In order to determine how and when Life began on Earth, we need to establish what exactly we mean by Life. Cisco Bradley Life is a very difficult thing to define.
Life is so complex and so old that scientists have had trouble deciding exactly what life is.
The main problem confronted when trying to define life is the diversity of organisms that have developed on the planet Earth. There are just a few characteristics that put life in a separate category from other, inorganic, molecules. Life defies a definition because of evolution. Through evolution life became diverse to adapt to the many different climates and habitats. Because of this drive to evolve, some extremely different life-forms were produced.