若人类灭绝了 地球谁来接管？

Which species would take over the world if humans went extinct?
如果人类灭绝了，哪类物种会统治世界？

来自Quora的网友总结：

Well it won't be fecking dolphins, that's for sure. Because:
当然，那TM肯定不可能是海豚。因为：

1. No opposable thumbs.
没有对生拇指。

2. No means of locomotion on land.
不能在陆地上移动。

3. Pseudo-fish scumbags who lie about all day.
这些看起来像鱼类的家伙整天游手好闲。

And it won't be chimpanzees, orang-outans, gorillas, dogs, cats or bats. Sorry crazy cat-people. Why? Because that isn't how evolution works. Evolution does not have a goal like "become sentient, take over the planet", evolution is a thing that happens to a population when mutations prove favourable for survival.
而且它也不会是黑猩猩，红毛猩猩，大猩猩，狗，猫或蝙蝠。疯狂的喵星人，不好意思啦。为什么呢？因为进化不是这样纸的。 进化的过程没有像“要有意识，能掌管整个地球”这样的一个目标。进化是一个物种碰巧有利于生存的基因突变的时刻。

Monkeys do not become intelligent monkeys given enough time: they get - as a species - to continue existing, that's the 'prize'.
猴子的话，没有足够的时间让它们变得聪明：它们能够作为一种物种继续生存——这就是最大的奖励了。

My candidate, my boy, for taking over the crown of Top of The World is possibly the most alien order of life mankind has ever encountered....I give you: the octopus!
我的候选人，我的孩纸，掌握“世界之巅”这座桂冠的，很可能是人类遇到过生活秩序最为外星的……我给你个答案：章鱼！

Utterly, utterly alien, here are some fun facts about the octopus.
这个说法彻底很陌生吧，但是确实有一些很有趣的事实。

They have three hearts. Almost like Klingons.
它们有三颗心，几乎跟克林贡人一样。

They are highly intelligent and are believed to have individual personalities.
它们是高度智能化的，被认为具有个性。

They have four pairs of arms and can move on land as well as under water. The dexterity of their arms in combination is easily the equal of opposable thumbs and being able to move on land, they have no hard and fast obstacle to mastering fire.
他们有四对手足，可以在陆地和水下移动。他们触手的灵活性无疑来自于对生拇指让它们能够在陆地上移动，在灭火问题上，也没有什么硬性障碍。

They have vertebrate-like eyes, evolved independently. Beautiful, pretty, vertebrate eyes...
他们有像脊椎动物那样单独进化的眼睛。美丽的，漂亮的像脊椎动物那般的眼睛...

In summary therefore, their ascendance is a matter of when, not if.
总之，它们的崛起只是时间问题，而不是假设性的。