Humans, water, and the colonization of Australia

Excluding four Willandra Lakes sites, 84% of archaeological sites >30,000 y old (46 of 55 sites) are within 20 km of modern permanent water.

“A connected network representing the least-cost distance between water bodies and graded according to terrain cost shows that 84% of archaeological sites >30,000 y old are within 20 km of modern permanent water.”

• Also stated in: § Results and Discussion · plain

  “Excluding four sites in the Willandra Lakes area that were within 10 km of water at the time of initial occupation but now are >50 km from permanent water because of the avulsion of the Lachlan River (38), 84% of the sites from >30 ka (46 of 55 sites) are <20 km, or approximately a day’s walk, from modern permanent water”

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  The paper describes archaeological traces at Lake Mungo and the Willandra Lakes (section 627, lines 627–633), but does not report a survey of 55 sites or the claimed 84% within 20 km of modern permanent water. Searches for the figures and for a least-cost network or terrain-cost analysis found no passage addressing that result. (LLM, conf=0.77)

  Experimental — accuracy not yet measured

This connectivity would facilitate ready dispersal by hunter-gatherers with an average daily foraging range of 10-15 km.

“This connectivity would facilitate ready dispersal by hunter-gatherers with an average daily foraging range of 10–15 km (41, 42).”

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  The Results report a mean daily walking distance of 11.4 km for Hadza men, within the claimed range, but 5.8 km for Hadza women. The paper measures daily travel distance, not a general 10–15 km foraging range for hunter-gatherers, and the cited passages do not address whether connectivity facilitates dispersal. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Multiple, well-watered routes into the semiarid and arid continental interior were available throughout the period of early human occupation.

“We further show that multiple, well-watered routes into the semiarid and arid continental interior were available throughout the period of early human occupation.”

Approximately 818,000 km2 of land, about 11% of the total mainland area, mostly in the center and west of the continent, is >50 km from permanent water.

“for example, ∼818,000 km2 of land (∼11% of the total mainland area), mostly in the center and west of the continent (Fig. 3), is >50 km from permanent water (Fig. 2).”

From the Gulf of Carpentaria south, multiple paleohydrological corridors through interior Queensland existed following abundant permanent water points <20 km apart that would be directly connected at times of inundation.

“From the Gulf of Carpentaria south, multiple paleohydrological corridors [sensu Breeze et al. (30)] through interior Queensland existed following abundant, permanent water points <20 km apart that would be directly connected at times of inundation.”

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All archaeological sites from >30 ka are closely associated with the least-cost pathways identified on the basis of modern permanent water distribution.

“All the archaeological sites from >30 ka are closely associated with the least-cost pathways identified in Fig. 2 on the basis of modern permanent water distribution.”

All archaeological sites >30,000 y old are less than 40 km from modern permanent water.

“and all sites are <40 km, or a 2-d walk.”

A strictly coastal route from a point of entry in the northwest to the south and then east would be at a minimum five times longer than an overland route across the north of the continent and south through Queensland.

“A strictly coastal route from a point of entry in the northwest (20) to the south and then east is possible, but such a western coastal route, thence up the Murray-Darling River to Willandra Lakes (for example) would be at a minimum five times longer than an overland route across the north of the continent and south through Queensland (and would be even longer at times of lowered sea level).”

• cites [20]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

A striking feature of the spatial analysis is the clear linkage of well-watered routes from northern Australia, through the eastern semiarid and arid zone, to southeastern Australia and into the rocky arid center of the continent.

“A striking feature of the spatial analysis presented here is the clear linkage of well-watered routes from northern Australia, through the eastern semiarid and arid zone, to southeastern Australia and into the rocky arid center of the continent.”

Depletion of high-ranked resources over time in paleohydrological corridors potentially drove a wave of dispersal farther along well-watered routes to patches with higher foraging returns.

“Depletion of high-ranked resources over time in these paleohydrological corridors potentially drove a wave of dispersal farther along well-watered routes to patches with higher foraging returns.”

• Also stated in: § Results and Discussion · hedged

  “Depletion of high-ranked resources in these patches over time would drive a wave of dispersal farther along well-watered routes to patches with higher foraging returns (1, 25).”

