Shimona Kealy

Islands Under the Sea: A Review of Early Modern Human Dispersal Routes and Migration Hypotheses Through Wallacea

ABSTRACT Wallacea is the transitional biogeographic zone between the continents of Sunda (Southeast Asia) and Sahul (Australian-New Guinea). It consists of a series of island chains unique in the region for never having been connected to either continent. Movement of early modern humans from Sunda to Sahul during the late Pleistocene required dispersal through Wallacea, and hence would have necessitated sea crossings. However, the archeological evidence for early modern humans in Wallacea is still a work in progress, and none of it pre-dates the archeological record from Sahul. While numerous models of this significant colonization event have been proposed, selecting the most likely model for first landfall in Sahul using current archeological evidence has proven difficult, if not impossible. Here the late Pleistocene archeological evidence of early modern humans from Wallacea and its neighbors are reviewed, and the key colonization models that have been proposed are explored. We consider the use of computer simulations and the input variables necessary to test the likelihood of the different colonization models. We highlight the importance of the greater than 100 additional submerged islands observed within the Wallacean archipelago following a simple analysis of bathymetric data and sea-level curves, and their potential impacts on the dispersal and ecology of early human colonizers.

Hominin Dispersal and Settlement East of Huxley’s Line: The Role of Sea Level Changes, Island Size, and Subsistence Behavior

The thousands of islands east of Huxley’s Line have never formed a single land mass or been connected to Sunda or Sahul. The earliest records of hominins in this area are stone tools recovered from Pleistocene deposits on Flores and Sulawesi. Subsistence by these hominins as well as the later subsistence patterns exhibited by Homo floresiensis suggest that exploitation of marine resources was, at best, rare and opportunistic. Likewise, the fragmentary hominin remains recovered from Late Pleistocene deposits from Callao Cave in the Philippines exploited large game at the expense of marine resources. In contrast, the earliest zooarchaeological records of modern humans are dominated by marine fish and shellfish and include the earliest evidence of pelagic fishing using shell tools, implying complex fish-capture technology. Pleistocene lithic assemblages on these islands are unspecialized, indicating reduction of predominantly locally available stone to produce flakes and irregularly retouched pieces. By the terminal Pleistocene, records of human subsistence on very small islands indicate almost total reliance on marine foods for protein. We propose that strong links exist between subsistence strategies and dispersal throughout Wallacea, with subsistence strategies available to pre-sapiens hominins in the region being a major limiting factor in their dispersal.

Fishing in life and death: Pleistocene fish-hooks from a burial context on Alor Island, Indonesia

Abstract Fish-hooks discovered among grave goods associated with an adult female burial at the Tron Bon Lei rockshelter on the island of Alor in Indonesia are the first of their kind from a Pleistocene mortuary context in Southeast Asia. Many of the hooks are of a circular rotating design. Parallels found in various other prehistoric contexts around the globe indicate widespread cultural convergence. The association of the fish-hooks with a human burial, combined with the lack of alternative protein sources on the island, suggest that fishing was an important part of the cosmology of this community. The Tron Bon Lei burial represents the earliest-known example of a culture for whom fishing was clearly an important activity among both the living and the dead.

Differential preservation of vertebrates in Southeast Asian caves

Caves have been an important source of vertebrate fossils for much of Southeast Asia, particularly for the Quaternary. Despite this importance, the mechanisms by which vertebrate remains accumulate and preserve in Southeast Asian caves has never been systematically reviewed or examined. Here, we present the results of three years of cave surveys in Indonesia and Timor-Leste, describing cave systems and their attendant vertebrate accumulations in diverse geological, biogeographical, and environmental settings. While each cave system is unique, we find that the accumulation and preservation of vertebrate remains are highly dependent on local geology and environment. These factors notwithstanding, we find the dominant factor responsible for faunal deposition is the presence or absence of biological accumulating agents, a factor directly dictated by biogeographical history. In small, isolated, volcanic islands, the only significant accumulation occurs in archaeological settings, thereby limiting our understanding of the palaeontology of those islands prior to human arrival. In karstic landscapes on both oceanic and continental islands, our understanding of the long-term preservation of vertebrates is still in its infancy. The formation processes of vertebrate bearing breccias, their taphonomic histories, and the criteria used to determine whether these represent syngenetic or multiple deposits remain critically understudied. The latter in particular has important implications for arguments on how breccia deposits from the region should be analysed and interpreted when reconstructing palaeoenvironments.

Ideology, Ritual Performance and Its Manifestations in the Rock Art of Timor-Leste and Kisar Island, Island Southeast Asia

Painted rock art occurs throughout the islands of the Western Pacific and has previously been argued to have motif and design elements in common, indicating that it was created within the context of a shared symbolic system. Here we report five new painted rock-art sites from Kisar Island in eastern Indonesia and investigate the commonalities between this art and the painted art corpus in Timor-Leste, the independent nation that forms the eastern part of the neighbouring island of Timor. We examine the motifs in the Kisar art and suggest that, rather than being Neolithic in age, some of the figurative motifs more likely have a Metal Age origin, which in this region places them within the last 2500 years.

