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Abstract
Key Takeaways
Introduction
Materials and Methods
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Overall Shape Analysis of the Cranial Morphology
Discussion
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Anthropology
Biological Anthropology

The origin of Homo floresiensis and its relation to evolutionary processes under isolation

Profile image of George LyrasGeorge LyrasProfile image of Alexandra A E van der GeerAlexandra A E van der Geer

2008, Anthropological Science 117, 33-43.

https://doi.org/10.1537/ASE.080411
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11 pages

Abstract

"Since its first description in 2004, Homo floresiensis has been attributed to a species of its own, a descendant of H. erectus or another early hominid, a pathological form of H. sapiens, or a dwarfed H. sapiens related to the Neolithic inhabitants of Flores. In this contribution, we apply a geometric morphometric analysis to the skull of H. floresiensis (LB1) and compare it with skulls of normal H. sapiens, insular H. sapiens (Minatogawa Man and Neolithic skulls from Flores), pathological H. sapiens (microcephalics), Asian H. erectus (Sangiran 17), H. habilis (KNM ER 1813), and Australopithecus africanus (Sts 5). Our analysis includes specimens that were highlighted by other authors to prove their conclusions. The geometric morphometric analysis separates H. floresiensis from all H. sapiens, including the pathological and insular forms. It is not possible to separate H. floresiensis from H. erectus. Australopithecus falls separately from all other skulls. The Neolithic skulls from Flores fall within the range of modern humans and are not related to LB1. The microcephalic skulls fall within the range of modern humans, as well as the skulls of the Neolithic small people of Flores. The cranial shape of H. floresiensis is close to that of H. erectus and not to that of any H. sapiens. Apart from cranial shape, some features of H. floresiensis are not unique but are shared with other insular taxa, such as the relatively large teeth (shared with Early Neolithic humans of Sardinia), and changed limb proportions (shared with Minatogawa Man)."

Key takeaways
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  1. Homo floresiensis shows significant cranial similarity to H. erectus, suggesting a close evolutionary relationship.
  2. Geometric morphometric analysis distinguishes H. floresiensis from all H. sapiens, including pathological forms.
  3. H. floresiensis features relatively large teeth and unique limb proportions indicative of insular adaptations.
  4. Isolated evolution on Flores may explain the small brain size, deviating from typical trends in hominin evolution.
  5. The study aims to clarify the phylogenetic position of H. floresiensis through comparative cranial morphology.

Related papers

A preliminary analysis of long bone measurements of Homo floresiensis: Bone robusticity, body size, proportions and encephalisation
Vaclav Vancata

Anthropologie, 2005

This is the first preliminary analysis of long bone measurements and body size and proportion in Homo floresiensis. In contradiction to the original description (Brown et al. 2004) we have found the bones relatively very robust and that the individual was much taller than it is presented in the original description. A relatively extraordinary large femoral head and relatively short biomechanical neck length is a typical feature of this human fossil. The length of radius is relatively out of range of any known hominine. In summary the fossil find of Homo floresiensis LB1 fossil specimen represents relatively short, but very robust individual with a relatively very small brain comparable to earliest Homo species. The phylogenetic position of Homo floresiensis is not clear because there are not many archaic features typical for Homo erectus on the postcranial skeleton but many specific autapomorphic ones. Some of them are similar to Neanderthals or Upper Paleolithic anatomically modern...

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New wrist bones of Homo floresiensis from Liang Bua (Flores, Indonesia)
Caley Orr

The carpals from the Homo floresiensis type specimen (LB1) lack features that compose the shared, derived complex of the radial side of the wrist in Neandertals and modern humans. This paper comprises a description and three-dimensional morphometric analysis of new carpals from at least one other individual at Liang Bua attributed to H. floresiensis: a right capitate and two hamates. The new capitate is smaller than that of LB1 but is nearly identical in morphology. As with capitates from extant apes, species of Australopithecus, and LB1, the newly described capitate displays a deeply-excavated nonarticular area along its radial aspect, a scaphoid facet that extends into a J-hook articulation on the neck, and a more radially-oriented second metacarpal facet; it also lacks an enlarged palmarly-positioned trapezoid facet. Because there is no accommodation for the derived, palmarly blocky trapezoid that characterizes Homo sapiens and Neandertals, this individual most likely had a plesiomorphically wedge-shaped trapezoid (like LB1). Morphometric analyses confirm the close similarity of the new capitate and that of LB1, and are consistent with previous findings of an overall primitive articular geometry. In general, hamate morphology is more conserved across hominins, and the H. floresiensis specimens fall at the far edge of the range of variation for H. sapiens in a number of metrics. However, the hamate of H. floresiensis is exceptionally small and exhibits a relatively long, stout hamulus lacking the oval-shaped cross-section characteristic of human and Neandertal hamuli (variably present in australopiths). Documentation of a second individual with primitive carpal anatomy from Liang Bua, along with further analysis of trapezoid scaling relative to the capitate in LB1, refutes claims that the wrist of the type specimen represents a modern human with pathology. In total, the carpal anatomy of H. floresiensis supports the hypothesis that the lineage leading to the evolution of this species originated prior to the cladogenetic event that gave rise to modern humans and Neandertals.

