Desert systems are very fragile, with no buffer against abrupt climate swings.
Credit: Juan Moseinco/IPS
Discovering the Ancient Green Past of Argentina’s Arid Puna Plateau
By Marcela Valente
The change of climate in the Puna region thousands
of years ago may have played a key role in the
adoption of agriculture by hunter-gatherers.
BUENOS AIRES, Aug 6 (Tierramérica).- The arid high Andean Puna plateau in northwest
Argentina was much greener thousands of years ago.
Climate changes forced the local inhabitants to
develop adaptation strategies that could offer
lessons for today, researchers say.
“The Puna region was always a desert area. But
until about 10,000 years ago, there was greater
vegetation coverage and the productive parts were
much more abundant, because it rained year-round,”
archaeologist Hugo Yacobaccio of the University of
Buenos Aires (UBA), told Tierramérica.
But changes that occurred over the space of
thousands of years left the Puna region extremely
According to the evidence, one of the factors that
played a role was the El Niño/Southern Oscillation
(ENSO), a cyclical phenomenon in which the surface
temperatures of the equatorial Pacific rise, which
has been occurring for at least 3,000 years.
But the period 6000 to 2000 BC was characterized
by extremely arid conditions at the planet’s lower
“That is when the Sahara Desert was formed in the
north of Africa, in an area that was previously
savannah,” said Yacobaccio.
The inhabitants had to adapt to the new
challenges. “The mobility of groups of hunter-
gatherers was reduced and relative population
density rose as they grouped around small oases or
ecological refuges,” said Marcelo Morales, another
archaeologist at UBA.
Paleoenvironmental studies have provided evidence
that during that period, the human presence in
those areas significantly shrank, but did not
“The ultimate objective of these studies is to
better understand how society functioned thousands
of years ago, in relation to climate changes, and
draw on that for lessons in the face of global
warming today, which is much more accentuated,”
The two researchers work at UBA’s Institute of
Archaeology and the National Scientific and
Technical Research Council, in the area of
environmental archaeology - the study of the long-
term relationship between humans and their
They have published several studies on an
environment and time period that are important for
The Puna altiplano region extends, with different
names and characteristics, through southern Peru,
northeast Chile, western Bolivia and northwest
Argentina. The Argentine portion, peppered with
salt flats, is one of the most arid parts of the
It is also, Yacobaccio explained, one of the few
regions of the world where evidence of an
autochthonous transition of hunter-gatherer groups
to more sedentary and complex societies dedicated
to plant cultivation and animal husbandry can be
“This transition can be found in five or six
places around the world, and it spread from those
few sites to the rest of the world,” he added. The
other sites where the transition has been
documented are in the Middle East (Israel, Syria
and Turkey), China, Mesoamerica (southern Mexico
and northern Central America), and Peru, he said.
Desert systems are very fragile, with no buffer
against abrupt climate swings. “That’s why we
believe these changes definitely had an impact on
the populations, because streams and wetlands
disappeared,” he said.
Vegetation became sparser and prey animals
dispersed. Some inhabitants migrated, and others
began to understand that it made more sense to
stay for longer periods in more suitable areas,
where supplies of basic resources like water, food
or sources of energy were available, Morales
These places were nearly always over 4,000 meters
above sea level, where there were still wetlands,
streams and rivers.
“Whereas before they had moved about in groups of
around 15 people, now groups of as many as 70
people came together in those areas, and that
marked the start of experimentation with certain
economic practices like the domestication of
camelids” - guanacos and vicuñas, which were the
main wild mammals in that region, he said.
And to a lesser extent, they began to cultivate
species like squash, quinoa, and potatoes and
other tubers, he said.
“All of this brought about a change in habits,
because those refuges where they could graze their
animals, cultivate vegetables, and find firewood
were isolated areas separated by deserts,” Morales
In their field research, the scientists have found
evidence of incipient villages, and artifacts of
tools, bags woven from vegetable fibers and crops
adapted from the valleys.
As the climate was modified, hunting strategies
also changed: it became a group rather than a
solitary activity, which used lookout perches.
There was also greater planning involved, as well
as more intensive processing of the prey.
The groups that settled in wetland areas “began to
play a greater role in the selection of animals
for domestication, selecting the tamer ones, and
that had an impact on the animal populations,” the
Other researchers working in the most arid parts
of the Puna, where salt flats abound, are
replicating an irrigation system that is thousands
of years old but has proven to be effective today.
“The idea is to extrapolate from past experience,
to come up with new alternatives and improve
current practices in the face of climate
conditions that have become harsher,” Morales