Marsupial translocations in the Circum–New Guinea archipelago and a model for prehistoric maritime mobility

1 Introduction

The Circum–New Guinea Archipelago (CNGA) comprises the islands east and west of Sahul, including the Wallacean island groups (the Lesser Sundas, Sulawesi, and the Moluccas), the satellite islands of New Guinea and Papua, the Bismarck Archipelago, and the Solomon Islands. Although New Guinea itself was periodically connected to the Australian continent during phases of lowered sea level (continental Sahul) most recently during the Last Glacial Maximum (LGM), the vast majority of islands in the CNGA have always been separated by oceanic barriers (excluding Aru). As a result, all terrestrial organisms—plants, animals, and humans—were required to cross open water in order to reach and persist on these islands (Kealy et al., 2016; Louys et al., 2023).

This persistent insularity has made the CNGA a key region for debates concerning dispersal, colonisation, and biogeographic patterning in Island Southeast Asia and Near Oceania. Marsupials (Infraclass: Marsupialia), a group of pouched mammals endemic to Australia and New Guinea and of Gondwanan ancestry, are central to these debates. Traditionally regarded as poor over-water dispersers (Calaby, 1984), marsupials are assumed to be incapable of crossing substantial marine gaps unaided, with even the strongest-swimming macropods thought to be limited to distances of less than 10 km (Wilson, 1974). Their presence on islands beyond Australia and New Guinea therefore poses a longstanding question: how did taxa conventionally considered unable to traverse deep-water barriers come to occupy a wide array of oceanic islands both east and west of Sahul? In insular settings such as the CNGA, long-term isolation and distinct natural biogeographic baselines provide clear conditions for identifying such movements, as the absence and subsequent appearance of taxa can be more readily detected in bounded archaeological records than in continental contexts where movements and their drivers are often obscured across connected landscapes (Gaffney et al., 2025; Grayson, 2001; Hofman and Rick 2018).

Island species distributions are most commonly explained through vicariance or natural dispersal. In the CNGA, however, prehistoric ethnophoresy—the deliberate or incidental human-mediated transport of animals, has increasingly been recognised as a plausible alternative explanation (Heinsohn, 2003, 2010). The mismatch between marsupial dispersal capabilities and their island distributions has made this anthropogenic translocation a particularly compelling hypothesis in this region (Flannery and White, 1991; Heinsohn, 2003; Spriggs, 1997). In this paper, the term “prehistoric” is used strictly in reference to periods preceding written documented evidence of marsupial translocations, and does not imply an absence of indigenous history, which is recognised as extending through their wealth of oral, cultural, and archaeological records.

Support for this perspective comes from multiple lines of archaeological and biogeographic evidence. Zooarchaeological assemblages across the CNGA increasingly indicate that several marsupial taxa appear in the archaeological record only after initial human settlement, often abruptly and without clear precursors in earlier faunal sequences (Heinsohn, 2010; Leavesley, 2005; Leavesley and Chappell, 2004). Such patterns have revealed what Heinsohn (2003, 2010) describes as a substantial “crypto-anthropogenic factor” within Oceanic biotas, demonstrating that many insular faunal communities previously regarded as natural are in fact composed, at least in part, of “camouflaged exotics” established through millennia of human-mediated ethnophoresy. The combination of persistent water barriers and isolated archaeological sequences makes island records the earliest demonstrable sources of evidence for human-mediated animal translocation globally.

In several cases, proposed CNGA translocations date to the Late Pleistocene, with emerging evidence suggesting that human-mediated movements of marsupials may have begun as early as ∼40,000 years ago (Flannery and White, 1991; Kaharudin et al., 2024, forthcoming). This potentially represents the earliest archaeological evidence of animal translocation anywhere in the world, and certainly the earliest known instance of their successful over-water transportation. While earlier continental translocations are probable from humanity's long occupation of Africa and initial dispersal into Asia, these remain currently undetected.

When viewed at an archipelagic scale, the patterned presences and absences within the zooarchaeological record can be approached as historical “meta-artefacts” (Heinsohn, 1997, 2003): ecological experiments and biological frontiers created when humans translocate species or new genetic material to an island. These archipelagic meta-artefacts map the spread of ethnotramps across the CNGA through sustained maritime interaction, while local or total species loss creates extinction meta-artefacts that reflect anthropogenic restructuring of faunal distributions over time.

Such early translocations are consistent with existing evidence for human maritime capabilities in the region. The earliest peoples of the CNGA possessed watercraft and navigational skills sufficient for purposeful open-water voyaging, as demonstrated by their dispersal through Wallacea and arrival in Australia more than 50,000 years ago (Bird et al., 2019; Kealy et al., 2018). Within this context, the movement of live animals between islands can be understood not as exceptional but as an extension of maritime interaction networks and subsistence strategies mitigating the faunal impoverishment characteristic of many oceanic islands (Heinsohn, 1997, 2003; O’Connor et al., 2022; Shipton, 2026).

This paper synthesises zooarchaeological, biogeographic, linguistic, and chronological evidence to evaluate prehistoric marsupial translocations in the CNGA and to assess whether these movements can be understood as episodic outcomes of heightened maritime connectivity. Particular attention is given to the Phalangeridae (cuscuses), the most geographically widespread and frequently implicated marsupial group, whose distribution provides a uniquely informative proxy for tracing long-term patterns of human mobility, interaction, and ecological intervention across the islands of the CNGA. While many modern island populations have been interpreted as the result of translocation occurring both before and after written accounts (Heinsohn, 2003, 2010), the present synthesis focuses specifically on islands where archaeological and zooarchaeological records provide dated evidence for the past presence of these taxa (Figure 1).

Table 1. Archaeological records for cuscus in comparison with initial human occupation on the island.

Material dated is indicated in brackets, ’shell’ refers to marine shell unless otherwise stated. Radiocarbon dates were calibrated using Marine20 (for marine shell) and a mixed IntCal20 & SHCal20 (for charcoal, bone, & seeds) calibration curves (Heaton et al., 2020; Hogg et al., 2020; Riemer et al., 2020) using OxCal v.4.3 Online (Bronk Ramsey, 2009). 1 Wickler, 2001; 2 Spriggs 1991; 3 Kirch 1988,; 4 Kirch et al., 1991; 5 Fredericksen et al., 1993; 6 Williams, 1999; 7 Leavesley and Chappell, 2004; 8 Allen et al., 1989; 9 Bellwood et al., 1998; 10 Bellwood et al. 2019; 11 Irwin et al., 1999; 12 Shipton et al., 2020; 13 Shipton et al. 2024; 14 O’Connor, 2015; 15 Glover, 1969.

