important than its volume.
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 bonesHumerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
, and the thickness of the leg bones. The presence of each of these features has been confirmed by independent investigators but their significance has been disputed.
The forearm
Forearm
-See also:*Forearm flexors*Forearm muscles...
and pectoral girdle of H. floresiensis have been examined by Larson et al. (2007). Modern humans have the top of the bone twisted between 145 to 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. 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
Clavicle
In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...
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 may have been able to make tools.
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 ape
Ape
Apes are Old World anthropoid mammals, more specifically a clade of tailless catarrhine primates, belonging to the biological superfamily Hominoidea. The apes are native to Africa and South-east Asia, although in relatively recent times humans have spread all over the world...
s or Australopithecus
Australopithecus
Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...
.
The feet of H. floresiensis were unusually flat and unusually long in relation with the rest of the body. As a result, when walking, it would have to bend its knee
Knee
The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...
s further back than modern people do. This forced the gait to be high stepped and the creature was not able to walk very fast. The toes had an unusual shape and the big toe
Hallux
In tetrapods, the hallux is the innermost toe of the foot. Despite its name it may not be the longest toe on the foot of some individuals...
was very short.
Recent survival
The species is thought to have survived on Flores at least until 12,000 years before presentBefore Present
Before Present years is a time scale used in archaeology, geology, and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use AD 1950 as the origin of the age scale, reflecting the fact that radiocarbon...
, making it the longest lasting non-modern human, surviving long past the Neanderthal
Neanderthal
The Neanderthal is an extinct member of the Homo genus known from Pleistocene specimens found in Europe and parts of western and central Asia...
s (H. neanderthalensis), which became extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
about 24,000 years ago.
Because of a deep neighboring strait
Strait
A strait or straits is a narrow, typically navigable channel of water that connects two larger, navigable bodies of water. It most commonly refers to a channel of water that lies between two land masses, but it may also refer to a navigable channel through a body of water that is otherwise not...
, Flores remained isolated during the Wisconsin glaciation (the most recent glacial period), despite the low sea levels that united Sundaland
Sundaland
Sundaland is a biogeographical region of Southeastern Asia which encompasses the areas of the Asian continental shelf that was exposed during the last ice age. It included the Malay Peninsula on the Asian mainland, as well as the large islands of Borneo, Java, and Sumatra and their surrounding...
. 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 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.
Local geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
suggests that a volcanic
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
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
Stegodon
Stegodon , is a genus of the extinct subfamily Stegodontinae of the order Proboscidea. It was assigned to the family Elephantidae , but has also been placed in Stegodontidae . Stegodonts were present from 11.6 mya to 4,100 years ago...
. Gregory Forth hypothesized that H. floresiensis may have survived longer in other parts of Flores to become the source of the Ebu Gogo
Ebu Gogo
Ebu Gogo are a group of human-like creatures that appear in the mythology of Flores, Indonesia. In the Nage language of central Flores, ebu means 'grandmother' and gogo means 'he who eats anything'.-Appearance:...
stories told among the Nage
Nage
For the poaching liquor, see nage The Nage are an indigenous people living on the eastern Indonesian island of Flores.-Study of the tribe:...
people of Flores. The Ebu Gogo are said to have been small, hairy, language-poor cave dwellers on the scale of this species. 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. Gerd van den Bergh, a paleontologist working with the fossils, reported hearing of the Ebu Gogo a decade before the fossil discovery. On the island of Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
, there are reports of a 1-1.5m tall humanoid, the Orang Pendek
Orang Pendek
Orang Pendek is the most common name given to a cryptid, or cryptozoological animal, that reportedly inhabits remote, mountainous forests on the island of Sumatra....
which might be related to H. floresiensis. Henry Gee
Henry Gee
Dr Henry Gee is a British paleontologist, and evolutionary biologist. He is a senior editor of Nature, the scientific journal....
