Australia: The Land Where Time Began
The Colonisation of Greater Australia in the Pleistocene - A Re-examination
In this paper the problem with the initial peopling of Australasia is re-examined in light of recent evidence suggesting that settlement may have taken place earlier than the conventional view of 40,000-35,000 BP. The initial settlement of people in Australia earlier than the applicable limits of conventional analysis is suggested by dating methods including palaeoecological changes that are interpreted anthropogenically, and the application luminescence dating techniques. At the Ngarrabullgan Cave (David et al., 1997), Malakunanja II (Roberts et al., 1994), Nauwalabila I (Roberts et al., 1994) and are suggested by Zazula1 to indicate clearly that the initial phase of Australian prehistory needs to be re-examined and that the age determination of the initial settlement in Australia the radiocarbon age determination may not be applicable in regards the earliest arrival of people on the Australian continent.
In the latter part of the 20th century radiocarbon dating became available for the archaeological sites in Australia that provided evidence that the ancestral Aboriginals arrived in Australia during the Pleistocene. The first settlers in Australia originated in the closest proximal landmass in Pleistocene Southeast Asia. These 2 land areas have not been connected at any time during the Quaternary, therefore watercraft must have been used to reach Australia from Asia. A temporal chronology for the initial occupation of Australia has been attempted by the past generation of research into the prehistory on the continent and the now adjacent islands of Tasmania and New Guinea. Much scholarly debate continues as to the peopling of Greater Australia, though a large amount of information has now been accumulated. In this paper Zazula1 reviews the issue of the first Australians and the current state of the archaeological, palaeoenvironmental and palaeoanthropological evidence, as well as the major interpretations of the material discussed. The debate concerning the timing and species involved in the initial hominid occupation of Australia is focused on, and the related debate on the dating methods used for the Pleistocene material.
Greater Australia and Southeast Asia - Pleistocene Geography
The geography of Australia and Southeast Asia have changed over time (Lowe & Walker, 1997), with global water reserves being largely stored in continental glaciers in the Northern and Southern Hemispheres throughout much of the Pleistocene. The sea levels dropped 150 m lower than their present level as a result of the dramatic change in the hydrological regime of the Earth resulting in the exposures of the continental shelves of Australia and the South Pacific (Birdsell, 1977). This resulted in open plains connecting the present islands of Tasmania and New Guinea to the mainland of Australia, leading to the formation of the vast continent of Greater Australia, aka Sahul, during the Pleistocene. The present islands of Sumatra, Java, Bali and Borneo were connected by land bridges of exposed continental shelf to South East Asia to form the continent of Sunda, allowing the islands of Wallacea, comprised largely of Sulawesi and Timor, to become probable "stepping stones" connecting the 2 continents of the Pleistocene (Fagan, 1995). An important point is that between Sahul and Sunda there was never a land bridge connecting these 2 continents and the islands of Wallacea were never connected to either continent. At the lowest sea levels of the Pleistocene gaps of 30 km remained between Wallacea and Sunda and of about 90 km between Wallacea and Sahul. During this period these relatively short distances are considered to be key factors that allowed the probable colonisation by humans of Sahul (Birdsell, 1977).
Archaeology of Sunda in the Pleistocene
Zazula, (2000/2001)1 suggests an understanding of the inhabitants of Sunda is necessary as the earliest colonisers of Sahul originated on the Sunda landmass. At Sangiran in Java (Jones, 1989), a Homo erectus dated to 1.16 Ma was the first evidence to be found of the earliest hominid population in southeastern Sunda, though some still debate the antiquity of this find (Fagan, 1995), but there is firm evidence of H. erectus being in the region by 780,000 BP (Jones, 1989). Homo erectus soloensis, with a more modern appearance, apparently a more advanced stage of evolution, has since been discovered and may have existed in Java from about 200,000 BP to 100,000-75,000 BP. It has been indicated (Jones, 1992) that a single lineage of erectus populations have been present on the shore of Sunda for almost 1 million years. Zazula1 suggests there are potentially revolutionary implications for the multi-regional approach to the origins on a global scale, based on evidence of the presence of H. erectus populations with a more modern appearance in Java between 75,000-100,000 BP, as well as for the species of hominid populations that initially colonised Australia.
