2. Abiogenesis

During the early times, when the science and technology were not widespread all over the world, the people were believed that all the living things on the earth were created by their Supreme Power called The God. Many religions teaches people that life did not evolved spontaneously, but was deliberately created by God. But this is just a part of Creationism Theory which didn't have any evidence to prove, so that almost all scientists did not accept it. But still, it was generally agreed that all life today evolved by a common descent from a single primitive life form but no one knows what kind of life form was it but whereas it was believed that this living matter was formed from non-living matter and this kind of hypothetical process is known as Abiogenesis.

 

Abiogenesis is the natural process by which life has arisen from non-living matter such as simple organic compound. It was not single event but an evolutionary process of increasing complexity that involves the molecular self-replication, self-assembly, auto-catalysis and also the emergence of cell membrane. The study of abiogenesis can be geophysical, chemical or biological with more recent approaches attempting a synthesis of all three, as life arose under conditions that are strikingly different from those on Earth today.

Life functions through the specialized chemistry of carbon and water and builds largely with four key families of chemicals: lipids (fatty cells walls), carbohydrates (sugars, cellulose), amino acids (protein metabolism) and nucleic acids (self-replicating DNA and RNA). Any successful theory of abiogenesis must explain the origin and interactions of these classes of molecules. Many approaches to abiogenesis investigate how self-replicating molecules or their components, came into existence.