5. Origin and Evolution of life

Origin of life: (Proteinogenesis)

The living matter shows characters like responsiveness, growth, metabolism, energy transformations and reproduction.

Various theories and hypotheses have been proposed to find the origin of life

a. Theory of special creation:

It is the oldest theory and is based on religious belief without any scientific proof. It states that all living organisms are created by a super-natural power.

b. Cosmozoic theory/Theory of Panspermia:

According this theory life did not arise on the planet Earth. It may come to the earth from other planets in the form of spores or micro-organisms, called cosmozoa/ panspermia. Recently, NASA has reported fossils of bacteria-like organisms on a piece of Martian rock recovered from Antarctica.

c. Theory of spontaneous generation (Abiogenesis):

According to this theory, life originated from non-living material spontaneously. This theory was disproved by Louis Pasteur.

                                

                                     1. Redi’s Experiment                                                            

                                     2. Louis Pasteur’s Experiment

d. Theory of biogenesis:

According to this theory, living organisms are always produced from pre-existing living forms, by process called reproduction.