Though there is a long fossil record the archaeological evidence from the islands or the mainland of Southeast Asia is very scarce (Jones, 1992). No reliable evidence has been found in archaeological material associated with any of the H. erectus fossils known from Java in Sunda (Jones, 1989). Zazula1 suggests the lack of cultural evidence from H. erectus sites may possibly be attributed to geomorphic conditions that hinder site formation in the beds bearing hominids. It may also be possible that the H. erectus populations from Java did not use stone tools, relying instead on split bamboo as the material of choice for cutting purposes (Jones, 1989). Zazula1 also suggests the hypothesised ability of H. erectus to make tools from wood and plants may suggest they may have had the technological capability to build rafts or boats. One of the hallmark cultural innovations of H. erectus is the use of fire, and evidence of its use may exist in the archaeological and palaeoecological record in the form of charcoal or charred food processing remains. It is likely H. erectus populations from Sunda left some record of their cultural activities that are yet to be discovered.
On the island of Flores in eastern Indonesia archaeological evidence suggesting the activity of H. erectus on the islands of Wallacea, that have been dated to 880,000 ± 70,000 BP have recently been discovered (Moorwood et al., 1998). Faunal material native only to continental Sunda, as well as stone tool assemblages that have been dated by fission-track method. Moorwood et al., 1998). The faunal material must have crossed a water gap to get to get to Flores as the island, to the southeast of the biogeographic line of Wallace, was never part of Sunda. As the faunal components were found associated with the archaeological components suggested to the researchers that they must have been with the H. erectus population when they crossed to Flores by some form of watercraft (Moorwood et al., 1998). This is the only known archaeological evidence that suggests H. erectus populations were present in Flores or the remainder of Sahul. It is clearly shown by the stone tool assemblages that H. erectus must have crossed an expanse of sea, so had the potential to colonise the Australian continent, provided the stone tool assemblage date is accepted.
From Sunda to Sahul
The routes and method of travel used in the crossing from Sunda to Sahul are matters of conjecture, though there is general agreement that human colonisation of Greater Australia from Sunda took place during the Pleistocene. According to the first hypothesised route it involved a set-off point from the Sunda Shelf for Sulawesi which passed through a series of islands and eventual reaching the northern tip of New Guinea, or the exposed shelf of Sahul between New Guinea and northeastern Australia. Such a route would include about 3 major optional sub-routes and a minimum of 8 water crossings, and on each route there would have been 1 or more crossings of more than 65 km, based on an estimated eustatic sea level drop of 150 m during the period around 53,000 BP (Birdsell, 1977). The more southerly of the major routes would leave from Sunda near the present eastern shore of Java and pass through the island chain to Timor, with 2 sub-routes that arrived in the Sahul shelf of northern Australia. It was surmised (Birdsell, 1977) that the more southerly route would have been more attractive as its initial water crossings are considerably shorter than the northern routes. Along this route the final water crossing would have been at least 90 km, though there were shorter island hops along in the majority of the voyage. It is suggested by computer simulations that a drifting raft would have taken 7 days to reach the coast of Australia from Timor with the assistance of monsoon winds (Fagan, 1995).
