Speaker 1: Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff. Louren Boglebaum.
Speaker 1: Here Back in nineteen twenty nine, Colonel Charles Lindbergh, the
Speaker 1: same aviator who two years before had become famous by
Speaker 1: flying solo across the Atlantic Ocean, was flying a Pan
Speaker 1: American Airways plane from Miami to Panama when he decided
Speaker 1: to do a little sight seeing over what's now Belize.
Speaker 1: Lindberg veered inland and flew over a stretch of southern
Speaker 1: Mexico and Central America that was covered with dense vegetation,
Speaker 1: a region so remote and inaccessible that outsiders reportedly had
Speaker 1: never ventured there. As Lindberg soared over the trees, something
Speaker 1: ahead caught his attention, what an Associated Press account later
Speaker 1: described as two emerald eyes staring up at him out
Speaker 1: of the tangle of the jungle brush. As Lindberg swooped
Speaker 1: in low to investigate, he was astonished. It was the
Speaker 1: ruins of a vine enshrouded city about eight miles across
Speaker 1: that's about thirteen kilometers, dotted with numerous small periods, and
Speaker 1: what turned out to be a stone temple two hundred
Speaker 1: and fifty feet tall that seventy five meters with twin
Speaker 1: reflecting pools, the green reflections from which had looked to
Speaker 1: him like a pair of eyes, But there were no
Speaker 1: signs of humanity anywhere around the site. E Lindberg was
Speaker 1: filled with awe as he gazed upon the ruined grandeur
Speaker 1: of a once mighty Maya city whose builders apparently had
Speaker 1: abandoned it to be swallowed by the jungle. But why,
Speaker 1: That's a question that archaeologists, scientists, and historians have been
Speaker 1: puzzling about ever since. During its heyday, what's called the
Speaker 1: Classic Maya Civilization, which blasted from about two hundred and
Speaker 1: fifty to nine hundred CE, the Maya peoples had one
Speaker 1: of the most advanced and complex civilizations on the planet.
Speaker 1: They built more than forty network worked, yet independently run
Speaker 1: cities across what's now Central America and Mexico, filled with
Speaker 1: temples and palaces and elaborate sculpture and carvings whose magnificence
Speaker 1: still impresses. They developed advanced irrigation techniques for growing crops,
Speaker 1: and performed astronomical observations that enabled them to predict solar eclipses.
Speaker 1: They had a family of around thirty languages that included
Speaker 1: written hieroglyphs, which some Maya used to write books on
Speaker 1: paper made from fig trees. They devised an elaborate calendar
Speaker 1: whose cycles ran for centuries into the future. And yet
Speaker 1: by the time Spanish conquerors arrived in Central America in
Speaker 1: the early fifteen hundreds, many of the Great Maya cities
Speaker 1: were empty, and the builder's descendants had integrated into other
Speaker 1: communities or cultures, or returned to smaller communities with smaller
Speaker 1: scale architecture. We should note that the entire civilization did
Speaker 1: not collapse. No civilization at that large of a scale
Speaker 1: as a monolith, and the fact that there are Maya
Speaker 1: peoples living today attests that the entire population didn't just vanish,
Speaker 1: but several large urban centers were all abandoned between around
Speaker 1: eight hundred to nine hundred CE. Over the years, scholars
Speaker 1: have developed numerous theories about why the mighty Classic Maya
Speaker 1: civilization went through this fall, but recent discoveries point to
Speaker 1: a cluster of causes that sounds eerily familiar, one centered
Speaker 1: on climate change. Oh, we are lucky that at least
Speaker 1: some of the Classic Maya's written records survived, and that
Speaker 1: they were also written about by post classic Maya peoples.
Speaker 1: That some of those records survived, which has enabled scholars
Speaker 1: to partially reconstruct their history. But in some ways, those
Speaker 1: tenalizing clues have only made the mystery of the decline
Speaker 1: more frustrating. Over the years, researchers have developed various theories
Speaker 1: about what caused the decline of those Maya cities, though
Speaker 1: it was most likely a combination of these and other
Speaker 1: factors and not anyone alone. Here are a few of
Speaker 1: the most prominent theories, in no particular order. First, we
Speaker 1: have over farming. Some scholars have argued that my society
Speaker 1: grew too rapidly for its own good. As the population
Speaker 1: of some cities increased, it put vocal farmers under more
Speaker 1: and more pressure to grow food, and gradually they ran
Speaker 1: out of fresh forest land. Clear that would have forced
Speaker 1: them to plant crops in their fields without an adequate
Speaker 1: fallow cycle, that is the time it takes soil to
Speaker 1: rebuild its nutrients supply. Deforestation like that can also disrupt
Speaker 1: the water supply by rerooting rainwater and groundwater. A Second,
Speaker 1: we have interior and exterior political turmoil. Each Maya city
Speaker 1: state had its own rulers who often had their populations
Speaker 1: convinced that they had ties with deities and were powerful
Speaker 1: enough to control the weather. Hard to say whether or
Speaker 1: not those leaders believed in those magical powers themselves. Their
Speaker 1: efforts to conquer neighboring cities and peoples may have backfired,
Speaker 1: as long periods of war sapped resources been led to retaliation.
