First Australian populations followed footpath ‘superhighways’ across the continent of Australia/New Guinea
From: Santa Fe Institute
April 29, 2021 -- The best path across
the desert is rarely the straightest. For the first human inhabitants of Sahul
— the super-continent that underlies modern Australia and New Guinea — camping
at the next spring, stream, or rock shelter allowed them to thrive for hundreds
of generations. Those who successfully traversed the landmarks made their
way across the continent, spreading from their landfall in the Northwest
across the continent, making their way to all corners of Australia and New
Guinea.
By simulating the physiology and
decisions of early way-finders, an international team* of archaeologists,
geographers, ecologists, and computer scientists has mapped the probable
“superhighways” that led to the first peopling of the Australian continent some
50,000-70,000 years ago. Their study,
published in Nature Human Behaviour, is the largest reconstruction of a
network of human migration paths into a new landscape. It is also the first to
apply rigorous computational analysis at the continental scale, testing 125
billion possible pathways.
"We decided it would be really
interesting to look at this question of human migration because the ways that
we conceptualize a landscape should be relatively steady for a hiker in the
21st century and a person who was way-finding into a new region 70,000 years
ago,” says archaeologist and computational social scientist Stefani
Crabtree, who led the study. Crabtree is a Complexity Fellow at the Santa
Fe Institute and Assistant Professor at Utah State University. “If it's a new
landscape and we don't have a map, we're going to want to know how to
efficiently move throughout a space, where to find water, and where to camp —
and we'll orient ourselves based on high points around the lands.”
“One of the really big unanswered
questions of prehistory is how Australia was populated in the distant past.
Scholars have debated it for at least a hundred and fifty years,” says
co-author Devin White, an archaeologist and remote sensing scientist at Sandia
National Laboratories. “It is the largest and most complex project of its kind
that I’d ever been asked to take on.”
To re-create the migrations across
Sahul, the researchers first needed to simulate the topography of the
supercontinent. They “drained” the oceans that now separate mainland Australia
from New Guinea and Tasmania. Then, using hydrological and paleo-geographical
data, they reconstructed inland lakes, major rivers, promontory rocks, and
mountain ranges that would have attracted the gaze of a wandering human.
Next, the researchers programmed in-silico stand-ins
for the human travelers. The team adapted an algorithm called “From Everywhere
to Everywhere,” created by White*, to program the way-finders based on the
caloric needs of a 25-year-old female carrying 10 kg of water and tools.
The researchers imbued these individuals
with the realistic goal of staying alive, which could be achieved by finding
water sources. Like backcountry hikers, the digital travelers were drawn to
prominent landmarks like rocks and foothills, and the program exacted a caloric
toll for activities such as hiking uphill within the artificial
landscape.
When the researchers “landed” the
way-finders at two points on the coast of the re-created continent, they began
to traverse it, using landmarks to navigate in search of freshwater. The
algorithms simulated a staggering 125 billion possible pathways, run on a
Sandia supercomputer, and a pattern emerged: the most-frequently traveled
routes carved distinct “superhighways” across the continent, forming a notable
ring-shaped road around the right portion of Australia; a western road; and
roads that transect the continent. A subset of these superhighways map to
archaeological sites where early rock art, charcoal, shell, and quartz tools
have been found.
“Australia’s not only the driest, but
it’s also the flattest populated continent on Earth,” says co-author Sean Ulm,
an archaeologist and Distinguished Professor at James Cook University. Ulm is
also Deputy Director of the Australian Research Council Centre of Excellence
for Australian Biodiversity and Heritage (CABAH), whose researchers contributed
to the project. “Our research shows that prominent landscape features and water
sources were critical for people to navigate and survive on the continent. In
many Aboriginal societies, landscape features are known to have been created by
ancestral beings during the Dreaming. Every ridgeline, hill, river, beach and
water source is named, storied and inscribed into the very fabric of societies,
emphasising the intimate relationship between people and place. The landscape
is literally woven into peoples’ lives and their histories. It seems that these
relationships between people and Country probably date back to the earliest
peopling of the continent.”
The results suggest that there are
fundamental rules humans follow as they move into new landscapes and that
the researchers’ approach could shed light on other major migrations in human
history, such as the first waves of migration out of Africa at least 120,000
years ago.
Future work, Crabtree says, could inform
the search for undiscovered archaeological sites, or even apply the techniques
to forecast the movements of human migration in the near future, as populations
flee drowning coastlines and climate disruptions.
Read the paper, “Landscape
rules predict optimal superhighways for the first peopling of Sahul” in Nature
Human Behaviour (April 29, 2021)
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