Total evidence phylogeny and evolutionary timescale for Australian faunivorous marsupials (Dasyuromorphia)

BackgroundThe order Dasyuromorphia is a diverse radiation of faunivorous marsupials, comprising >80 modern species in Australia and New Guinea. It includes dasyurids, the numbat (the myrmecobiid Myrmecobius fasciatus) and the recently extinct thylacine (the thylacinid Thylacinus cyncocephalus). There is also a diverse fossil record of dasyuromorphians and “dasyuromorphian-like” taxa known from Australia. We present the first total evidence phylogenetic analyses of the order, based on combined morphological and molecular data (including a novel set of 115 postcranial characters), to resolve relationships and calculate divergence dates. We use this information to analyse the diversification dynamics of modern dasyuromorphians.ResultsOur morphology-only analyses are poorly resolved, but our molecular and total evidence analyses confidently resolve most relationships within the order, and are strongly congruent with recent molecular studies. Thylacinidae is the first family to diverge within the order, and there is strong support for four tribes within Dasyuridae (Dasyurini, Phascogalini, Planigalini and Sminthopsini). Among fossil taxa, Ankotarinja and Keeuna do not appear to be members of Dasyuromorphia, whilst Barinya and Mutpuracinus are of uncertain relationships within the order. Divergence dates calculated using total evidence tip-and-node dating are younger than both molecular node-dating and total evidence tip-dating, but appear more congruent with the fossil record and are relatively insensitive to calibration strategy. The tip-and-node divergence dates indicate that Dasyurini, Phascogalini and Sminthopsini began to radiate almost simultaneously during the middle-to-late Miocene (11.5–13.1 MYA; composite 95% HPD: 9.5–15.9 MYA); the median estimates for these divergences are shortly after a drop in global temperatures (the middle Miocene Climatic Transition), and coincide with a faunal turnover event in the mammalian fossil record of Australia. Planigalini radiated much later, during the latest Miocene to earliest Pliocene (6.5 MYA; composite 95% HPD: 4.4–8.9 MYA); the median estimates for these divergences coincide with an increase in grass pollen in the Australian palynological record that suggests the development of more open habitats, which are preferred by modern planigale species.ConclusionsOur results provide a phylogenetic and temporal framework for interpreting the evolution of modern and fossil dasyuromorphians, but future progress will require a much improved fossil record.

Kisar and the Archaeology of Small Islands in the Wallacean Archipelago

ABSTRACT The occupation of small islands presents particular challenges for people largely related to limited terrestrial resources and susceptibility to natural disasters. Nevertheless, the challenges and risks inherent in maintaining stable populations on small islands can be offset or overcome through the use of maritime technologies and exchange networks. The archaeology of Here Sorot Entapa rockshelter (HSE) on Kisar Island in the Wallacean Archipelago provides an unparalleled record for examining these issues in Southeast Asia. Kisar is the smallest of the Wallacean islands known to have a Pleistocene occupation record, and one of the smallest permanently inhabited today. Our results indicate that Here Sorot Entapa was first occupied in the terminal Pleistocene by people with advanced maritime technology who made extensive use of local marine resources and engaged in social connections with other islands through an obsidian exchange network. As a result, populations appear to have been maintained on the island for approximately 6,000 years. In the early Holocene occupation at HSE ceased for unknown reasons, and the site was not reoccupied until the mid-Holocene, during which time a major change in the lithic resources can be observed and the exchange network appears to have ceased.

Least-cost pathway models indicate northern human dispersal from Sunda to Sahul

Archaeological records from Australia provide the earliest, indirect evidence for maritime crossings by early modern humans, as the islands to the north-west of the continent (Wallacea) have never been connected to the mainland. Suggested in 1977 by Joseph B. Birdsell, the two main routes from Sunda (mainland Southeast Asia) to Sahul (Australia-New Guinea), still in debate today, are a northern route through Sulawesi with a landing in New Guinea, or a southern route through Bali, Timor and thence landing in northern Australia. Here we construct least-cost pathway models of human dispersal from Sunda to Sahul at 65 ka and 70 ka by extending previous out-of-Africa least-cost models through the digitization of these routes. We recover overwhelming support for a northern route into Sahul, with a landing location on present-day Misool Island. Minimal support is also recovered for the southern route at 70 ka, with a possible crossing to Sahul from eastern Timor. Review of archaeological records on the Wallacean islands crossed by our northern route indicate a dearth of archaeological research in this region. Meanwhile, the comparatively better studied southern islands still lack any archaeological dates comparable to those known for initial occupation in Sunda and Sahul. Based on our model results we suggest Misool Island as the initial landing site for early modern humans on Sahul and recommend a future focus on archaeological fieldwork in the northern Wallacean islands.

Additional file 1: Table S1. of Total evidence phylogeny and evolutionary timescale for Australian faunivorous marsupials (Dasyuromorphia)

Table of taxa, indicating whether or not they have been scored for morphological characters, percentage completeness (if scored for morphological characters) and Genbank accession numbers for molecular sequences. (XLSX 18 kb)