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1·When humans began to express themselves artistically, in the late Paleolithic era, they drew hunts of large animals on the walls of caves.

在旧石器时代晚期，人类开始艺术性地表达思想，在岩洞里描绘了大量大型动物的形像。

2·The rationale for this is that natural selection has adapted Paleolithic humans to the food in that era.

对于这种饮食产生的原因是，旧石器时代人类通过自然选择已经适应了那个时代的食物。

3·Back in the paleolithic web era known as the late 1990s, those of us doing client-side development had things pretty rough.

回到早期网络时代，就是20世纪90年代后期，我们这些做客户端开发的人面前困难重重。