1 00:00:01,840 --> 00:00:08,480 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff. Louren Boglebaum. 2 00:00:08,480 --> 00:00:14,080 Speaker 1: Here Back in nineteen twenty nine, Colonel Charles Lindbergh, the 3 00:00:14,120 --> 00:00:17,280 Speaker 1: same aviator who two years before had become famous by 4 00:00:17,360 --> 00:00:20,880 Speaker 1: flying solo across the Atlantic Ocean, was flying a Pan 5 00:00:20,880 --> 00:00:24,560 Speaker 1: American Airways plane from Miami to Panama when he decided 6 00:00:24,560 --> 00:00:28,320 Speaker 1: to do a little sight seeing over what's now Belize. 7 00:00:28,440 --> 00:00:31,520 Speaker 1: Lindberg veered inland and flew over a stretch of southern 8 00:00:31,520 --> 00:00:35,120 Speaker 1: Mexico and Central America that was covered with dense vegetation, 9 00:00:35,720 --> 00:00:39,920 Speaker 1: a region so remote and inaccessible that outsiders reportedly had 10 00:00:40,000 --> 00:00:45,000 Speaker 1: never ventured there. As Lindberg soared over the trees, something 11 00:00:45,040 --> 00:00:48,760 Speaker 1: ahead caught his attention, what an Associated Press account later 12 00:00:48,800 --> 00:00:52,120 Speaker 1: described as two emerald eyes staring up at him out 13 00:00:52,120 --> 00:00:56,480 Speaker 1: of the tangle of the jungle brush. As Lindberg swooped 14 00:00:56,480 --> 00:00:59,680 Speaker 1: in low to investigate, he was astonished. It was the 15 00:00:59,760 --> 00:01:03,520 Speaker 1: ruins of a vine enshrouded city about eight miles across 16 00:01:03,600 --> 00:01:08,120 Speaker 1: that's about thirteen kilometers, dotted with numerous small periods, and 17 00:01:08,200 --> 00:01:10,759 Speaker 1: what turned out to be a stone temple two hundred 18 00:01:10,800 --> 00:01:14,240 Speaker 1: and fifty feet tall that seventy five meters with twin 19 00:01:14,319 --> 00:01:17,920 Speaker 1: reflecting pools, the green reflections from which had looked to 20 00:01:18,000 --> 00:01:20,959 Speaker 1: him like a pair of eyes, But there were no 21 00:01:21,080 --> 00:01:24,840 Speaker 1: signs of humanity anywhere around the site. E Lindberg was 22 00:01:24,880 --> 00:01:28,080 Speaker 1: filled with awe as he gazed upon the ruined grandeur 23 00:01:28,280 --> 00:01:31,680 Speaker 1: of a once mighty Maya city whose builders apparently had 24 00:01:31,720 --> 00:01:37,640 Speaker 1: abandoned it to be swallowed by the jungle. But why, 25 00:01:38,760 --> 00:01:42,680 Speaker 1: That's a question that archaeologists, scientists, and historians have been 26 00:01:42,720 --> 00:01:47,200 Speaker 1: puzzling about ever since. During its heyday, what's called the 27 00:01:47,200 --> 00:01:50,640 Speaker 1: Classic Maya Civilization, which blasted from about two hundred and 28 00:01:50,640 --> 00:01:54,240 Speaker 1: fifty to nine hundred CE, the Maya peoples had one 29 00:01:54,240 --> 00:01:57,440 Speaker 1: of the most advanced and complex civilizations on the planet. 30 00:01:58,400 --> 00:02:01,440 Speaker 1: They built more than forty network worked, yet independently run 31 00:02:01,480 --> 00:02:05,320 Speaker 1: cities across what's now Central America and Mexico, filled with 32 00:02:05,480 --> 00:02:09,839 Speaker 1: temples and palaces and elaborate sculpture and carvings whose magnificence 33 00:02:09,880 --> 00:02:14,680 Speaker 1: still impresses. They developed advanced irrigation techniques for growing crops, 34 00:02:14,840 --> 00:02:19,040 Speaker 1: and performed astronomical observations that enabled them to predict solar eclipses. 