It has been said that we might not even recognize an alien life form should we encounter one, nor the ruins of an alien civilization (at least not on Mars, if NASA and JPL have their way). But how about ancient ruins here on Earth? Are we often looking in the wrong places and overlooking evidence of cultures that do not fit our preconceived notions? Can we even define “civilization”? There is reason to believe that the ruins of ice age “Atlantean” cultures may lie under water on the continental shelves, and the remnants of cultures that flourished during the Holocene Optimum may yet be found in areas that are today very arid or very cold.
Archaeologists always assumed that civilization began about 5,500 to 6,000 BP (before the present). First people developed agriculture, and then woven fabrics and fired ceramics, and began building towns of adobe brick or stone. Writing followed soon after. Aside from the fact that agriculture was developed by 12,000 B.P. at the latest, and the fact that the origins of the alphabet are a complete mystery, recent finds cast serious doubt on all of our assumptions.
Hunter-gatherers in Central Europe made woven fabrics and fired ceramics by 28,000 BP Other hunter-gatherers at the Gobekli Tepe site in what is now Turkey built large monuments of cut stone bearing at least some resemblance to Stonehenge and other stone circles and possibly indicating some knowledge of mathematics and astronomy. Our assumption that fabrics, ceramics, and shaped stone structures were possible only after the invention of farming is clearly mistaken.
We know of five ways for a people to obtain food. There are hunter-gatherers, fishermen (a variant of hunting), herdsmen, farmers (like many North American Indians a few centuries ago) who hunted for their animal protein, and farmers who also keep domestic livestock. It is now obvious that any of these systems can allow a civilization to develop; fishing during the last ice age could have supported quite a large population of seafarers.
Early Spanish explorers searched for lost cities like El Dorado in the rain forests of the vast Amazon river system. In 1541 Francisco de Orellana and Friar Gaspar de Carvajal went down the Amazon tributaries from the west and claimed to have seen huge walled cities, gleaming white, and roads up to sixty feet wide. But European diseases decimated the native population in what may have been the greatest epidemic in history, and later explorers and settlers found only “primitive” farmers in small villages, who hunted for their meat, rather like many of the Indians of North America. Yet the legends persisted.
Percy Fawcett, a colonel in the Royal Artillery and a veteran of World War One, was born in 1867 in Devon, England, to a rather adventurous family. His father was a Fellow in the Royal Geographic Society, and his brother Edward was a mountain climber. A man with intellectual interests (some would say obsessions), he believed that the ruins of Atlantis, or at least one of its colonies, might be found in the Brazilian rainforest. He made several expeditions, and, in 1925, he and his oldest son Jack went into the (then largely unexplored) Matto Grosso region in search of a lost city he called “Z.” They vanished off the face of the Earth and were apparently never seen again. They may have been murdered and robbed by the Kalapalos Indians, who admitted being the last to see them and who had some of their possessions, or by Indians further along on their route, like the Arunas, Suyas, or Xavantes. The Kalapalos claimed to have seen Fawcett’s nightly campfire smoke further in the distance each day for five days. This is certainly possible, as travel in dense jungle can be painfully slow. Supposedly, one member of the Kalapalos tribe admitted that they had murdered and robbed the Fawcett’s; and it is a fact that the tribe captured and robbed the members of an expedition in 1996, but they released them unharmed. There are other rumors that Fawcett and his son were captured by Indians and lived among them for years, even marrying into the tribe, but there is no evidence of this.
Whatever happened to Fawcett and his son, we know that he was looking for a stone city in a region where there was little stone to be found, and practically none suitable for building. In the humid and rainy Amazon, structures of wood and thatch decay and adobe would be washed away, and whatever remained would be covered by the forest. Blinded by his own assumptions, Fawcett could have walked directly over the remains of an advanced culture and never seen or recognized it. Actually, in at least one part of the Amazon there is an ancient stone structure, the so-called “Amazon Stonehenge” in Brazil near the border with French Guiana, discovered by Brazil’s Amapa Institute of Scientific and Technological Research. It consists of 127 blocks of granite, many of them ten feet tall, and there is a hole in one that aligns with the sun at the time of the winter solstice. Ceramics nearby have been dated as early as 2,000 BP In the Andean foothills of southeast Peru, there are oddly symmetrical structures that may be the remains of cities and of pyramids rivaling in size those at Giza. Or they may be natural formations…no one yet is willing to finance excavations in this relatively inaccessible area.
