Exoplanets come in a variety of types, and so-called “water worlds”—planets with at least ten percent of their total mass consisting of water, and no land exposed to the atmosphere—appear to be among the most common.
This begs the question: Assuming life can originate on a water world, say, at a hydrothermal vent at the bottom of the ocean, how far could it evolve? Could we expect intelligent life, or even technologically advanced life, on a world with no exposed land area?
Octopi and other cephalopods evolved in the oceans of our planet, so there is no obvious reason why such intelligent animals could not exist on an alien water world. Whales and dolphins, on the other hand, evolved from land animals, so we wouldn’t expect to find their analogs on exoplanets covered by oceans.
What about technologically advanced life? Fire can’t exist underwater, and fire is thought to have been essential for humans to develop technology. There would be no controllable electricity underwater, either, and without electricity, it’s difficult to imagine what kind of technology could exist on a water world.
The evolutionary path may seem harder to us, but maybe only because we’re land animals.
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