35 00:02:19,960 --> 00:02:22,680 Speaker 1: They had a family of around thirty languages that included 36 00:02:22,720 --> 00:02:25,960 Speaker 1: written hieroglyphs, which some Maya used to write books on 37 00:02:26,040 --> 00:02:29,919 Speaker 1: paper made from fig trees. They devised an elaborate calendar 38 00:02:30,120 --> 00:02:35,400 Speaker 1: whose cycles ran for centuries into the future. And yet 39 00:02:35,600 --> 00:02:38,680 Speaker 1: by the time Spanish conquerors arrived in Central America in 40 00:02:38,720 --> 00:02:41,800 Speaker 1: the early fifteen hundreds, many of the Great Maya cities 41 00:02:41,840 --> 00:02:45,200 Speaker 1: were empty, and the builder's descendants had integrated into other 42 00:02:45,240 --> 00:02:49,480 Speaker 1: communities or cultures, or returned to smaller communities with smaller 43 00:02:49,520 --> 00:02:54,679 Speaker 1: scale architecture. We should note that the entire civilization did 44 00:02:54,720 --> 00:02:58,280 Speaker 1: not collapse. No civilization at that large of a scale 45 00:02:58,280 --> 00:03:00,840 Speaker 1: as a monolith, and the fact that there are Maya 46 00:03:00,880 --> 00:03:05,240 Speaker 1: peoples living today attests that the entire population didn't just vanish, 47 00:03:05,880 --> 00:03:10,160 Speaker 1: but several large urban centers were all abandoned between around 48 00:03:10,240 --> 00:03:16,519 Speaker 1: eight hundred to nine hundred CE. Over the years, scholars 49 00:03:16,560 --> 00:03:19,919 Speaker 1: have developed numerous theories about why the mighty Classic Maya 50 00:03:19,919 --> 00:03:23,919 Speaker 1: civilization went through this fall, but recent discoveries point to 51 00:03:23,960 --> 00:03:28,480 Speaker 1: a cluster of causes that sounds eerily familiar, one centered 52 00:03:28,600 --> 00:03:33,720 Speaker 1: on climate change. Oh, we are lucky that at least 53 00:03:33,720 --> 00:03:36,800 Speaker 1: some of the Classic Maya's written records survived, and that 54 00:03:36,840 --> 00:03:39,680 Speaker 1: they were also written about by post classic Maya peoples. 55 00:03:40,040 --> 00:03:43,160 Speaker 1: That some of those records survived, which has enabled scholars 56 00:03:43,200 --> 00:03:47,839 Speaker 1: to partially reconstruct their history. But in some ways, those 57 00:03:47,920 --> 00:03:51,080 Speaker 1: tenalizing clues have only made the mystery of the decline 58 00:03:51,240 --> 00:03:56,120 Speaker 1: more frustrating. Over the years, researchers have developed various theories 59 00:03:56,200 --> 00:03:59,360 Speaker 1: about what caused the decline of those Maya cities, though 60 00:03:59,360 --> 00:04:02,160 Speaker 1: it was most likely a combination of these and other 61 00:04:02,240 --> 00:04:05,880 Speaker 1: factors and not anyone alone. Here are a few of 62 00:04:05,920 --> 00:04:10,320 Speaker 1: the most prominent theories, in no particular order. First, we 63 00:04:10,440 --> 00:04:14,480 Speaker 1: have over farming. Some scholars have argued that my society 64 00:04:14,560 --> 00:04:17,960 Speaker 1: grew too rapidly for its own good. As the population 65 00:04:18,080 --> 00:04:21,360 Speaker 1: of some cities increased, it put vocal farmers under more 66 00:04:21,400 --> 00:04:24,440 Speaker 1: and more pressure to grow food, and gradually they ran 67 00:04:24,480 --> 00:04:27,840 Speaker 1: out of fresh forest land. Clear that would have forced 68 00:04:27,880 --> 00:04:30,360 Speaker 1: them to plant crops in their fields without an adequate 69 00:04:30,440 --> 00:04:33,520 Speaker 1: fallow cycle, that is the time it takes soil to 70 00:04:33,640 --> 00:04:38,440 Speaker 1: rebuild its nutrients supply. Deforestation like that can also disrupt 71 00:04:38,440 --> 00:04:43,880 Speaker 1: the water supply by rerooting rainwater