1 00:00:00,000 --> 00:00:06,520 When you think of an archaeologist, what do you picture? 2 00:00:06,520 --> 00:00:10,000 Someone just digging spearheads, or maybe pottery, or writing down the words of some 3 00:00:10,000 --> 00:00:11,000 primitive tribe? 4 00:00:11,000 --> 00:00:17,000 My name is Tom Seaver, and I'm a NASA archaeologist, and what I do is try to understand why human 5 00:00:17,000 --> 00:00:19,920 cultures succeed and why they fail. 6 00:00:19,920 --> 00:00:24,240 I also excavate artifacts in an attempt to understand the ancient past. 7 00:00:24,240 --> 00:00:29,960 These artifacts consist of ceramic bowls, of bone material, and of spearheads, lithic, 8 00:00:29,960 --> 00:00:30,960 stone material. 9 00:00:30,960 --> 00:00:36,960 More importantly, what I do is examine the soil structures to try to understand and reconstruct 10 00:00:36,960 --> 00:00:40,320 prehistoric environments and ancient climate patterns. 11 00:00:40,320 --> 00:00:45,620 Where the Patan Rainforest of Guatemala now stands, a great civilization once flourished, 12 00:00:45,620 --> 00:00:46,760 the Maya. 13 00:00:46,760 --> 00:00:51,360 The Maya built vast cities, ornate temples, and towering pyramids. 14 00:00:51,360 --> 00:00:57,160 At its height, around 850 A.D., the population numbered 500 people per square mile in rural 15 00:00:57,160 --> 00:01:02,660 areas and more than 2,000 people per square mile in the cities, comparable to modern-day 16 00:01:02,660 --> 00:01:04,520 Los Angeles County. 17 00:01:04,520 --> 00:01:09,800 The Maya initially depended on a type of farming known as slash and burn, which means exactly 18 00:01:09,800 --> 00:01:11,280 what it sounds like. 19 00:01:11,280 --> 00:01:16,240 In order to grow crops, such as corn, they would completely cut away, or slash, the dense 20 00:01:16,240 --> 00:01:20,260 jungle vegetation, exposing soil for planting crops. 21 00:01:20,260 --> 00:01:22,820 They would burn the debris that had been cleared. 22 00:01:22,820 --> 00:01:28,260 Initially, ash from the burned debris gives the soil its fertility, but within three to 23 00:01:28,260 --> 00:01:34,980 five years, the soil becomes exhausted, forcing the farmer to move on and cut down a new section. 24 00:01:34,980 --> 00:01:39,780 Eventually, slash and burn would not support the large population of the Maya, so they 25 00:01:39,780 --> 00:01:42,760 developed new agricultural techniques. 26 00:01:42,760 --> 00:01:46,920 We are trying to determine exactly what these techniques were. 27 00:01:46,920 --> 00:01:51,800 Without trees, erosion worsened, carrying away fertile topsoil. 28 00:01:51,800 --> 00:01:55,800 Topsoil is the fertile layer of soil with enough nutrients to support healthy plant 29 00:01:55,800 --> 00:01:57,240 growth. 30 00:01:57,240 --> 00:02:01,800 In the rainforest, this layer of soil is very thin. 31 00:02:01,800 --> 00:02:06,320 Slash and burn agriculture is being practiced in Guatemala today, and many researchers like 32 00:02:06,320 --> 00:02:12,600 myself feel that this technique of agriculture is affecting local climate today in the area. 33 00:02:12,600 --> 00:02:16,960 Our computer models suggest that when the forest is completely cut down, the temperature 34 00:02:16,960 --> 00:02:20,360 of a region can rise five to six degrees. 35 00:02:20,360 --> 00:02:24,640 If the Maya had completely deforested the region, the warmer temperatures would have 36 00:02:24,640 --> 00:02:29,540 dried out the land, making it very difficult for raising crops. 37 00:02:29,540 --> 00:02:33,520 Rising temperatures would also have disrupted rainfall patterns. 38 00:02:33,520 --> 00:02:39,000 During the dry season in the Paten, water is scarce, and the groundwater is too deep, 39 00:02:39,000 --> 00:02:42,240 500 feet deep, to tap with wells. 40 00:02:42,240 --> 00:02:47,680 The Maya must have relied on rainwater saved in reservoirs to survive, so a disruption 41 00:02:47,680 --> 00:02:52,440 in rainfall could have a terrible consequence on their ability to grow food. 42 00:02:52,440 --> 00:02:57,280 Even when the Maya filled up all their reservoirs, they only had an 18-month supply. 43 00:02:57,280 --> 00:03:02,080 A two- or a three-year drought would have had a devastating effect on them. 44 00:03:02,080 --> 00:03:06,320 Remember what I said about the lack of trees causing erosion? 