The origins of plant domestication in the upper Madeira River basin in lowland South America

1万年前不久，在美洲和世界上其他几个主要中心，植物驯化和农业发展就开始了，这是人类最重要的成就之一。古植物学和分子遗传学的最新进展为理解这种关键变化的发生时间、地点、方式和原因开辟了新的途径。例如，对现存种群的系统发育和系统地理研究通常可以确定野生祖先种群，从而确定每个驯化物种的地理起源摇篮，为考古学家指明一个有限的区域进行调查和挖掘。越来越多的遗传学、生物地理学和考古植物学资料现已将亚马逊地区确立为世界上最重要的植物驯化中心之一。最近的遗传和生物地理学研究表明，西南亚马逊地区季节性森林和大草原的过渡边缘，包括马德拉河上游流域，可能是几种主要美洲作物驯化的摇篮，包括木薯（Manihot esculenta），花生（Arachis hypogaea），桃棕（Bactris gasipaes），古柯（Erythroxylum coca），辣椒（Capsicum baccattum），红木（Bixa orellana）和烟草（Nicotina tabacco） (Clement et al. 2010；Piperno and Pearsall 1998)。尽管它是南美洲低地最重要的驯化中心，但到目前为止，还没有跨学科的项目记录了这些重要作物在其原产地的驯化。针对这一问题，我们建议组织两次研讨会，开展前期研究活动，策划、撰写并提交一项3-5年的国际跨学科项目，将分子遗传学、植物生物地理学、考古学、考古植物学和古生态学结合起来。该项目的主要目标是：i)调查亚马逊地区主要作物的历史，包括木薯、桃棕、辣椒和红木；Ii)重构早期农业的语境；iii)调查人类对西南亚马逊马德拉河上游环境影响的时间和性质。这些目标建立在以前由Iriarte和Clement协调的两个独立的研究方向上：巴西南部Araucaria森林景观转变的古生态学和考古植物学（AHRC-Fapesp）和普鲁-马德拉穿插带（ERC），以及亚马逊原生作物的起源、扩散和系统地理学（Fapeam, Fapeam- aird, CNPq, Fapesp）。该项目恰逢其时，结合了最先进的技术来解决植物驯化和农业发展的复杂性。对作物起源的研究正受益于微化石植物学技术的改进，特别是从用于加工植物的石器残留物中提取淀粉颗粒，这使得植物考古学家能够记录热带地区根系作物，这些作物的大植物遗迹保存不佳（可见的种子和水果遗迹）（Piperno 2011）。古生态技术将有助于重建马德拉河上游晚更新世到全新世的植被历史，特别是自然环境和植物协会，其中第一批作物被驯化。特别强调的是人类如何以及何时开始改变他们的环境，利用火灾历史来重建自然和人为过程之间的关系。遗传分析可以确定野生种群，从这些种群中产生了开始驯化我们现代作物的第一个选择，也可以追踪这些驯化中心以外的分散。

Plant domestication and the development of agriculture began shortly after 10,000 years ago in the Americas and several other primary centres around the world, and was one of humankind's most pivotal achievements. Recent advances in palaeobotany and molecular genetics have opened new avenues for understanding when, where, how, and why this crucial change first came about. For example, phylogenetic and phylogeographic studies of extant populations can often identify the wild ancestral population and thus the geographic cradle of origin for each domesticate, pointing the archaeologists to a limited area for survey and excavation. A growing body of genetic, biogeographical, and archaeobotanical data has now established Amazonia as one of the most important centres of plant domestication in the world. Recent genetic and biogeographic studies show that the transitional fringe of seasonal forests and savannahs in SW Amazonia, which encompass the upper Madeira River Basin, were probably the cradle of the domestication of several major American crops, including manioc (Manihot esculenta), peanuts (Arachis hypogaea), peach palm (Bactris gasipaes), coca (Erythroxylum coca), chilli peppers (Capsicum baccattum), annatto (Bixa orellana), and tobacco (Nicotina tabacco) (Clement et al. 2010; Piperno and Pearsall 1998). Despite being the most important centre of domestication in lowland South America, until now no interdisciplinary projects have documented the domestication of these important crops in their cradle of origin. To address this issue, we proposed to organise two workshops and conduct preliminary research activities to plan, write and submit a 3-5 yr international interdisciplinary project integrating molecular genetics, plant biogeography, archaeology, archaeobotany and paleoecology. The main objectives of the project will be to: i) investigate the history of major Amazonian crops including manioc, peach palm, chilli peppers and annatto; ii) reconstruct the context of early agriculture; and iii) investigate the timing and nature of human impact on the environment in the upper Madeira River, SW Amazonia. These objectives build on two previously separate lines of research coordinated by Iriarte and Clement: paleoecology and archaebotany of landscape transformations of the Araucaria forests of southern Brazil (AHRC-Fapesp) and the Purus-Madeira interfluve (ERC), and the origin, dispersal and phylogeography of native Amazonian crops (Fapeam, Fapeam-AIRD, CNPq, Fapesp), respectively.The project is well-timed to combine state-of-the-art techniques to address the complexity of plant domestication and the development of agriculture. Research on crop origins are benefiting from the refinement of microfossil botanical techniques, in particular starch granules retrieved from the residues of stone tools used to process plants, which are allowing archaeobotanists to document root crops in tropical regions exhibiting poor preservation of macrobotanical remains (visible remains of seeds and fruits) (Piperno 2011). Palaeoecological techniques will help reconstruct the Late Pleistocene through Holocene vegetation history of the upper Madeira River and, in particular, the natural environment and plant associations in which the first crops were domesticated. Particular emphasis will be given to how and when humans began to alter their environments, using fire history to reconstruct the relation between natural- and human-caused processes. Genetic analysis can identify the wild populations from which the first selections were derived to start the domestication of our modern crops, as well as to trace dispersals out of these centres of domestication.