Spatial Structure among the Geometric Earthworks of western Amazonia (Acre, Brazil).

Abstract

Field­work and desk-based re­search in the west­ern Ama­zon basin has led to an ex­plo­sive growth in the state of knowl­edge sur­round­ing the pre-Columbian ar­chae­ol­ogy of this re­gion. Pre­vi­ously thought to be a sparsely oc­cu­pied en­vi­ron­ment, ar­chae­ol­o­gists have recorded hun­dreds of geo­met­ric earth­works be­tween the Purús and Acre rivers in re­cent years, spurring re­newed in­ter­est in un­der­stand­ing the dis­tri­b­u­tion, age, and func­tion of these struc­tures. A chal­lenge has been to iden­tify pos­si­ble re­la­tion­ships be­tween sites and to place them in their broader land­scape set­ting. The pre­cise spa­tial scale, rel­a­tive im­por­tance of dif­fer­ent fac­tors, and strength of any re­la­tion­ships that con­tributed to shap­ing their dis­tri­b­u­tions re­main an open ques­tion. This pa­per de­vel­ops and ap­plies an ex­plic­itly spa­tial frame­work to ad­dress this prob­lem, draw­ing on a rich body of re­cent re­search in Acre state (Brazil) and ad­vanced point process mod­el­ling. The an­a­lyt­i­cal ap­proach, which is fully doc­u­mented and re­pro­ducible with the ac­com­pa­ny­ing code, in­fers the fac­tors af­fect­ing geo­met­ric earth­work dis­tri­b­u­tion at mul­ti­ple spa­tial scales. This en­ables the first ro­bust pre­dic­tions of ter­ri­to­r­ial in­te­gra­tion in the re­gion, which is dis­cussed con­text of ex­tant ar­chae­o­log­i­cal mod­els. The find­ings sup­port the in­ter­pre­ta­tion that non-strat­i­fied so­ci­eties likely oc­cu­pied Acre dur­ing the late pre-Columbian pe­riod.