We do not know whether complex life is common or rare. If mutating your genetic material and passing it onto your offspring is the only mechanism you have for evolution, you might not ever achieve complexity. Contained within the DNA of complex creatures is the ability to create their own versions of simpler creatures. Prokaryotes still existed (and still do), but were no longer the most complex creatures on our world. For life's complexity to explode, however, there were two more steps that needed to not only occur, but to occur in tandem: multicellularity and sexual reproduction.

Source: Forbes May 01, 2019 06:00 UTC