That is, the major axis of the Americas is north–south.

也就是说，美洲主轴线是南北向。

In contrast, the major axis of Eurasia is east–west.

相比之下，欧亚大主轴线是东西向。

It lacks the severe ecological barriers transecting the major axes of the Americas and Africa.

它没有横贯美洲和非洲主轴线严重生态障碍。

Its east–west major axis permitted many inventions adopted in one part of Eurasia to spread relatively rapidly to societies at similar latitudes and climates elsewhere in Eurasia.

它东西向主轴使得欧亚大某一地区采用许多发明能够相对较快地传播到欧亚大其他地区类似纬度和气候社会。