Islands in the Sky - How the Inca Farmed the Impossible

There's a certain grandeur and wild beauty to the Andes, this massive range of thorny, craggy peaks rocketing up out of the desert, jungles clawing their way up the eastern flank, described as some of the tallest, starkest mountains in the world. A wild, unpredictable landscape where, even in some densely populated regions, crops could fail two out of three years. Earthquakes, floods, unpredictable rains, disease, the odd volcano. And yet, these mountains were home to one of the so-called cradles of civilization, places where people seemed to have forged their way to make a large, organized society with centralized planning and government without the influence of other large civilizations before them. From this land came a colorful and diverse multitude of people groups, states, and empires that sought to tame the landscape and survive, but in ways that often defy the usual order of events historians see throughout history. Monumental architecture with a people who hadn't made pottery, a vast empire stretching 40,000 kilometers north to south with extensive over-engineered road systems, but without wheeled transportation, currency, or a system of written language, in the conventional sense at least. And surviving and thriving despite the effects of the high altitude and the thinner air. In the words of John Moura, here people begin. Where elsewhere, population stops. How did they do this? Well, journey with me up the Andes Mountains and let's look at how the people transformed the landscape, peeled back deserts, and used careful, intricate engineering and planning to the odds. Let's begin at the coast. When people think of South America, especially the regions up near the equator, often their first thought is something like this. Steamy rainforests, hot humid atmosphere, warm beaches, wild sprays of fruit, plant life, colorful birds, and insects. But for the middle west coast of South America, Peru, and Chile, the reality is instead more like this. A bizarre mix of dry desert with almost no rainfall, but high humidity, and a sky that's often cloudy, and almost constant fog at certain times of year. It's right on the equator, but with a cold yet rich ocean carrying waters from deep down near the Antarctic Circle. For the most part, this land is barren of life. And yet, this wasteland was home to the earliest known large-scale civilization in the Americas, Karalsupe, older by some reckonings than dynastic Egypt. This, and others after it, large structured societies with central urban planning, distinct art, monumental architecture, etc. Here in this barren land, we see the start of a theme that runs throughout the Andes. As Kevin Lane puts it in his book on the Inca, the key to civilization in South America was mastery over water. There is of course water in the ocean, and it's no surprise that fish and other seafood was a major resource for coastal peoples here. But against all odds, these desert-bound peoples were also farmers, and good ones. And to be fair, if they weren't good ones, they probably wouldn't have survived here. Now, you may say, the coast will have some rivers, and that means fresh water, and anyone can farm in that case. And you may be right. Though rain is rare here, it does fall high in the mountains, and from there, rivers flow down through barren rocky gorges to the coast. The occasional oasis in the desert too. But it wasn't quite as easy as simply planting crops next to such a river, and then fishing. Rainfall was not consistent, and El Nino events could cause frequent catastrophic disruptions to the rains that fed the rivers, and to the ocean currents. Crops planted one year close to the river could be flooded and torn out by the water the next, and some years the rains wouldn't come enough, and the change in ocean currents would mean drastically less fish. And in any case, it's hard to cultivate much land this way. Definitely not to the extent these groups did. So how did they do it? Well, first, foremost, and most dramatically, these people built canals. The Chimu and Moche peoples especially were known for their extensive megasystems, turning a fertile riverside into a fertile valley, and sometimes even crossing mountains with the canals to bring water to surrounding valleys. For the Chimu, it became a part of showing one's capabilities as a leader to lead projects like these, to demonstrate control over the unpredictable environmental forces. The most impressive example is the Chicama-Moche canal, which runs around 70 kilometers long. Now, it's unknown if this one was ever fully functional, or if partway through construction it was disrupted by earthquakes, but if nothing else, the ambition was impressive. But one of the more intriguing inventions made to deal with this water problem seems to have come from the Nazca people. And yes, that's the same Nazca people who made the Nazca lines. These were puquillos, a sort of wind-powered combination well and aqueduct. The desert may be dry, but like most places, there is fresh water hidden deep underground, too deep for most plants to access by route. So if one can dig a well deep enough, they can draw water from this source. But here, the Nazca went a step beyond that. To make a puquillo, a well would be dug in a sloped area, down to where the water starts to spring up. But then a tunnel, almost horizontal, is made going between the well bottom and