Table 2. Archaeological records for macropods in comparison with initial human occupation on the island.

Material dated is indicated in brackets, ’shell’ refers to marine shell unless otherwise stated. Radiocarbon dates were calibrated using Marine20 (for marine shell) and a mixed IntCal20 & SHCal20 (for charcoal, bone, & seeds) calibration curves (Heaton et al., 2020; Hogg et al., 2020; Riemer et al., 2020) using OxCal v.4.3 Online (Bronk Ramsey, 2009). 1 Wickler, 2001; 2 Flannery 1988; 3 Leavesley and Chappell, 2004; 4 Allen et al., 1989; 5 Gaffney et al., 2024; 6 Gaffney et al, 2025.; 7 Bellwood et al., 1998; 8 Hull et al. 2019; 9 Kaharudin et al. 2024.

Table 3. Archaeological records for bandicoots in comparison with initial human occupation on the island.

Material dated is indicated in brackets, ’shell’ refers to marine shell unless otherwise stated. Radiocarbon dates were calibrated using Marine20 (for marine shell) and a mixed IntCal20 & SHCal20 (for charcoal & seeds) calibration curves. (Heaton et al., 2020; Hogg et al., 2020; Riemer et al., 2020) using OxCal v.4.3 Online (Bronk Ramsey, 2009). 1 Fredericksen et al., 1993; 2 Roberts et al. 2022; 3 Bellwood et al., 1998; 4 Flannery et al., 1998; 5 Lilley 1986.

2 Evidence of marsupial translocations in the CNGA

Heinsohn (2010) estimated that approximately 70%–75% of the 33 marsupial species currently recorded from the CNGA were likely introduced through human agency, although many of these introductions occurred more recently as documented in written sources. Prehistoric evidence of translocations have been proposed for members of several marsupial families, most notably the Phalangeridae (cuscuses), Macropodidae (wallabies and pademelons), and Peramelidae (bandicoots), with more limited or equivocal evidence for gliding possums (Petauridae) (Figure 1). A single record from Malai (Sissau Islands) also suggests possible quoll (Dasyuridae) translocation about 600 cal BP (Lilley, 1986). The strength of support for these hypotheses varies substantially between taxa, islands, and time periods, reflecting uneven archaeological preservation, taxonomic uncertainty, and differences in research intensity across the region (Flannery and White, 1991; Heinsohn, 2003, 2010; Spriggs, 1997).

Zooarchaeological inference of translocation is typically based on the convergence of three lines of evidence: temporal discontinuity in stratified archaeological sequences, association with human activity, and the biogeographical improbability of natural over-water dispersal. The clearest indicator is the sudden appearance of a taxon in sequences that previously lacked it, particularly where earlier deposits are well sampled and associated with prolonged human occupation. On Timor, for example, Phalanger orientalis appears abruptly in deposits dated to ∼3,300 cal. BP following millennia of earlier occupation without marsupial remains (O’Connor, 2015; Table 1), a pattern also observed in parts of the Bismarck Archipelago. Such occurrences gain interpretive strength when remains are recovered from clear cultural contexts, including hearths, middens, or butchery assemblages, where they form part of food refuse deposits alongside other exploited fauna.

In practice, however, such inferences are complicated by taphonomic biases. Poor bone preservation in early or moisture-rich deposits, particularly those dating to the Late Pleistocene, can produce false absences that obscure earlier occurrences (Louys et al., 2017, 2023; Pasveer and Bellwood, 2004). As a result, both the timing and, in some cases, the anthropogenic nature of proposed marsupial translocations remain contested and must be evaluated on a case-by-case basis.

2.1 Phalangeridae (cuscuses)

The Phalangeridae, commonly referred to as cuscus (kuskus), represent the most geographically widespread and species-rich family of Australasian marsupials implicated in prehistoric translocation. Their distributions extend from northern Australia and New Guinea eastward through the Bismarck Archipelago and Solomon Islands, and westward into Wallacea, including Sulawesi and the Talaud Archipelago. Among the marsupials of the CNGA, cuscus recur most consistently in archaeological, biogeographic, genetic, and ethnohistorical discussions of anthropogenic movement.

Zooarchaeological evidence from New Ireland indicates that Phalanger orientalis was introduced during the Late Pleistocene, around 23,000 cal. BP (Leavesley and Chappell, 2004; Leavesley, 2005; Table 1). During the Holocene, its range expanded substantially through continued human agency, reaching the Solomon Islands by approximately 9,000 cal. BP and later being translocated westward to Timor (Table 1). Other cuscus with suggested translocations include the Admiralty Cuscus (Spilocuscus kraemeri), established in the Manus group by approximately 14,000 cal. BP, although the extent to which this represents human introduction vs. earlier natural dispersal remains debated (Heinsohn, 2010; Summerhayes, 2007).

Table 1 summarises the earliest zooarchaeological evidence for cuscus on islands across the CNGA. Where dates for initial human occupation pre-date the appearance of cuscus remains, these sequences are considered to provide stronger archaeological support for translocation. While the islands of Buka, Manus, New Ireland, Gebe, and Timor all document the sudden appearance of cuscus remains after human arrival (Table 1), Timor is the only record where this evidence of marsupial translocation is supported by direct dates on cuscus remains (O’Connor, 2015; O’Connor and Aplin, 2007). The Gebe sequence also remains in question as reflecting a ‘true’ arrival sequence due to the generally poor preservation of bone, marsupial or otherwise, below the layers in which cuscus first appear (Hull et al., 2019; Pasveer and Bellwood, 2004).

Together, these occurrences indicate repeated movement of cuscus across substantial marine barriers and time periods, producing distributions that extend well beyond those expected under simple models of natural dispersal.