There is also evidence that at about 13,500 BP there was a major expansion of global ice volume. The Blake Event apparently occurred at the same time as a climate cooling with a build-up of ice that followed immediately, and terminated, the Ermian, the last interglacial stage. It has been found by studies of oxygen isotope ratios in deep-sea cores (Shackleton, 1976, 1977; Johnson, 1978) and sea level changes recorded in tropical reef terraces (Mathews, 1972) suggesting that at about 115,000-110,000 BP the sea level dropped 60-70 m in less than 10,000 years (Andrews & Mahaffy, 1976). See Possible Global Ice Volume Changes and Geomagnetic Excursions and Earth Orbital Eccentricity
Intervisibility was a major factor for water crossings between Sunda, Wallacea and Sahul, and this proposal has been examined (Birdsell, 1977), according which at least 3 of the northern sub-routes would have involved Intervisibility along the entire island chain. There would have been at least partial intervisibility along the 2 remaining northern sub-routes, with the more southerly routes being completely blind along inter-island voyages, though these determinations are hypothetical models of possible conditions during the Pleistocene. It is believed (Lourandos, 1997) that intervisibility between islands was an important factor concerning international colonisation. Some islands may not have been intervisible along various water-crossing routes, it is suggested the extant H erectus must have had some idea that other lands must have existed over the horizon, as they could have noticed the direction from which migratory birds flew.
Considerable debate continues over whether the earliest settlement of Greater Australia was intentional or accidental. The long sea trips taken on the route to Sahul is believed to "...[imply] that the settlement was both accidental and unlikely to have been much supplemented by later voyagers" (White & O'Connell,1982:46). It has been suggested, in contrast, that the colonisation of Greater Australia was a result of a "...constant if somewhat straggling trickle of small groups of human beings over all or most of the routes" (Birdsell, 1977:123), Birdsell also hypothesising that the groups probably consisted of small biological family units as the water craft that would likely be used would be too small to carry large groups. These people had the technology to build ocean-going watercraft capable of surviving long, treacherous crossings between islands, and when needed, up to 90 km of ocean suggests the had sufficient knowledge of sea-faring skills and navigation on the ocean to colonise Sahul. It has been suggested that with many short inter-island crossings experience was gained and it is likely the number of intentional voyages and the distances crossed by these voyages increased (Irwin, 1992:29). These populations probably inhabited a coastal environment so already had knowledge of nearby islands, and it has been surmised they would assume that travelling further away from land would likely result in the discovery of more islands. Zazula1 suggests that this worldview would have been largely a product of their environment, possibly leading to ocean exploration by coastal populations due to their familiarity with the marine cultural strategies. It has been suggested that to explain the expansion of the original population following the initial arrival in Sahul there were probably many later arrivals of several individuals, both men and women, needed to maintain a viable breeding gene pool. According to Zazula1 the settlement of Australia could have occurred by accident in a number of isolated events that were unrelated, it is more likely the continued colonisation of Australia was an intentional act in order to expand their resource base, or even to satisfy human curiosity in exploring a new frontier.
The initial settlement of Sahul
The antiquity of the earliest evidence of human occupation in Sahul has been hotly debated, with much of the debate focusing on the reliability of the current dating methods, TL or radiocarbon, and how the archaeological material is dated by these methods. According to conventional views the earliest arrival in Australia was about 35,000-40,000 BP, essentially as this is the oldest date found for recovered archaeological materials (Allen & Holdaway, 1995). More recently there has been criticism of these conventional views, with the suggestion that the reasoning on which these 40,000 BP dates are based on may simply reflect the limitations of the radiocarbon dating of these sites, not the actual age of occupation (Roberts et al., 1994; Chapell et al., 1996). According to the other view of the occupation of Australia, it suggests humans were present in Australia prior to 40,000 BP, based on more recent work in which TL dating was used and including palaeoenvironmental change evidence (Singh & Geissler, 1985; Kershaw, 1986). It has been suggested (Arnold, 1995) that radiocarbon dates must be reviewed, given the known limitations of the radiocarbon dating method, based on more recent evidence from TL dating (Roberts et al., 1994; Hutt & Raukas, 1995; Chapell et al, 1996).