45 00:03:06,320 --> 00:03:11,520 Archaeologists have also studied samples of soil from ancient lake sediment in the Paten 46 00:03:11,560 --> 00:03:12,560 forest region. 47 00:03:12,560 --> 00:03:16,000 In these samples of sediment, they have discovered tree pollen. 48 00:03:16,000 --> 00:03:22,280 The curious part of all of this is that around 1,200 years ago, just before the Maya civilization's 49 00:03:22,280 --> 00:03:27,600 disappearance, tree pollen disappeared almost completely and was replaced by the pollen 50 00:03:27,600 --> 00:03:28,880 of weeds. 51 00:03:28,880 --> 00:03:32,800 In other words, the region became almost completely deforested. 52 00:03:32,800 --> 00:03:38,360 Did the Maya experience a natural drought that was made worse by the deforestation of 53 00:03:38,360 --> 00:03:39,680 their environment? 54 00:03:39,680 --> 00:03:45,000 A lot of researchers think that this is exactly what happened at 800 AD. 55 00:03:45,000 --> 00:03:47,680 However, there is a bigger question. 56 00:03:47,680 --> 00:03:53,120 The Maya survived for centuries in the delicate tropical forest of Central America. 57 00:03:53,120 --> 00:03:54,760 Exactly how did they do it? 58 00:03:54,760 --> 00:03:57,480 An important clue comes from space. 59 00:03:57,480 --> 00:04:01,720 Data collected from satellites orbiting the Earth show evidence of an ancient system of 60 00:04:01,720 --> 00:04:07,400 canals and irrigation ditches in low-lying swamps called bajos, the Spanish word for 61 00:04:07,400 --> 00:04:08,400 low-lying. 62 00:04:08,400 --> 00:04:11,440 Today's residents make little use of the bajos. 63 00:04:11,440 --> 00:04:16,880 For years, archaeologists believe that the Maya hadn't used these swampy areas either. 64 00:04:16,880 --> 00:04:21,720 During the rainy season from June to December, the bajos are too muddy and in the dry season 65 00:04:21,720 --> 00:04:22,720 they're parched. 66 00:04:22,720 --> 00:04:25,720 Neither condition is good for farming. 67 00:04:25,720 --> 00:04:31,480 Not only do I use data collected from satellites, I also practice what is called ground-truthing. 68 00:04:31,480 --> 00:04:36,000 Using a coordinate grid system, I am able to create maps of where I think I might find 69 00:04:36,000 --> 00:04:39,480 evidence of the Maya canals and irrigation ditches. 70 00:04:39,480 --> 00:04:44,520 Using satellite images, I explore the Earth up close to see that my data matches what 71 00:04:44,520 --> 00:04:46,600 I can observe on the ground. 72 00:04:46,600 --> 00:04:50,560 Data collected through remote sensing and ground-truthing have led archaeologists to 73 00:04:50,560 --> 00:04:56,000 hypothesize that these ancient canals and habitation sites were part of a system devised 74 00:04:56,000 --> 00:05:01,640 by the Maya to manage water in the ancient bajos and to use these areas for farming. 75 00:05:01,640 --> 00:05:04,580 The bajos make up almost half of the region. 76 00:05:04,580 --> 00:05:08,980 By making good use of the bajos for farming, the Maya would have been able to grow a much 77 00:05:08,980 --> 00:05:12,540 larger and more dependable supply of food. 78 00:05:12,540 --> 00:05:16,340 They could have farmed the bajos during the dry season by draining the water to lower 79 00:05:16,340 --> 00:05:18,340 areas into reservoirs. 80 00:05:18,340 --> 00:05:23,020 This way, they could have had two crops on the elevated ridges during the rainy season 81 00:05:23,020 --> 00:05:25,740 and two crops during the dry season in the bajos. 82 00:05:25,740 --> 00:05:30,740 It is the evidence of these features in the bajos that is leading researchers and environmentalists 83 00:05:30,740 --> 00:05:34,100 to help the people of the Patan rainforest today. 84 00:05:34,100 --> 00:05:39,180 One goal of our NASA research is to see if we can rediscover how the ancient Maya used 85 00:05:39,180 --> 00:05:41,320 this environment successfully. 86 00:05:41,320 --> 00:05:46,780 If we can determine the agricultural techniques that they used, we can use those techniques 87 00:05:46,780 --> 00:05:54,940 and apply them to modern-day populations who are living in the area today. 88 00:05:54,940 --> 00:05:59,980 By learning what the Maya did right and what they did wrong, maybe we can help local people 89 00:05:59,980 --> 00:06:05,580 find sustainable ways to farm the land while stopping short of the excesses that doomed 90 00:06:05,580 --> 00:06:06,900 the Maya. 91 00:06:06,900 --> 00:06:12,420 Using satellite data to examine Mayan ruins gives Seaver a big-picture view otherwise 92 00:06:12,420 --> 00:06:15,660 impossible from his perspective here on Earth. 