and groundwater. A Second, 72 00:04:44,040 --> 00:04:49,119 Speaker 1: we have interior and exterior political turmoil. Each Maya city 73 00:04:49,160 --> 00:04:52,640 Speaker 1: state had its own rulers who often had their populations 74 00:04:52,680 --> 00:04:55,760 Speaker 1: convinced that they had ties with deities and were powerful 75 00:04:55,839 --> 00:04:59,040 Speaker 1: enough to control the weather. Hard to say whether or 76 00:04:59,080 --> 00:05:04,040 Speaker 1: not those leaders believed in those magical powers themselves. Their 77 00:05:04,040 --> 00:05:07,440 Speaker 1: efforts to conquer neighboring cities and peoples may have backfired, 78 00:05:07,640 --> 00:05:11,680 Speaker 1: as long periods of war sapped resources been led to retaliation. 79 00:05:12,560 --> 00:05:15,040 Speaker 1: There's evidence that a number of Maya cities eventually were 80 00:05:15,080 --> 00:05:21,520 Speaker 1: besieged and fell to invaders. Third, we have disease, though 81 00:05:21,600 --> 00:05:24,479 Speaker 1: in this case the theory is about an agricultural epidemic, 82 00:05:24,640 --> 00:05:27,560 Speaker 1: not a human one. A maze was a staple crop 83 00:05:27,680 --> 00:05:31,400 Speaker 1: across the Maya civilization, and the Maze mosaic virus may 84 00:05:31,440 --> 00:05:36,400 Speaker 1: have destroyed much of their food supply. A note that 85 00:05:36,440 --> 00:05:39,480 Speaker 1: all three of these factors are connected to the fourth theory, 86 00:05:40,040 --> 00:05:43,800 Speaker 1: the aforementioned climate change. A destruction of the food and 87 00:05:43,839 --> 00:05:48,479 Speaker 1: water supply by overfarming, deforestation, warfare, and disease would have 88 00:05:48,520 --> 00:05:53,360 Speaker 1: been exacerbated by the happenstance of natural climate change. Add 89 00:05:53,400 --> 00:05:55,920 Speaker 1: to this the fact that political leaders were supposed to 90 00:05:56,000 --> 00:06:00,520 Speaker 1: be able to control the weather. Anthropologists say this chain 91 00:06:00,600 --> 00:06:03,600 Speaker 1: of unfortunate events would have caused the people to deeply 92 00:06:03,680 --> 00:06:07,159 Speaker 1: lose trust in their leaders, which would in turn further 93 00:06:07,200 --> 00:06:12,200 Speaker 1: disrupt agriculture and infrastructure and trade, everything that ties the 94 00:06:12,200 --> 00:06:17,960 Speaker 1: city together. A while our modern civilization is driving global 95 00:06:17,960 --> 00:06:21,800 Speaker 1: warming by polluting the atmosphere, the Earth's climate is affected 96 00:06:21,839 --> 00:06:25,800 Speaker 1: by other factors, such as changes in solar activity and volcanoes. 97 00:06:26,680 --> 00:06:29,200 Speaker 1: The plight of the Maya seems to be largely the 98 00:06:29,240 --> 00:06:34,120 Speaker 1: result of such natural cycles. Scientists who have studied mineral 99 00:06:34,120 --> 00:06:37,359 Speaker 1: deposits left by dripping water in caves have been able 100 00:06:37,360 --> 00:06:40,039 Speaker 1: to construct a two thousand year long history of weather 101 00:06:40,080 --> 00:06:44,279 Speaker 1: patterns in Central America. In an article published in Science 102 00:06:44,360 --> 00:06:47,400 Speaker 1: back in twenty twelve, the researchers revealed that for the 103 00:06:47,400 --> 00:06:51,560 Speaker 1: first several hundred years of classic Maya civilization, they benefited 104 00:06:51,600 --> 00:06:54,479 Speaker 1: from unusually wet weather that made it easier to grow 105 00:06:54,480 --> 00:06:58,880 Speaker 1: crops and enabled the population to expand. That also made 106 00:06:58,920 --> 00:07:01,799 Speaker 1: the Maya kings look pretty good because they could claim 107 00:07:01,839 --> 00:07:04,480 Speaker 1: credit for conducting the rituals that kept the rains coming. 