2.2 Macropodidae (wallabies and pademelons)

Macropods (family Macropodidae), including wallabies and pademelons, provide further evidence for early human-mediated dispersal. The Northern Pademelon (Thylogale browni) was established in New Ireland by approximately 8,500 cal. BP, while the Brown Dorcopsis (Dorcopsis muelleri) was introduced to Waigeo in the Raja Ampat islands by ∼13,000 cal. BP and later to Gebe and Halmahera between 8,000–6,000 cal. BP before subsequently going extinct in those locations during the Late Holocene (Heinsohn, 2010; Hull et al., 2019; Gaffney et al., 2025; Table 1). Gebe is notable for two direct dates on Dorcopsis remains which, in addition to their appearance above levels in which cuscus are preserved, make this instance the most reliable dated evidence for macropod translocation (Table 2).

More recently, archaeological evidence from Fordata Island in the Tanimbar group indicates exploitation of pademelons (Thylogale) and wallabies (Notomacropus) in deposits dated from near-historic levels to over 41,000 cal. BP (Kaharudin et al., 2024, forthcoming). Given the island's distance of more than 100 km from the nearest mainland source, these findings raise the possibility of very early human-mediated introductions during the initial settlement of the region. If confirmed, such translocations would represent the earliest evidence of deliberate animal movement by humans anywhere in the world, and suggest that it was wallabies that were first translocated west from New Guinea rather than cuscus to the east.

2.3 Peramelidae (bandicoots)

Evidence for bandicoot translocation is more limited but nonetheless significant. The Common Spiny Bandicoot (Echymipera kalubu) appears in the archaeological record of Manus Island by approximately 15,000 cal. BP, coincident with human occupation (Heinsohn, 2010; Williams, 1999). As with other taxa, the absence of earlier faunal deposits complicates definitive interpretation, but the biogeographical improbability of natural dispersal across deep-water barriers supports a human-mediated explanation. Halmahera to the west of New Guinea and Tuam (Siassi) to the east both also record bandicoots in their archaeological deposits much more recently, but post-dating initial human occupation (Table 3).

2.4 Corroborating evidence beyond zooarchaeology

The archaeological record across the CNGA remains uneven. Well-preserved sequences on Timor and New Ireland provide relatively high-resolution evidence for introduction events, whereas in regions such as New Britain or the Admiralty Islands the absence of comparable stratified assemblages leaves the status of some marsupial populations unresolved and “biogeographically enigmatic” (Heinsohn, 2003, 2010). Although zooarchaeological context provides the primary basis for identifying translocation, interpretations are strengthened when supported by independent lines of evidence.

Genetic studies demonstrating low diversity or monophyletic island populations have been used to suggest single, possibly recent founder events rather than long-term natural dispersal (Kealy et al., 2020; Osborne and Christidis, 2002). However, it is noted that monophyly may also arise through long-term isolation following natural dispersal, and founder events do not necessarily result in reduced genetic diversity, especially where multiple introductions or admixture have occurred (Uller and Leimu, 2011). Likewise, low diversity may arise through stochastic bottlenecks or environmental disturbance in island systems. Discrepancies between molecular divergence estimates and archaeological chronologies further highlight the limitations of genetic data when considered in isolation (Kealy et al., 2020; Osborne and Christidis, 2002). As such, genetic patterns are best interpreted as one line of evidence within a broader, multi-proxy framework rather than as standalone indicators of translocation.

Linguistic evidence, including widely shared terms for marsupials across island language families, points to the cultural salience of these animals within maritime interaction networks. Ethnozoological observations of people transporting live marsupials as pets, trade items, or food reserves provide behavioural analogues for the mechanisms inferred archaeologically (Heinsohn, 2003, 2010; Sillitoe, 2003). Quantitative modelling has also begun to test alternative dispersal mechanisms: agent-based simulations suggest that while limited natural drift across short straits from New Guinea to nearby islands such as Raja Ampat may be survivable for some taxa, longer distance dispersal to more distant islands such as Halmahera is highly improbable, strengthening the case for human-mediated movement (Gaffney et al., 2025).

3 Phalangeridae as ethnotramps

Among the marsupial taxa implicated in these movements, cuscuses are particularly informative because their biological characteristics and cultural importance make them especially suitable for repeated human-mediated dispersal. The prominence of cuscus in discussions of marsupial translocation reflects the convergence of economic importance and biological suitability: cuscuses combine high subsistence value with traits that facilitate capture, transport, and establishment, making them classic ethnotramps: wild animals whose distributions have been repeatedly reshaped through sustained human mobility and exchange (Heinsohn, 2004).

Cuscuses were, and remain, highly valued by island communities as reliable sources of meat and fat, particularly in insular environments where terrestrial resources are limited (Latinis, 1996; Leavesley, 2005; O’Connor et al., 2017). As Wallace (1869 [2017]: 425) observed, “the natives everywhere eat their flesh, and as their motions are so slow, easily catch them by climbing; so that it is wonderful they have not been exterminated.” In western Seram, for example, cuscuses are the most frequently hunted terrestrial species and the third largest contributor of animal protein in the Nuaulu diet (Latinis, 1996). Cuscus fur and skins are widely used in body adornment and ceremonial display, while bones are incorporated into specialised tools, embedding them within broader systems of craft production and exchange. Ethnographic accounts further indicate social and ritual significance, with cuscuses featuring in feasting contexts, initiation ceremonies, and, in some regions, clan or ancestral associations (Latinis, 1996).

These cultural incentives intersect with biological traits that favour human-mediated dispersal. As Wallace (1869) noted, most cuscus can be captured with relative ease, tolerate captivity, and require minimal care during transport (Heinsohn, 2003, 2010). Phalanger orientalis is further distinguished by its tendency to produce twin offspring, increasing reproductive output and reducing demographic risks associated with small founding populations (Flannery and White, 1991). As nocturnal generalist herbivores with broad dietary tolerance, cuscuses are capable of establishing viable populations across a wide range of forest and disturbed habitats (Flannery and White, 1991; Heinsohn, 2005, 2010). On high oceanic islands such as Seram, P. orientalis has demonstrated “competitive release”, occupying a much wider altitudinal range (sea level to ∼3,000 m) than in New Guinea, illustrating the ecological flexibility that facilitates successful establishment following introduction (Heinsohn, 2005; Heinsohn and Hope, 2006).

