Question

What was the composition of the primitive atmosphere that favoured abiotic origin of life on the earth?

Answer 1

The composition of the primitive atmosphere that favored the abiotic origin of life on Earth was markedly different from today’s atmosphere. According to the Oparin-Haldane hypothesis and subsequent studies, the primitive atmosphere about 3600 million years ago was reducing rather than oxidizing. It contained large quantities of hydrogen (H₂), nitrogen (N₂), carbon dioxide (CO₂), methane (CH₄), ammonia (NH₃), and water vapor (H₂O), but it lacked free oxygen (O₂).

This reducing atmosphere is crucial because the presence of free oxygen would have destroyed many intermediate organic molecules necessary for the origin of life. The gases and vapors in this atmosphere, combined with energy sources such as lightning, allowed the formation of simple organic molecules (like amino acids and sugars) through abiotic synthesis, as demonstrated in the Miller-Urey experiment. These organic molecules eventually led to the formation of more complex compounds and the first primitive life forms.