or it chooses to flee rather than to live under their opponents.

或者是逃离他们的敌对派系的压迫
So, defeated political groups might well

所以政治上失利的一方
--or individuals who were the heads of those groups

或者这方的领导人
might decide they have to get out of town.

会做出决定离开城市
And now that we do have something, namely,

这与我们找到的证据相符
this wave of colonization, they join that as well.

这些人加入了殖民的浪潮
Then there are always things that

另外还有其他的一些原因
we might call much less rational than that.

我们称之为非理性决定
In any group of people there is a small minority,

任何一个人类群体总有一小撮人
I want to emphasize small,

我说是很少的一部分人
who just love to do risky things.

他们很喜欢投机冒险
They just love adventure; they're never happy if they're safe,

他们是天生的冒险家他们乐此不疲