the lower part of the slope. This is already more useful than a conventional well, since it allows the water to flow without a person needing to draw it up by bucket. But there's more. More shafts were then dug, this time along the length of the horizontal shaft, going up to the surface. And at the surface of each, the strangest looking part, a downward spiral cut into the earth. A puzzling sight. Why did they do this, precisely? At first glance, one might guess this is a decorative or maybe ritual practice, or perhaps a way to get down closer to the bottom to draw water. But what appears to be happening here is that these spirals are channeling the wind down into the holes. And once down there, the natural direction for the wind to go is out the horizontal shaft. So this creates a difference in air pressure, and the wind pushes the water along and out. In a subtle way, this acts as a natural pump, allowing the water to flow more quickly through the tunnel, and thus subtly also allowing the water to leak from the aquifer into the first shaft a bit more quickly, resulting in not only quicker water, but a bit more water. This could obviously vary a bit with the wind, but even in low wind times, it provided a consistent source of water, more consistent than a river, less prone to floods and droughts, and being in a cool sheltered tunnel, less was lost to evaporation. And having a And so, while these would have been difficult to make, they were quite effective. So much so that many ancient piquillos are actually still in use today. And it's through efforts like these that coastal peoples were able to grow a variety of crops. Corn, squashes, cotton, beans, peppers, sweet potato, other roots, various fruits. And through this, well, still a difficult environment to live in, it was remarkable how they managed to take such a barren land and make it inhabitable for so many people. But while these desert areas did house the earliest Andean civilizations, the largest and the most expansive were not found at the coast. So why don't we ascend and see what was going on a little higher up, on the eastern side of the Andes this time, towards the Amazon rainforest? The difference here from both the coast down to the west and the lands above is stark. Dense, twisting greenery as far as the eye can see, billowing clouds twining around the slopes, and the foggy rainforest people associate with South America, though perhaps a bit cooler at these heights. Colorful birds, snakes, jaguars, and many of the charismatic animals one expects from the Amazon. It has been said that the Andes contain the richest biota of any zone of its size in the world, and here that is on full display. Now, the lower Amazon rainforest also had its fair share of human activity, including large-scale societies, but that is a story for another day. Here we look at its upper reaches, poetically called the ceja de selva, or eyebrows of the jungle. This is the montaña zone, admittedly a confusingly generic name since it simply means mountain. In areas in this zone, other than a couple well-preserved sites like Machu Picchu, at the zone's highest end, it's often harder to see remnants of people's past engineering, partly because of how these areas were used, but more because of the nature of this zone. Once abandoned, structures here tended not to last long, quickly covered up again by the relentless forest, the rains, and the valley bottoms getting ravaged periodically by flash floods. For the Andean highlands' largest and best-known civilization, the Inca Empire, their reach extended here, but it was their least inhabited zone, though certainly not uninhabited. This was a place with resources plentiful enough to live on, peppers, fruits, squashes, peanuts, at the lower end, cassava, and this wasn't just a neglected fringe zone. It produced several specialty resources highly esteemed by those living in the more populated regions higher up the mountains, such as colorful feathers. One chronicler mentions, perhaps exaggerating, a storehouse in lands above housing over a hundred thousand dried birds, probably many of which would have come from these lower regions. Coca would be another valued resource from here, a plant prized both for ritual and medicinal use for coping with the high altitude conditions, and this was a place whose beauty inspired the construction of the royal estate of Machu Picchu, today one of the New Seven Wonders of the World. In contrast to Machu Picchu, however, much of the evidence of past feats of engineering lower in the main part of the montaña zone has been swallowed up by time and forests, but in places you will see remains of a structure that will show up again and again as you work your way up these mountains. These here are the remains of a set of terraces. Now, the Andes are not the only place in the world where terraces were invented, but like those elsewhere, Andean terraces had their own features and techniques. The base idea of a terrace is simple, turn sloped land into flat land. Geometrically speaking, this does decrease the surface area, but it makes it more usable and productive for most farming and human habitation. These are dry terraces, built a bit differently from the famous wet terraces typically used for rice in Asia. A particularly well-designed Inca period Andean terrace might look something like this inside. Inside the stone retaining walls, a series of layers would be created. On