The term Wallacea refers to the islands that lie between the now submerged continental shelves of Sunda (which during Pleistocene glacial phases connected Sumatra, Java, and Borneo to mainland Southeast Asia) and Sahul (which connected New Guinea to Australia), an area which includes islands of eastern Indonesia (Sulawesi, Lesser Sunda Islands, and the Moluccas) and the independent country of Timor-Leste (East Timor) on Timor. The area derives its name from the 'Wallace Line', which separates the region from Sunda, and marks the distinctive biogeographical region observed by Alfred Russel Wallace, with the flora and fauna of Wallacea being quite distinct from that of Sunda.
Modern Humans are known to have reached Wallacea between 46 000 and 40 000 years ago, the oldest known colonisation which had to be achieved using boats. The high marine biodiversity of the region, combined with its low terrestrial biodiversity led to the development of a unique culture in the region, a cultural distinctiveness which persists to this day. However, the fluctuating climate of the Late Pleistocene combined with the tropical climate of the region means that little archaeological evidence of these earliest settlers remains.
In a paper published in the journal Scientific Reports on 2 January 2024, a team of scientists led by Stuart Hawkins of the College of Asia and the Pacific at the Australian National University describe a Late Pleistocene burrial from a cave site on the small island of Kisar in eastern Indonesia.
Kisar today has a surface area of 81.15 km², and is not thought to have been much larger during the Late Pleistocene despite lower sea levels, due to the steep sides of the island. The island is volcanic, forming part of the Banda Arc, formed by the collision of the Indo-Australian, Eurasian, and Pacific Plates, with a metamorphic core covered by a series of limestone terraces. The island is visible from Timor-Leste, which lies about 25 km to the southwest, and has a dry tropical climate, being mostly covered with savanna grasslands, with patches of woodland, having few sources of fresh water, and receiving only small amounts of rain during the Southern Monsoon Season, which lasts from November to May. The island is thought to have first settled by Humans around 15 500 years ago, with more-or-less continuous occupation since this time, although the dry climate would have made settlements on the island vulnerable to climatic variations.
The cave site, Ratu Mali 2, is located on a limestone terrace 38 m above sealevel and 200 m from the modern shore. It measures roughly 40 m by 20 m, with a floor which slopes gently and a ceiling about 10 high. A stone cairn is located next to the entrance.
Hawkins et al. excavated a 1 m² square trench near the entrance to the cave, to a depth of 55 cm, where they hit bedrock. In doing so they exposed part of a grave near the base, causing them to dig a 1 m by 50 cm extension on the eastern side of the original trench. Five distinct layers of sediment were exposed, based upon colour and consistency, and based upon radiocarbon dates obtained from material within these layers, suggest three major cultural intervals are recorded at the site.
The first phase of occupation is thought to have started about 16 000 years before the present, and ended some time between 15 000 and 7000 years before the present. The grave, which contains two individuals, lies within this layer. Two shells within the grave, an Abalone and a Chiton, yielded radiocarbon dates of between 15 179 and 14 725 years before the present, and between 15 504 and 15 043 years before the present. This matches with the earliest phase of settlement at Here Sorot Entapa, another archaeological site on the south coast of the island, about 5.8 km from Ratu Mali 2.
Another Abalone shell was found at the edge of the burial cut, higher up than the other two shells, and yielded a date of between 8642 and 8362 years before the present. This was quite close to the contact point between the fifth and lowest layer and the fourth layer, where a piece of charcoal produced a date of between 9419 and 9135 years before the present. It is thought likely that the shell originated in the fourth layer and was moved downwards after being buried or during the excavation process.
The second phase of occupation is thought to have started around 8000 years ago and persisted to about 4000 years ago, covering the Early-to-Middle Holocene, and is represented by the fourth and third layers at Ratu Mali 2. These yielded a sparse collection of chert tools, Animal bones, and Mollusc shells. Two pieces of charcoal from within layer four yielded dates of between 7268 and 7165 years before the present, and between 4419 and 4291 years before the present.
The final phase is thought to have begun about 4000 years ago and ended about 3000 years ago. This contains a greater concentration of stone tools, bones, and shells. A piece of charcoal from layer 2 yielded a radiocarbon date of between 3967 and 3729 years before the present, well within the early Neolithic, which is considered to have started about 4200 in Island Southeast Asia, when people began using pottery and keeping domestic Animals.