Accounts from the late nineteenth and early twentieth centuries describe people transporting live cuscuses by canoe between islands, with escaped or released animals subsequently establishing feral populations (Groves, 1976; Heinsohn, 1997, 2002; Menzies and Pernetta, 1986). One documented example is the introduction of the Common Spotted Cuscus (Spilocuscus maculatus) from the St Matthias group to New Ireland in the early twentieth century, where it successfully established and expanded its range (Flannery and White, 1991). Such cases demonstrate that the mechanisms inferred archaeologically formed part of well-established practices that persist into recent times. Even today, the practice of raising juvenile cuscus in captivity as pseudo-pets and a “living larder” (Heinsohn, 2002, 2003), following the successful hunting of their mothers, remains widespread across eastern Indonesia and Timor-Leste (Figures 2,3; Heinsohn, 2003; Gaffney et al., 2025; pers. obs.). Translocation may therefore occur through both deliberate provisioning of island resources and the informal movement of captive animals within exchange networks (Gaffney et al., 2025).

Recent field observations from central and south-eastern Maluku further illustrate the complexity of these distributions. Populations of Phalanger (P. cf. orientalis) occur today on Wetar, Romang, Leti, and the remote island of Damar (Figure 3), while Spilocuscus cf. maculatus has also been recorded on Damar (Figure 2), representing a substantial south-westward extension of the genus’ known range (Flannery, 1995; Helgen and Jackson, 2015; pers. obs.). Additional occurrences of Spilocuscus have been documented on Gorong, Watabela, and Kesui (pers. obs.). However, these distributions do not always align chronologically with the archaeological record. Despite the modern abundance of cuscus on Wetar and its importance in contemporary subsistence practices, excavations of an early–mid Holocene sequence on the island have so far failed to recover evidence of cuscus exploitation (pers. obs.; O’Connor et al., forthcoming), raising the possibility of a relatively recent introduction. A comparable case occurs on Halmahera, where the sugar glider (Petauridae) is present today but absent from a ∼5 ka archaeological sequence, suggesting a recent introduction from New Guinea (Flannery et al., 1995). The presence of two cuscus genera on the small and isolated island of Damar is therefore particularly striking, potentially reflecting either exceptionally successful early translocations or comparatively recent introductions that have since become ecologically established. Resolving the timing of these arrivals will be critical for evaluating the role of such islands within wider networks of marsupial movement across the CNGA.

Taken together, the economic importance, cultural salience, biological resilience, and transportability of cuscus help explain why they dominate the archaeological signal for marsupial translocation in the CNGA and why they provide particularly sensitive indicators of long-term human mobility across island environments. Ethnographic observations across New Guinea demonstrate that hunters frequently capture and rear wild animals such as marsupials, birds, and reptiles, with juveniles often kept as pets or trade items before eventual consumption or exchange (Gaffney et al., 2025; Sillitoe, 2003). These practices form part of what Gaffney et al. (2025) describe as the “culturing” of island biomes, in which human capture, transport, and management of wild animals contributed to the long-term shaping of insular ecosystems.

4 Taxonomy, phylogeny, and interpreting marsupial distributions

While the ecological and cultural characteristics of cuscuses help explain why they were frequently translocated, reconstructing the timing and direction of these movements increasingly looks to advances in molecular taxonomy and phylogenetics. Genetic research has reshaped understanding of marsupial distributions across the Asia–Pacific, demonstrating that some island populations once assumed to be natural endemics instead reflect relatively recent dispersal events, in several cases likely involving human agency. In this context taxonomy functions not simply as a classificatory framework but as a critical tool for evaluating competing explanations for island distributions (Heinsohn, 1997, 2003).

For cuscus in particular, morphology-based classifications have proven insufficient for resolving biogeographic histories. The genus Phalanger exhibits fragmented distributions, considerable phenotypic plasticity, and a long history of human interaction, all of which have contributed to persistent taxonomic instability (Crosby, 2007; Helgen and Jackson, 2015; Kealy et al., 2020). Consequently, many archaeological identifications made prior to molecular analyses likely conflate multiple taxa, complicating reconstructions of prehistoric translocation.

4.1 The phalanger orientalis complex and translocation histories

The Northern Common Cuscus (Phalanger orientalis) has long occupied a central place in discussions of prehistoric translocation, but recent phylogenetic research shows that this taxon comprises genetically distinct lineages rather than a single cohesive species (Kealy et al., 2020). Populations historically grouped under P. orientalis form multiple divergent clades with important implications for interpreting island distributions.

Genetic evidence suggests that modern cuscus populations in the Bismarck Archipelago and Solomon Islands represent a distinct species, Phalanger breviceps, most closely related to populations from Oro Province in northeastern Papua New Guinea (Kealy et al., 2020). This reclassification suggests these island populations likely resulted from a single introduction followed by stepwise eastward dispersal through the archipelago, rather than multiple independent movements from New Guinea.

The same mitochondrial DNA analyses demonstrate that the Timor cuscus population is monophyletic, consistent with introduction from a single source population rather than repeated dispersal events (Kealy et al., 2020). Although molecular divergence estimates predate the archaeological evidence for its arrival (∼3,300 cal. BP), extending into the Mid to Late Pleistocene (∼820–570 ka), this discrepancy likely reflects limitations in both sampling and molecular inference. The dataset used by Kealy et al. (2020) lacks coverage of geographically intermediate populations, particularly from western New Guinea and far-east Wallacea, meaning that the estimated divergence likely represents the deeper split between eastern New Guinea and Timor lineages, rather than the timing of translocation itself from a nearer, unsampled population. More broadly, as the Kealy et al. (2020) analysis was limited to modern, mitochondrial sequences, calibration of the molecular clock was restricted to node-calibrations which have been frequently shown to overestimate ages due to the time-dependency of molecular rates (Beck and Lee 2014; Kealy and Beck, 2017). Such molecular limitations are further complicated by the effects of gene flow (e.g., admixture and introgression; Tiley et al., 2023). As such, these results are best limited to interpretations of source relationships and island population structure, highlighting the need for further sampling and research in this space (Kealy et al., 2020).