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Homo floresiensis: Microcephalic, pygmoid, Australopithecus, or Homo?
Debbie Argue, Colin Groves

Journal of Human Evolution, 2006

The remarkable partial adult skeleton (LB1) excavated from Liang Bua cave on the island of Flores, Indonesia, has been attributed to a new species, Homo floresiensis, based upon a unique mosaic of primitive and derived features compared to any other hominin. The announcement precipitated widespread interest, and attention quickly focused on its possible affinities. LB1 is a small-bodied hominin with an endocranial volume of 380e410 cm 3 , a stature of 1 m, and an approximate geological age of 18,000 years. The describers [Brown, P., Sutikna, T., Morwood, M.J., Soejono, R.P., Jatmiko, Wayhu Saptomo, E., Awe Due, R., 2004. A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia. Nature 431, 1055e1061] originally proposed that H. floresiensis was the end product of a long period of isolation of H. erectus or early Homo on a small island, a process known as insular dwarfism. More recently Morwood, Brown, and colleagues [Morwood, M.J., Brown, P., Jatmiko, Sutikna, T., Wahyu Saptomo, E., Westaway, K.E., Awe Due, R., Roberts, R.G., Maeda, T., Wasisto, S., Djubiantono, T., 2005. Further evidence for small-bodied hominins from the Late Pleistocene of Flores, Indonesia. Nature 437, 1012e1017] reviewed this assessment in light of new material from the site and concluded that H. floresiensis is not likely to be descended from H. erectus, with the genealogy of the species remaining uncertain. Other interpretations, namely that LB1 is a pygmy or afflicted with microcephaly, have also been put forward.

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Post-Cranial Skeletons of Hypothyroid Cretins Show a Similar Anatomical Mosaic as Homo floresiensis
Ben Kefford

PLoS ONE, 2010

Human remains, some as recent as 15 thousand years, from Liang Bua (LB) on the Indonesian island of Flores have been attributed to a new species, Homo floresiensis. The definition includes a mosaic of features, some like modern humans (hence derived: genus Homo), some like modern apes and australopithecines (hence primitive: not species sapiens), and some unique (hence new species: floresiensis). Conversely, because only modern humans (H. sapiens) are known in this region in the last 40 thousand years, these individuals have also been suggested to be genetic human dwarfs. Such dwarfs resemble small humans and do not show the mosaic combination of the most complete individuals, LB1 and LB6, so this idea has been largely dismissed. We have previously shown that some features of the cranium of hypothyroid cretins are like those of LB1. Here we examine cretin postcrania to see if they show anatomical mosaics like H. floresiensis. We find that hypothyroid cretins share at least 10 postcranial features with Homo floresiensis and unaffected humans not found in apes (or australopithecines when materials permit). They share with H. floresiensis, modern apes and australopithecines at least 11 postcranial features not found in unaffected humans. They share with H. floresiensis, at least 8 features not found in apes, australopithecines or unaffected humans. Sixteen features can be rendered metrically and multivariate analyses demonstrate that H. floresiensis co-locates with cretins, both being markedly separate from humans and chimpanzees (P,0.001: from analysis of similarity (ANOSIM) over all variables, ANOSIM, global R.0.999). We therefore conclude that LB1 and LB6, at least, are, most likely, endemic cretins from a population of unaffected Homo sapiens. This is consistent with recent hypothyroid endemic cretinism throughout Indonesia, including the nearby island of Bali.

