Hominin diversity in the western indonesian archipelago during the quaternary: a dental record perspective
- Autores: Sofwan Noerwidi
- Directores de la Tesis: Carlos Lorenzo Merino (dir. tes.)
- Lectura: En la Universitat Rovira i Virgili ( España ) en 2020
- Idioma: español
- Tribunal Calificador de la Tesis: François Sémah (presid.), Robert Sala Ramos (secret.), Amelie Vialet (voc.)
- Programa de doctorado: Programa de Doctorado Erasmus Mundus en Cuaternario y Prehistoria por la Universidad Rovira i Virgili; Muséum National d'Histoire Naturelle(Francia); Universidade de Trás-os-Montes e Alto Douro(Portugal) y Università degli Studi di Ferrara(Italia)
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- Resumen
Teeth are the most frequently preserved of part in the skeleton. They are preserved in greater numbers than any other parts of the skeleton, closer reflection of the genotype, more directly affected by the forces of natural selection, and easily treated by quantitative methods (Brace, Rosenberg and Hunt, 1987). Teeth have been a focus of interest in paleoanthropological studies for over many years. They provide a multitude of information about humans, including: cultural treatment, pathology, morphological variation, and development. An understanding of dental morphological variation among living humans has proven to be important for assessing biological relationships between recent groups (Bailey and Hublin, 2007).
The human population of Indonesian archipelago shows a great diversity in temporal and spatial distribution. In fact, there are very limited studies on the variability of human populations in this region based on dental evidence. On another hand, teeth are the most common and best preserved remains in the fossil record, and supposed to be the important on our understanding about human evolution. This situation makes it opportunities to explore the variability of human populations in Indonesia based on dental evidence. In the wide perspective, addressing questions related to that diversity is not only a taxonomical position problem, but is clearly associated with the problem of early expansion from Africa into Eurasia and within Asia, also their isolation, adaptation and local evolution even coexistence with others population.
Based on the research background stated in the previous part, the research question of this work is as follows: To what extent does dental metric and morphological variability reflect human evolutionary history, adaptations and dispersals in the western part of the Indonesian archipelago (Sundaland), especially during key stages of the Quaternary Period? This research aims to develop an original approach to the human dental evidence recovered from the western part of the Indonesian archipelago during the Quaternary Period, from the Early Pleistocene to the Holocene, to characterize variability and understand its spatio-temporal distribution. In fact, since teeth are the most abundant fossils among the hominid collection from the region, they are scattered among various collections and institutions. Some fossils were found in situ in prehistoric excavations, others have a more or less reliable stratigraphical context, and others are surface finds, meaning that a proper revision of the material and their chronostratigraphy is important in order to build a reference collection. Some of the teeth have been the subjects of previous studies, but this work would represent the first comprehensive study of the entire human dental sample from the Early Pleistocene to the Holocene in Sundaland. Thus, beyond the study of isolated samples, this study will provide a better understanding of the evolutionary history of Pleistocene-to-Holocene hominins from the region.
Because of these issues and questions, it is appropriate to develop a study on the hominin diversity in the western Indonesian Archipelago during the Quaternary, based on dental record perspective. Such a study would lead to a better understanding on the history of ancient human migrations in this archipelago during the Early Pleistocene-to-Late Holocene, from the first appearance of early humans to the extinction of Homo erectus and the emergence of early anatomically modern Homo sapiens.
This research will result in a comprehensive database of all human dental collections from Java, specimens of which are housed in 7 different institutions in Indonesia and Europe: the Sangiran Museum, Balai Arkeologi Yogyakarta, Geological Museum Bandung, Gadjah Mada University Yogyakarta, Institute of Technology Bandung, Naturmuseum Senckenberg Frankfurt, and National Museum of Natural History Leiden. The specimens represent (mostly fragmentary) 15 maxilla, 19 mandibles and 102 isolated teeth. The Pleistocene sites are Rancah (West Java), Sangiran and Patiayam (Central Java), and Trinil and Kedungbrubus (East Java).