Taxonomic reassessment of museum collections has also revealed widespread historical misidentification, with many specimens previously assigned to P. orientalis later split into several species such as those from eastern New Guinea now recognised as P. intercastellanus or P. mimicus. This taxonomic uncertainty obscures potential source populations for island introductions (Colgan et al., 1993; Menzies and Pernetta, 1986; Norris and Musser, 2001).

Recent field observations from central and south-eastern Maluku further highlight unresolved taxonomic issues. Populations identified as Phalanger cf. orientalis on Wetar, Romang, Leti, and Damar (pers. obs.) may represent unsampled lineages within the P. orientalis complex or comparatively recent introductions from already translocated island populations. Preliminary genetic work on cytochrome b sequences from Maluku cuscus populations placed the Lakor population (near Moa and Leti in south-western-most Maluku) as closely related to those on Seram and Gorong and together, sister to mainland New Guinea/Papua samples (Kunda et al., 2016). This genetic relationship provides tentative support for a consecutive, step-wise dispersal scenario of these remote Maluku populations. However, without further molecular or archaeological data, it remains unclear whether these western Wallacean populations derive from a single introduction or multiple temporally distinct events.

4.2 Phylogenetics and current limitations

Phylogenetic evidence also illustrates the difficulty of distinguishing anthropogenic translocation from natural dispersal. Long-term human-mediated movement can generate “ethnospecies”: populations whose apparent distinctiveness reflects introduction followed by isolation, genetic drift, or hybridisation rather than natural evolutionary divergence alone (Heinsohn, 2003).

The Admiralty Cuscus (Spilocuscus kraemeri), endemic to Manus Province, provides a possible example. Although morphologically distinctive, it has been hypothesised that this taxon may have originated through admixture following the introduction of a mixed founding population from New Guinea (Flannery, 1994; Heinsohn, 1997, 2010). Unfortunately, this taxon has not yet been integrated into large-scale molecular frameworks alongside other Spilocuscus species, so we cannot currently use DNA to distinguish between a natural evolutionary divergence and an anthropogenic admixture event (Kealy et al., 2020).

Not all island populations, however, reflect human-mediated movement. Some taxa exhibit levels of genetic divergence consistent with long-term isolation and founder-event speciation. The Ornate Cuscus (Phalanger ornatus) of the Northern Moluccas represents a taxon for which a natural endemic lineage is still a probable hypothesis for part of its distribution (Kealy et al., 2020), while the status of the Common Spiny Bandicoot (Echymipera kalubu) on New Britain remains ambiguous, potentially reflecting either anthropogenic introduction or rare natural rafting events (Heinsohn, 2003, 2010). Finally, the Bear Cuscus (Ailurops ursinus) on Sulawesi is a confirmed endemic with a phylogenetically estimated dispersal date well before the arrival of humans in the region, confirming that at least one cuscus species successfully dispersed from Sahul by natural means (Kealy et al., 2020).

These examples illustrate both the power and the limits of phylogenetic approaches. Molecular data can identify source populations, clarify directionality, and reveal founder effects, but the current record is sporadic and difficulties persist in disentangling natural dispersal from long-term human-mediated movement. In the CNGA, where human interaction with island faunas extends deep into the Pleistocene, distinctions between native and introduced taxa are often blurred. Phylogenetic insights therefore provide an important framework for interpreting archaeological distributions but represent only one component of the broader evidence for marsupial movement across the region.

5 Linguistic perspectives on cuscus dispersal

If marsupials circulated as culturally valued animals within inter-island exchange systems, it is unsurprising that their names circulated as well, often crossing linguistic boundaries alongside the animals themselves. Indigenous terms for marsupials across the CNGA, including kandoRa (‘cuscus’) and mans(a,ə)r (‘cuscus’ or ‘bandicoot’), have long been cited as linguistic evidence for the timing and pathways of marsupial dispersal. The origins of these terms in Austronesian or pre-Austronesian languages remain actively debated (Blust, 2009, 2012; Ross, 2020; Schapper, 2011).

5.1 Inheritance and diffusion models of marsupial terminology

In the inheritance model championed by Blust, these terms were innovated by Austronesian-speaking populations only after crossing Wallace's Line and encountering unfamiliar Sahulian fauna. This hypothesis forms part of his reconstructed Proto–Central Eastern Malayo-Polynesian (CEMP) subgroup (Blust, 1982, 1993, 2002, 2009). The subsequent distribution of these terms is then interpreted as reflecting the eastward Austronesian expansion into Near Oceania during the mid- to Late Holocene, broadly coinciding with the spread of the so-called “Neolithic package” (Bellwood, 2007). Blust (1982 2009), further notes that Austronesian groups entering Sulawesi independently developed a different term (kusay), reinforcing the argument that marsupial vocabulary emerged in response to newly encountered fauna beyond Wallacea.

Archaeological evidence, however, indicates that marsupial translocations began far earlier than the Austronesian expansion. Zooarchaeological data show that Phalanger orientalis was present on New Ireland by ∼20,000–23,500 cal BP and that macropods (Thylogale and Notomacropus) had reached the Tanimbar Islands by ∼40,000 cal BP (Tables 1, 2). Indeed, approximately half of the currently documented marsupial translocation events in the CNGA predate the ∼4,000–3,500 BP Austronesian arrival window. These earlier movements suggest that linguistic reconstructions associated with Austronesian dispersal capture only one phase within a much longer history of human–marsupial interaction in the region.

An alternative interpretation emphasises the role of Wanderwörter, loanwords that spread between languages through trade and contact networks (Donohue and Grimes, 2008; Gasser, 2020; Schapper, 2011). Under this diffusion model, irregular sound correspondences and patchy lexical distributions indicate that terms such as kandoRa and mans(a,ə)r were repeatedly borrowed across maritime interaction networks linking Papuan and Austronesian-speaking communities. One possible source is the Proto–Timor–Alor–Pantar term mader (‘bat’), which may have undergone semantic shift during borrowing to produce the Austronesian form mans(a,ə)r referring to cuscus or bandicoot. The shifting semantic range of this term, referring primarily to cuscus in eastern Indonesian languages but to bandicoots in Oceanic languages, further reflects the complex linguistic histories generated through such contact (Schapper, 2011).