, senior editor at Nature magazine, speculates that species like H. floresiensis might still exist in the unexplored tropical forest of Indonesia.
Scandal over specimen damage
In early December 2004, Teuku Jacob removed most of the remains from their repository, JakartaJakarta
Jakarta is the capital and largest city of Indonesia. Officially known as the Special Capital Territory of Jakarta, it is located on the northwest coast of Java, has an area of , and a population of 9,580,000. Jakarta is the country's economic, cultural and political centre...
's National Research Centre of Archaeology, with the permission of only one of the project team's directors and kept them for three months. 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 and missing two leg bones 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" and causing the discovery team leader Morwood to remark "It's sickening, Jacob was greedy and acted totally irresponsibly". Jacob, however, denied any wrongdoing. He stated that the damages occurred during transport from Yogyakarta
Yogyakarta (city)
Yogyakarta is a city in the Yogyakarta Special Region, Indonesia. It is renowned as a centre of classical Javanese fine art and culture such as batik, ballet, drama, music, poetry, and puppet shows. Yogyakarta was the Indonesian capital during the Indonesian National Revolution from 1945 to...
back to Jakarta despite the physical evidence to the contrary that the jawbone had been broken while making a mold of bones.
In 2005 Indonesian officials forbade access to the cave. Some news media, such as the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
, 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 the death of Jacob.
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 analysed by Dean FalkDean Falk
Dean Falk is an American academic anthropologist who specializes in the evolution of the brain and cognition in higher primates...
et al. This team concluded that the brainpan
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
was not that of a pygmy nor an individual with a malformed skull and brain.
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. 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. 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)).
Falk et al. (2007) offered further evidence that the claims of a microcephalic H. sapiens were not credible. 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.
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.
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.
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 syndromeLaron syndrome
Laron syndrome, or Laron-type dwarfism, is an autosomal recessive disorder characterized by an insensitivity to growth hormone , caused by a variant of the growth hormone receptor. It causes short stature and a resistance to diabetes and cancer....
, a genetic disorder first reported in 1966. The next year, a team including Laron
Zvi Laron
Zvi Laron is an Israeli paediatric endocrinologist, born in Cernăuţi, Romania, a professor emeritus at Tel Aviv University.In 1966, he described the type of dwarfism later called Laron syndrome...
himself published a paper arguing that the morphological features of H. floresiensis are essentially indistinguishable from those of Laron syndrome. The team said 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. 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.
Endemic cretinism hypothesis
In 2008 Australian researchers Peter J. Obendorf, Charles E. Oxnard, and Ben J. Kefford suggested that LB1 and LB6 suffered from myxoedematousMyxedema
Myxedema describes a specific form of cutaneous and dermal edema secondary to increased deposition of connective tissue components in subcutaneous tissue as seen in various forms of hypothyroidism and Graves' disease. It is more common in women than in men...
(ME) endemic cretinism resulting from congenital hypothyroidism
Congenital hypothyroidism
Congenital hypothyroidism is a condition of thyroid hormone deficiency present at birth. Approximately 1 in 4000 newborn infants has a severe deficiency of thyroid function, while even more have mild or partial degrees. If untreated for several months after birth, severe congenital hypothyroidism...
and that they were part of an affected population of H. sapiens on the island. 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. Affected people, who were born without a functioning thyroid
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
, have both small bodies and reduced brain size but their mental retardation
Mental retardation
Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...
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, unusually straight and untwisted tops of the upper arm bone and relatively thick limbs, are signs of this diagnosis. The double rooted lower premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
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.
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. Peter Brown declared that the remains of the pituitary fossa were very poorly preserved and no meaningful measurement was possible.
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. However, an article by Oxnard, Obendorf and Kefford rejects Groves and FitzGerald's argument and revives the cretinism hypothesis. Oxnard et al also criticise the cladistic analysis
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
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.
Bone structure
The bone structure of H. floresiensis’ shoulders, arms and wrists have been described as very different from modern humans', much closer 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.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.