This comparative study will also included Sinanthropus teeth, which are the Pleistocene hominins sensu strico from the Zhoukoudian localities, the nearest Mainland Asia region. The Holocene Homo sapiens teeth are from the Insular Sundaland region (Java and Sumatra), including Tamiang and Sukajadi shellmidden sites (Northern Sumatra), Gua Harimau (South Sumatra), Gua Pawon (West Java), Gua Kidang (Central Java), Gua Braholo and Song Tritis (western part of Southern Mountains), also Song Keplek and Song Terus (eastern part of Southern Mountains). A collection of Sinanthropus dental casts is housed in the Institut de Paléontologie Humaine, Paris, and original Holocene Homo sapiens collections are conserved in Museum Si Pahit Lidah (South Sumatra), Balai Arkeologi Bandung (West Java), Balai Arkeologi Yogyakarta, Gadjah Mada University Yogyakarta, and Laboratory of Gunung Sewu, Pacitan (East Java). In the end, this study will include 715 teeth, including 290 teeth from Pleistocene hominins and 425 teeth from Holocene Homo sapiens.
The Holocene Homo sapiens samples used in this study are important because, in contrast to specimens referred to Homo erectus, we know they are Homo sapiens from the Indonesian archipelago and some have only been superficially studied and most are unpublished.
This study will be based on a morphological and metric characterization of dental tissues to reconstruct the diversity and evolutionary history of ancient human populations in the western Indonesian archipelago. The study of external morphology will include: a. Comparative morphology b. Classical morphometry c. Geometric-morphometric analysis d. Crown size and cusp proportions These approaches serve different functions in achieving the goal of the proposed research. Morphological comparisons and classical morphometry are amenable to multivariate analysis, which is important for distinguishing between fossils and characterizing groups or populations. Geometric-morphometric analysis tests group characterizations with regard to specimens of differing size. Crown size and cusp proportions can help identify the dynamic and morphological changes in evolutionary and chronological contexts.
This manuscript will consist of six main parts.
Chapter 1) Sundaland and its environment, and a geographical overview of western Indonesia, especially Sundaland, including Sumatra and Java. Tectonics and volcanics correlated with the formation time and factors underlying the emergence of Sundaland. Climatic and physiographic dynamic regarding glacial-interglacial cycles and landscape changes correlated with migration. Geological conditions and stratigraphy regarding primary lithological formation and chronological correlation. The palaeoenvironmental condition regarding floral variation and biostratigraphy that are correlated with faunal succession and human migration. This chapter will conclude with a brief overview of the emergence of the genus Homo, the initial human occupation of Sundaland during the Early Pleistocene, early anatomically modern humans of Southeast Asian islands during the Late Pleistocene, and the Holocene populations of the archipelago.
Chapter 2) The general condition of the prehistoric sites and human dental collections. The presentation of the sites will be divided into the geo-physical zones of Java and Sumatra Islands. The central zone of Java: sites along Bogor-Kendeng Mountains and great central depression, including Trinil and Kedungbrubus at Kendeng, Sangiran Dome at the Solo depression, Rancah at the Bogor anticlinal zone, and Gua Pawon at the Bandung Highland. Northern zone of Java: Patiayam Dome at the Muria Mountain slope and Gua Kidang at the Rembang karstic mountains. The Southern Mountain of Java: sites in the Gunungsewu and Campurdarat Karstic Mountains, including Gua Braholo and Song Tritis at the western part of Gunungsewu, Song Terus and Song Keplek at the eastern part of Gunungsewu, and Wajak in the Campurdarat karstic mountains. The southern Sumatra zone: includes Gua Harimau at the Baturaja karstic region part of the Barisan Mountains, and the northern Sumatra zone consists of shellmidden sites located at the northern basin of Sumatra, including Tamiang and Sukajadi Pasar.
Chapter 3) Materials and methods of analysis, e.g. basic dental terminology, a summary of the material, and the technical analysis. Basic dental terminology: tooth definition and orientation; the cusps and occlusal landmarks. Materials: summary of upper and lower jaw teeth. The four analytical approaches: a) the scoring of non-metric or morphological characters, b) classical morphometrics, c) comparison of crown size and cusp proportions, and d) geometric-morphometric comparisons.
Chapter 4) Results following the presentation in Chapter 3.
Chapter 5) Population diversity, including three early hominin Early-to-Middle Pleistocene groups, and three Late Pleistocene-to-Holocene Homo sapiens groups. Interpretation results, including the chronology of human occupation in Sundaland, from the Early Pleistocene to the Late Holocene. Populations/groups in their faunal and floral palaeoenvironmental context, including habit and culture as adaptations. Reconstructing the origin and evolution of human populations in the archipelago, including dispersal and interaction during the glacial period; isolation, adaptation, and local evolution during the interglacial period.