top would be a good compost-rich growing soil. Underneath would be a finer sand and gravel, then a coarser gravel, and then larger stones before the natural soil of the mountainside. And this was actually a brilliant combination in a few ways. At a more basic level, it provided a much thicker layer of soil than could be usually found on a mountainside, and provided many flat, level surfaces for growing, so there was less worry of water or landslides eroding the surface, and less flooding than on the valley bottom. In more specific ways, many of the main Andean crops here, and even more so higher up in the mountains, were very sensitive to soil drainage, sitting in could drown the plants or have them rot, but the sand, gravel, and stones helped water drain past, leaving the soil more breathable and meaning the soil wouldn't swell and push the walls out. Useful in such a wet environment. And from there, the water could diffuse through the soil underneath the walls, so the walls themselves also didn't get eroded much. Good for crops, less time needed for maintenance. So these terraces were very helpful, allowing more fruitful, less risky growth of crops for sustenance, and sometimes crops that people in higher zones couldn't grow. So, helpful for a wet environment, but what about the drier lands above, where the terraces were still much more extensive? Well, to see that, and to understand at a glance why the Montaña Zone's wood was such a valued resource to those living above, we'll need to toward the heart of the Andes' largest and most extensive civilizations. This is the Quechua Zone. Once again, a stark difference. A little cooler, the air a bit thinner, a lot less trees, but a whole lot more. The classic views of the grand sweeping mountain passes, fertile valleys, and sites in a sacred valley near Cusco, a land important to the people of Andes throughout history and still today. This was the prized farmland region for many Andean groups. Here we've passed above the rain clouds that drench the Amazon to a drier zone. Not totally dry, it may look at first glance quite brown and unproductive, but in the wet season the area comes alive with green, and one can start to see hints of its hidden biodiversity. But while the water isn't as sparse here as in the desert far below, or the cold as dramatic as in the lands above, this is still in many ways an unpredictable and difficult land. Any Inca certainly would have agreed. To quote scholar Terence Daltroy, the Incas approached farming with weapons in their hands and prayers on their lips. They envisioned agriculture as warfare, a victory claimed by disemboweling the earth. Now that isn't the whole picture on their beliefs, and taken on its own can miss that much was also revered about the earth in Andean mythologies, but this element was there, and shows how seriously they took the unpredictability of farming here. And it's here in this zone we can start to see that in the sheer scale of their terraces. Up here the terraces cover not only the hillsides, but even many valley floors too, which was a specialty of the Incas. Again, it was partly for drainage reasons, but also to hang on to nutrients that otherwise might too easily get swept along the valley floodplain. And this was prime corn land, and the Inca wanted to grow corn. Lots and lots of corn. It figured heavily in their mythology, their artwork, their cultural symbolism, and was a highly valued crop for food, rituals, and alcohol. They even actually claimed to have introduced corn to everyone else in the Andes themselves. A big exaggeration, but they certainly did help it spread and gave it a new prestige. So they developed many valley bottoms with extensive terraces and canals for water, allowing the common folk to continue farming their hillside terraces above of perceivably lower class foods like potatoes or quinoa. Interestingly, some have suggested they built these terraces taller than they needed to. The Inca were known to over-engineer. Their roads are an example of this. Things built so much better and or fancier than they needed to be. And this was done to impress, to show off to the common person the majesty of their empire and ruler, and instill a sense of awe. Not to say this was the case with everything they built, by any means. Much was also elaborate in useful ways. And their sheer resources and workforces meant they could plan and build large, complex, sufficient, integrated systems of farming and irrigating. It's been estimated that at the height of the Inca empire in the 1400s, terraces covered around a million hectares of land. Many have since been abandoned, whether due to fighting and political upheaval, or people leaving them to return back to ancestral lands after being forcibly relocated by the Inca. But starting at this elevation, we can see another advantage of using these terraces, not quite as relevant down in the Montaña zone. Most of the crops raised by the Inca and other highlanders were not tropical, at least not in the way we often think of tropical plants, as preferring year-round hot, humid environments. In fact, many of their plants were later spread to other more temperate areas around the world, places like Europe, Canada, and New Zealand. Like the Amazon to the east, but with a vastly different array of plants, the Andean highlands are also a major hotspot of biodiversity. And so, Andean peoples were able to and bring in many others