Landscape rules predict optimal superhighways for the first peopling of Sahul

Crabtree, Stefani A.; White, Devin; Bradshaw, Corey J. A.; Saltré, Frédérik; Williams, Alan N.; Beaman, Robin J.; Bird, Michael I.; Ulm, Sean

doi:10.1038/s41562-021-01106-8

Cited by 45 publications

(30 citation statements)

References 81 publications

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“…We applied the same model developed and applied in Bradshaw et al 18 , which is a combination of a cellular automaton 19 and directionally weighted by 'superhighways' of plausible movement corridors 17 . This model explored the initial peopling of Sahul between 75 and 50 ka; here, we present the model continuing from 40-5 ka.…”

Section: Methodsmentioning

confidence: 99%

“…Extreme conditions influencing past human behaviour could have occurred anytime during this period, leading to a more localised picture of lower biological productivity across Sahul over a prolonged period that extends from 28.6 (± 2.8) ka to 17.7 (± 2.2) ka 16 . More recently, complex modelling of the initial peopling of Sahul has revealed several probable pathways across the continent, with some extending across the arid core and suggesting such environments did not form a barrier to past migration 17 . Only through such complex models incorporating human demography, landscape features, and changing climatic conditions can such questions of residency and finer-scale movements be addressed [17][18][19] .…”

Section: Introductionmentioning

confidence: 99%

“…More recently, complex modelling of the initial peopling of Sahul has revealed several probable pathways across the continent, with some extending across the arid core and suggesting such environments did not form a barrier to past migration 17 . Only through such complex models incorporating human demography, landscape features, and changing climatic conditions can such questions of residency and finer-scale movements be addressed [17][18][19] .…”

Section: Introductionmentioning

confidence: 99%

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Stochastic population projections in Sahul refine the human-refugia hypothesis for early Last Glacial Maximum

Bradshaw¹,

Williams²,

Ulm³

et al. 2022

Preprint

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Pleistocene archaeology in Australia has focussed on the survival and behaviour of Indigenous populations across Sahul during the Last Glacial Maximum (28.6 ± 2.8 ka to 17.7 ± 2.2 ka). A long-standing conceptual model proposes people occupied ecological refugia while abandoning drier regions during extreme climatic conditions, with inferred patterns of subsequent recovery essential for describing the evolution of societies in the Holocene. Radiocarbon-derived population estimates partially support the conceptual model while genetic evidence does not, but how human populations were influenced by the Last Glacial Maximum remains untested. To test the refugia hypothesis, we developed a spatial-demographic model of human movement to project population patterns across Sahul from 40,000 years ago (ka) to the mid-Holocene (5 ka). The model predicts little population change in eastern Sahul or New Guinea during the Last Glacial Maximum. However, extensive movement and potential abandonment in the central-western deserts and the north-northwest coastal regions are predicted during the first half of the Last Glacial Maximum (~ 26–20 ka), with some recovery after 15 ka. The demographic implications to societies appear to have extended beyond the Last Glacial Maximum, with increasing populations not evident until the early Holocene in many regions. Our model describes a complex pattern where large areas of Sahul provided refugia that maintained populations throughout the Last Glacial Maximum, providing a possible explanation for the disparity between archaeological and genomic evidence. There was also a correlation between predicted rates of population change and those derived from radiocarbon dates, supporting the realism of applying dates to infer past demography.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stochastic population projections in Sahul refine the human-refugia hypothesis for early Last Glacial Maximum

Bradshaw¹,

Williams²,

Ulm³

et al. 2022

Preprint

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“…The current as well as future expansions of SahulArch will further facilitate modelling efforts aimed to better understand the history of human occupation of the Sahul landmass. The utility of these data collections has been illustrated recently by two studies looking at the first peopling of Sahul (Bradshaw et al, 2021;Crabtree et al, 2021) that rely on a precursor of SahulArch (Williams et al, 2014) to provide chronological data for numerical modelling of possible peopling pathways across the landmass. The SahulArch collection is currently biased towards ages published since 2014 and the geographical areas of the northern and south-eastern Australia where data entry has focussed to date.…”

Section: Sahul Archaeology (Sahularch)mentioning

confidence: 99%

“…We hope that with the expansion of SahulSed to include OSL and TL ages from aeolian and lacustrine sedimentary archives, in addition to the fluvial archives that were part of OCTOPUS v.1, and with the inclusion of SahulArch, OCTOPUS v.2 will become an equally important resource for the Australian Quaternary and archaeology research communities. The utility of these data collections has been illustrated recently by two high-profile studies looking at the first peopling of Sahul (Bradshaw et al, 2021;Crabtree et al, 2021) that rely on a precursor of SahulArch (Williams et al, 2014) to provide chronological constraints on numerical modelling and select most plausible modelled scenarios. Ultimately, it is our hope that OCTOPUS will continue to ensure that data are reusable beyond the scope of the project for which they were initially collected, and so continue to enable large-scale synoptic studies that would otherwise not be possible.…”

Section: Technical Validationmentioning

confidence: 99%

OCTOPUS Database v.2

Codilean

Munack

Saktura

et al. 2022

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Abstract. OCTOPUS v.2 is an Open Geospatial Consortium (OGC) compliant web-enabled database that allows users to visualise, query, and download cosmogenic radionuclide, luminescence, and radiocarbon ages and denudation rates associated with erosional landscapes, Quaternary depositional landforms and archaeological records, along with ancillary geospatial (vector and raster) data layers. The database follows the FAIR (Findable, Accessible, Interoperable, Reusable) data principles and is based on open-source software deployed on Google Cloud Platform. Data stored in the database can be visualised, queried, and downloaded via a custom-built web interface and via desktop GIS applications that support OGC data access protocols. OCTOPUS v.2 hosts five major data collections. CRN Denudation and ExpAge consist of published cosmogenic 10Be and 26Al measurements in modern fluvial sediment and glacial samples, respectively. Both collections have a global extent and in addition to geospatial vector layers, the former also includes raster layers, including digital elevation model, gradient raster, flow-direction and flow-accumulation rasters, atmospheric pressure raster, and CRN production scaling and topographic shielding factor rasters. SahulSed consists of published optically stimulated luminescence (OSL) and thermoluminescence (TL) ages for fluvial, aeolian, and lacustrine sedimentary records across the Australian mainland and Tasmania. SahulArch consists of published OSL, TL, and radiocarbon ages for archaeological records and FosSahul consists of published late Quaternary records of direct and indirect non-human vertebrate (mega)fauna fossil ages that have been systematically quality rated. Supporting data are comprehensive and include bibliographic, contextual, and sample preparation and measurement related information. In the case of cosmogenic radionuclide data, OCTOPUS also includes all necessary information and input files for the recalculation of denudation rates using the open-source program CAIRN. OCTOPUS v.2 and its associated data curation framework allow the harnessing of valuable legacy data that would otherwise be lost to the research community. The database can be accessed at https://octopusdata.org (last access: 30 January 2022). The individual data collections can also be accessed via their respective digital object identifiers (DOIs).

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