A likely explanation for this involves the fact that intercontinental migrations require both a land bridge connecting the two continents and the suitable habitat both on and across that land bridge.

对此，有一种可能的解释是，洲际迁移既需要连接两个大陆的大陆桥，也需要大陆桥上和桥对面存在合适的栖息地。

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But when that's not true, then there is a typical sort of modern frontier, a land bridge which there a line is-a theoretical line is drawn through it, and on one side is one city, and the other side is another city.

但还不止这些天然边界,另外还有种边界形式,和现代国境线很类似,是由一座陆桥,分割出一条界线…假象的界线,界线的一边是一个城邦,另一边是另一个城邦

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Another 20 had entered a few days before after crossing a land bridge between Jordan and Israel.

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The Jewish state would not have included western Galilee, Jaffa or even a land bridge from the Mediterranean coast to Jerusalem.

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"Presumably, conditions were favourable on the Bering land bridge which was more of a large filter than an open highway, " suggested Professor Poinar.

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