H 2 being most numerous combined with all O 2 to form water molecules (initially as vapour). remained in outermost layer to form the gaseous atmosphere.Ītoms coming closer formed molecules, the outer layer got solidified while inner core remained boiling which used to erupt as volcanoes at times the hot lava combined with C & N of atmosphere and formed carbides and nitrides appearing as rocks (lithosphere). came in the centre to form core (hot boiling), the next heavy elements like Ca, Mn, Na, K, Si, Al, S & P deposited around the core as shell and lightest like C, O, H, N etc. The heaviest metallic atoms like Fe, Ni, Cu, Au, Ag etc. The hot (5000–6000✬) rotating clouds of atoms got condensed and segregated in 3 concentric layers due to rotational and gravitational forces and gradual lowering of temperature.
Primitive earth had no oxygen (in free gaseous form) but only as bound in water and some metallic oxides on surface of rocks, hence it was reducing atmosphere.The sequence of change, an 8-step process, begins right from the formation of earth. Hence it was first by abiogenesis and then biogenesis ever since. Haldane (1929) a British said that first life originated from nonliving things at some point of time in very long past when conditions on earth would have been very different. Haldane (1929) supported it Oparin named it as materialistic theory in his book, Origin of Life (1938).Ī.I. Charles Darwin (1857), Joseph Hooker, A.I.
There is general consensus of scientific opinions hence also called as Modern Theory or Scientific hypothesis or the Naturalistic Theory or Theory of chemical origin.
Life arose by series of “sequential chemical reaction” from nonliving (inorganic) matter.
Theory of Terrestrial or Abiogenic Origin: Erasmus Darwin (1731–1802), the grand father of Charles Darwin, proposed about “species changing by modification” in his book Zoonomia on evolution. Buffon (1707-1788), the father of modern concept of evolution was the first serious naturalist to talk about “evolving living forms”. Lucretius, a Roman philosopher believed in gradual change in living being similar to Greek thoughts.Empedocles was called “Father of concept of evolution” by Osborn (1896). non living plants sponge animals once formed organism start reproducing like themselves Cuvier (1800), father of paleontology.Aristotle believed hierarchial increase of complexity as shown in “scala naturae”, e.g. Theory of catastrophism (or cataclysmus) : Richter (1865) Helmholtz (1884) Arrhenius (1808), Hoyle (1950) believed in eternity of life, which came on earth in sperm or spores like form, from cosmos or other planetīut it seems illogical as life can not survive while passing through cold, dry and radiating space. Huxley (1870) supported it.Ĭosmozoic theory or Extraterrestrial theory or Theory of Panspermia: Louis Pasteur (1862) finally disproved it by his experiment of “Swan necked flask” in sterilized sugar syrup the microorganisms could grow only when polluted air (with spores) passed into it.įounded upon the conclusion of Louis Pasteur (1862) – “Life originates from pre-existing life” (or “Omnis vivum ex vivo”) Harvey (1651), T.H.
Van Helmont (1642) claimed rat to arise from sweat-soaked dirty clothes if kept in dark bran-house for 20 days with wheat grains.įrancesco Redi (1621–1697) Spallanzani (1729–1799) tried to disprove this theory experimentally but their plea were rejected by people like Leeuwenhoeck, Buffon, Huxley, Newton & others