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

相比之下，欧亚大陆的东西向的。

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

也，美的南北向的。

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

它没有横贯美和非的严重生态障碍。

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.

它的东西向使得欧亚大陆某一地区采用的许多发明能够相对较快地传播到欧亚大陆其他地区类似纬度和气候的社会。