泥河湾盆地中更新世气候转型期人类的适应行为

Human adaptive behaviors during the Middle Pleistocene Climatic Transition in the Nihewan Basin

中更新世气候转型期(1.25-0.7 MaBP)是晚新生代最重要的气候变化时段之一。该时期大陆内部干旱化加剧,北半球冬季温度迅速下降,动植物群发生变化,对古人类的环境适应能力提出新的挑战。泥河湾盆地发育我国北方第四纪典型的河湖相沉积体系,其间富集众多早-中更新世旧石器时代遗址,是探讨更新世环境变化与人类适应行为的关键区域。本文选取盆地内岑家湾台地飞梁、麻地沟、岑家湾和东谷坨等重要遗址,通过多指标的统计分析,解读中更新世气候转型期古人类的适应策略。研究结果显示,因地制宜、就地取材是古人类获取石器原料的途径,不同遗址利用者对不同原料的选择和利用主要和遗址距离原料的远近有直接关系,而针对不同原料类型采取的差异化开发策略,预示着古人类认知能力的提高。尽管锤击法是古人类常用的剥片技术,但是砸击技术可能与本地原料质量具有更直接的关系;作为锤击法的有效补充,砸击技术的运用或许与古人类的认知水平提高存在关联。石核和石片的特征表明,该时期古人类对石核开发利用程度显著提高,剥片技术多样化,灵活性增强,展示了计划性和认知能力的提高。对优质燧石原料的青睐一直是古人类制作石器的主要策略,该时期修理类产品不仅种类增多,加工方式多样化程度也相对较高,加工精细的小型刮削器、钻、尖状器、凹缺器、齿状器和多边修理工具等产品增多指示对多种功能的适应,暗示古人类对区域生态景观多元化的积极响应。古人类灵活的技术多样化策略可能与其认知水平的提高存在关联,而气候与环境波动造成的生存压力等多方面叠加因素,可能共同作用于古人类的认知行为上,促使人类调整技术,适应多变的区域环境。本研究对探讨泥河湾盆地更新世古人类生存行为演化与环境关系、人类对东亚高纬度半干旱区适应策略具有重要意义。

The relationship between hominin evolution,technological developments,and environmental change has always been at the frontier of academic attention.The mid-Pleistocene Climate Transition(MPT)where the cycle,frequency and amplitude of climate change alters,occurred between 1.25 and 0.7 MaBP.This critical period promoted an initial migration wave of Homo erectus(Out of Africa I)and accelerated the spread of Homo erectus(equipped with Acheulean technology)to Eurasia from Africa.According to recent studies,the spread of Homo erectus taking Oldowan toolkits to middle/high latitudes of East Asia can be traced back to 2.12 MaBP.Around 1.66 MaBP,humans occupied the Nihewan Basin,leaving behind abundant and dense Paleolithic archaeological sites showing clear diverse and flexible adaptive behavioral characteristics.This paper presents a preliminary study between environmental change and human survival behaviors of several important sites(Feiliang,Madigou,Cenjiawan,and Dongutuo,etc.)during the MPT from the Cenjiawan platform in the eastern part of the Nihewan Basin.Raw material procurement and exploration strategies indicate that local materials were adopted by early humans in the Cenjiawan platform.Exploration of different raw materials from sites depended on the distance from the raw material source instead of being directly influenced by environmental fluctuations.Freehand direct hard hammer percussion was the dominant technique especially during the MPT period.Although bipolar knapping was adopted by early humans,it had a complementary role that showed flexibility in knapping skills and enhancement of cognitive abilities of early humans to overcome constraints imposed by different qualities of raw materials.Attribute analysis of cores and flakes showed that core reduction and flaking procedures improved during the MPT period.The high quality of chert was selected as the most favorable raw material for stone knapping in the Nihewan Basin.Not only the number of tool types increased and the degree of retouch methods diversified,but complexity of various types of small scrapers,points,bores,notches,denticulates and multi-edged small tools increased significantly over time.In addition,evidence of core rotation and bifacial working of small clasts across some of the Nihewan assemblages like the Madigou knappers,indicate that hominins had the ability to fashion bifacial implements and potentially LCTs.It can be deduced that increased environmental fluctuation and paleoecological variability during the MPT may have contributed to technological flexibility and diversification in response to new climatic challenges.This paper provides new insights into the understanding of human behavioral adaptation that corresponded with environmental fluctuations from African to high-latitude arid-semi-arid regions in East Asia.