Introduction

The origin of life on Earth was never a widely discussed issue until the middle of the nineteenth century. In those times, people were pious and good-natured and believed firmly that God has created the world and all living forms, once and for all. It would have been a blasphemy to doubt such a simple truth. And the blasphemy arrived in the form of a book written in 1859 by a British scientist named Charles Darwin, who refused the idea that living forms were fixed, saying instead that they were changing with time, and that they were evolving from a common ancestor. The blasphemy was very convincing and spread rapidly in the scientific community, also contaminating fields beyond biology. Darwin – adding one blasphemy to the other – arrived to postulate, in a letter written to Joseph Dalton Hooker on February 1st of 1871, that life might have originated from natural causes:

Thus the idea of the warm little pond, later called prebiotic soup or similar names, was born. And generally, in that time philosophers and biologists were increasingly accepting the idea of an origin of life based on natural laws.

At the time of Darwin, in parallel to the belief in the divine creation, there was also the idea of the spontaneous generation (abiogenesis) of simple life forms. The rationale was that God, in his grandeur, could not have had the time and will to think about the creation of such primitive forms of life. Thus, ants, flies, beetles, mosquitoes, and even rats would originate spontaneously from decaying meat or dirty laundry in the wet cellar. The work of Redi (already in 1668), and by Spallanzani one century later, aimed at providing evidence against abiogenesis, was not convincing to the community of the time.