Through most of the 20th century, scientists thought that life began with a stupendous chemical fluke, unique in the observable universe. Today, as physicist and astrobiologist Paul Davies of Arizona State University, points out it is fashionable to say that "life is written into the laws of nature - easy to get started and therefore likely to be widespread in the universe. The truth is, nobody has a clue. It could be either extreme, or somewhere in the middle."
The Daily Galaxy via beyond.asu.edu