"The question of evolution of life on the Earth and elsewhere in the Universe has ever been as challenging as the question of evolution of the Universe itself. Science does not provide authentic explanation regarding the origin of the Universe in the controversial ‘Big Bang’(1,2) theory for evolution of the Universe, nor does it provide any satisfactory explanation regarding the origin of life despite considerable advancements in the fields of genetics and microbiology in recent years. The ‘Big Bang’ model for evolution of the Universe is not secure enough to serve as a foundation for beliefs about the origin of life, which is exemplified very much by the fact that the most distant galaxies, we can see today, look as rich and fully evolved as our own, even though they are theoretically only 5 per cent as old. Among the several factors leading to beginning of life on this planet, ‘panspermia’ appears to provide the most favoured hypothesis for emergence of life on our planet. This paper examines the various prevailing hypotheses regarding origin of life on this planet. It also hints at a very interesting inference that probably delivery of life-bearing organic molecules by the comets in the early history of Earth alone was not sufficient to provide the requisite trigger mechanism for initiation of life on our planet."
(excerpted from EVOLUTION OF LIFE by BY ASHWINI KUMAR LAL)