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Fanciful. Preposterous. Absurd.
The Black Earth of the Amazon

Posted on Wednesday 18 May 2005

Was the Amazon basin a pristine wilderness in pre-Columbian times or was it home to advanced societies in any way comparable with civilisations of the Andes or Mexico? Judging by the material conditions of the hunting and gathering tribes that live in the rainforest today and if we consider the poor suitability of rainforest soil for agriculture, the answer would seem to be a resounding "no".

And yet we have stories, eye-witness accounts dating back to the earliest years of the Conquest which describe a densely populated Amazon with villages and towns packed closely together along much of its length. A very different place even to the one we see today.

Francisco de Orellana, one of the original Conquistadors, was in charge of the first European expedition down the Amazon river. His story is remarkable not least because it was a completely accidental voyage of discovery. He and 60 men had been separated from another expedition led by Gonzalo Pizarro who had been in search of cinnamon in the jungles of Ecuador. Their boat had been carried downstream by the swift current of the Napo river which turned out to be a major tributary of the Amazon. Seven months later their boat arrived at the Atlantic coast, more than 6,000 kilometres away from where they started out.


Orellana's voyage

Orellana and most of his crew managed to make it back to safety and they brought with them fantasic tales of the sights they had seen on this river. Orellana described the Amazon as a busy waterway which had on both sides of the river populous towns with elaborate temples, plazas and fortresses. As his chronicler, Fray Gaspar de Carvajal relates it:
...we tarried so long in this land of Machiparo's which is 80 leagues in extent, all speaking one language and densely populated with towns and villages with scarcely more than a crossbow shot between them. Some of the towns extended for five leagues without any separation between the houses, quite a wonderful thing to see [a league is about 5.5 kilometres].

The people they encountered lived in towns and villages along the river and were organised into confederations which traded and fought with another. As Orellana's party moved downstream from the Napo to the Amazon proper they found the region becoming more populous.

and at this confluence there were great numbers of people and a very pretty and a very fruitful country. Being already the lands and mountains of the Omagua and having so many large towns with so many people who did not like us to land in their port, we had to fight our way through.
The river communities were well connected and the expedition faced increasingly stronger opposition as they passed through more and more territory hostile to their presence. Orellana's group had little in the way of weaponry and knew how important it was to conserve the little gunpowder that they had so they tried to avoid fighting the Indians as much as they could. That said, however they were after all conquistadors and they survived by plundering the villages of their food stocks and they committed several atrocities along the way including burning down a dwellings with women and children inside. This could not have helped but enrage the local population. In some places they had to ward off attacks by armies of Indians several thousand strong.
There was great amount of food, that turtles in corrals and alberques of water, and much meat and fish and sponge cake, and this in as much abundance that it could have fed a army of a thousand men for a year which we took from this population without resistance. We also found much food in the way of a special fish that was so much in abundance that we could load well our brigs. This fish the Indians take up into the mountains to sell.
The Omagua people also produced arts and crafts of a very high level. Carvajal describes their pottery:
...there was a villa in which there was a great deal of porcelain ware of various makes, both jars and pitchers, very large, with a capacity of more than twenty-five arrobas, and other small pieces such as plates and bowls and candelabra of this porcelain of the best that has ever been seen in the world, for that of Malaga is not its equal, because it is all glazed and embellished with colours, and so bright that they astonish, and, more than this, the drawings and paintings which they make on them are very accurately drawn just as with the Romans.
None of the tricks that had served the Europeans so well when dealing native peoples seemed to work. When they attempted to trade useless trinkets for gold, the Omagua valued what the Spaniards offered for exactly what they were worth:
...a canoe came up to the gourd containing the chaqutra, and they picked it up and showed it to the other Indians, and they valued it so little that it became evident to us that they were making fun of it.
Even a brief account of Orellana's expedition would not be complete without mentioning their encounter with an army of natives taht fought under the command of female warriors. The classically inclined Spaniards naturally named these women "Amazons".
...we came suddenly upon the excellent land and dominion of the Amazons. These said villages had been forewarned and knew of our coming, in consequence whereof they came out on the water to meet us, in no friendly mood. ...Orellana gave orders to shoot at them with the crossbows and arquebuses, so that they might reflect and become aware that we had wherewith to assail them.
The Spaniards continued on but had not gone more than half a league before they encountered and were forced to do battle with several squadrons of Indians led by ten or twelve Amazons who fought
in front of all the Indian men as women captains, and these latter fought so courageously that the Indian men did not dare to turn their backs, and anyone who did turn his back they killed with clubs right there before us. [these women were] very white and tall, and have hair very long and braided and wound about the head, and they are very robust and go about naked, with their privy parts covered, with their bows and arrows in their hands.
It was only after seven or eight of the women were killed that "the Indians lost heart, and they were defeated and routed with considerable damage to their persons." Although Orellana had wished to name the great river after himself, it was the more evocative name Rio del Amazonas that is the one we know today.

