Are we humans alone in the universe? Opinion seems to be changing right now from “no” to “yes”. Of course, it is still a “maybe”.

Maybe life can self-organize under many environmental conditions that we would consider adverse. Recall the thermophilic anoxic Archeobacteria that probably started life on Earth, and still persist in the deep ocean and in hotsprings. There are others able to survive extreme cold in the Polar regions. They could well be (or were in the past) on Mars or Jupiter’s moon Europa or Saturn’s moon Titan.

Here on Earth, the real breakthrough was the invention of photosynthesis, which covered the Earth with mats of blue-green bacteria. And then the symbiosis of several primitive cells to give us Eukaryotes, soon able to use the newly created oxygen for much more efficient energy production (respiration as the reverse of photosynthesis), and the rise of multicellular plants and animals. Could this have happened on Mars, Europa, or Titan? Quite unlikely.

On Earth, higher energy production made possible warmblooded birds and mammals, probably necessary for brain development. Eventually in humans, biological evolution led to cultural evolution, which is a million times faster. Only then could a technological civilization arise. Is this possible on Mars, Europa, or Titan? Extremely improbable, as it also depends on the previous step, also improbable.

So we need to add several steps to the Drake equation, and try to evaluate each. We may well be alone. Especially, in addition, because if any technological civilization really managed to arise, it would have quickly self-destructed, as we are about to do. It is like trying to build the Tower of Babel. God will not allow it, or we might destroy the whole universe.