Schapper (2011) identifies the Aru Islands as a critical control case supporting this diffusion model. Unlike many islands of Wallacea, where marsupials represent introduced “ethnotramps,” these animals are indigenous to Aru, which remained connected to Sahul until approximately 10,000 years ago. If the term mans(a,ə)r was inherited from Proto-Austronesian, regular reflexes would be expected in the languages of Aru. Instead, several Aru languages exhibit irregular forms associated with the loanword mans(a,ə)r that cannot be reconstructed to Proto-Aru, and occur alongside a distinct, inherited indigenous term, wagal (‘cuscus’) (Schapper, 2011). Schapper (2011) argues that this discordance demonstrates that mans(a,ə)r functioned as an itinerant “trade vernacular” item moving through maritime exchange networks independently of the animal's natural distribution.

5.2 Linguistic stratigraphy and maritime interaction networks

Recent archaeological and genomic research lends support to this diffusion perspective. Purnomo et al. (2024), for example, identify a Late Holocene “West Papuan interaction hub,” likely centred on the Bomberai Peninsula, through which Papuan genes, technologies such as ground shell adzes, and elements of faunal vocabulary spread westward into Wallacea. In this view, the distribution of marsupial terminology reflects the cumulative effects of long-standing maritime interaction networks rather than a single episode of linguistic innovation.

At the same time, elements of both models may be partially correct when viewed within a broader framework for Austronesian dispersal. Pre-Austronesian maritime interaction networks likely generated the earliest marsupial terminology alongside Late Pleistocene animal translocations (Donohue and Grimes, 2008, Schapper, 2011), while the subsequent Austronesian expansion may have stabilised and amplified the distribution of these terms across the western Pacific (Blust, 1993, 2009). Recent genomic evidence suggests that the mid-Holocene period around 3,500 BP involved not only Austronesian expansion but extensive admixture with Papuan populations (Purnomo et al., 2021, 2024), potentially intensifying both animal translocation and lexical diffusion. This perspective aligns with proposals to view Austronesian dispersal as a network of interacting dialect continua rather than discrete subgroup nodes (Smith, 2025).

A further linguistic layer is represented by the widespread modern terms kuskus, kusu, kuso, and kusay, which belong to a separate etymological complex linked to Sulawesi and the North Moluccas. Schapper (2011) reconstructs a Proto–North Halmaheran form (kusoro) corresponding to Ternate-Tidore kuso and related forms, and possibly linked to the Proto-Sulawesi term kusay identified by Blust (2009). The widespread modern distribution of these terms (Latinis, 1996; Schapper, 2011; pers. obs.) likely reflects a later pulse of linguistic diffusion associated with historical spice-trade networks centred on Makassar and Ternate–Tidore, which played major roles in regional exchange systems prior to, and during, European contact (Andaya, 1995; Bellwood, 2017, 2019; Swadling et al. 2019).

The linguistic evidence indicates a multi-layered history of marsupial naming across the CNGA. Early terms associated with Late Pleistocene translocations were subsequently incorporated into expanding Austronesian networks, while later trade vernaculars spread through historical maritime exchange systems. In this sense, linguistic diffusion mirrors the biological history of marsupial translocation itself: both reflect enduring maritime interaction networks that connected island communities across the region. The linguistic evidence further highlights that animal translocation was not merely a biological or economic process but also a cultural one, involving the circulation of knowledge, practices, and meanings linking distant island societies. Rather than functioning as chronological markers in isolation, linguistic data provide an index of cultural connectivity that helps illuminate the social conditions under which marsupial translocations emerged within long-term maritime interaction networks whose intensity fluctuated through time.

6 Discussion

Australia's marsupial fauna has played a central role in shaping evolutionary theory, from Darwin's insights into convergent evolution to Wallace's identification of the biogeographic boundary now known as Wallace's Line. Within this tradition, the presence of marsupials on islands beyond Australia and New Guinea was originally treated as anomalous, explained through vicariance, rare natural dispersal, or deep-time evolutionary processes. However, a substantial body of research has shown that many of these distributions instead reflect prehistoric human translocation (e.g., Flannery and White, 1991; Heinsohn, 2003, 2010). Building on this work, the synthesis presented here integrates zooarchaeological, linguistic, and phylogenetic evidence to demonstrate that across the CNGA marsupial distributions form part of long-term systems of human mobility and ecological intervention.

These lines of evidence indicate that prehistoric marsupial translocations were neither isolated curiosities nor confined to a single cultural horizon. Instead, they represent recurrent features of island lifeways from the Late Pleistocene that continue through to today. Cuscuses are particularly informative in this regard, not only because of their archaeological visibility but also because their biology, cultural value, and transportability make them sensitive indicators of sustained human–animal entanglement in insular environments.

6.1 Pulsed translocation and maritime interaction

When considered individually, archaeological records of marsupial translocation across the CNGA appear spatially and temporally heterogeneous. Introductions involve different taxa, occur on widely separated islands, and span tens of thousands of years (Tables 1–3). Yet when examined collectively, a patterned distribution emerges. Marsupial introductions tend to cluster around periods of intensified human mobility and maritime interaction, described as “pulses” of activity by Leavesley and Allen (1998) and reflected in the archaeological, genetic, and linguistic datasets discussed above.

To explore these patterns, archaeological dates associated with marsupial translocations compiled here (Tables 1–3) were plotted and stacked in OxCal 4.3 (Figure 4). Although some dates provide stronger evidence for translocation than others, this aggregated approach nevertheless offers a useful means of examining the temporal distribution of potential translocation events across the CNGA. The resulting distribution reveals seven chronological clusters spanning the Late Pleistocene and Holocene. These clusters group naturally into four broader phases of intensified maritime interaction which correspond with broader models of coastal and maritime adaptation in Island Southeast Asia, describing a transition from early exploratory dispersal to increasingly developed inter-island interaction networks. Rather than occurring continuously, these translocations appear to have been episodically activated during periods when social, technological, and demographic conditions favoured sustained maritime interaction.

6.1.1 Phase 1 (∼45–40 ka BP): initial expansion

The earliest possible evidence for anthropogenic marsupial translocation occurs during the initial human expansion through southern Wallacea (Figures 1, 4). Archaeological evidence from Elivavan rockshelter on Fordata Island in the Tanimbar Islands indicates that macropods were present by ∼42 ka cal. BP, coincident with initial occupation on the island (Kaharudin et al., 2024; forthcoming). Because the Tanimbar Islands have remained permanently isolated by sea barriers throughout the Pleistocene, these Sahulian taxa must have arrived either through rare natural dispersal or human transport.

