Posted on Aug 23, 2018
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?
Exoplanets come in a variety of types, continues astrobiologist, Dirk Schulze-Makuch in Air & Space, 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.
While super-Earth water worlds are probably uninhabitable due to very high surface temperature, smaller, cooler water worlds could be habitable, according to a recent paper by Ramses Ramirez from the Tokyo Institute of Technology and Amit Levi from the Harvard-Smithsonian Center for Astrophysics. They point out that subpolar sea ice may enhance the habitability of water worlds by moderating their climate.
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.