Accepted dates for the initial occupation of Sahul - the conventional radiocarbon method
The time range of 35,000-40,000 BP are the earliest dates for the initial occupation of Australia (Fagan, 1995). This date range has been found throughout the Australian continent, such as sites on the Swan River (Pearce & Barbetti, 1981), Devil's Lair and Lake Mungo (Lourandos, 1997). Throughout Greater Australia an age of 40,000 BP is the earliest date that has been found by radiocarbon dating of archaeological material (Allen & Holdaway, 1995). Near the coast of southwestern Australia the Swan River has provided the cultural evidence of human occupation which has been suggested to be demonstrably the oldest on the mainland (Lourandos, 1997). More than 200 retouched and un-retouched flakes have been recovered from this site, and 4 radiocarbon dates ranged from 35,000-39,500 BP for associated material. The excavators of this site regard these radiocarbon dates as too recent for this site as they are too close to the limit of radiocarbon dating (Pearce & Barbetti, 1981:177). As insufficient amounts of measurable radiocarbon remains in these samples, Zazula1 suggests this site clearly portrays the limitations of dating by the radiocarbon method for material from the Pleistocene.
The devils Lair, situated in a coastal limestone cave in southwestern Australia is another archaeological site where dates have been reported within the period that is considered to represent the conventional view of the earliest occupation of Sahul, the upper layers displaying a clear record of human activity occurring throughout the stratigraphic profile of the site. A layer of charcoal was found in the lowest stratified layer, though stone tools are not present, is believed to be a cultural deposit, the charcoal giving a radiocarbon date of 38,000 BP (Jones, 1992).
Sites in the Willandra Lakes system, and Lake Mungo in southeastern Australia, have produced evidence of early cultural activity in the form of archaeological material and human remains that were buried intentionally. At Lake Mungo the finds consist of tools, hearths in which there are charred animal bones, and stratified shell middens (Bowler et al., 1970). At Lake Mungo stone tools from the lowest level of the lunette dune were found associated with a sample of charcoal which gave a radiocarbon date that was indistinguishable from background, leading to the belief the archaeological site may be older than 40,000-45,000 BP (Jones, 1989). At Lake Arumpo, a nearby lake, other shell middens were dated by radiocarbon to 37,000 BP, though the reliability of the ages obtained from freshwater shell material must be questioned because of the common reservoir effect, according to which carbon accumulation is common in such specimens Taylor, 1987).
Earlier dates for the occupation of Sahul
It has been proposed that there are 2 lines of evidence placing the arrival of humans in Australia much earlier than 35,000-40,000 BP. One is based on palaeoecological data, while the other is based on thermoluminescence dating of contextual archaeological sediments. It appears to be suggested by both lines of evidence that the initial arrival of humans in Sahul may have taken place in the last interglacial at 125,000 BP. Zazula1 suggests these reports can be revolutionary, both in terms of conventional views of the prehistory of Australia and cultural chronology on a global level.
Kershaw (1986) and Singh & Geissler (1985) proposed the line of evidence based on palaeoecological research. Pollen studies of the Lake George site, southeastern Australia, have shown there was a sudden change in vegetation according to the pollen present in sediments that are indicated to date to oxygen isotope sub-stage 5e. There was a decrease in fire-sensitive species of trees and ferns that was accompanied by a definite increase in fire-adapted eucalyptus and grasses of open savanna type. There was also a sudden increase in charcoal in the same deposits that occurred concurrently. The Lake George record of charcoal persisted from the last interglacial to the Upper Pleistocene, which included periods of treeless full glacial conditions. Such a change in vegetation history and the frequency of fire could not be explained on the basis of climate change, so they were considered to be the result of human fire use that began about 125,000 BP (Singh & Geissler,1985). According to Zazula1 it needs to be noted that correlation of marine sediment sequences with terrestrial records poses some problems (Lowe & Walker, 1997), and the age of the Lake George sediments that were proposed by Singh & Geissler (1985) may prove to be not completely accurate. Analysis of the Lake George cores was carried out (Wright, 1986) and the zone of change in question were correlated with the interstadial within a glacial period dating to 60,000 BP.
Pleistocene arrival of people in Australia . The existence of archaeological material dating to the Last Interglacial would support the suggestion by Singh & Geissler (1985) of anthropogenic fire causing the ecological change evidenced by the cores at Lake George, if the work of Fullagar and colleagues (1996) is accepted. The possibility of other Australian sites displaying similar ecological changes to those at Lake George is suggested by these combined lines of evidence. Zazula1 suggests that further evidence of such palaeoecological changes, in turn, might also be correlated with cultural from this age.