Larson et al. also studied the relatively short clavicle
Clavicle
In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...
and the unusual formation of the pectoral girdle. They compared their finding with the skeleton of Nariokotome Boy
Turkana Boy
Turkana Boy, also occasionally, Nariokotome Boy is the common name of fossil KNM-WT 15000, a nearly complete skeleton of a hominid who died in the early Pleistocene. This specimen is the most complete early human skeleton ever found. It is 1.5 million years old...
(variously classified as H. ergaster or H. erectus), and suggested that the pectoral girdle of H. floresiensis was a transitional stage
Transitional fossil
A transitional fossil is any fossilized remains of a lifeform that exhibits characteristics of two distinct taxonomic groups. A transitional fossil is the fossil of an organism near the branching point where major individual lineages diverge...
in human shoulder evolution.
While some specialists, including paleoanthropologist Russell Ciochon of the University of Iowa
University of Iowa
The University of Iowa is a public state-supported research university located in Iowa City, Iowa, United States. It is the oldest public university in the state. The university is organized into eleven colleges granting undergraduate, graduate, and professional degrees...
, supported the conclusion, others, including Eric Delson of Lehman College
Lehman College
Lehman College is one of the constituent colleges of the City University of New York, USA. Founded in 1931 as the Bronx campus of Hunter College, the school became an independent college within the City University in 1968. The college is named after Herbert Lehman, a former New York governor,...
, 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.
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 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
Homo antecessor
Homo antecessor is an extinct human species dating from 1.2 million to 800,000 years ago, that was discovered by Eudald Carbonell, Juan Luis Arsuaga and J. M. Bermúdez de Castro. H. antecessor is one of the earliest known human varieties in Europe. Various archaeologists and anthropologists have...
, and that they were comparable to carpal bones of Australopithecus
Australopithecus
Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...
. 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
Embryogenesis
Embryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote...
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 conclusion was challenged by Robert Martin, since 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. 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. Project leader Morwood countered that there were also other features, such as the stature, body proportions, brain size, shoulder, pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
, jaw, and teeth which suggested that H. floresiensis is a separate species that evolved in isolation on the island.
DNA extraction
In around 2006, two teams attempted to extract DNA from a tooth discovered in 2003 - both teams were unsuccessful. It has been suggested that this happened because the dentine was targeted, whereas new research suggests that the cementum has higher concentrations of DNA. Also, the heat generated by the high speed of the drill bit may have denatured the DNA.See also
- Denisova homininDenisova homininDenisova hominins , or Denisovans, are Paleolithic-Era members of the genus Homo that may belong to a previously unknown species. In , scientists announced the discovery of a finger bone fragment of a juvenile female that lived about 41,000 years ago, found in Denisova Cave in Altai Krai, Russia, a...
- a fossil of a new species of Homo found in Russia in 2008. - List of fossil sites
- List of human evolution fossils
Further reading
- "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 SciencePublic Library of ScienceThe Public Library of Science is a nonprofit open-access scientific publishing project aimed at creating a library of open access journals and other scientific literature under an open content license...
, Biology
External links
- Hawks, JohnJohn D. HawksJohn Hawks is a professor of Anthropology at the University of Wisconsin–Madison. He also is the author of a widely read paleoanthropology blog.-Biography:...
. Blog of a professor of anthropology who closely follows this topic.
}
}
}
- Scientific American Interview with Professor Brown 10/27/2004
- National Geographic News article on H. floresiensis
- Homo floresiensis - The Smithsonian Institution's Human Origins Program Blog commentary on the Obendorf paper.
- Washington University in St. Louis Virtual Endocasts of the "Hobbit" – Electronic Radiology Laboratory
- Nova's Alien from Earth documentary website, complete program available through Watch Online feature
- Hobbits in the Haystack: Homo floresiensis and Human Evolutions – Turkhana Basin Institute presentment at the Seventh Stony Brook Human Evolution Symposium