So the question that has been asked ever since is: Were Orellana and Carvajal lying when they said that the Amazon basin was heavily populated and urbanised? The seemingly objective style and the great attention to minor details in the narrative does make this somewhat hard to believe. Presumably some things were exaggerated but Carvajal's geographic and linguistic descriptions have since proven to have been accurate. The problem is that there are little in the way of documented accounts of contact with the Omagua for a century after this and information about the region remains scanty until the end of the 18th century. By this time the Omagua and their towns had long since vanished almost without a trace.

The reasons behind the tradition of scepticism regarding Orellana's story are very sound. For one thing, if the Indians really did live in large numbers then by definition they would have had to have engaged in a very different type of food production from the one they use now. Tribal Amazonians today live in remote and inaccessible regions of the forest and survive by hunting and gathering and subsistence agriculture based on slash and burn. Slash and burn when conducted on a very large scale can be immensely damaging to the rainforest environment but on a smaller scale is a rational response the extreme soil infertility. Despite the exuberant growth that one sees in the Amazonian rainforest, its soil is highly acidic and paradoxically very low in organic matter and nutrients. This makes it highly unsuitable for agriculture and in order to obtain even a modest crop, farmers hack down sections of the rainforest and set fire to it. This releases the carbon and nutrients that were locked up in the vegetation which they can then plant into. Unfortunately this relatively fertile soil never lasts terribly long and within a few years the combination of intense sunlight and heavy rainfall will have rapidly degraded and eroded it away, leaving only the barren earth behind. When this happens the cleared field must be left fallow for a decade or more to give the forest time to reclaim it once again. As a result, slash and burn farmers must periodically uproot themselves move from place to place. The yield from this style of agriculture is very low and really only enough to sustain the farmer's immediate family. If the pre-Columbian Amazonians really did live a sedentary life in towns and villages as described by Orellan and Carvajal then they could not have been dependent on slash and burn farming but some form of intensive agriculture instead.

For all its primitiveness, slash and burn agriculture may not, in fact, be all that ancient a practice anyway. Ancient farmers armed with only stone axes could not have cleared new fields every few years the way that present-day farmers armed with steel axes do. At the very least this suggests that they must have operated on a different agricultural cycle that required them to stay much longer on their land. Another point to consider is that, just as in so many parts of the New World, the native population of the Amazon underwent a cataclysmic collapse due disease, enslavement and ruthless exploitation. It is commonly estimated that native populations fell by between 90 and 95 percent in the first centuries after contact with Europeans. It is likely that under these circumstances more sophisticated farming practices that may have required a higher degree of social organisation would have been abandoned in favour of simpler ones.

What could these ancient farming practices have been and how could a sedentary population have been sustained? For this we need to turn to archaeology. Unfortunately, archaeology in the rain-drenched Amazon has its own special problems. Unlike the Mayans who we known had built a highly sophisticated society in the midst of a mountainous rainforest, the plain-dwelling Amazonians did not build out of stone. Instead they would have surely built their dwellings out of the only resource that they had in plentiful supply: timber. Wood like all organic material decays and in very wet tropical environment this decay can be very rapid. Consequently very little of the kind of materials that would be valuable to archaeologists can be expected to have survived. What remains then of these ancient villages and towns? Well, nearly nothing — nothing but compost and broken pots.