Evidence of a pre-40,000 BP occupation of Sahul has been suggested by the use of TL to date other sites in Australia and New Guinea. They tend to support the presence of humans in Sahul in the period which is clearly beyond the practical limit of radiocarbon dating, though these TL dates are nearly half the age of those from Jinmium. A TL age determination of 45,000 ± 9,000 BP has been determined from a sample of sediment overlying feature that contained stone artefacts and haematite from Malakunanja II site in the Northern Territory (Roberts et al., 1994). Deposits associated with the lowest artefact that has been recovered at the site gave TL ages of 61,000 ± 13,000 BP. Their results were checked (Roberts et al., 1994) by also investigating the Nauwalabila I site in northern Australia. The sand lens deposit that produced the earliest artefacts had an upper OSL date of 53,400 ± 5,400 BP and the lower OSL date was 60,300 ± 6,700 BP. A rubble layer in the stratigraphic profile ruled out post-depositional disturbance, according to the researchers, as it would have prevented artefact movement in or out of the sand lens.
According to Zazula Roberts and colleagues are confident of the "stratigraphic integrity and chronological coherence of the Malakunanja II and Nauwalabila I sites", suggesting that at these 2 sites there is clear evidence of human occupation between 53,000-60,000 BP in northern Australia based on age determinations by a combination of the TL and OSL methods. At Malakunanja II there is accordance between luminescence and 14C dates from associated charcoal samples at 3 points in the upper portion of the stratigraphy, though the earliest TL dates at both sites could not be cross checked with radiocarbon ages. Further support of these early dates of occupation of Australia is given by a statement by Chappell et al. (1996:551) "...the luminescence method has been well supported beyond the age range of the early Australian archaeological sites, with the same type of sample material, there is no good reason to doubt the TL or OSL dates reported by Roberts et al. (1994)." At these 2 sites the evidence provided implies that human occupation of Australia occurred at least 15,000-20,000 years earlier than is suggested by the conventional view of colonisation based on previous radiocarbon dates.
Further evidence that the OSL method for dating early Australian archaeological material is a reliable technique (David et al.,1997) came from their work at Ngarrabullgan Cave site in north Queensland. At this site the lowest stratigraphic layer was dated using both OSL and radiocarbon methods, given an OSL age for the sample of 34,7000 ± 2,000 BP, which is about 2,200 older than the average radiocarbon age for the stratum. It is believed by David and colleagues that these 2 dating techniques will produce ages that are broadly comparable for the period between 35,000-40,000 BP following proper calibration of the 14C results, and they also suggest that their results support the TL and OSL ages reported by Roberts et al. (1994).
The dating controversy - early Australian sites
The considerable controversy regarding the reliability of the radiocarbon method for dating archaeological layers that were deposited before 40,000 BP is emphasised by evidence provided in support of the opposing views that have been outlined above relating to the age of the initial settlement of Australia. Investigations of the integrity of using radiocarbon dating of archaeological material from the Pleistocene have been taking place over a long period (e.g., Jones, 1989; Roberts et al., 1994; Chappell et al., 1996). The problem being that very little isotopic material remains to measure the decay, the counts required being too long, even with AMS, as disintegration is an extremely long process. The practical limit of radiocarbon measurements is reached at about 40,000 BP, given the half-life of 14C, even when mass spectrometry is used.