108 00:07:06,080 --> 00:07:10,240 Speaker 1: But around sixteen sixty CE, the weather changed and rain 109 00:07:10,360 --> 00:07:14,440 Speaker 1: became more infrequent in some regions of the area. The 110 00:07:14,520 --> 00:07:17,880 Speaker 1: Maya also may have accelerated that climate change by cutting 111 00:07:17,880 --> 00:07:21,480 Speaker 1: down the forest around them, probably for fuel and create 112 00:07:21,520 --> 00:07:24,240 Speaker 1: wood plaster for use in their ornate buildings and to 113 00:07:24,400 --> 00:07:28,960 Speaker 1: clear land. From studying pollen found in ancient layers of 114 00:07:29,000 --> 00:07:33,320 Speaker 1: Central American lake sediment, scientists learned that around eight hundred CE, 115 00:07:33,720 --> 00:07:37,720 Speaker 1: tree pollen disappeared almost completely and was replaced by pollen 116 00:07:37,800 --> 00:07:42,120 Speaker 1: from weeds. That suggests that the region's forests had all 117 00:07:42,120 --> 00:07:47,920 Speaker 1: but disappeared. Without trees and their root systems to keep 118 00:07:47,960 --> 00:07:51,800 Speaker 1: soil in place, erosion would have worsened, carrying away fertile 119 00:07:51,840 --> 00:07:56,240 Speaker 1: top soil, which would have crippled local agriculture. Additionally, trees 120 00:07:56,280 --> 00:07:59,640 Speaker 1: function as natural air conditioners, a drawing water through their 121 00:07:59,720 --> 00:08:03,160 Speaker 1: leaves in cooling the surrounding air. When the water evaporates, 122 00:08:03,680 --> 00:08:05,720 Speaker 1: you can experience the same effect if you live in 123 00:08:05,720 --> 00:08:08,680 Speaker 1: a city. In a park with trees, it's going to 124 00:08:08,720 --> 00:08:11,400 Speaker 1: seem cooler than it does out on a city block 125 00:08:11,440 --> 00:08:16,120 Speaker 1: with just buildings an asphalt all around you. Computer simulations 126 00:08:16,160 --> 00:08:19,480 Speaker 1: indicate that some regions temperature could have increased by as 127 00:08:19,560 --> 00:08:22,160 Speaker 1: much as six degrees fahrenheit or around three and a 128 00:08:22,200 --> 00:08:26,280 Speaker 1: half degrees celsius. That change would have been enough to 129 00:08:26,320 --> 00:08:30,200 Speaker 1: alter the weather even more. Researchers who have analyzed changes 130 00:08:30,240 --> 00:08:32,880 Speaker 1: in river sediment have found that in the century after 131 00:08:33,000 --> 00:08:37,360 Speaker 1: deforestation in some regions, a rainfall declined there, with intense 132 00:08:37,559 --> 00:08:40,600 Speaker 1: multi year droughts occurring around the years eight ten, eight 133 00:08:40,720 --> 00:08:46,400 Speaker 1: sixty and nine ten CE. Because the people in these 134 00:08:46,400 --> 00:08:50,440 Speaker 1: cities probably depended upon rain captured in reservoirs for drinking water, 135 00:08:50,720 --> 00:08:53,560 Speaker 1: they would have faced not only hunger, but thirst as well. 136 00:08:54,360 --> 00:08:57,680 Speaker 1: It's not hard to imagine how a panicked population would 137 00:08:57,679 --> 00:09:00,760 Speaker 1: have fled its once great city their way of life 138 00:09:00,840 --> 00:09:05,040 Speaker 1: collapsed into a sort of pre Columbian mad max. Though 139 00:09:05,200 --> 00:09:08,920 Speaker 1: again the note that Classic Maya civilization was not a monolith. 