Evidence Of Agriculture In The Amazon Ca. 1500 BCE

Some of the least well understood prehistoric cultures of the Americas are the sedentary food producing cultures of the Amazon river basin in South America, much of which is marsh and jungle now, and some of which was transformed into a savanna landscape when European cattle ranchers cleared the forest for this purpose. 

This farming and fish farming culture existed from at least 1500 BCE to 300 CE in the region.

The University of Central Florida's press release regarding a new paper notes that:

[P]re-Columbian people of a culturally diverse but not well-documented area of the Amazon in South America significantly altered their landscape thousands of years earlier than previously thought. . . . [There is] evidence of people using fire and improving their landscape for farming and fishing more than 3,500 years ago. This counters the often-held notion of a pristine Amazon during pre-Columbian times before the arrival of Europeans in the late 1400s. The study . . . also provides mores clues to the past of the diverse, but not well-documented, cultures that live in the area known as the Llanos de Mojos in northeastern Bolivia.

"This region has one the highest diversity of languages in the world, which reflects distinct ways of life and cultural heritage," says study co-author John Walker, an associate professor in UCF's Department of Anthropology. "We know something about the last 3,000 to 4,000 years of, say Europe or the Mediterranean, but we don't have some of that same information for the people here. That makes this an incredible story waiting to be written.". . . 

The flat, wetland landscape of the Llanos de Mojos is used for cattle ranching today, but archaeologists have noted for years the evidence from remnants of pre-Columbian raised fields and fish weirs for aquaculture. These remnants indicated the land was once used instead for farming and fishing. The archaeologists just didn't know when or how far back in time these activities started -- until now.

Previous research pointed to a date of about 300 C.E., or about 1,700 years ago. However, the new study combined expertise from multiple disciplines, such as anthropology, paleoethnobotany and paleoecology, to indicate that intensive land management started much earlier, at about 1,500 B.C.E, or about 3,500 years ago.

"This finding is important because it provides evidence that the Amazon is not a pristine wilderness but has been shaped and designed by indigenous people thousands of years before the Spanish arrived," Walker says.

This is new information for both the history of the cultures of the Amazon, which have not been studied as much as other cases, like the Mayas or Incas, and for the area, which is often thought of as an untouched world before the arrival of the Spanish.

Neil Duncan, the study's lead author . . . extracted two, five-foot long cores of earth from two locations about 13 miles apart in the Llanos de Mojos. By examining these cores, Duncan found corn and squash phytoliths dating as early as 1380 B.C.E and 650 B.C.E, or about 3,000 years ago. Phytoliths are microscopic silica particles from plant tissue, and the findings suggest these were crops grown in the numerous raised fields that dot the area. . . .

Both cores showed similar trends of initial dry conditions in the oldest layers of earth, followed by increased wet conditions and increased use of wood burning, as evidenced by the presence of high diatom concentrations and charcoal concentrations, respectively. The researchers say wood burning could be for cooking, pottery, warmth and more. . . .

"The intensification of plant, fire and water management occurred at the same time, which emphasizes how farming or fishing were equally important to the people of the region," . . .

Also of note is that the shifts in the two cores to more intensive land management happened at different periods, the researchers say.

One core, known as the Mercedes core, showed the shift to wetter conditions and increased fire use starting at 1,500 B.C.E, or about 3,500 years ago. The other, extracted from a location about 13 miles farther south and known as the Quinato-Miraflores core, showed the shift occurring at about 70 B.C.E., or about 2,100 years ago.

Since broadscale climate changes would have affected both areas at the same time, the time difference between the two cores suggests humans were purposefully engineering the land, including draining water in some areas, retaining it in others, and using trees for fuel.

"So, what's happening in the landscape is that that it's becoming wetter, and we think that some of those trees are being flooded out and so they're not as well represented," Duncan says. "And if things are getting wetter then we shouldn't see more charcoal. So, the interpretation is that we would only see these high amounts of charcoal if it's humans doing some very intentional and intensive burning."

The paper and its abstracts are as follows:

Significance

The Chavín, Moche, Tiwanaku, and Inka are well-known pre-Columbian cultures, but during the same time, in the southwestern Amazon, people were transforming a 100,000-km2 landscape over thousands of years. The extent of earthworks in the Llanos de Mojos has become clear since the 1960s, but dating these features has been difficult. We show that pre-Columbian people used hydrological engineering and fire to maximize aquatic and terrestrial resources beginning at least 3,500 years ago. 

In the 17th century CE, cattle and new technologies brought by Jesuit missions altered the form and function of these landscapes. 

The scale and antiquity of these Amazonian earthworks demand comparison with domesticated landscapes and civilizations from around the world.

Abstract

In landscapes that support economic and cultural activities, human communities actively manage environments and environmental change at a variety of spatial scales that complicate the effects of continental-scale climate. 

Here, we demonstrate how hydrological conditions were modified by humans against the backdrop of Holocene climate change in southwestern Amazonia. 

Paleoecological investigations (phytoliths, charcoal, pollen, diatoms) of two sediment cores extracted from within the same permanent wetland, ∼22 km apart, show a 1,500-y difference in when the intensification of land use and management occurred, including raised field agriculture, fire regime, and agroforestry. Although rising precipitation is well known during the mid to late Holocene, human actions manipulated climate-driven hydrological changes on the landscape, revealing differing histories of human landscape domestication. 

Environmental factors are unable to account for local differences without the mediation of human communities that transformed the region to its current savanna/forest/wetland mosaic beginning at least 3,500 y ago. Regional environmental variables did not drive the choices made by farmers and fishers, who shaped these local contexts to better manage resource extraction. 

The savannas we observe today were created in the post-European period, where their fire regime and structural diversity were shaped by cattle ranching.

Neil A. Duncan, et al., "Pre-Columbian fire management and control of climate-driven floodwaters over 3,500 years in southwestern Amazonia" PNAS (June 7, 2021).