The parameters of the universe we inhabit are incredibly well tuned to allow life to develop. All the constants governing the four known forces of the universe, the masses of the elementary particles etc. have exactly the required values to enable complex molecules and thus life to develop. With even a slightly tweaked set of parameter values the universe would never have developed the way it has, let alone come to life. These facts have been used by creationists as a “proof” for the existence of a creator. There is an alternative theory:
I have re-read a book by Leonard Susskind, The Cosmic Landscape, on my vacation. It’s one of those rare books that has changed my outlook on life just a little bit (a couple of others include Gödel, Escher, Bach by Douglas Hofstadter, The Fifth Discipline by Peter Senge and parts of the Pali Canon). Professor Susskind is generally acknowledged as the father of the string theory, a possible successor of the extremely successful standard model of elementary particles. Susskind argues that the most recent string theory yields not one but 10^500 (that’s a one followed by five hundred zeros) different possible ways to configure the universe in terms of the aforementioned parameters. Each configuration has a different set of physical laws.
An old Swedish saying has it that even a blind hen sometimes finds a seed (given enough seeds and time). If we try out all the 10^500 different configurations of the universe, we will sooner or later stumble upon a universe with exactly the right set of parameters to support life, like ours.
What gives 10^500 universes? Quantum jitter (a kind of inherent restlessness of every object in nature) and the tendency of everything to seek it’s lowest potential energy level causes according to Susskind an existing universe to spawn new “pocket” universes each potentially with a different sets of parameters and a lower inherent energy level (vacuum energy) than the parent universe. As eternity is a long time, sooner or later (“time” is admittedly a somewhat unclear concept here) all the 10^500 universes are given a chance to exist. Some collapse immediately but a few go on expanding and eventually producing life.
Susskind doesn’t attempt to answer the question of where it all started but I believe he gives a plausible explanation for why the seemingly so improbable phenomenon of life may not be so improbable after all. It may even be inevitable.
 Leonard Susskind. The Cosmic Landscape – String Theory and the Illusion of Intelligent Design.