Modern medicine removes many of these selective pressures by keeping us alive when our genes, sometimes combined with infectious diseases, would have killed us.

现代医学解决了很多类似的选择压力，比如说，在我们的基因遇到致命传染病时，保护了我们的生命。

The adaptation of a beak that made eating easier potentially weakened the selective pressure for teeth.

使进食更容易的喙的适应可能削弱了牙齿的选择压力。

Convergent evolution is an interesting process that happens when animals are under similar selective pressures.

趋同进化是一个有趣的过程，当动物处于相似的选择压力下时就会发生。

This happened because similar selective pressures existed, not because the animals shared a common ancestor with that feature.

发生这种情况是因为存在相似的选择压力，而不是因为这些动物拥有具有该特征的共同祖先。

Similar selective pressures can cause natural selection to favor the same evolutionary strategy in species with vastly different evolutionary pasts.

相似的选择压力会导致自然选择倾向于在具有截然不同的进化历史的物种中采用相同的进化策略。

And that, in turn, creates a selective pressure for timidity, to avoid getting trapped—with small body size coming along for the ride.

而这反过来又会产生一种选择性的胆怯压力，以避免被困——小体型也随之而来。

Plus, by competing with fish and cephalopods, they put themselves under selective pressure, and launched an evolutionary arms race with other swimmers.

此外， 通过与鱼类和头足类动物竞争，它们使自己处于选择性压力之下，并与其他游泳者展开了进化军备竞赛。

So there's all these selective pressures where other things are just more important–whether it's… I would call it somewhat the illusion of crime prevention.

因此，存在着所有这些选择性压力，而其他事情则更为重要——无论是… … 我会称之为预防犯罪的幻觉。

And more recently computer simulations have developed--have been developed that have crafted eyes under plausible assumptions of selective pressure and what the starting point is.

最近，计算机模拟已经发展起来，可以在选择性压力和起点的合理假设下制作眼睛。

And they often wound up repeating some of their body plans, too -- a classic example of convergent evolution, where similar selective pressures can lead to similar physical results.

他们也常常以重复他们的一些身体计划而告终——这是趋同进化的一个典型例子，相似的选择压力可以导致相似的身体结果。

And while it's difficult to pin down what drove the repeated shifts from teeth to beaks, the transitional fossils that have both structures suggest that there was a shift in selective pressure.

虽然很难确定是什么导致了从牙齿到喙的反复转变，但具有这两种结构的过渡化石表明选择压力发生了转变。

But rather, as particular traits came about from selective pressures, such as choosing wolves who were not afraid of humans, or ones that were less aggressive, over many generations we can see big genetic and behavioral trait differences.

但有些特殊的特质是来自选择压力，例如，选择不怕人或是较不具攻击性的狼好几代之后，我们可以观察到非常大的基因和行为特质差异。

But the story of Thylacoleo carnifex and its relatives shows us that inside even the least likely species is the evolutionary potential to become an apex predator, given enough time and the right selective pressures.

但袋狼及其近亲的故事告诉我们，只要有足够的时间和适当的选择压力， 即使是最不可能的物种也有成为顶级捕食者的进化潜力。