140 00:09:09,559 --> 00:09:13,000 Speaker 1: Different communities faced slightly different pressures and came up with 141 00:09:13,000 --> 00:09:18,959 Speaker 1: different solutions. As some cities fell, others prospered. That said, 142 00:09:19,160 --> 00:09:22,040 Speaker 1: there are some lessons from the so called collapse of 143 00:09:22,080 --> 00:09:25,120 Speaker 1: the Classic Maya that we ignore at our own peril. 144 00:09:26,040 --> 00:09:28,800 Speaker 1: Scientists warn that we are repeating the same pattern of 145 00:09:28,840 --> 00:09:32,640 Speaker 1: deforestation that may have exacerbated climate change in Central America 146 00:09:32,679 --> 00:09:36,040 Speaker 1: a millennium ago, except on a far more massive scale. 147 00:09:37,080 --> 00:09:39,920 Speaker 1: Trees are about fifty percent carbon, and in the US 148 00:09:39,960 --> 00:09:43,160 Speaker 1: alone they presently absorb or sinc a little less than 149 00:09:43,200 --> 00:09:47,160 Speaker 1: a million metric tons of atmosphere warming carbon dioxide, which 150 00:09:47,360 --> 00:09:50,720 Speaker 1: offsets between ten and twenty percent of what Americans spew 151 00:09:50,760 --> 00:09:54,520 Speaker 1: into the atmosphere by burning coal and gasoline. But when 152 00:09:54,559 --> 00:09:57,280 Speaker 1: we cut down trees or burn them, they released their 153 00:09:57,280 --> 00:10:00,640 Speaker 1: stored carbon into the atmosphere, and they aren't around to 154 00:10:00,720 --> 00:10:04,439 Speaker 1: absorb any more of it. Over the past several centuries, 155 00:10:04,559 --> 00:10:07,240 Speaker 1: the US has cut down about ninety percent of the 156 00:10:07,280 --> 00:10:10,800 Speaker 1: forests that once covered the continent, and what still remains 157 00:10:11,000 --> 00:10:15,200 Speaker 1: is in peril and in currently developing nations, once lush 158 00:10:15,280 --> 00:10:19,480 Speaker 1: forests have been disappearing at an alarming rate thanks to logging, agriculture, 159 00:10:19,600 --> 00:10:23,559 Speaker 1: and the need for human living space. In recent years, 160 00:10:23,559 --> 00:10:26,400 Speaker 1: there has been some international progress in slowing the rate 161 00:10:26,400 --> 00:10:29,560 Speaker 1: of deforestation, but we still face the risk that it 162 00:10:29,559 --> 00:10:33,640 Speaker 1: will push us even faster into climate chaos. It's a 163 00:10:33,679 --> 00:10:36,640 Speaker 1: problem that we must work harder to solve, both as 164 00:10:36,679 --> 00:10:41,880 Speaker 1: a broad civilization than within our own differing communities. Personal 165 00:10:41,960 --> 00:10:44,560 Speaker 1: choices feel small, but they do add up, and you 166 00:10:44,600 --> 00:10:46,680 Speaker 1: can make your voice heard in your local government on 167 00:10:46,720 --> 00:10:51,319 Speaker 1: bigger issues. If you're here, you probably agree that learning 168 00:10:51,400 --> 00:10:53,760 Speaker 1: is the fun part, So learn what you can do 169 00:10:53,920 --> 00:10:57,080 Speaker 1: by checking out your government agencies in the US that's 170 00:10:57,120 --> 00:11:00,559 Speaker 1: going to be at EPA dot gov, and what local 171 00:11:00,600 --> 00:11:07,959 Speaker 1: activists are up to. Today's episode is based on the 172 00:11:08,040 --> 00:11:11,079 Speaker 1: article did the Maya civilization end because of climate change? 173 00:11:11,120 --> 00:11:13,680 Speaker 1: On how stuffworks dot com written by Patrick J. Kiger. 174 00:11:14,160 --> 00:11:16,520 Speaker 1: Brain Stuff is production of by Heart Radio in partnership 175 00:11:16,520 --> 00:11:19,000 Speaker 1: with how stuffworks dot Com and is produced by Tyler Klang. 176 00:11:19,559 --> 00:11:22,640 Speaker 1: Four more podcasts my heart Radio, visit the iHeartRadio app, 177 00:11:22,720 --> 00:11:25,600 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.