This period also coincides with the earliest occupation of other southern Wallacean islands such as Timor and Alor (Kealy et al., 2020; Shipton et al., 2024), as well as the colonisation of the Bismarck Archipelago (Leavesley and Chappell, 2004). Leavesley and Allen (1998) describe this interval as a phase of low-intensity exploratory incursions. Within this context, animal movement likely reflects exploratory colonisation behaviour rather than established exchange systems. Following initial dispersal from Sunda across to Sahul ∼65–50 ka cal. BP (Clarkson et al., 2017; Oktaviana et al., 2026), early settlers of Wallacea moving into these virgin island chains may have transported valued terrestrial resources as part of the process of provisioning these newly occupied landscapes.

6.1.2 Phase 2 (∼23–13 ka BP): Late Pleistocene intensification

A second phase of translocation occurs during the Late Pleistocene around the peak of the LGM and the subsequent period of climatic change (Figures 1, 4). This phase begins with the introduction of the cuscus (Phalanger orientalis) to New Ireland ∼23.5–20 ka cal. BP, documented at sites such as Matenbek and Buang Merabak (Leavesley, 2005; Leavesley and Chappell, 2004). The appearance of this species coincides with the first arrival of exotic New Britain obsidian in New Ireland middens, indicating the emergence of sustained inter-island interaction across the Bismarck Sea (Leavesley and Allen, 1998).

A further cluster occurs during the terminal Pleistocene (∼17–13 ka), when the bandicoot (Echymipera kalubu) and cuscus (Spilocuscus kraemeri) appear in the Admiralty Islands (Roberts et al., 2022). At the same time, the archaeological record documents the introduction of Dorcopsis to Raja Ampat (Gaffney et al., 2025) and the spread of cuscus populations westward into the northern Moluccas (Irwin et al., 1999; Shipton et al., 2020). This cluster represents the first major pulse of marsupial translocation in the CNGA.

This interval coincides with increasing evidence for maritime interaction across the CNGA and Near Oceania, including the emergence of long-distance obsidian exchange networks and the initial settlement of smaller islands such as Obi and Kisar (O’Connor et al., 2019, 2022; Reepmeyer et al., 2019). Rising sea levels following the LGM may have further stimulated mobility by fragmenting landscapes and increasing the importance of inter-island connections. The proposed association between the expansion of exchange networks (O’Connor et al. 2022) around ∼17–13 ka and the development of dugout canoe technology (Shipton et al., 2020) aligns with recent agent-based modelling of macropod dispersal in the Raja Ampat region, which demonstrates that canoe transport dramatically increases the probability of successful island crossings compared with passive swimming or drifting mechanisms (Gaffney et al., 2025). These developments suggest the emergence of sustained maritime interaction networks capable of facilitating deliberate animal translocation.

6.1.3 Phase 3 (∼9–5 ka): Early–Mid Holocene interaction networks

A third phase of translocation occurs during the early to mid-Holocene, following the stabilisation of sea levels after the post-glacial rise (Figures 1, 4). Notable translocation examples include the introduction of the pademelon (Thylogale browni) to New Ireland between ∼8,400 and 7,000 BP (Allen et al., 1988, 1989) and the appearance of wallabies (Dorcopsis muelleri) on Gebe and Halmahera around ∼8,000–5,500 BP (Hull et al., 2019).

Environmental conditions during the early Holocene differed substantially from those of the Late Pleistocene. Expanding rainforest environments replaced the more open landscapes of the LGM, while stabilized coastlines allowed the development of more permanent coastal settlements (Gaffney and Tolla, 2025; Hope et al., 2004; O’Connor et al., 2022; Wurster and Bird, 2014). These conditions supported increasingly structured maritime interaction networks linking island communities across Wallacea and Near Oceania.

Zooarchaeological and isotopic evidence suggests that during this period subsistence strategies diversified, incorporating both coastal resources and terrestrial foods (O’Connor et al., 2022; Roberts et al., 2020). Within this context, the deliberate introduction of terrestrial fauna may have served as a strategy for enhancing food security by establishing reliable hunting resources within island ecosystems (Heinsohn, 2003, 2010). Alongside Phase 2, these periods of intense maritime activity across the CNGA possibly coincides with the pre-Austronesian linguistic sharing of terms as these island communities worked towards perhaps their first, although certainly not last, trade vernacular (Schapper, 2011).

6.1.4 Phase 4 (∼3.5–1 ka): Late Holocene interaction intensification

The final major phase corresponds with the Late Holocene intensification of maritime exchange networks following Austronesian arrival (Figures 1, 4). The first cluster aligns with the Austronesian expansion beginning around ∼3.5–3 ka (Bellwood, 2007, 2017; Carson et al., 2013; O’Connor, 2015; Xu et al., 2012). During this period P. orientalis was transported westward into Wallacea, including Timor, where its arrival is directly dated to ∼3,300 cal. BP (O’Connor et al., 2015). These introductions coincide with the appearance of other transported taxa such as pigs and dogs, as well as material culture and the spread of shared terms, associated with Austronesian maritime dispersal.

A further cluster between ∼2–1 ka likely reflects the continued expansion of regional interaction networks associated with emerging protohistoric trade systems in eastern Indonesia and western New Guinea (Andaya, 1995; Bellwood, 2017, 2019; Swadling et al. 2019). Dates from this interval emphasise eastward translocation of several marsupial taxa, including additional introductions of bandicoots, pademelons, and possibly quolls (Dasyurus). This aligns somewhat with Gray et al.'s (2009) “Pulse 2” into Remote Oceania. The linguistic evidence may also reflect the presence of this phase of intensified interaction to the west. The widespread distribution of terms such as kusu and related forms for cuscus likely spread through maritime trade networks linking Sulawesi and the northern Moluccas during this period, functioning as Wanderwörter that circulated alongside the animals themselves (Gasser, 2020; Latinis, 1996; Schapper, 2011).