from surrounding areas. But the problem is, these are very jagged mountains, and the zones good for producing many of these crops, especially flat land that can be worked and watered easily, are not large. The higher you go, the colder and the shorter your warm growing season gets, the less productive your farms tend to be. One estimate says that for every 10 meters you go up in elevation, you have one day shorter growing season. So climb 300 meters, and you're already down a whole month. That will have a big impact on what you can grow. So this balance of a climate that you have in the Quechua zone, the most productive highland zone, the low warm end of a cool highland climate, if you can extend that upward, that is a huge advantage. And that is one of the For one, compared to a bare slope, the stones in the walls are good at absorbing the heat from sunlight, and over the course of the night, they'll release it back into the soil. This, combined with the shape of the terraces disrupting the wind a bit and reducing cooling, makes for a slightly longer growing season for the plants, and helps reduce ripening time, creating a sort of microclimate, simulating a lower elevation. And these have good drainage, but good drainage does not mean total drainage. So properly constructed and balanced, these are actually also good at conserving water. One excavation was done on a terrace six months after it was irrigated, and they found the soil inside actually still damp after all that time, which is fantastically helpful when rains are limited, and irrigation water is a precious resource. For many plants here, moisture is a big signal that the wetter growing season has started, and it's time to start growing. So especially if these terraces are combined with irrigation, this means a farmer could start the growing season earlier than it would naturally come. These dramatically boosted the available land and increased the number of crops possible to grow in an area, and the Inka made good use of these observations and techniques. Some sites left intact today, such as this one here at Moreh, seem to have actually been used as testing sites, where different varieties of corn and other crops could be grown at different heights, testing the limits of their hardiness, the effectiveness of their terraces in altering conditions, possibly breeding varieties to survive at different heights, and also to have access to more varieties in one place. Very impressive feats of engineering. But while maximizing this good land in the Quechua zone was of huge importance to the Inka and other peoples who lived here, and this was the heartland of many groups, population did not stop at this height, not even close. For those above, was it just necessity that pushed them up out of this good land, or were there other reasons? To find out, let's continue on our journey upward. From the Quechua, we move up to the Suni zone. Now, this zone's boundaries, where it starts and ends, is a matter of definitions and debate, but all agree this is the next higher, colder zone, a land of cold hills, ridges, and deep valleys. The high snowy mountaintops are in view, but still a ways off, colder and drier than below, but seldom actually freezing. The landscape starts to look more barren, but not completely. Still a land for wild deer, perhaps a roosting condor, many wild plants, still a productive land, but shifting more in favor of cold hardy root crops, including a couple thousand varieties of potatoes, and some shorter season varieties of other crops like quinoa or tarui. The cold here may seem a big disadvantage, and it's easy to assume that people living here were here simply because, well, not everyone could farm the best land down below, and certainly you did see technologies made to help keep the land slightly warmer, like in lower lands. But at least in pre-Incan cultures, before the corn craze, some of the crops produced here were the higher valued prestige crops, potatoes especially, so in that sense, this was good land in its own right. But beyond that, in a way that was seized upon by the Inca late in the era before the Spanish arrival, the cold could also be an asset, and with a bit of planning, one providing a big advantage to anyone who had access to these altitudes. These here are colcas. The Inca weren't the first to make these, but they did drastically expand their use because they faced a predicament. Resources need to be not just plentiful, but also usable, so they can be gathered up, redistributed, provisioned to armies, etc. And reciprocity was a huge element in Andean cultures, the idea that if one was given gifts of labor or resources, similar gifts should be given in return. And the Inca used this in their method of ruling, cultivating loyalty by giving to their subjects in ways that left the subjects feeling obliged to give back to their rulers. So in their ruling, they needed to be able to tax goods and produce, redistribute to nobles, subjects, and clergy during feasts or famines. But there was a problem. Many of the resources wouldn't store well in the heat, and even ignoring heavy resources like metals, even just with food, transport in the mountains was difficult. The Inca had no wheeled vehicles, and there was very little in the way of boat-based travel. Llamas were their only pack animal for carrying goods, and they were a finicky one that refused to move when tired. So if armies needed to carry