Common soil (left) and terra preta (right)

Dotted across the "wet desert" landscape of infertile red and yellow soils are pockets of fertile black soil. These deposits, ranging in size from a few to a few hundred hectares, are generally located on elevated land near waterways and while not large in extent are certainly numerous and thought to comprise up to 10% of the entire region. Originally thought to be of natural origin, this soil, which is high in organic material and nutrients, has been convincingly proven to instead be the product human activity over an extended period. The oldest deposits have been dated to more than 3000 years of age and all of them predate the arrival of Europeans. The locals, who understandably prize this soil for its high fertility and its ability to resist erosion, refer to it matter-of-factly as terra preta do Indo (the black earth of the Indians).

Terra preta deposits are thought to be the kitchen middens of ancient villages and in many cases these deposits are surrounded by wide bands of less dark but still high in organic material known as terra mulata which is also thought to have been the product of intensive agricultural production. As mentioned earlier, in the absence of stone, the only other things of archaeological value that could be expected to survive in this kind of environment are ceramics and, in fact, fragments of pottery occur in terra preta in thick profusion. This pottery takes the form of jars, cups and plates, lightly fired and often painted with images of animals or abstract designs.


So many potsherds

The exact nature and composition of terra preta is still the subject of intense research. It serves as proof that ancient farmers were able to take previously infertile soil and permanently enrich it in ways that we do not know how to do today. This research holds out the hope that one day it may be possible to practice an ecologically sustainable farming in the Amazon and hopefully change the economics that currently favours the destruction of rainforests worldwide.

One thing is clear, however, terra preta wasn't the product of slash and burn agriculture. It is thought that the ancient Indians used a different process which has been dubbed "slash and char" where they partially burnt the forest to produce charcoal rather than ash. They then mixed this charcoal into the ground and augmented it with human and animal wastes. The charcoal provides a site for binding the nutrients to the soil and this also enables it to resist erosion. But the whole story is likely to be more complex and involve the action of various presently unidentified micro organisms and fungi which keep the soil alive and capable of regeneration even after 500 years.


Distribution of terra preta deposits today. The remaining legacy of the lost Amazonians.

What happened to the Amazonian societies after first contact with the Europeans is the familiar tragedy that unfolded again and again in the histories of indigenous peoples around the world. Unfortunately for the Omagua, after Orellana they had became intimately associated with the myth of El Dorado and became the subject of missions of plunder and enslavement. Diseases for which the Indians had no immunity quickly swept through the Amazon basin and decimated the population.

When the Portuguese began to explore deep into the Amazon from their bases in the East they found few signs of the advanced societies described by Orellana but it is now thought that the population of pre-Columbian Amazonia was probably in the order of a million people and possibly far more.

Further reading:

The Amazons - the search for the Amazonian Amazons

Bird's-Eye View of the Amazon - using aerial photography to spot ancient Indian farming sites

A rain forest debate: Could it have been home to complex societies? - Study reconfirms theory on sedentary societies in the Amazon

Lost cities of the Amazon revealed - Archaeologists discover a grid of villages and managed parks

Pay Dirt: Thriving civilization or ‘counterfeit paradise'? - The clues are underfoot as a UVM professor and an alumnus join forces to rethink the Amazon's past

The Real Dirt on Rainforest Fertility - Ancient Amazonians left behind widespread deposits of rich, dark soil, say archaeologists. Reviving their
techniques could help today's rainforest farmers better manage their land

Terra Preta Web Site - the official Tera Preta website. Get authorised merchandise here including an official Terra Preta glow-in-the-dark key-ring dispenser.

Gonzalo Pizarro's Expedition - from the point of view of Gonzalo Pizarro who condemned Orellana as a traitor for abandoning his post. The original purpose of Orellana's boat trip was to find food for the starving expedition and to return within twelve days.

Lope de Aguirre - a bizarre sequel, seventeen years after Orellana a boat sets out to find the Omagua. Whereas the predominant theme of Orellana's journey was one of discovery, this one was of mutiny, murder, piracy and betrayal. A ripping yarn to be sure (and which in 1972 inspired a film by Werner Herzog).