陇东地区全新世早中期人类生产方式转换与环境变化

The origin and development of millets-based agriculture and environment change during early-mid Holocene, and their impact on culture evolution and human dispersal during prehistoric times, are hot scientific issues and widely concerned. East Gansu Province is one of the most important areas for the origin of millets-based agriculture, prehistoric human activities and its relation to climate changed in that area has been intensively studied in recent years. However, these researches focus on late Neolithic and Bronze periods, while human-land relation evolution during early-mid Holocene, which was the key period for the transition of subsistence strategies from hunting-gathering to intensive millets cultivation, still remains unclear. To resolve these problems, we systematically collected samples from the stratum of late Paleolithic and early-mid Neolithic from the excavation of Dadiwan site, which is suggested as a key site for domestication of millet crops. We aim to study the transition of human subsistence strategy and behaviours during early-mid Holocene through the application of archaeometry methods including archaeobotanic and zooarchaeological analysis, carbon and nitrogen isotope analysis, radiocarbon dating, and reconstruct high-resolution environment during early-mid Holocene in east Gansu Province with the analysis of paleoclimatic index such as MBT/CBT, pollen, grain sizes from the paleosol-loess sediments. Combined with the systematic archaeological investigation of other late Paleolithic and early-mid Neolithic sites, and review of archaeological and paleoclimate researches in east Gansu Province and its surrounding areas, to explore the transition of human subsistence strategy in relation to environment change during early-mid Holocene in the study area. This work will provide new and valuable dataset for understanding human-land relation evolution and its influencing factors during the key period for human evolution, and the exact timing of the emergence of millet crops and agriculture.

粟黍农业起源与发展和环境变化对史前文化演化和人群流动的影响，是当前国际前沿和热点科学问题。作为粟黍农业起源研究的重要区域，陇东地区史前人类生产方式转换及其与环境变化关系的研究备受关注，已开展工作集中在新石器晚期和青铜时代。全新世早中期是从狩猎采集向成熟粟黍农业转换的关键阶段，但其过程及与环境变化的关系仍不清晰。本项目通过在大地湾遗址发掘中系统采集旧石器晚期至新石器中期连续地层样品，结合陇东地区旧石器晚期和新石器早中期遗址的调查和重点遗址发掘，应用动植物遗存分析、碳氮同位素分析和碳十四测年等方法，揭示全新世早中期人类生产方式的变化。通过对大地湾自然黄土古土壤沉积高分辨率年代序列的建立和环境指标分析，重建该时期环境背景。结合已有研究，探讨陇东地区全新世早中期人类生产方式转换与环境变化的关系。本项目将为认识人类社会演化关键时段的人地关系演变过程与规律，及旱作农业起源过程与机制提供重要的科学依据。

本项目研究目标是揭示陇东地区旧石器末期至新石器早中期生业模式的变化、粟黍农业的起源过程，以及从驯化粟黍农作物出现到成熟粟黍农业建立阶段的发展过程及其影响因素。在项目执行期间，对研究区旧石器末期至青铜时代遗址开展了细致的调查，参与了3个考古遗址的发掘并采集样品，另在30处新石器时期遗址和42处青铜时代遗址采集了样品，开展了系统的动植物遗存分析和测年工作。共采集浮选土样1673 份，鉴定炭化植物种子75044个，采集人和动物骨骼100余份，测定碳十四年代86个，获得6680粒农作物种子的长宽厚粒径测量数据，297份炭化植物种子稳定碳氮同位素数据，以及90份人和动物骨骼碳、氮同位素数据。此外，在大地湾遗址清理了1个厚度为300 cm的黄土-古土壤剖面，以2cm间隔采集了150份沉积物样品，开展了元素含量指标的测定。在旧石器晚期-新石器时期地层采集了陆生蜗牛化石，测定氧、碳同位素数据95份。基于上述工作，在大地湾遗址获得目前世界上最早的（单粒）黍直接测年数据（7794±133 cal BP），提出陇东地区黍的利用至少在约7800 BP，但直至在约6000 BP粟黍农业才成为主要生业模式，在约6000-4000 BP种植粟和黍，在约4000-2200 BP主要种植粟和黍，次要种植小麦和大麦。陇东地区新石器至青铜时代人类对粟、黍、大麦和小麦这四种农作物不存在灌溉行为，存在着施肥和优化培育行为。蜗牛化石壳体氧同位素在40000-7000 BP与石笋氧同位素的变化具有一致性，可作为古气候重建的指标。结合周边地区古气候记录的对比分析，显示6500 BP后气候冷干化导致植被由森林草原交错带的环境向开阔环境的转换，是促使大地湾遗址周边在约6000 BP后粟黍农业为主的体系建立的原因，从多学科的视角提出了早期粟黍农业演化动力的新认识。综上所述，项目的各项研究目标基本达成，在这些工作基础上，发表了19篇标注项目的文章，依托本项目培养研究生8名，3名研究生获得国家奖学金，1名博士生获兰州大学优秀毕业研究生。本研究的结果对推进旱作农业起源过程与机制的研究具有重要的学术价值。