What is the spontaneous generation hypothesis?
The spontaneous generation hypothesys, or abiogenesis, asserts that life on earth has come from nonliving material. For instance, the fact that with time rats appeared around waste was considered in the past a confirmation of this hypothesis. Some supporters of spontaneous generation associated it with the existence of an active principle (the vital elan) that would be the source of life, a theory called as vitalism.
Origin of Life - Image Diversity: abiogenesis