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Initial human occupation of Australia from the north began before 47 kyBP.

“Initial occupation from the north appears to have begun before 47 kyBP (1–8) with relatively rapid movement therafter”

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These data imply a maximum dispersal interval of ∼5,000-10,000 y, during which most of the readily habitable parts of the continent were occupied.

“These data imply a maximum dispersal interval of ∼5,000–10,000 y, during which most of the readily habitable parts of the continent were occupied.”

Rather than continental-scale refuges, these areas may have been a patchwork of smaller, individually isolated refugia distributed more broadly across the continent.

“Rather than continental-scale refuges (16, 43, 44), these areas may have been a patchwork of smaller, individually isolated refugia (45, 46) distributed more broadly across the continent.”

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The Willandra Lakes region in southeast Australia may have been occupied within 1,000 y after human arrival.

“the Willandra Lakes region in the southeast of the continent may have been occupied within 1,000 y after the arrival of humans (1, 9, 10).”

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The association between archaeological sites from >30 ka and modern permanent water suggests that the distribution of modern permanent water is a reasonable analog for the distribution of permanent water in the past.

“The association between archaeological sites from >30 ka and modern permanent water suggests that the distribution of modern permanent water is a reasonable analog for the distribution of permanent water in the past.”

• AssumptionThe authors state this as an assumption: The gross routing of floodwaters at the continental scale is unlikely to have changed dramatically in the last 50,000 y, except locally in response to geomorphic changes as a result of neotectonism.

A lag in the occupation of central Australia amounting to ∼10,000 y suggests that the arid interior was relatively difficult to access.

“A lag in the occupation of central Australia amounting to ∼10,000 y suggests that the arid interior was relatively difficult to access.”

There was a lag in occupation of the arid bedrock core of the continent, which was not occupied until 36.5-42.5 ka.

“There was a lag in occupation of the arid bedrock core of the continent, which was not occupied until 36.5–42.5 ka (23).”

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The duration of inundation, the connectedness of water at times of inundation, and the location of permanent water in the landscape dictate where and for how long humans could reside in or transit through most of interior Australia.

“It is the duration of inundation, the connectedness of water at times of inundation, and the location of permanent water in the landscape that dictates where, and for what length of time, humans could reside in or transit through most of interior Australia.”

More recent populations developed the ability to journey farther from permanent water than populations could during the initial dispersal.

“This distribution suggests that more recent populations have developed the ability to journey farther from permanent water than populations could during the initial dispersal.”

Immediate and rapid continent-wide dispersal is unlikely because large regions have very limited accessible permanent water and long distances between permanent water points.

“Immediate and rapid continent-wide dispersal (11) is unlikely, because there are large regions where, at any time, accessible permanent water is very limited and the distance between permanent water points is long”

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As the continent dried during the Last Glacial Maximum, populations contracted into smaller areas with access to a reduced number of permanent water points and reduced food resources.

“As the continent dried during the Last Glacial Maximum, populations contracted into smaller areas with access to a reduced number of permanent water points and reduced food resources.”

The broad-scale patterns of water distribution observable in the present are likely to have held in the past, particularly during the wetter periods of initial human dispersal.

“Nevertheless, the broad-scale patterns observable in the present are likely to have held in the past and particularly during the wetter periods of initial human dispersal.”

• AssumptionThe authors state this as an assumption: The gross routing of floodwaters at the continental scale is unlikely to have changed dramatically in the last 50,000 y, except locally in response to geomorphic changes as a result of neotectonism.

The Pleistocene global dispersal of modern humans required transit of arid and semiarid regions where the distribution of potable water was a primary constraint on dispersal pathways.

“The Pleistocene global dispersal of modern humans required the transit of arid and semiarid regions where the distribution of potable water provided a primary constraint on dispersal pathways.”

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The WOfS dataset, in combination with other terrain attributes, can be used predictively to identify areas worthy of investigation for their potential to yield previously unrecognized archaeological sites to delimit the initial dispersal routes better.

“These alternatives, in turn, suggest that the dataset, in combination with other terrain attributes, can be used predictively to identify areas worthy of investigation for their potential to yield previously unrecognized archaeological sites to delimit the initial dispersal routes better.”

