Turns out to be from the Smithsonian.
Public release date: 1-Dec-2004
Contact: José Iriarte
iriartej@si.edu
202-786-2094 x8350
Smithsonian Institution
A complex agricultural society in Uruguay's La Plata basin, 4,800-4,200 years ago
A complex farming society developed in Uruguay around 4,800 to 4,200 years ago, much earlier that previously thought, Iriarte and his colleagues report in this week's Nature (December 2). Researchers had assumed that the large rivers system called the La Plata Basin was inhabited by simple groups of hunters and gatherers for much of the pre-Hispanic era.
Iriarte and coauthors excavated an extensive mound complex, called Los Ajos, in the wetlands of southeastern Uruguay. They found evidence of a circular community of households arranged around a central public plaza. Paleobotanical analyses of preserved starch grains and phytoliths –tiny plant fossils- show that Los Ajos' farmers adopted the earliest cultivars known in southern South America, including maize, squash, beans and tubers.
Over time, around 3,000 years ago, the mound complex architectural plan of Los Ajos exhibited sophisticated levels of engineering, planning, and cooperation revealing an earlier, new, and independent architectural tradition previously unknown from this region of southern South America. The formal and compact layout of the central part of the site (Inner Precinct) consists of seven imposing platform mounds surrounding a central plaza area.
Iriarte extracted a sediment core from nearby wetlands to reconstruct what the environment was like when this farming society arose. Combined analyses of preserved pollen and phytoliths indicated that, as in other regions of the world, the mid-Holocene was characterized by significant climatic and ecological changes associated with important cultural transformations. During this period, around 4,500 years ago, the climate was much drier than it is today and "Wetlands became biotic magnets for human habitation providing an abundant, reliable, and a resource-rich supply of foods and water. Furthermore, wetland margins offered an ideal place for the experimentation, adoption, and intensification of agriculture encouraging the Los Ajos' community to engage into horticulture", explains Iriarte, currently a post-doctoral fellow at the Smithsonian Tropical Research Institute (STRI) in Panama.
At Los Ajos, cultural artifacts are spread out over 12 ha. suggesting the presence of a large resident population. Moreover, as Iriarte indicates "Los Ajos is far from a lonely isolated community in southeastern Uruguay. In the ten square kilometers surrounding Los Ajos alone there are ten other large and spatially complex mound sites. These were thriving societies that probably were integrated into regional networks of towns and villages". Iriarte believes that "this region was a locus of early population concentration in lowland South America."
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Reference:
Iriarte, J., Holst, I, Marozzi, O., Listopad, C., Alonso, E., Rinderknecht, A., and Montana, J. 2004. Evidence for cultivar adoption and emerging complexity during the mid-Holocene in the La Plata basin. Nature, 2 December.
I am with you on the question of why did the global trade stop, Monk.
I, personally, have no doubt it once existed. That was the basis for my idea that ones running away from Mesopotamia had some idea where to go. And that would account for the sudden appearance of this knowledge base on a world wide scale in a short time.
The only thoughts I have for it going away are that the Euro centric view of the Romans when they became the Western power would kill it in the Atlantic, and that the Chinese may have gone through one of their cycles of withdrawal to kill it in the Pacific.
There is plenty of evidence of regional trade, thorough out the Indian Ocean and China Sea, up and down the West Coast of the Americas, even across the isthmus from Chile into the Caribbean and on. But the trans-oceanic travel seems to have died off.
The concept is that the knowledge would die off in a generation or two if not used.
That is the argument put forth In Guns, Germs and Steel, I believe, for the “savage” way of life of decedents of the people that built the huge works of the upper Amazon. Once most of the people died off from Small Pox, the ones left were so intent on pure survival, they didn’t have time for the more fancy things in life. Father to son teaching reverted to the best way to hunt a pig. In their case the meanings of star movements, ocean currents, etc. just went away from disuse.
It would seem people pass on what they think is important at that point in time.