Thus it is possible that there was no gap in settlement on the island since the Late Pleistocene, but it is more likely that there was a gap between settlement phases 1 and 2.
The two individuals uncovered were buried together in a shallow grave about 90 cm in diameter, directly upon the bedrock. They were orientated along an east-west axis, facing south, towards Timor-Leste, and both had large limestone rocks placed next to their heads. Both were in a flexed position, on their right sides, with their hands placed under their head or chin. The first burial had a shattered cranium, though most of the teeth were intact, as were the ribs and hands; less than 10% of the lower body was preserved. Based upon enamel peptides, this skeleton was sexed as being male. The second skeleton had a more fragmentary cranium, with only about 20% of teeth present, along with 60% of the hands and 30% of the lower limbs. This skeleton was also sexed from enamel peptides, this time as female. These two skeletons are the oldest upon which this method has been successfully used.
Most of the material associated with Phase 1 at Ratu Mali 2 comes from within the grave fill. This includes 26 obsidian flakes of between 3.7 mm and 21.2 mm in length. A total of five such flakes were recovered from Phases 2 and 3. Obsidian from all three phases was found to be geochemically similar, and exotic to the island; its point of origin could not be identified, but it is thought likely to have come from one of the nearby volcanic islands. Analysis of strontium isotopes from the tooth enamel of the two buried individuals suggests that they grew up on either Kisar or another island with similar limestone geology.
Large numbers of Mollusc shells were recovered from all layers within the trench, emphasizing the importance of shellfish as a food source to the people of the island throughout its history. Carbon isotope analysis of the teeth of the two individuals supports hypothesis that their diet was heavily dependent on this food source, and the shells were present at a greater concentration in the (Late Pleistocene) burial fill than in later (Holocene) phases of occupation. The shell sample was very diverse, with 89 species recorded, suggesting generalist foraging on a vibrant littoral reef, although the earliest, Phase 1, shells from the grave infill were less diverse, suggesting a concentrated effort on collecting Neritidae and Chitonidae. The abundance of shells is higher in Phase 3 than Phase 2, although there is no change in diversity between these later two phases. A small amount of Fish and Crab remains were also present, although the Crab remains were concentrated close to the surface and may have been recent in origin.
The use of terrestrial resources at Ratu Mali 2 is hard to determine. Animal bone was found throughout the sequence, but this was mostly Tetrapod microfauna, such as small Rodents, Lizards, Frogs, Snakes, Birds, and Bats, more consistent with the action of Avian predators than Human ones. Large Rats and terrestrial Megafauna, present on other islands in Wallacea from the earliest phases of Human occupation, always seem to have been absent from Kisar. The majority of stone tools were made from obsidian or chert, with smaller amounts of quartz, quartzite, a fine-grained silicified limestone and chalcedony. Nautilus Shell bead ornaments with single holes were recovered from the Phase 3 deposits; similar Nautilus shell beads are known from Timor, Alor, and the Here Sorot Entapa site on the south coast of Kisar. Two adze blanks made from Tridacna (Giant Clam) shells, one from Phase 2 and one from Phase 3.
Very little is known about funerary practices in Island Southeast Asia during the Pleistocene. Anatomically Modern Humans first appear in the region on Sumatra, about 73 000 years ago, and the earliest burial is known from Liang Tebo on Borneo, on the west Sunda shelf, where a young adult individual was buried in a flexed position; remarkably this individual appeared to have had one foot surgically amputated and to have survived for several years after. A burial at the Gua Braholo 6 site on Java, has been dated to between 15 731 and 12 698 years before the present, overlapping in age with the Ratu Mali 2 individuals, but this would again have been on the Sunda landmass, making the Ratu Mali 2 grave the oldest known burial east of the Wallace Line. Some disarticulated Human bones have been recovered from Roti Island, from a layer which dates to about 23 000 years before the present, although these appear to be derived from a secondary burial. Another secondary burial from Liang Lembudu on Pulau Kobroor in the Aru Islands dates to 18 000–16 000 years before present, although Pulau Kobroor would have formed part of the Sahul landmass in the Late Pleistocene. Further to the east, Human remains dated to between 12 300 and 11 300 years before present have been found at the Pamwak site on Manus Island in the Bismarck Archipelago. Within Wallacea, two burials at Tron Bon Lei on Alor Island have been dated to between 11 700 and 11 300 years before present, and between 17 000 and 7000 years before present.
