ORIGIN OF LIFE
We salute the spirit of inquisitiveness of man, which gave birth to the discipline of science. The same spirit of questioning also led man to often wonder how life or the first organism came into existence. This quest led him to find answers to how, when and where life originated.
For centuries, it was believed that life originated de novo. In addition several other scientific and non-scientific theories were also put forward.
Some of them are:
(i) Theory of special creation: (or Biblical Theory) – It was put forward by Father Suarez, a
Spanish Monk.
(ii) Theory of spontaneous generation (or Abiogenesis): (Gr, ‘a’ – absence, “bios” – life,
“genesis” – origin) or origin from non-living matter.
(iii) Theory of Panspermia or Cosmozoic Theory: According to this theory, life came from some
other planet. It’s still believed to be true by some scientists like Wikramsinghe, Francis Crick
and Leslie Orgel.
(iv) Biogenesis: Francesco Redi and Louis Pasteur laid the foundation for the Theory of
Biogenesis, which propounded that living organisms arise from pre-existing ones and not from
non-living matter.
(v) Chemosynthetic Theory or Chemogeny: This theory proposed that first form of life originated
from inorganic chemical elements by formative action of some external physical force viz.
lightening or cosmic rays, etc. It was put forward by A.I. Oparin and J.B.S. Haldane and the
experimental evidence was provided by Stanley Millar & Harold Urey. For example, Mighi
meteorite in Ukraine and analysis of another meteorite content viz. Murchison, Victoria in
Australia by space biologists also revealed similar composition indicating that similar processes
are still occurring elsewhere in space. However, in this case, although the presence of amino
acids and polynucleotide are similar to DNA, these are of chemical origin and therefore have
identical strands instead of complementary strands.