93 00:06:15,660 --> 00:06:21,260 Combining remotely sensed or satellite data with conventional down-in-the-dirt archaeological 94 00:06:21,260 --> 00:06:27,420 findings and working with NASA climate scientists, he may have uncovered a clue that will solve 95 00:06:27,580 --> 00:06:32,380 one of history's greatest mysteries, as well as provide clues about what will happen to 96 00:06:32,380 --> 00:06:34,900 our Earth in the future. 97 00:06:34,900 --> 00:06:35,900 Wow. 98 00:06:35,900 --> 00:06:40,980 You know, right now, as you watch this show, the rainforest is still falling under the 99 00:06:40,980 --> 00:06:42,100 axe. 100 00:06:42,100 --> 00:06:47,700 About half of the original rainforest has been destroyed in the past 40 years, cut down 101 00:06:47,700 --> 00:06:51,400 by farmers practicing slash-and-burn agriculture. 102 00:06:51,400 --> 00:06:55,820 This cycle repeats endlessly, or until the forest is gone. 103 00:06:55,820 --> 00:07:02,420 By 2020, only 2 percent to 16 percent of the original rainforest will remain if current 104 00:07:02,420 --> 00:07:04,900 rates of destruction continue. 105 00:07:04,900 --> 00:07:09,580 Changes in cloud formation and rainfall are occurring over deforested parts of Central 106 00:07:09,580 --> 00:07:11,460 America today. 107 00:07:11,460 --> 00:07:14,420 Is history repeating itself? 108 00:07:14,420 --> 00:07:18,900 If the residents of the rainforest cannot learn to live with their environment, many 109 00:07:18,900 --> 00:07:22,780 scientists believe history will, in fact, repeat itself. 110 00:07:22,780 --> 00:07:27,260 The bottom line is, how well do we, can we relate to our environment? 111 00:07:27,260 --> 00:07:33,020 As we seek to explore new worlds, such as Mars, we are taking our cues from the mistakes 112 00:07:33,020 --> 00:07:34,460 of the past. 113 00:07:34,460 --> 00:07:40,340 Before sending humans to create colonies, NASA has a carefully planned series of uncrewed 114 00:07:40,340 --> 00:07:43,740 missions designed to observe the environment of Mars. 115 00:07:43,740 --> 00:07:48,860 Now, these missions are looking for water, testing the atmosphere, and monitoring the 116 00:07:48,860 --> 00:07:50,660 cycles of weather. 117 00:07:50,660 --> 00:07:56,140 Armed with as much detailed information as possible, future explorers and colonists to 118 00:07:56,140 --> 00:08:01,420 the Red Planet will have a better understanding of how to work with their environment before 119 00:08:01,420 --> 00:08:02,420 they arrive. 120 00:08:02,420 --> 00:08:08,620 They will be much better prepared for survival than were the Jamestown colonists in 1607. 121 00:08:08,620 --> 00:08:15,140 In fact, it is very likely that you are sitting among some of the first explorers and colonists 122 00:08:15,140 --> 00:08:16,140 of Mars. 123 00:08:16,660 --> 00:08:17,660 That's right. 124 00:08:17,660 --> 00:08:23,460 NASA predicts that they will put humans on Mars as early as 30 years from now. 125 00:08:23,460 --> 00:08:28,380 So here's my challenge to you, the next generation of explorers. 126 00:08:28,380 --> 00:08:33,600 How can you learn from the past mistakes we've made here on Earth and apply that information 127 00:08:33,600 --> 00:08:39,220 to making better decisions for your future exploration of new worlds? 128 00:08:39,220 --> 00:08:41,540 Well that wraps up another episode of NASA Connect. 129 00:08:41,540 --> 00:08:45,020 We'd like to thank everyone who helped make this program possible. 130 00:08:45,100 --> 00:08:52,140 If you have a comment, question, or suggestion, well then email them to connect at lark.nasa.gov. 131 00:08:52,140 --> 00:08:55,580 And don't forget to check out this program's student challenge. 132 00:08:55,580 --> 00:08:58,340 You can find it on the NASA Connect website. 133 00:08:58,340 --> 00:09:03,700 So until next time, stay connected to math, science, technology, and NASA. 134 00:09:03,700 --> 00:09:04,460 Goodbye for now. 135 00:09:15,020 --> 00:09:21,020 NASA Jet Propulsion Laboratory, California Institute of Technology 136 00:09:45,020 --> 00:09:47,020 NASA Jet Propulsion Laboratory, California Institute of Technology