Regarding the “Stonehenge” and its associated pottery, there is no way to be certain that the circle and the ceramics were made by the same culture or at the same time, although it seems likely. There is really no way to date stone blocks. Ceramics and stones used in hearths and heated to a high enough temperature can be dated by thermoluminescence. Electrons are trapped in the crystal lattice of ceramics and are driven out when they are fired. Over the centuries, new electrons seep back in and can be measured by the dim light they emit when the material is heated during testing. Supposedly, the older the material is the brighter the light, as there has been time for more electrons to be trapped, and the dating method can be used for artifacts up to several hundred thousand years old. In practice, there are many uncontrollable variables that reduce the accuracy, and the older something is the less accurate the dating. The method is pretty good for artifacts dating from about 300-10,000 B.P. Charcoal from cooking fires and other organic material can be dated using carbon 14, a radioactive isotope caused by ordinary carbon’s exposure to cosmic rays. Once the carbon is trapped by plants using atmospheric carbon dioxide for photosynthesis, the radiation begins to decrease as the carbon 14 decays back into ordinary carbon 12. Carbon 14 has a half life of 5,700 years, meaning that it is only half as radioactive after that time; so the older the material the less accurate the dating, with the maximum being about 60,000 years. There are numerous other problems, including the possibility of contamination of samples, but carbon 14 dating, within the last few tens of thousands of years, is usually fairly accurate.
A number of years ago there were reports in the media of the discovery in the Amazon basin of the ruins of ancient towns, roads, canals, and huge, earthen mounds. There were claims that some of the ruins might date back as far as 7,000 BP and that the Indians, presumably, had even dug canals connecting different rivers with one another. More recently, articles have been published with photographs and detailed information on this culture, but all references to canals actually connecting rivers have been dropped; and all accounts now claim that the culture dates back only to about 1,800 BP at the most and that it survived until about 700 BP Dozens of sites, ironically exposed by deforestation, have been discovered. There are huge, geometric earthworks with canals (none of which, it is now claimed, connect rivers to one another), and mounds upon which towns were built. Other towns were surrounded by earthen walls and moats and housed up to 2,500-5,000 people each. The towns were built on high ground between rivers, usually near springs, and the moats were up to 36 feet wide and three feet deep. The walls around the towns were low, about three feet, so their real function is a mystery; clearly they would not be effective for defense. The houses were presumably like those used by more recent Indians, constructed of wood and thatch (many of the contemporary ones are quite large, well engineered, and beautifully built). Of course, such structures would not survive long in the rainforest. The Indians used fired ceramics, but, so far, there is no evidence of metals.
There is no evidence of domestic livestock, so presumably they hunted and fished for animal protein. Their agriculture was quite advanced, and archaeologists are only beginning to understand it. One of their developments, if it can be fully understood, could have important benefits for modern inhabitants of the area. The soil in much of the Amazon is actually quite poor and is particularly deficient in many minerals, so when land is cleared for farming and ranching, often, after only a few growing seasons, it becomes infertile and a wasteland is created. But the ancient Indians in these towns seem to have practiced a peculiar variant of slash and burn agriculture, somehow managing to control the burning so as to create large amounts of charcoal, which was then pulverized and worked into the soil. The tiny and highly absorptive charcoal grains hosted fungi and bacteria which seem to aid in capturing and retaining soil nutrients. The resulting black soil is now called “terra preta,” and if the technology can be relearned, the region may become fertile farmland again.
Some archaeologists also suspect that the Indians modified the surrounding forests, planting more useful trees. Since this was not the kind of monoculture we practice today (with huge fields or orchards devoted to one crop), and since the trees were probably not planted in rows, we would not recognize such an area as being anything special. Note that North American Indians also modified the natural environment, sometimes burning wooded areas to create more grassland for deer and other game animals. This would be a kind of intermediate step between hunting and animal husbandry, and the planting of useful trees would be intermediate between gathering and farming. A lot of our assumptions about early cultures are proving to be incorrect.
But what of early accounts of canals connecting rivers and of the culture dating back many thousands of years? Was this just a mistake, an exaggeration, or are archaeologists now covering something up or being overly conservative? This has been known to happen. The massive Amazon system drains into the Atlantic Ocean, and the Orinoco system empties into the Caribbean. It is, to say the least, highly unusual for river systems going in different directions to connect with one another naturally. For example, the Tigris and Euphrates, which flow almost parallel to one another through Iraq and whose deltas combine before reaching the Persian Gulf, are not connected at all in the mountains that are their source. A tributary of the Tigris will drain one way, and a tributary of the Euphrates, on the other side of a narrow ridge, will drain another way. But the Guarina River, a tributary of the Rio Negro, which flows into the Amazon, is connected by the 300 kilometer long Casiquiare River (if it is a river) to the upper Orinoco. This connection was, of course, always known to the local Indians, but the first Europeans to travel its entire length were the great German explorer and naturalist, Alexander von Humboldt and his French comrade, Aime Bonpland. Now it is (just barely) possible to imagine a way such a connection might be formed naturally. If the two drainages were once separated by high ground and then the river basins silted up until they were as high as the divide, and if there was a flood in one system but not the other, maybe, somehow, this could form without human intervention. But it looks like an incredibly long canal.