Adapting to change
to On the Brink-]
Tree ring data from the prehistoric American
Southwest, approximately 10751200 AD, tell the story. Extreme climate
fluctuation. In the resulting draught, water sources dried up for the
forager-farmers and their crops, leading to the abandonment of large
towns and ceremonial centers. Dispersed into the desert, people fought
for the scarce resources in order to survive.
Midden evidence points to poorer diets and decreasing health. Graves
indicate an infant mortality rate of nearly 70 percent. Disease likely
increased and famine was probably rampant, says University of Maine
Professor of Anthropology and Climate Change Kristin Sobolik, who has
studied human adaptations in desert environments, primarily in the
American Southwest, for more than two decades.
By the time the first Europeans came to the Puebloan Southwest, the
remaining Native communities were small, the once thriving population a
shadow of its prehistoric self.
"When you look at the collapse of civilizations around the world,
environmental change and human environmental destruction are two of the
linchpins leading to societal collapses," says Sobolik, associate
director of UMaine's Climate Change Institute. "That's why we're upset
about what we're seeing now with more human-induced global warming."
Changing climate is a fact of life on this planet and humans' ability to
adapt to that change has shaped societies. Evidence of that adaptability
or lack thereof is found in the archaeological record, according to
anthropologists. So, too, are cues for modern societies facing an
increasingly uncertain future with human-induced climate change.
"If you look at human evolution, climate was a really important factor
in the ability of our ancestors to become us," says Dan Sandweiss,
UMaine professor of anthropology and Quaternary and climate studies, who
studies prehistoric coastal adaptations, primarily in Peru. "Much of the
human story revealed through archaeology shows the increasing ability of
humans to deal with difficult climate change.
"When climate changes, people change in some way," he says. "We may not
be able to predict what will happen, but if there's a major change in
climate, there will be change in human systems."
One of the clearest examples of radical climate change leading to the
upheaval of civilization occurred in Mesopotamia, says Sandweiss, where
the extensive archaeological record has provided evidence of a 300-year
drought that caused people in the north to abandon their societies and
move south around 22001900 BC.
The Medieval Warm Period around 985 AD allowed Norse colonies to spring
up in Greenland, where the climate at that time was much like their
European homeland. The onset of the Little Ice Age around 1400 AD
brought that colonization to a close.
In Peru about 6,0009,000 years ago, humans began shifting from small
nomadic hunter-gatherer bands to permanent, more complex settlements and
social organization. But with the onset of more frequent El Niño events
about 3,000 years ago, pyramids and temples were abandoned.
"People have to eat to survive. But when they move beyond small-scale
food producers, they are more at the mercy of climate," Sandweiss says.
"When the population gets too big to go back to the land, then it's
truly at the mercy of climate change."
Like any other organisms, humans' ability to adapt determines our
success as a species. That ability to adapt is stymied when humans start
relying on domesticated plants and animals, Sobolik says.
"What we see in paleonutrition is that smaller groups living off the
environment had a better diet, better nutrition and health," she says.
"It was downhill once they became dependent on a single crop rather than
using a wide variety of foods as hunters and gatherers. They became more
sedentary around their crops, increasing population size and passing
disease more easily from one person to another. Most important, they
started living with their waste products and getting disease from
domesticated animals and the vermin attracted to the stored crops."
The preferable climate and natural environment for humans are
predictable from year to year, Sandweiss says. Humans can cope when the
unpredictable happens every once in a while. But when changes in the
natural world shift so dramatically that fish, birds and animals die,
rains are torrential, and disease and insect events common, human
civilization is at risk.
"When there's increased variability, people have to respond proactively
or reactively," says Sandweiss. "In more complex societies with
increased agricultural productivity and irrigation systems, there's less
option to move around. Large populations are dependent on the fixed
infrastructure for food needed to survive, so that when events become
more severe, the consequences become more dire."
Today, people argue that such rudimentary struggles for survival are
behind us, that a sophisticated society replete with technology will
help us bypass such threats. But the fact remains that, despite human
intelligence, we remain the only species capable of annihilating
ourselves, says Sobolik. In light of current climate change, people need
to be prepared to adapt, including changing consumption habits and
societal infrastructure, resulting in cultural shifts.
"The most important thing is that the major underpinning of societal
collapse is environmental degradation and we need to learn from that,"
she says. "The hope is that we can develop the technology and the smarts
to think as a human around the globe, as one group that needs to change
by Margaret Nagle