Look at the figure below from his book. It shows a longitudinal section of cork on the left and a transverse section on the right. Origin of life - special conditions on Earth. The energy source of the sun, under reducing conditions, may have driven the formation of the first macromolecules. Or, energy could have come from volcanic activity.
Cells seem to have appeared first in the oceans.
Evolution of the first unicellular organisms - The timetable of early evolution. First cells may have been heterotrophs, obtaining energy from breaking down large macromolecules. Then, photoautotrophs appeared. Or, chemoautotrophs which obtained energy from breaking down molecules such as hydrogen sulfide gas produced by volcanic activity, may have been the first cells. In this scenario, heterotrophs and photoautotrophs would have appeared later.