Origin of life

life is an inherent capacity that an organism posses to maintain and reproduce itself. most of the ideas on the origin of life fall in to either of the following four theories:

Theory of special creation

proposed by a Spanish monk, Father Saurez.This theory assumes that life was created by some supernatural power, beyond the analytic capacity of physics and chemistry. According to Christianity the Bible states that the creator formed all living organisms with in six natural days. Materia prima on first day, plants on the third day,fish and fowl on fourth day and animals including man on fifth day. according to Hindu mythology Brahma created various forms of life on one stroke. Manu and Shradha were first man and women on the earth.

Cosmozoic Theory or Theory of Panspermia

This theory is proposed by Richter and Arrhenius. The life in the form of resistant spores called panspermia reached to the earth accidentally from other planets and developed in to organisms.

Theory of Abiogenesis (Spontaneous Generation)

Von Helmont proposed that life in the form of simple organisms originated spontaneously from non living substances. Anaximander proposed the air as sole cause of life. Von Helmont proposed that mice will be developed when human sweat and wheat are kept together for 21 days. Like wise insects from dew, butterflies from the cheese and moggots from the decaying meat.

Theory of Biogenesis

This theory is proposed by Francesco Redi provided major set back to the Theory of Abiogenesis. On the basis of experiments, Redi concluded that flies arise only from the eggs laid down by parent flies, i. e, life can arise only from preexisting life. Louis Pasteur also supported theory of biogenesis through swan necked flask experiment and put forward by Redi. he succeeded in disapproving the spontaneous generation theory because he was ingenious in drawing out the neck of glass flasks so as to provide access of air but not to micro organisms. Pasteur was famous for germ theory of disease and immunology.

Modern Theory of origin of life

Proposed by Haeckel and evidence by the brilliant works of Oparin , Halden as well miller and Urey. The modern theories state that life arose on the early earth by series of progressive biochemical reaction. The entire process presumably involves the following sequence of events.