In the afternoon, Neves takes me to the Hatahara site, about eightmiles from Donna Stella, which contains traces of a more sedentary wayof life. Here pottery shards litter the ground. At one of the site’stwo excavations, the broken bits stick out from the earthen walls of alarge square pit. The layers of protruding pottery are so tight andthick they look almost like wall coverings.
The Hatahara site contains traces of four separate occupations byfarmers. The people of the Açutuba phase, who are thought to have comefrom the Caribbean coast, may have been the first to settle the area,living in villages up to five acres in size, each supporting 100 to 200people. Neves believes that they lived on fish, wild meats, palms,fruits, and manioc, a root that can grow in poorer soils year-round.Although this early culture had only rudimentary agriculturalpractices, Neves says, the plant and animal refuse they were leavingprovided the substrate for future terra preta soils.
Helena Lima, a Ph.D. student at the University of São Paulo, istrying to pinpoint when and how this soil was used to support greaterpopulations in the Amazon Basin. She sees a stark difference betweenthe Açutuba phase, from 300 B.C. to A.D. 400, and the later Manacapuruphase, from A.D. 400 to 900. “The Manacapuru were the first people whoreally changed the soil,” she says.
The terra preta soils at Hatahara and the other sites are made froma mixture of plant refuse and animal and fish bones, along with largequantities of charcoal that were deposited after settlers used stoneaxes and slow-burning fires to clear forest. Such smoldering firesproduced more charcoal than ash. The charcoal, soot, and other carbonremains (collectively called biochar) retained nutrients, particularlypotassium and phosphorus, that are limited in tropical soils. Theresulting improvement in soil fertility may have allowed the land tosupport a larger, more stable crop-based population, although studiesof fossilized pollen have not yet revealed the specific plants theycultivated.
The next phase of settlement, the Paredão, occurred from about A.D.700 to 1200. Neves suspects that the Paredão were outsiders from thesouth. The occupation is peaceful, though, and the Paredão and theManacapuru lived and traded with each other.
The Paredão exploited terra preta soils even more than theirpredecessors. While the initial settlers in this area may have createdthe dark soils by accident, William Woods, director of environmentalstudies at the University of Kansas, says that “at some point theyrecognize their importance and start to promote them.” Over time, thevillages of the Paredão become larger, denser, and surrounded byagricultural fields. Populations grow into the thousands at sitesranging from 5 to 40 acres. The lack of fortification strongly suggeststhat the groups lived in peace.