An assumption that is made when using the radiocarbon method is that the sample had remained in a closed system from the time of formation to the time of measurement, with no carbon exchanges. The archaeological material being dated could have been contaminated by carbon migration within the sediments during burial. There is also the risk that modern carbon could come into contact with, and be mixed in with the sample, at the time of recovery, which would make the dates obtained from the sample incorrect. According to Zazula1 it is difficult to test if the process of isolating the 14C is the only tracer, though various method are used in the lab to isolate the original in a sample, the problem being that there is only a very small amount of original carbon isotope remaining in very old samples that makes it is difficult to measure the remaining isotope. If a sample that is actually 50,000 years old is contaminated with 0.5 % of modern carbon the age obtained from the sample will be about 35,000-40,000 BP (Allen, 1994). A time range of 35,000-40,000 BP for the initial occupation of Australia, when obtained by radiocarbon dating, was referred to as an "event horizon,"(Chappell et al., 1996). It has been suggested (Roberts et al., 1994) that ages of 35,000-40,000 BP that are reported are actually older, and problems with contamination affect the early part of the 14C chronology for the early human arrival in Australia. It has been concluded that"...our ability to measure low levels of 14C often surpasses our ability to remove contamination by sample pretreatment; at the very least all 14C dates near 40,000 BP require close scrutiny." (Chappell et al., 1996:551). It is suggested by the TL ages provided (Roberts et al., 1994; Fullagar et al., 1996) that radiocarbon dating no longer be trusted to represent the initial colonisation of the Australian continent.
Radiocarbon ages of 35,000-40,000 BP obtained for the initial settlement of Australia are still advocated by some workers to be valid. It has been claimed (Allen & Holdaway, 1995) that the supposed "event horizon" for radiocarbon ages exists for only Australian archaeological samples, and there is sufficient evidence for radiocarbon ages up to 54,000 BP, for geological contexts in Australia. They claim the reason for the no radiocarbon dates older then 40,000 BP (uncalibrated) being that humans did not arrive in Australia prior to 40,000 BP. It has been stressed (Allen, 1994) that it is unreasonable to assume that all ages of 35,000-40,000 BP obtained by radiocarbon dating result from contamination, the only way to determine which dates are accurate is to re-excavate and re-date the sites in question. He also suggests that when a proper calibration curve for radiocarbon dating becomes available the results may change (Allen, 1994).
An alternative approach for dating the earliest archaeological sites in Australia has been provided by TL dating techniques. Luminescence is 1 of a number of techniques that can be used for samples older than the 40,000 BP limit of radiocarbon dating, and according to Zazula1 has proved to be reliable in the upper stratigraphic sequences at some sites from the Pleistocene where is was possible to obtain radiocarbon dates for comparison. The earliest sites are too old to be dated by radiocarbon dating because of its limit of 40,000 years. TL and OSL dating techniques seem adequate methods having been employed successfully beyond the range of radiocarbon dating. Zazula1 suggests it would be useful to re-date the sites that are believed to represent the earliest evidence of people in Australia by luminescence techniques instead of the radiocarbon method.
In the islands of southeast Asia and Wallacea there is a long record of fossil hominids, which Zazula1 suggests poses many questions concerning the antiquity and species that first settled in Australia. It is suggested by fossil evidence from Java and archaeological evidence from Flores that there were populations of humans on the shores of Sunda and Wallacea for almost 1 million years. Zazula1 suggests it probably seems unlikely to most archaeologists that a H. erectus population could have reached Sahul by watercraft, and he suggests this possibility should not be ignored, in spite of no material being found. Recent finds in Flores seem to indicate that by 880,000 BP H. erectus had the technology to allow a water crossing on craft that possibly also carried animals (Moorwood et al., 1998). If H. erectus had the technology to construct watercraft there is no reason to doubt they could have reached Australia, suggesting that Australian archaeologists and palaeoanthropologists can no longer ignore the likelihood and bear this in mind as they search for sites of early settlement which must be continued. It will only be known if H. erectus were the original settlers in Australia if their skeletal remains are found in Sahul.