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The simplicity of Homo floresiensis tools as a sign of insular dwarfism
Samantha Foraker

The simplicity of Homo floresiensis tools as a

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Brief communication: “Pathological” deformation in the skull of LB1, the type specimen of Homo floresiensis
Iwan Kurniawan

American Journal of Physical Anthropology, 2009

If the holotype of Homo floresiensis, LB1, suffered from a severe developmental pathology, this could undermine its status as the holotype of a new species. One of the proposed pathological indicators that still remains untested is asymmetric distortion in the skull of LB1 (Jacob et al.: Proc Natl Acad Sci USA 103 in Wiley InterScience (www.interscience.wiley.com).

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FAQs

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What morphological features distinguish Homo floresiensis from modern humans?add

H. floresiensis exhibits a lower cranial vault and a more prognathic face, differentiating it from both modern and microcephalic humans.

How do the cranial shapes of Homo floresiensis and H. erectus compare?add

H. floresiensis shares a distinct cranial morphology with H. erectus, particularly in postorbital constriction and vault height.

What findings support the hypothesis of H. floresiensis being a new species?add

Geometric morphometric analysis reveals distinct cranial features of H. floresiensis, confirming its uniqueness compared to both modern humans and other hominins.

What evidence challenges the view of H. floresiensis as a pathological human?add

The distinct cranial and postcranial anatomy of H. floresiensis lacks the morphological characteristics typical of microcephalic or pathological modern humans.

When did early hominins likely reach the island of Flores?add

Fossils indicate that H. erectus arrived on Flores approximately 800,000 years ago, supporting H. floresiensis's ancestry.

About the authors
George Lyras
National & Kapodistrian University of Athens, Department Member
Alexandra A E van der Geer
NCB Naturalis, Faculty Member

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iwan kurniawan

Nature, 2016

The evolutionary origin of Homo floresiensis, a diminutive hominin species previously known only by skeletal remains from Liang Bua in western Flores, Indonesia, has been intensively debated. It is a matter of controversy whether this primitive form, dated to the Late Pleistocene, evolved from early Asian Homo erectus and represents a unique and striking case of evolutionary reversal in hominin body and brain size within an insular environment 1-4. The alternative hypothesis is that H. floresiensis derived from an older, smaller-brained member of our genus, such as Homo habilis, or perhaps even late Australopithecus, signalling a hitherto undocumented dispersal of hominins from Africa into eastern Asia by two million years ago (2 Ma) 5,6. Here we describe hominin fossils excavated in 2014 from an early Middle Pleistocene site (Mata Menge) in the So'a Basin of central Flores. These specimens comprise a mandible fragment and six isolated teeth belonging to at least three small-jawed and small-toothed individuals. Dating to ~0.7 Ma, these fossils now constitute the oldest hominin remains from Flores 7. The Mata Menge mandible and teeth are similar in dimensions and morphological characteristics to those of H. floresiensis from Liang Bua. The exception is the mandibular first molar, which retains a more primitive condition. Notably, the Mata Menge mandible and molar are even smaller in size than those of the two existing H. floresiensis individuals from Liang Bua. The Mata Menge fossils are derived compared with Australopithecus and H. habilis, and so tend to support the view that H. floresiensis is a dwarfed descendent of early Asian H. erectus. Our findings suggest that hominins on Flores had acquired extremely small body size and other morphological traits specific to H. floresiensis at an unexpectedly early time. This paper reports morphological analyses of hominin fossil materials excavated from the open site of Mata Menge in 2014 (ref. 7) (Extended Data Table 1). Mata Menge is one of the Middle Pleistocene fossil-bearing localities in the So'a Basin, and is situated 74 km east-southeast of Liang Bua. The specimens (n = 7) under study were recovered in situ from the upper part of a lens-shaped fluvial sandstone unit (Layer II) measuring up to 30 cm in thickness. Layer II is capped by a 6.5 m thick sequence of clay-rich volcanic mudflows (Layer Ia-f) that filled in the stream valley and effectively sealed off Layer II (ref. 7). All hominin fossils were excavated within a maximum linear distance of 15 m. They are associated with stone tools and the fossil remains of dwarfed proboscideans (Stegodon florensis), murine rodents, Komodo dragons, and other insular fauna of Flores. The age of Layer II is constrained to between 0.65 and 0.8 Ma, using 40 Ar/ 39 Ar dating and other methods of age determination 7. The hominin fossils display some minor dissolution pitting; generally, however, the surface preservation of these specimens is quite good.

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Related topics

  • Paleoanthropology
  • Human Evolution
  • Island Studies
  • Vertebrate Paleontology
  • Homo Erectus

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