food and drink, they would be carrying much of it on their backs. So the Inca couldn't rely too heavily on long-distance resource hauling. So what's an empire to do? Well, fortunately, even in the heartland of the warm prime cornland, colder land, the Sunni zone, was seldom far away. And so the answer they found was to build miles and miles and miles of storehouses. At first glance, these might look like pretty basic structures, typical thick stone walls and thatched roof for insulation, but the builders did have a few more tricks up their proverbial sleeves. For instance, location. Builders noted that in warmer parts, up on the slopes, it was usually windier than down below on valley floors. But not every hill equally. Some hills, wind would be periodically blocked by other nearby hills. So builders observed and built on the windiest, most consistently cool slopes. This kept the buildings cooler, and then the wind was also allowed to flow directly through the colca using windows and vent holes that could be closed whenever the air outside was too hot. This cold already helped a lot with food storage. Harder for mold to grow, harder for insects to survive or be active. But there were some other features too. Stored grains would need low humidity, so sometimes their buildings would be made with elevated floors where air could circulate between the floor and the ground underneath. And, well, one source I read did lament that all methods of potato storage are but compromises. The general need for tubers, like potatoes, is to trick them into thinking it's not time to sprout for the growing season yet. But also not to dry out. So, low temperature, high humidity. One interesting set of colcas was found. Ones with loose, irregular rocks for a floor so air or water could get through, with small water canals running underneath. Helping ventilate, but also with the wet. No identifiable remains were found in those particular colcas, but potatoes or other tubers would at least seem a reasonable guess. It may have also been another ongoing area of experimentation when the Inca Empire crumbled, trying to find improved methods of storage. All that said though, the high altitudes were especially helpful because the higher you went, the less fancy features were needed, since ambient temperatures were cooler and varied less throughout the day. But the most impressive aspect of these storehouses was the scale. As scholar Craig Morris notes, the real genius of Inca storage was based on a finely tuned understanding of natural environments for storage, coupled with an elaborate organizational framework that was able to build massive storage facilities and to move people and goods to regions advantageous to storage. The exact scale at the height of the Inca Empire is hard to know. Much has been destroyed since then, but it was massive. Massive complexes of hundreds of colcas all together, thousands of storehouses scattered strategically all over the landscape in reach of road networks, government buildings, settlements. It's part of how the Inca managed to rule such a large area so effectively. So if a needed several weeks worth of food at a time, provisions were never far away. A great use for the cold. But this wasn't actually the coldest or highest inhabited region. For that, let's ascend one final time. It's easy to forget one is in the tropics at this height, and less than a day's drive from the Amazon rainforest. Up here in the cold and windy plateaus where nights can be below freezing, in large parts even considered a tundra climate. The highest habitable zone below the permanent snow peaks of the Andes. Here where the grass blows and the cushioned plants peek out from amongst the rocks. This is the Puna zone. Unsurprisingly, most of the crops grown by the Inca and other Andean peoples do not grow at these heights. And yet, people lived here, and even thrived. For the Tiwanaku, one of the Andes' larger civilizations, this was even their heartland. Or between here and the Sunni region, depending how you draw those boundaries. But how? Well, to be fair for the Tiwanaku specifically, having a massive freshwater lake certainly would have helped. Fish transport, irrigation, and today many people still live around the banks of Lake Piricaca in Peru and Bolivia, and some even on traditional man-made floating islands on the lake itself. That is a fascinating story for another day. But to look more broadly throughout the Puna, where this wasn't an option, you start to see a recurring theme, with parallels to many other arid parts of the globe. What does this place have in abundance? Grass. Did people eat it? No, not to my knowledge, but it could be converted to food for humans through the age-old process of shepherding, grazing livestock. The Andes' most charismatic animals. Llamas and alpacas. These were used for many things. Meat, leather, bones for making tools, fleece, obviously a useful source of warm clothing in the high mountains, dung for fuel and fertilizer. Llamas are the larger of the two species, and as mentioned, they were also used to help carry things over long distances. South America's only domesticated beast of burden. Again, though, not a perfect one. But wild animals could be found here too. Several species of deer and the alpaca's wild cousins, huanacos, and the holy grail of wool-producing animals even today, the vicuña, the species with the warmest fur, prized to the point that