According to Zazula1 the evidence from Jinmium Rockshelter "...are truly revolutionary for Australian and hominid prehistory because the TL dates obtained are almost double other TL ages and nearly triple the conventional radiocarbon dates for initial Australian colonisation."1. Many questions are posed by the age of 116,000 ± 12,000 BP at Jinmium (Fullagar et al., 1996) in regard to the species that occupied the site. The first modern humans, Homo sapiens sapiens, in the world are estimated to have arisen between 200,000-100,000 BP (Wilson & Cann, 1992; Thorne & Wolpoff, 1992). It is not unreasonable to assume the 116,000 ± 12,000 BP date at Jinmium may represent modern humans of African origins living on the Australian continent, based on genetic evidence and the "Out-of Africa" hypothesis (Wilson & Cann, 1992). However, there is a suggestion, based on the fossil evidence (Thorne & Wolpoff, 1992), of a regional continuity of hominid populations from H. erectus to modern H. sapiens sapiens in the Australasian region. Zazula1 suggests the fossils from Java of a modern-looking H. erectus soloensis population that is more evolved, that lived 100,000-75,000 BP, may also be the population that is ancestral to the occupants of northern Australia. As it seems a population of H. erectus could cross Wallace's line by watercraft at 880,000 BP, then it is very likely the same cultural ability to cross open water was retained by the more highly evolved H. erectus soloensis. The Java and Flores discoveries suggest to Zazula1 a lineage of non-African, modern Homo sapiens that evolved locally, either in Australia, Wallacea or South East Asia. The possibility that the inhabitants may have been equally of a late H. erectus lineage, an archaic or transitional Homo sapiens, or a fully modern H. sapiens sapiens population is indicated by the age of the archaeological material recovered at Jinmium.
At the time of writing the only fully modern skeletal material has been found in Australia, though there is a degree of variation that is evident in the skeletal morphology within the populations, it is not possible to determine the degree of modernity in the initial settler population from the current osteological material. It has been argued (Thorne & Wolpoff, 1992) in favour of regional continuity in the Australasian region during the Pleistocene, and link the population of Australia back to H. erectus populations in Java. It would help prove the ancestry of the Aboriginal population of Australia if a potential discovery of Australian hominid material could be made the dated to a similar age as the artefacts at Jinmium, and the palaeoecological evidence reported from Lake George (Singh & Geissler, 1985).
In world prehistory the age of the initial settlement of Australia is a highly debated topic. Providing a chronological date for the crossing of the Straits of Wallacea, which occurred at some point in the Pleistocene, has proven very difficult for archaeologists. TL and OSL dating at Malakunanja II, Nauwalabila I and Jinmium rockshelter sites provided archaeometrical evidence that apparently suggests that the human occupation of Australia occurred much earlier than the conventional date of 35,000-40,000 BP. Together with possible palaeoecological changes, the TL dates from Jinmium Rockshelter could be interpreted to suggest that by at least 116,000 BP humans had occupied Australia, and it is also possible that the initial settlement could have occurred during the last interglacial. The excavators of Jinmium suggest caution regarding the early dates obtained from the sediments, though they believe there is enough evidence that the TL ages from this site may reflect the true antiquity of the associated artefacts (Fullagar et al., 1996). According to Zazula1 confirmation that the radiocarbon ages between 35,000-40,000 BP should no longer be used as the only line of evidence of the initial settlement of the continent comes from the existence of TL and OSL dates from at least 3 archaeological sites in Australia, which challenges the conventional view of the prehistory of Australia. It is confirmed by luminescence dates that radiocarbon dates of the range 35,000-40,000 BP should be considered with a great degree of skepticism. Evidence has been provided that the OSL and TL methods cover a dating range with enough time depth to determine reliable ages of Australia's first people, by the work at Ngarrabullgan Cave (David et al., 1997), Malakunanja II (Roberts et al., 1994), Nauwalabila I (Roberts et al., 1994), and Jinmium (Fullagar et al., 1996). Early occupation sites in Australia should also be dated by a 3rd technique such as Electron Spin Resonance (ESR) (Blackwell, 1995) to confirm the ages obtained by the use of the luminescence method, and the building of a stronger chronological case for the occupation of the continent. It appears the conventional views of Australian prehistory, that were based on radiocarbon dating, are being overthrown by luminescence dating that is becoming a method that is more applicable for the provision of accurate ages for the early settlement of the continent.
Homo erectus near Australia
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