The experiment of Miller and Urey demonstrated that: That multicellular organisms form easily in test tubes. The early Earth atmosphere was rich in both oxygen and carbon dioxide. Complex proteins and DNA can self-assemble into protobionts in the early Earth atmosphere Simple organic compounds can be synthesized in an abiotic environment. Lamarck's ideas about common ancestry and spontaneous generation were incorrect. 1 point Which of the following was critical in the origin of life? A reducing atmosphere with little free O2 The formation of protobionts The origin of hereditary material All of the other answers are correct The formation of polymers