In his 1999 book, The Life of the Cosmos, Lee Smolin suggested that the reason the universe appeared to be so fine-tuned for complexity and life was what he termed “cosmic natural selection”, in which new baby universes were born during the formation of black holes, each with physical properties that differed from their parent universe due to quantum uncertainty. Universes in which, for example, star formation was impossible would have no progeny and die out, and those that collapse to a single black hole would create only one child universe. Only those in which the initial conditions allowed the formation of massive stars would produce a multitude of black holes, and these would come to dominate the population of universes. But the massive stars that end up as black holes are the prerequisite for creating the heavy elements which are necessary to form planets and living beings. So, we shouldn't be surprised to find ourselves in a universe which appears to have been fine tuned to create the requirements for our form of life.
Now, Harvard astronomy professor Avi Loeb proposes an even more breathtaking speculation in a Scientific American opinion piece, “Was Our Universe Created in a Laboratory?”. Loeb argues that an advanced technological civilisation, which he calls “Class A”, will eventually develop the capability, perhaps by manipulating dark matter and dark energy, or via some means we haven't yet imagined, to perform the ultimate experiment—creating baby universes. If they can control the physical parameters of these universes, they would naturally fine tune them so they would, in turn, eventually produce their own Class A inhabitants. The process of natural selection would, then, operate on the scale of the multiverse, with universes that never produce a Class A civilisation producing no progeny, while those that eventually evolve Class A civilisations are fruitful and proliferate.
Loeb considers humanity at present a Class C civilisation, as we are unable to re-create a habitat for ourselves when the Sun dies. “A class B civilization could adjust the conditions in its immediate environment to be independent of its host star. A civilization ranked class A could recreate the cosmic conditions that gave rise to its existence, namely produce a baby universe in a laboratory.”