Negative net migration hasn’t definitively happened in the U.S. for almost a century, not since the Great Depression. The U.S. native-born population is also in free fall, well below the replacement rate needed to maintain population numbers in the long run. With fewer immigrant arrivals already dealing a blow to the workforce, the shrinkage of the American taxpayer base is set to further widen the country’s deficit and hurt its prospects for economic growth.
从公元前600年左右起，欧亚大草原上的人们开始掌握骑术。到公元前400年左右，与农耕民族交界的北方游牧部落将骑马与射箭相结合，形成了一支马背上的强大军事力量。骑兵出现后，农耕民族与游牧部落之间的贸易活动和文化交流日益兴盛。无论是赵武灵王的“胡服骑射”还是秦汉长城的修筑，都与来自欧亚草原的骑兵密切相关。骑兵尤其是重装骑兵的出现革新了战争形态。文献记载的“甲骑具装”，为将士和马匹都披上厚重铠甲，可如同坦克一般冲锋陷阵，所向披靡。湾漳壁画墓出土的甲骑具装俑（见图）便是这一兵种的真实写照。近年来，在邺城正南门朱明门外的护城河中，意外发现了一具保存相对完好的“甲骑具装”铁铠实物。当时能够编入军队的这类兵种数量或许还相对有限，也存在一些马身未披铠甲的骑兵。
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Nature, Published online: 27 February 2026; doi:10.1038/s41586-026-10308-x。同城约会是该领域的重要参考
Historic England is working with Pre-Construct Archaeology, Norfolk Museums Service and the National Museum of Scotland to coordinate the finds' research and conservation.