the Inca ruler, the Sapa Inca, claimed to own all the wild vicuñas himself. And well crops were limited up here. There were a few. Maca, a root and leaf vegetable, and a few varieties of potatoes. Cañiwa, a close relative of quinoa. And like in the Sunni zone below, on the one hand, they fought the cold, and on the other, they embraced it. The fighting would sometimes look similar to the engineering in lands below, terraces for instance. But for something more unique to the or camellones. These may not be quite as photogenic and visually stunning as some of the other engineering feats, at least not always, but these peculiar looking fields, whether in the wetter parts of the puna or the drier, hide a surprising versatility. In plain English, these are raised ridge fields. They are made by creating a series of trenches and ridges built up from clay. In the middle of each ridge, a growing bed is formed and filled with better growing soil, and possibly compost. This construction allows drainage within the bed, and water from the canals can seep through to the plants. But clay only allows water through very slowly, which keeps the growing soil from getting waterlogged, and the plants from drowning. Sometimes pasture grass is also planted on the sides of the ridge, stabilizing it to help reduce erosion, meaning less maintenance is necessary and giving more space to raise animals. The water in the canals could come from various sources, rivers, rainwater, or maybe groundwater. At first glance, the advantage seems obvious here, a stable source of water for the plants. Perhaps even raise fish and aquatic plants in the canals if there's water enough, which would provide extra food and fertilizer to improve the soil quality. But there's another big hidden advantage here. Like the terraces, these change the way heat is absorbed throughout the day. Anything you can do here to help lengthen the growing season and lower the risk of surprise frosts killing your food source could mean the difference between a good harvest and losing most of a year's crop. Studies in modern times have confirmed these fields' usefulness. Like the terraces, throughout the day the water absorbs heat from the sun, better than the ground normally would, and then throughout the night the heat is slowly released back into the ridges and the surrounding air. One study also noted that as cold air settles down at night, the coldest air sinks down past the plants and into the canals, helping the plants avoid that frost damage. Studies on these waru-waru found a difference of between 1 and 3 degrees Celsius from the surrounding environment. A subtle difference, yes, but a difference big enough to be life-saving when it comes to unexpected frost damage here. And on the flip side, harsher heat in the day could be tamed by the cooling effect of the waters, stabilizing night and day, helpful for a lot of plants. And then, of course, water could also be stored here or other nearby parts of the irrigation systems for other uses. These did fall out of later in Andean history and most have been overgrown or replaced with fields more suited to mechanized agriculture, but they have undergone a resurgence of interest in the last few decades, and further studies have found that while they do need proper planning and upkeep, if done well, they can be very effective. One found that compared to a standard flat field, food yields doubled, though there were other factors at play in that one, like better fertilizing. Another study did say yields were lower in one sense, which makes sense, there's less growing area than a flat field, but they also noted that there was less surprise crop loss, which could in itself make this well worth the effort and an effective weapon against the cold. But the cold, again, isn't all bad here, and to touch briefly on how it could even be an asset, it is because of the that two of the Andes' most valuable foods were produced here, chuno and charqui. Chuno, these shriveled potatoes, for them it was through the back and forth between intense daytime sun and freezing nights up in these mountain heights that people managed a type of traditional freeze drying, so potatoes could be carried far more lightly and stored potentially for years. More on that in another video. A similar process, or sometimes just simple drying in the dry thin atmosphere, could be done for alpaca and llama meat, creating charqui, where we get our word jerky from. Both of these, chuno and charqui, were understandably highly valuable resources for those who were carrying their food on their backs. When it came to travel, the lighter and higher density the nutrition, the better, to be able to carry more while being less weighed down, and having food in a form that didn't necessarily even need storehouse conditions. So, with all these things, the camisiones, the terraces, the preservation techniques, it makes sense how an individual family or even village might be able to survive at these heights in the Puna. But people seem to have lived better here than one would expect, given the drastically limited foods and resources available, and unpredictability. How did that happen? And then much more so, there's the question, the large societies, like the Tiwanaku. How did they do it? How did they get so large and wealthy way up here? Well, one might point out trade as an option. And that's fair, but confusing, because we have very little evidence of