Fertile fossils of a Wetland.

• Author: Hardman, Chris
• Position: !Ojo!

SCIENTISTS HAVE discovered one of the earliest complex societies in the Americas in an unexpected place--the wetlands of southeastern Uruguay. Traditionally, archaeologists believed that the oldest organized societies in the Americas were found exclusively in parts of the Amazon and the Andes.

But research produced by Jose Iriarte and his team of scientists from Panama, the United States, and Uruguay contradicts that view. What they found at a site called Los Ajos has convinced them that a complex society began to develop in southeastern Uruguay some four thousand years ago.

Based on the traditional assumption that only simple hunter-gatherers inhabited the wetlands and grasslands that cover much of southeastern Uruguay, archaeologists concentrated their efforts on the great civilizations of Peru and Amazonia. Although Uruguayan scientists did conduct initial studies of Los Ajos a decade ago, it was not until recently that a new excavation team realized the importance of the site. "Not much research has been carried out in the area," explains Iriarte, a post-doctoral fellow at the Smithsonian Tropical Research Institute in Panama. "Uruguay is a very young country in terms of archaeology."

Los Ajos is part of the La Plata River Basin, a lengthy river system rich with subtropical grasslands, forests, and vast expanses of wetlands. The thirty-acre study area sits atop a level knoll that juts out into a nearby marsh. The main feature of the site is a flat plaza--a couple hundred feet in diameter--that is surrounded by seven carefully positioned flat-top mounds. The rest of the site is more informal with less deliberately shaped mounds. According to Iriarte and his colleagues, about four thousand years ago the mounds became permanent homes for the people who were using them and a definite village was formed. By three thousand years ago, "they started bringing gravel and earth from around the site and intentionally building the mounds and changing the...