Chapter 6) Conclusion and perspectives.
Result Based on four approach of analysis used in this research, there are six hominin groups who inhabitant the western part of Indonesian archipelago during the Quaternary periods, including four groups of Pleistocene hominin and two groups of Holocene Homo sapiens.
The first hominins arrived in the Solo Basin during the sedimentation periods of Pucangan Formation at least 1.6 Ma. The area at these times was a low relief landscape along the upper reaches of a shallow estuary (Sémah 1986). Freshwater marshes and marsh-edge environments supported aquatic and semiaquatic vertebrates such as small hippos, cervids, bovids and crocodiles (Bettis et al. 2009). From the chronological point of view, the Group 1 Meganthropus type and the Group 2 Mojokertensis type from the Lower Pleistocene correspond to the first hominin groups who settled in Java. The Group 1 type includes Lower Pleistocene fossil mandibles from Sangiran, (Sangiran 6b or Meganthropus A (von Koenigswald 1950) and Arjuna 9 (see Widianto 1993) from the Pucangan and Grenzbank series in Sangiran stratigraphy. The Group 2 type includes the Sangiran 1b fossil (called ‘Pithecanthropus modjokertensis’ (von Koenigswald 1940) from the Pucangan series, and also Sangiran 37 from the early Middle Pleistocene of Grenzbank/Kabuh layers.
During the accumulation of the Kabuh Formation, local environmental conditions had changed. Braided streams draining nearby volcanic highlands provided intermittent floods of sandy, silty and clayey sediment (Brasseur et al. 2015), forming a dynamic and diverse riverine landscape characterized by open woodland, savanna and tree lined channels (Bettis et al. 2009). The large rivers draining on the Sundaland probably provided refugia along their banks. Savannah habitant, such as elephant, antelopes, hippo, deer and carnivore were flourished, along with the hominins (Whitten et al. 1996). The Middle Pleistocene of human occupation occurred between 0.9 Ma to 125 Ka BP. Three type groups were found in this period, they are the last survived of Group 2 Mojokertensis type, Group 3 Sangiran type and the new comer of Group 4 Wajak type. The last Group Mojokertensis 2 type fossil which still survive to this period is Tjg 1993-05 from lower Kabuh formation. The Group 3 Sangiran type includes Sangiran 33 (called ‘Pithecantropus H’ by Aziz 1983) and Ng 8503 from the lower Kabuh series. The Wajak type includes NG 91 G10 and NG 92 D6 from lower Kabuh, also Abimanyu 1 from mid-Kabuh.
In the other hand, the Group 4 Wajak type might be identified as a newcomer because it seems that there is no possibility of gradual evolution from previous Group 1 Meganthropus type or Group 2 Mojokerto type. The discoveries of specimen member of the group with the Acheulian artifacts in Ngebung 2 occupation layer in the Sangiran dome suggest that the Wajak type migrated to Java on the boundary of Lower to Middle Pleistocene around 0.8 Ma (Sémah et al. 1992; Simanjuntak, Sémah, and Gaillard 2010). This event could be the reflection of the ‘mid Pleistocene revolution’ as proposed by Sémah et al. (2010), which could be described as the formation of a new geographical territories of the archipelago, with a new genetic flow from the mainland which represented by the Group 4 Wajak type. Finally, this group including ‘Homo wajakensis’, were survived from the dramatic climatic change through the Middle Pleistocene until the Late Pleistocene.
During the Holocene, the Sundaland was occupied by Group 5 of Preneolithic population in the Early Holocene and Group 6 of Neolithic-Paleometallic population in the Late Holocene.
The Milestones Recent East and Southeast Asian human fossils (e.g. Homo floresiensis (Brown et al., 2004), the Denisovans (Meyer et al., 2012), and Homo luzonensis (Détroit et al., 2019)) appear to reflect extreme variability of ancient human populations in the region. In terms of recent human genetic variation, more than 90% of East Asian (EA) haplotypes are found in Southeast Asian (SEA) or Central-South Asian (CSA) haplotypes, and with the diversity decreasing from south to north. Furthermore, 50% of EA haplotypes are found in SEA and 5% in CSA, indicating that SEA was a major geographic source of EA populations (HUGO, 2009). Based on external dental characters, this study contributes to a better understanding of the history of human occupation in the Southeast Asian archipelago during the Quaternary.
