LB1

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Skull and long bones from LB1

LB1 is the scientific name for the holotype of the biological species Homo floresiensis . The fossil was discovered in September 2003 during an archaeological excavation in the Liang Bua cave on the Indonesian island of Flores and in October 2004 in the journal Nature as a type specimen of another species of the genus Homo .

The epithet floresiensis refers to the island of Flores, the only place where remains of Homo floresiensis have been found so far . The archive number LB1 stands for the first hominine fossil that was discovered in the Liang Bua cave . The bones are kept at the Center for Archeology (Arkeologi Nasiona, ARKENAS) in Jakarta .

Dating

LB1 was discovered in excavation sector VII at a depth of 5.90 meters below the present-day cave floor, under a thick layer of volcanic ash that was radiometrically determined to be 13,100 years old. With the help of the calibrated accelerator mass spectrometry , an age of 18,000 years was published for LB1 in 2004; This finding was supported by an independently performed thermoluminescence dating , which showed an age of 35,000 ± 4000 to 14,000 ± 2000 years.

However, research results from 2016 call into question the initial dating of the Homo floresiensis finds . According to this, the cave floor had changed due to erosion , so that charcoal remains, which were initially used for dating, are younger than the immediately neighboring finds of Homo floresiensis . With the help of argon-argon dating and thermoluminescence dating in particular , the remains of Homo floresiensis were dated between 100,000 and 60,000 years ago; Artifacts assigned to it are therefore between 190,000 and 50,000 years old.

Find description

Skull and lower jaw of LB1 (copy)

The fossil LB1 is a partially preserved skeleton from which, according to the first description from October 2004, the completely preserved skull (archive number LB1 / 1) with the associated lower jaw was recovered, as well as the tubular bones of the legs (two thigh bones , two shins , two calves ) and two kneecaps , as well as some hand and foot bones, fragments of the vertebrae and sacrum , ribs , shoulder blades , collarbones and pelvis ; from the construction of the basin it was deduced that it probably came from a female individual.

From the bones it was concluded that the fossil was a small, upright walking individual during his lifetime , whose small body size and an internal skull volume of only 380 cm³ were comparable but smaller than Australopithecus afarensis ; however, the chewing tools ( teeth and jaws ) do not testify to any of the adaptations present in Australopithecus and Paranthropus . Instead, various features and proportions of the cranial bones and most of the teeth of the lower jaw resemble those of Homo erectus ; the skull roof is extremely small compared to the finds of Homo erectus , Homo ergaster and the hominine fossils of Dmanissi . The same applies to the long bones that have been preserved: with a maximum length of 280 millimeters, the thigh bones are less than the smallest thigh bone known from Australopithecus afarensis (which belongs to " Lucy " and is 281 mm long) and also the lower limit of the estimated value for the fossil OH 62 from Homo habilis . The size of the tibia corresponds to that of a chimpanzee . In 2005, the arm bones of LB1, which were only discovered in 2004, were described, which were interpreted in a further study published in 2009 as unusually long - reminiscent of Australopithecus - and as not comparable with the bones of healthy or pathologically altered modern humans .

Since there are no fossil comparison values ​​for the reconstruction of the body size of LB1, the first description is based on the proportions of pygmies living today . A body height of 106 centimeters was derived from this. But because of the small size of the skull, this calculation is probably too big. With reference to the anatomical conditions in pygmies, 16 to 28.7 kilograms have been determined for the body weight. On the other hand, if one were to take the cross-sectional area in the middle of the thigh bone as a basis (which is considerably larger in relation to the length of the bone than in modern humans), one would arrive at a weight of 36 kilograms.

The brain weight, derived from the volume of the cranial cavity, was 433 grams. An encephalization quotient of 2.5 to 4.6 was calculated from the estimated values ​​for body and brain weight , which corresponds to the situation for Homo erectus (3.3 to 4.4) and Homo habilis (3.6 to 4.3), but not comparable with Homo sapiens (5.8 to 8.1).

Due to the unique combination of features (internal cranial volume and body size similar to the Australopithecina , numerous other anatomical features similar to early representatives of the genus Homo ), the lack of features as a result of a possible hormonal disorder in Homo sapiens ( IGF-1 deficiency, hypohysial short stature , Microcephaly ) and the location on an island surrounded by water even during all ice ages , the most likely explanation for the appearance of LB1 was postulated to be an island dwarfing , descending from larger individuals of the genus Homo from the Pleistocene. With reference to studies by G. Philip Rightmire on the spread of the genus Homo in the Old Pleistocene , Homo erectus was most likely considered an ancestor . After a detailed study of the morphological peculiarities of the skull, published in 2011, the phylogenetic derivation of the Flores fossils from Homo erectus (more precisely: from the Java people ) is again considered to be the most likely.

Individual evidence

  1. ^ Peter Brown et al .: A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia. In: Nature . Volume 431, 2004, pp. 1055-1061, doi: 10.1038 / nature02999
  2. ^ Mike J. Morwood et al .: Archeology and age of a new hominin from Flores in eastern Indonesia. In: Nature. Volume 431, 2004, pp. 1087-1091, doi: 10.1038 / nature02956
  3. ↑ Thomas Sutikna et al .: Revised stratigraphy and chronology for Homo floresiensis at Liang Bua in Indonesia. In: Nature. Online advance publication of March 30, 2016, doi: 10.1038 / nature17179
  4. ↑ Homo floresiensis: The hobbit is really that old. On: focus.de from March 31, 2016
  5. ^ Mike J. Morwood et al .: Further evidence for small-bodied hominins from the Late Pleistocene of Flores, Indonesia. In: Nature. Volume 437, 2005, pp. 1012-1017, doi: 10.1038 / nature04022
  6. ^ SG Larson et al .: Descriptions of the upper limb skeleton of Homo floresiensis. In: Journal of Human Evolution. Volume 57, No. 5, 2009, pp. 555-570, doi: 10.1016 / j.jhevol.2008.06.007
  7. ↑ Gary J. Sawyer, Viktor Deak: The Long Way to Man. Life pictures from 7 million years of evolution. Spektrum Akademischer Verlag, Heidelberg, 2008, p. 132
  8. ^ G. Philip Rightmire: Part 6: Conclusion. The relationship between Homo erectus and younger Middle Pleistocene hominids. In: 100 years of Pithecanthropus. The homo erectus problem. In: Courier Research Institute Senckenberg. No. 171, Frankfurt a. M. 1994, pp. 319-326, ISSN  0341-4116
  9. ↑ Yousuke Kaifu et al .: Craniofacial morphology of Homo floresiensis: Description, taxonomic affinities, and implication evolutionary. In: Journal of Human Evolution. Volume 61, No. 6, 2011, pp. 644-682, doi: 10.1016 / j.jhevol.2011.08.008