Reconstructing vegetation and climate in the Nihewan Basinr North China,during the middle Pleistocene(〜603-587 ka)to trace the evolution of human environments

重建中国北方泥河湾盆地中更新世(〜603-587 ka)植被与气候

Aims The Nihewan Basin of North China,considered the cradle of Eastern civilization,contains a set of late Cenozoic strata and artifacts used by Homo ereettvs in the early Pleistocene(〜1.66 Ma to 780 ka)and the cranial bones and teeth of early H.sapiens from the late middle Pleistocene(~370 to 260 ka).Palynological studies provide an opportunity to explore the living environment of early humans.Methods Ralynological samples from the Hutouliang Section(-603-587 ka)of the Xiaodukou Formation of the Nihewan Basin were treated by heavy liquid flotation.Based on the palynological assemblages from the section,vegetation and climate in the Nihewan Basin were reconstructed.Important Findings The dynamic vegetation changed from temperate needle-and broad-leaved mixed forest-steppe(mainly Picea,Abies,Betula,luglans,Artemisia and Chenopodiaceae)to conifer forest(mainly Pinus,Picea and Abies),which saw the replacement of H.erectus by early H.sapiens.The comparison of the Nihewan Basin with other human sites around the world during the same period reveals that early humans preferred to live in caves,accompanied by relatively open steppe or forest-steppe environments,inhabited by numerous mammals.Therefore,it is inferred that the emergence of dense conifer forest and the disappearance of open steppe environments in the Nihewan Basin at approximately 603-587 ka provide new evidence that early humans followed most mammals to steppe or forest-steppe environments and thus left the Nihewan Basin.These new findings not only enrich our knowledge of early human behavior,such as their diet,migration and settlement,but also fill in gaps in paleovegetation and paleoenvironmental research in the Nihewan Basin during the middle Pleistocene(780-400 ka).

中国北方泥河湾盆地发育了一套含有东方人类活动证据的晚新生代地层,既发现有早更新世(距今~1.66 Ma-780 ka)直立人使用的石制品,也有中更新世晚期(~370-260 ka)早期智人的头盖骨、牙齿等直接证据。该系列地层中孢粉学的研究为我们探索早期人类生存环境提供了可能。本文研究的虎头梁剖面地质年代距今〜603-587 ka,介于直立人向早期智人演化的过渡时期。基于地层孢粉学组合分析,我们重建了当时的植被从温带针阔混交林-草原(以云杉属、冷杉属、桦木属、胡桃属、蒿属和藜科为主)逐渐向以松属、云杉属和冷杉属为主的针叶林转变的动态过程。通过对比同时期全球其他人类遗址,揭示了早期人类以洞穴生活为主,同时伴随比较开阔的草原或森林-草原植被,以及丰富的哺乳动物。据此,推测本研究揭示的~603-587 ka前泥河湾盆地茂密针叶林的出现和开阔草原的消失可能是人类追逐着大多数哺乳动物向草原或森林-草原等开阔地迁移,而离开了泥河湾的新证据。这些新发现有助于增进和丰富我们对早期人类饮食、迁徙和定居等行为方面的认知,同时也填补了泥河湾盆地中更新世(780-400 ka)时期古植被与古环境研究的空白。