Reblogged from Quora:
Hypothetical Questions: Which species would take over the world if humans went extinct?
- No opposable thumbs.
- No means of creating fire/combustion, whose use for cooking is theorised to be responsible for some of our intelligence  and which having is a pre-requisite for escape velocity.**
- No means of locomotion on land.
- Pseudo-fish scumbags who lie about all day, hitting the pfish chronic .
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.
Monkeys* do not become intelligent monkeys given enough time: they get – as a species – to continue existing, that’s the ‘prize’.
So it is worth reiterating, absent mankind and given zillions of years of the status quo, we will never see these species take over the world.
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!
Utterly, utterly alien, here are some fun facts about the octopus.
- They have three hearts. Almost like Klingons.
- They are highly intelligent and are believed to have individual personalities .
- 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.
- They have vertebrate-like eyes, evolved independently. Beautiful, pretty, vertebrate eyes…
- They are supremely able problem-solvers in terms of interacting with their environment, for example in the pursuit of food but have also been observed to play. They also build houses to protect them from under-sea weather .
- There is growing evidence for octopus intelligence in general terms.
- They appear to be evolved for:
selection of vertebrate-like neural organization and activity-dependent long-term synaptic plasticity. As octopuses and vertebrates are very remote phylogenetically, this convergence suggests the importance of the shared properties for the mediation of learning and memory. .
So, unlike chimps, cats, whatever, octopuses*** are already intelligent, they are just not technologically advanced in terms of manipulating their environment. This doesn’t count against them though in the terms of the question, it just means they haven’t got there yet.
After all, where were we a mere 60,000 years ago? Not launching rockets into space and trying to design interplanetary craft, that’s for sure. We were hiding from Castoroides in caves and the like. So their current status means nothing as regards to the question as written.
In summary therefore, their ascendance is a matter of when, not if.
I, for one, welcome our Cthulhoid Overlords!
* I know.
** yeah, yeah: organic bio-ships which use silk cables as Space elevators. I’ve read Hothouse too. Next!
*** look it up, it’s legit.
 Cooking Up Bigger Brains
Puff, puff, pass: Young dolphins deliberately chew puffer fish to get high with each other
 Top of the woild! White Heat
 Personality in octopuses
‘Home’ choice and modification by juvenile Octopus vulgaris (Mollusca: Cephalopoda): specialized intelligence and tool use?
 The Octopus: A Model for a Comparative Analysis of the Evolution of Learning and Memory Mechanisms