This pulse and phase-based interpretation situates marsupial ethnophoresy within long-term rhythms of maritime interaction spanning the Late Pleistocene and Holocene. Rather than occurring continuously, translocation appears to have been episodically activated during periods when social, technological, and environmental conditions favoured or encouraged sustained inter-island connectivity. In this sense, the pulsed structure identified here reflects broader patterns of regional interaction documented in archaeological, linguistic, and genetic research (Gray et al., 2009; Leavesley and Allen, 1998; Purnomo et al., 2021, 2024). These pulses suggest that the deliberate movement of terrestrial fauna formed a recurrent strategy embedded within regional systems of connectivity across the CNGA, producing anthropogenic island faunas whose histories range from long-term ecological integration to delayed introduction, extinction, or repeated restocking (Flannery et al., 1988; Heinsohn, 2003, 2010).

6.2 Limits of zooarchaeological inference

Despite the strength of converging evidence, interpretations of prehistoric marsupial translocation remain subject to important limitations. Taphonomic bias is a persistent challenge in tropical island contexts, where poor bone preservation in moist or acidic sediments can obscure early faunal records (Heinsohn, 2003; Pasveer and Bellwood, 2004). Apparent absences in Late Pleistocene deposits may therefore reflect preservation failure rather than true absence. Similarly, the role of humans as the main faunal-deposit accumulators in these islands limits the availability of pre-human faunal records (Louys et al., 2017) that could otherwise resolve questions around records where humans and marsupials appear simultaneously (e.g., Kaharudin et al., 2024, forthcoming).

Taxonomic instability further constrains inference. As demonstrated by recent phylogenetic reassessments, historical misidentifications and unresolved species boundaries can inflate apparent ranges or obscure source populations (Beck, 2017; Kealy et al., 2020; Menzies and Pernetta, 1986). Continued refinement of marsupial taxonomy, coupled with genetic analysis of both archaeological and extant populations, remains essential.

Natural dispersal also cannot be categorically excluded in all cases. Founder-event speciation during the Miocene or Pliocene likely accounts for some endemic taxa, and ethnophoresy should therefore be treated as a contextual hypothesis rather than a universal explanation (Gaffney et al., 2025; Heinsohn, 2003; Irwin et al., 1999). The strongest cases for anthropogenic movement remain those in which stratigraphic, biogeographic, and phylogenetic evidence converge.

6.3 Future directions

Future research should prioritise the recovery of direct evidence capable of resolving current ambiguities in the archaeological record of marsupial translocation. Direct radiocarbon dating of faunal remains represents best practice for establishing secure chronologies and avoiding depositional errors introduced by reliance on associated charcoal or sediment dates (Hull et al., 2019; O’Connor, 2015). Expanded ancient DNA (aDNA) analysis of archaeological specimens offers further potential to clarify species identifications and identify source populations for island introductions (Kealy et al., 2020). Although tropical preservation conditions remain challenging, emerging techniques including DNA recovery from petrous bone and collagen fingerprinting (ZooMS), are increasingly expanding the range of recoverable molecular information (Hofreiter et al., 2015; Peters et al., 2021; Pinhasi et al., 2015). Such approaches would enable both modern and fossil/archaeological materials to be incorporated within total-evidence phylogenetic frameworks that accommodate tip-and-node calibration, providing a more robust basis for reconciling genetic and archaeological chronologies (Kealy et al. 2020; Kealy and Beck, 2017). This effort also provides the opportunity to reanalyse existing phylogenetic datasets of island marsupials. Revisiting these datasets using genomic data, improved molecular clocks, and models that explicitly incorporate gene flow and admixture offers significant potential to refine divergence estimates and improve current phylogenetic and biogeographic interpretations.

In addition, the geographic scope of available evidence remains uneven. Current reconstructions of faunal movement across Near Oceania and Wallacea are based on a relatively small number of well-studied sites (Heinsohn, 2010), while many regions including the Tanimbar Islands, Manus, and parts of the Moluccas, remain poorly sampled. Targeted survey and excavation in these areas will be critical for testing proposed dispersal routes and evaluating the spatial extent of translocation events. Similar to phylogenetic datasets, reanalysis of legacy faunal collections from earlier excavations using modern analytical techniques also offers considerable potential to expand and reassess existing datasets.

The pulse-based framework proposed here invites formal testing through Bayesian chronological modelling, spatial network analysis, and comparative study of other translocated taxa. Such approaches offer a means of statistically evaluating the timing of introductions across multiple islands and reconstructing the interaction networks through which animals moved as components of wider systems of exchange (O’Connor et al., 2022). As archaeological datasets expand, these methods offer the potential to move beyond descriptive synthesis toward a more predictive understanding of when, how, and why human communities reshaped island faunas across the CNGA. At the same time, the pulse model provides an additional line of evidence for investigating long-term patterns of human activity and maritime connectivity across the region, particularly during the often overlooked interval between initial settlement and the arrival of Austronesians.

7 Conclusion

The synthesis presented here demonstrates that marsupial translocation was a recurrent feature of human interaction with island environments across the Circum–New Guinea Archipelago. Archaeological, linguistic, and genetic evidence together indicate that these movements occurred episodically, clustering around broader phases of intensified maritime connectivity spanning the Late Pleistocene and Holocene.

Rather than representing a single innovation or random events, the movement of marsupials appears to reflect a long-standing behavioural strategy embedded within regional systems of maritime mobility and exchange. Within these networks, animals were transported across deep-water barriers as portable subsistence resources, reshaping island ecosystems and creating anthropogenic faunal assemblages that persist in many islands today.

This pattern reinforces the growing recognition of sophisticated maritime capabilities in Island Southeast Asia and Near Oceania, including the capacity to transport live animals across substantial marine barriers well before the Holocene. More broadly, the pulse-based pattern identified here suggests that marsupial translocation formed part of wider rhythms of interaction linking island communities across the region.

Understanding the timing, mechanisms, and consequences of these movements therefore offers important insights into the ecological and social dynamics of early maritime societies and highlights the long-term role of human–animal relationships in shaping island ecosystems.

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Supplementary material

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Footnotes

Edited by: Jane Balme, University of Western Australia, Australia

Reviewed by: Karen Greig, University of Otago, New Zealand

Arthur Francis Sands, The University of Hong Kong, Hong Kong SAR, China