Refugial areas, particularly those located in the sandy deserts fringing the arid bedrock core of the continent, may well have been separated by truly uninhabited regions.

“Refugial areas, particularly those located in the sandy deserts fringing the arid bedrock core of the continent, may well have been separated by truly uninhabited regions.”

It is likely that substantially less water was available across the continent at some times in the past, particularly during the Last Glacial Maximum.

“Of course, it is likely that substantially less water was available across the continent at some times in the past and particularly during the Last Glacial Maximum (47, 48).”

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During the millennia following human arrival, the hydroclimate at the continental scale cycled several times through conditions similar to modern conditions, toward both wetter and drier periods, potentially with different timing and to differing degrees from the south to the north of the continent.

“However, during the millennia following human arrival, the hydroclimate at the continental scale cycled several times through conditions similar to modern conditions, toward both wetter and drier periods, potentially with different timing and to differing degrees from the south to the north of the continent (48–51).”

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  Checked before — its earlier verdict is held back until a new check runs.

In the context of early human dispersal, small isolated water points are likely to have been less significant than areas connected during times of inundation, because of the risk associated with striking out into an unknown area across an intervening landscape with no known water points.

“In the context of early human dispersal, small isolated water points (identified from topographic sheets) are likely to have been less significant than areas connected during times of inundation (identified by the WOfS data), because of the risk associated with striking out into an unknown area across an intervening landscape with no known water points.”

• AssumptionThe authors state this as an assumption: The areas where small permanent water features such as springs, gnammas, and rockholes have been located in the past can be assumed to be relatively constant because they require particular lithologies, hydrogeological environments, and/or geomorphic settings.

The clear relationship between archaeological sites from >30 ka and modern permanent water provides strong evidence that, at the continental scale, these factors have always been important.

“The clear relationship between archaeological sites from >30 ka and modern permanent water provides strong evidence that, at the continental scale, these factors have always been important.”

The location and connectivity of water in the landscape is critical to understanding early human dispersal through water-limited environments across the globe.

“The location and connectivity of water in the landscape is critical to understanding early human dispersal through water-limited environments across the globe (27, 28).”

• cites [27] Finlayson C. The Water Optimisation Hypothesis and the human occupation of the mid-latitude belt in the Pleistocene. Quat Int. 2013;300:22–31. [Google Scholar]Not checked yet
• cites [28] Oppenheimer S. Human’s association with water bodies: The ‘Exaggerated Diving Reflex’ and its relationship with the evolutionary allometry of human pelvic and brain sizes. Hum Evol. 2013;28(3-4):137–170. [Google Scholar]Not checked yet

Many small isolated water points, actively maintained in pre-European times to allow permanent habitation in arid regions, would not have been available to a party traversing new country except at times of significant inundation.

“Many of the small isolated water points, actively maintained in pre-European times to allow permanent habitation in arid regions (55), would not have been available to a party traversing new country except at times of significant inundation.”

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• AssumptionThe authors state this as an assumption: The areas where small permanent water features such as springs, gnammas, and rockholes have been located in the past can be assumed to be relatively constant because they require particular lithologies, hydrogeological environments, and/or geomorphic settings.

Some apparently well-watered, interconnected regions lie along potential dispersal routes but have yet to yield evidence of early, or in some places any, occupation in prehistory.

“A corollary of this analysis is that some apparently well-watered, interconnected regions lie along potential dispersal routes but have yet to yield evidence of early (or, in some places, any) occupation in prehistory.”

Permanent water, connected during periodic inundation events, provided-and provides-effective conduits for human movement over thousands of kilometers through much, but not all, of the continental interior.

“The analysis suggests that permanent water, connected during periodic inundation events, provided—and provides—effective conduits for human movement over thousands of kilometers through much, but not all, of the continental interior.”

• AssumptionRests on an assumption: The distribution and permanence of water bodies observed in the WOfS 30-year record are representative of water availability during the period of human colonization of Australia.
• AssumptionRests on an assumption: Least-cost paths between water bodies, graded by terrain cost, approximate the routes actually taken by ancient humans.

Radiocarbon dates from archaeological sites provide a measure of ancient human presence across Australia.

“A measure of ancient human presence across Australia is provided by radiocarbon dates from archaeological sites.”

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