trade or markets between zones. So then what? How did they survive so well when they were missing so many resources they would need to build and work on such a grand scale? Well, this isn't the whole picture. And the answer, and one of the things that makes the Andes fascinating, not only ecologically, but also as a group of cultures, is that many of them didn't. Didn't just stay up here in the Puna, didn't survive only on what was nearby. When we zoom out, we can see. To quote Mura again, every two or three or four hundred feet, you have a new ecologic floor. There is a new climate. And as you go up, these levels are compressed and get narrower and narrower, shallower and shallower. Every few hundred feet, you have a new ecological conditions, new terrains, new waters, new soils. And in every one of those floors, you have to domesticate new crops and find new ways of making a living. These lands, from the coast to the Puna to the jungles in between, were starkly different, but they were not far apart. And in lands such as these, for many people, settling down wasn't staying put. Of course, it makes sense that larger civilizations like the Inca or the Tiwanaku, they could have the population and the resources to extract and tax and pool resources from people at different elevations. Fair enough. Yes, those things happened. But this land, this massive mountain range, the longest in the world, yet still narrow, where so many disparate and diverse zones are packed so tightly together in a crazy mosaic, where even the tips of the mountains, halfway from the coast to the Amazon, could be reached in a couple weeks' walk, and where you could ascend by a whole kilometer in a matter of hours. Here, in this land, something else interesting happened. It wasn't just large societies that farmed the gamut from top to bottom. Many of the smaller societies did. This is what has become known as a vertical archipelago system. Why stay farming only one zone, with one set of crops, when you could farm several? Of course, that's easier asked than enacted, but for large swaths of population here, there was a system. Many people groups were organized into kinship groups called ayus. These would have a main village they were centered in, typically in the fertile middle zones, but then they would send members of the ayu group out to lands further up and down the mountains. Settlements of the same family, treated as the same family, but in a different location. And this wasn't just a strip of land. This term, vertical archipelagos, archipelago being a chain of islands, like islands in a sea, the ayu's main village would be like a main island, and then a chain of their other islands scattered up and down the mountains, with only unowned open sea in between. People might walk for a few days to get to their other settlements, the whole time potentially crossing over only land belonging to a large patchwork of other families. But because these islands were all one large kinship unit, resources could be pooled together and shared, rather than having to barter and sell with people in other zones. So people up in the tundra above were not on their own, since they had family down below, only a few days walk away, providing food they couldn't farm, valuables from further down, coca from the jungle to help deal with the effects of the high altitude. Those above the tree line could access wood for construction, and llamas and alpacas, resources whose importance is hard to overstate for Andean societies, for food for travelers and armies, leather, clothing, carrying goods, for governments a symbol of wealth, the charqui and the chuño. People in all the lower altitudes could have these too, because of the island networks trailing up into the clouds and back. A sort of microcosm of what the larger empires were able to do with their larger scale and resources. Impressively seen for instance in the Tiwanaku, with their heartland in the Puna zone around Lake Titicaca, but with islands reaching all the way down to the desert coast, several weeks walk away. Now, the nitty-gritty details of these systems, and all the politics and sociology they entailed, those are debated. How widespread were these sorts of systems? How far back before the Inca do these go? How large were they usually? Were there really virtually no markets and traders outside these groups, or are there some gaps in the historical record? These are all great questions, and one's best asked to someone more than a simple plant nerd, and it can be easy to paint this area with a broad brush and miss all the diversity between different cultures and the change over time at play here. The cultures were not an unchanging monolith, but in any case, the ingenuity, adaptability, and inventiveness at play in all this is fascinating. All the problems common to civilizations the world over, droughts, flooding, heat, and cold, but put side by side in a unique microcosm, hard to find so vividly elsewhere in the world. But through it all, the drive to survive, and where it led people, what they did to make it work. The Andes are a fascinating place, and a place I would love to go back and explore some more one day. And in some of my next few videos, I'll be zooming in and looking at a few of the plants that call this place home, some familiar, some very much not. So join me then for more plants weird and wonderful, mundane and strange. Until next time, on Ambling with Sam.