First Humans Out of Africa: Evidence from the Caucasus
David Lordkipanidze (Georgian State Museum, Tbilisi)
Some of the most controversial issues remaining in paleoanthropology
are when and why our ancestors left their motherland and began global colonization.
The site of Dmanisi (Southern Caucasus, Georgia) brings new evidence and
opportunities to address these questions. The site dated to ca. 1.75-1.8
million years ago, has in recent years produced what is incomparably the
finest record known of the earliest hominid dispersal beyond Africa. The
site yielded remains of several hominid individuals, along with many well-preserved
animal fossils of the Early Pleistocene age and quantities of artifacts
similar to the mode 1 (Oldowan) stone industry of East Africa.
We now have 4 hominid skulls, 3 of them with maxillas, 3 mandibles and isolated post-cranial remains. Despite certain anatomical differences between the Dmanisi specimens, we do not presently see sufficient grounds for assigning them to more than one hominid taxon. Thus, the Dmanisi assemblage gives us a unique opportunity to study variability within an early Homo population.
The Dmanisi specimens are the most primitive and small-brained fossils to be grouped with Homo erectus /ergaster group or any taxon linked unequivocally with genus Homo and also the ones most similar to the presumed habilis-like stem. This permits us to hypothesize that the ancestors of the Dmanisi population dispersed from Africa before the emergence of humans identified broadly with the H. erectus grade.
The Dmanisi hominid remains represent the missing link between Africa, Asia and Europe. They are oldest undisputed hominid remains ever unearthed outside Africa. Dmanisi finds expand the known geographic range of the early Homo. Dmanisi shows that hominids did not require large brains and sophisticated stone-tools to disperse out of Africa.
シンポジウム ４ 発表２ （10：10〜10：40）
○海部陽介, 馬場悠男 (国立科学博物館・人類), F. アジズ (バンドン地質研究開発センター・古生物)
What is Meganthropus? − On the oldest hominids in Java.
Yousuke KAIFU, Hisao BABA (National Science Museum, Tokyo), Fachroel AZIZ (Geological Research and Development Centre, Bandung)
Since the 1930ﾕs, the Sangiran region in Java has yielded several relatively
large fragments of hominid fossil mandibles. So far, various opinions have
been proposed concerning the systematics of these specimens. Such views
include they should be classified into a new genus which is different from
Homo; They belong to a group of African robust australopithecines; They
belong to a group of African early Homo (Homo habilis); They are within
normal variation range of the species Homo erectus.
Recent progresses in the understanding of morphological characteristics of early groups of Homo and relative chronology of each hominid specimen from Sangiran, and addition of newly discovered specimens from Sangiran permit a meaningful re-examination of these Sangiran mandibles, which include most of the oldest hominid remains so far known from Java. We examined most of the existing hominid mandibles and teeth from Sangiran, and investigated their affinities with other hominid groups from Africa and Eurasia. The results showed that there was remarkable morphological differences between the chronologically younger and older groups of Sangiran dento-gnathic remains, and the chronologically older group exhibited some features that are equally or even more primitive than early H. erectus of Africa (a relatively narrow alveolar arcade, a robust mandibular corpus, strong eversion of mandibular corpus, a well-developed lateral prominence and a narrow extra-molar sulcus, an anteriorly located lateral prominence, large tooth size, and complicated premolar root morphology).
Coupled with recent discoveries of the earliest form of primitive Homo remains from Dmanisi, Georgia, the primitive aspects of the oldest Javanese hominid remains suggests that hominid groups prior to the grade of circum 1.8-1.5 Ma African early H. erectus dispersed into eastern Eurasia during the earlier Early Pleistocene, although the age of the Javanese hominids themselves is yet to be resolved.
シンポジウム ４ 発表３ （10：40〜11：10）
Recent discoveries on Flores: implications for the genus Homo
Peter Brown (Palaeoanthropology, University of New England)
Until recently membership of the human genus, Homo, was primarily defined
on the basis of absolute, or relative, brain size. To this definition were
added a variety of anatomical traits designed to contrast with small-bodied,
and small-brained, Pliocene Australopithecus. At times evidence of cultural
complexity, and assumed more human-like, behaviour were included in the
definition as well, most notably in the initial discussion of Homo habilis.
These descriptions became unworkable when it was demonstrated that Australopithecus
must have also made tools, and the species H. habilis, included variation
in cranio-facial proportions which overlapped australopithecines. New discoveries
from Liang Bua cave, on Flores in eastern Indonesia, further complicate
definitions of what it is to be human. Homo floresiensis combines a body
height which would be considered short for an australopithecine, with a
brain size of chimpanzee proportions. The cranial and postcranial skeleton
of LB1, the best preserved of the new skeletons, combines a mosaic of primitive,
derived and unique traits. Overall facial anatomy and tooth size are like
Homo, rather than Australopithecus, but the skeleton combines traits recorded
from both genera. As we believe that H. floresiensis is the result of endemic
island dwarfing of a large bodied H. erectus, and the skeletal evidence
suggests human-like obligate bipedal locomotion, we have included the new
hominin in the genus Homo.