And that might have been one of the driving evolutionary forces that turned it into the nightmare fodder that it became.

这可能是将它变成噩梦的驱动力之一。

But whatever their relationship, and the evolutionary forces that have acted upon them, the Douglas is now the larger and more beautiful animal.

但无论它们之间的关系如何，以及作用于它们的进化力量如何，道格拉斯现在是更大更漂亮的动物。

" We were interested in whether breeds could be distinguished by their average level of playfulness and what are the evolutionary forces that makes different breeds behave differently."

“我们感兴趣的是，这些品种是否可以通过它们的平均玩耍水平来区分，以及是什么进化力量使不同品种的行为不同。”

Though there are many different evolutionary forces driving animals to smaller sizes, one of the drivers is certainly that the smaller you are the more likely you'll be able to find enough resources to sustain yourself.

虽然有许多不同的进化力量驱使动物变小，但其中一个驱动力肯定是你越小，你就越有可能找到足够的资源来维持自己。

Now, sexual selection can be a very powerful evolutionary force, and despite  the fact that we've known how it works for almost as long as we've known about natural  selection, it tends to be an afterthought.

现在， 性选择可能是一种非常强大的进化力量，尽管我们几乎从了解自然选择的时候就知道它是如何运作的，但它往往是事后才想到的。