It is worth noting that the Ratu Mali 2 burials have not been dated directly from bone collagen, but from associated shell material. This is common in Island Southeast Asia, where the tropical climate does not favour the preservation of bone collagen, placing a degree of uncertainty on the dating of all burials in the region.
The way in which the two individuals at Ratu Mali 2 were buried indicates that a degree of ritual was involved in the treatment of the dead, and shows similarities to other burials from Java, Borneo, and elsewhere in Wallacea, probably indicating a shared system of beliefs across the region. The bodies were flexed and placed on their rights sides along an east-west axis, facing towards the south and Timor Leste. The Gua Braholo 6 individual from Java, who was buried at about the same time, was also placed on his right side along an east-west axis, facing to the south. The Tron Bon Lei 1 individual from Alor Island, dated to between 12 300 and 11 300 years before present, was also buried in a flexed position, but was laying left side down. Both the Liang Tebo individual from Borneo and the Tron Bon Lei 1 individual had large rocks placed next to their heads, in a similar way to the Ratu Mali 2 individuals.
Shellfish remains and obsidian flakes were found at higher concentrations within the grave fill at Ratu Mali 2 than in subsequent archaeological layers. This may indicate that obsidian flakes were an intentional part of the burial prcedure, and/or that feasting on shellfish was also part of the rites. The limited range of taxa within the burial compared to later layers supports the idea that these shells were all part of a single, discrete, burial event, rather than an accumulation over time. This in turn supports the idea that the two individuals were buried at the same time, possibly indicating that they had been bonded in life. If correct, this represents the first recorded instance of ritual deposition of shellfish at a funerary site in Wallacea. In the Torres Strait Islands, which lie between Australia and New Guinea and would have been part of the Sahul landmass in the Late Pleistocene, shellfish mounds are associated with burial sites, although these are relatively modern, at less than 1000 years old. The Tron Bon Lei 1 burial, thought to be about 3000 years younger than Ratu Mali 2, contained fish-hooks and cobbles coated with red ochre, providing further evidence of ritual deposition at burial sites in Wallacea in the Late Pleistocene.
Following the Last Glacial Maximum, sea levels, precipitation levels, and temperatures were rising across Wallacea. Archaeological evidence suggests that Human populations in the region were also climbing rapidly, with settlement intensity increasing at a number of sites. At the same time, new populations were moving into the area from the east, bringing with them obsidian trade networks and new burial practices. The climate would have fluctuated across the Pleistocene-Holocene boundary interval, as the modern Australian-Indonesian Summer Monsoon became established. Human activity appears to have peaked during the cool, dry Bølling–Allerød interval, between 14 600 and 12 900 years before present, and then fallen as conditions became warmer and wetter, with possible hiatuses in settlement at sites such as Here Sorot Entapa and Ratu Mali 2. This may indicate that access to reef resources was more important to these people than rainfall levels, with higher sealevels cutting people of from these resources. By the Middle Holocene conditions had stabilised, and the population appeared to be rising again.
From about 15 500 years ago, people in the Lesser Sunda Islands became more mobile at sea and adopted a distinctive technology including tools such as shell adzes, and obsidian flakes, which suddenly appears on numerous islands without local obsidian, including Timor, Alor, and Kisar. This obsidian continues till about 4000 years before the present, although its source has yet to be identified, and is considered to be indicative of an extensive trade network, possibly the earliest Human maritime network. This would have reduced the risks of settling on islands with limited resources such as Kisar, as people would have been better equipped to relocate to other islands during periods of climate instability or reef bleaching if they already had good relations with the peoples of those islands. The spread of cultural items such as Nautilus shell beads is also indicative of such a network. Some items, such as Tridacna shell adzes, are found across a wider area, from other parts of Island Southeast Asia and even Pacific islands by the Middle Holocene, hinting at a trade network that went far beyond Wallacea. The obsidian flakes disappear around 4000 years ago, another time of social transformation in the region, when Neolithic tools, pottery, and domestic Animals were spreading across the area.
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