Speaker 1: There's evidence that a number of Maya cities eventually were
Speaker 1: besieged and fell to invaders. Third, we have disease, though
Speaker 1: in this case the theory is about an agricultural epidemic,
Speaker 1: not a human one. A maze was a staple crop
Speaker 1: across the Maya civilization, and the Maze mosaic virus may
Speaker 1: have destroyed much of their food supply. A note that
Speaker 1: all three of these factors are connected to the fourth theory,
Speaker 1: the aforementioned climate change. A destruction of the food and
Speaker 1: water supply by overfarming, deforestation, warfare, and disease would have
Speaker 1: been exacerbated by the happenstance of natural climate change. Add
Speaker 1: to this the fact that political leaders were supposed to
Speaker 1: be able to control the weather. Anthropologists say this chain
Speaker 1: of unfortunate events would have caused the people to deeply
Speaker 1: lose trust in their leaders, which would in turn further
Speaker 1: disrupt agriculture and infrastructure and trade, everything that ties the
Speaker 1: city together. A while our modern civilization is driving global
Speaker 1: warming by polluting the atmosphere, the Earth's climate is affected
Speaker 1: by other factors, such as changes in solar activity and volcanoes.
Speaker 1: The plight of the Maya seems to be largely the
Speaker 1: result of such natural cycles. Scientists who have studied mineral
Speaker 1: deposits left by dripping water in caves have been able
Speaker 1: to construct a two thousand year long history of weather
Speaker 1: patterns in Central America. In an article published in Science
Speaker 1: back in twenty twelve, the researchers revealed that for the
Speaker 1: first several hundred years of classic Maya civilization, they benefited
Speaker 1: from unusually wet weather that made it easier to grow
Speaker 1: crops and enabled the population to expand. That also made
Speaker 1: the Maya kings look pretty good because they could claim
Speaker 1: credit for conducting the rituals that kept the rains coming.
Speaker 1: But around sixteen sixty CE, the weather changed and rain
Speaker 1: became more infrequent in some regions of the area. The
Speaker 1: Maya also may have accelerated that climate change by cutting
Speaker 1: down the forest around them, probably for fuel and create
Speaker 1: wood plaster for use in their ornate buildings and to
Speaker 1: clear land. From studying pollen found in ancient layers of
Speaker 1: Central American lake sediment, scientists learned that around eight hundred CE,
Speaker 1: tree pollen disappeared almost completely and was replaced by pollen
Speaker 1: from weeds. That suggests that the region's forests had all
Speaker 1: but disappeared. Without trees and their root systems to keep
Speaker 1: soil in place, erosion would have worsened, carrying away fertile
Speaker 1: top soil, which would have crippled local agriculture. Additionally, trees
Speaker 1: function as natural air conditioners, a drawing water through their
Speaker 1: leaves in cooling the surrounding air. When the water evaporates,
Speaker 1: you can experience the same effect if you live in
Speaker 1: a city. In a park with trees, it's going to
Speaker 1: seem cooler than it does out on a city block
Speaker 1: with just buildings an asphalt all around you. Computer simulations
Speaker 1: indicate that some regions temperature could have increased by as
Speaker 1: much as six degrees fahrenheit or around three and a
Speaker 1: half degrees celsius. That change would have been enough to
Speaker 1: alter the weather even more. Researchers who have analyzed changes
Speaker 1: in river sediment have found that in the century after
Speaker 1: deforestation in some regions, a rainfall declined there, with intense
Speaker 1: multi year droughts occurring around the years eight ten, eight
Speaker 1: sixty and nine ten CE. Because the people in these
Speaker 1: cities probably depended upon rain captured in reservoirs for drinking water,
Speaker 1: they would have faced not only hunger, but thirst as well.
Speaker 1: It's not hard to imagine how a panicked population would
Speaker 1: have fled its once great city their way of life
Speaker 1: collapsed into a sort of pre Columbian mad max. Though
Speaker 1: again the note that Classic Maya civilization was not a monolith.
Speaker 1: Different communities faced slightly different pressures and came up with
Speaker 1: different solutions. As some cities fell, others prospered. That said,
Speaker 1: there are some lessons from the so called collapse of
Speaker 1: the Classic Maya that we ignore at our own peril.
Speaker 1: Scientists warn that we are repeating the same pattern of
Speaker 1: deforestation that may have exacerbated climate change in Central America
Speaker 1: a millennium ago, except on a far more massive scale.
Speaker 1: Trees are about fifty percent carbon, and in the US
Speaker 1: alone they presently absorb or sinc a little less than
Speaker 1: a million metric tons of atmosphere warming carbon dioxide, which
Speaker 1: offsets between ten and twenty percent of what Americans spew
Speaker 1: into the atmosphere by burning coal and gasoline. But when
Speaker 1: we cut down trees or burn them, they released their
Speaker 1: stored carbon into the atmosphere, and they aren't around to
Speaker 1: absorb any more of it. Over the past several centuries,
Speaker 1: the US has cut down about ninety percent of the
Speaker 1: forests that once covered the continent, and what still remains
Speaker 1: is in peril and in currently developing nations, once lush
Speaker 1: forests have been disappearing at an alarming rate thanks to logging, agriculture,
Speaker 1: and the need for human living space. In recent years,
Speaker 1: there has been some international progress in slowing the rate
Speaker 1: of deforestation, but we still face the risk that it
Speaker 1: will push us even faster into climate chaos. It's a
Speaker 1: problem that we must work harder to solve, both as
Speaker 1: a broad civilization than within our own differing communities. Personal
Speaker 1: choices feel small, but they do add up, and you
Speaker 1: can make your voice heard in your local government on
Speaker 1: bigger issues. If you're here, you probably agree that learning
Speaker 1: is the fun part, So learn what you can do
Speaker 1: by checking out your government agencies in the US that's
Speaker 1: going to be at EPA dot gov, and what local
Speaker 1: activists are up to. Today's episode is based on the
Speaker 1: article did the Maya civilization end because of climate change?
Speaker 1: On how stuffworks dot com written by Patrick J. Kiger.
Speaker 1: Brain Stuff is production of by Heart Radio in partnership
Speaker 1: with how stuffworks dot Com and is produced by Tyler Klang.
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