● Some scientists believe that life came from `color{Violet}"outer space"`.
● `color{Violet}"Early Greek thinkers"` thought units of life called `color{Violet}"spores"` were transferred to `color{Violet}"different planets"` including earth.
● `color{Brown}"Panspermia"` is still a favourite idea for some astronomers.
● For a long time it was also believed that life came out of `color{Violet}"decaying and rotting matter"` like straw, mud, etc.
● This was the `color{Brown}"theory of spontaneous generation"`.
● `color{Brown}"Louis Pasteur"` by careful experimentation demonstrated that life comes only from `color{Violet}"pre-existing life"`.
● He showed that in `color{Violet}"pre-sterilised flasks"`, life did not come from killed yeast while in another flask `color{Violet}"open to air"`, new living organisms arose from ‘killed yeast’.
● `color{Violet}"Spontaneous generation"` theory was dismissed once and for all. However, this did not answer how the first life form came on earth.
● `color{Brown}"Oparin of Russia"` and `color{Brown}"Haldane of England"` proposed that the first form of life could have come from pre-existing `color{Violet}"non-living organic molecules"` (e.g. RNA, protein, etc.).
● They also theorized that formation of life was preceded by `color{Violet}"chemical evolution"`, i.e., formation of diverse `color{Violet}"organic molecules"` from inorganic constituents.
● The conditions on earth were – `color{Violet}"high temperature"`, `color{Violet}"volcanic storms"`, `color{Violet}"reducing atmosphere"` containing C`H_4`, N`H_3`, etc.
● In 1953, `color{Brown}"S.L. Miller"`, an American scientist created similar conditions in a `color{Violet}"laboratory scale"`.
● He created `color{Violet}"electric discharge"` in a closed flask containing C`H_4`, `H_2`, N`H_3` and water vapour at `color{Violet}"8000 degree C"`.
● He observed formation of `color{Violet}"amino acids"`.
● In similar experiments others observed, formation of `color{Violet}"sugars"`, `color{Violet}"nitrogen bases"`, `color{Violet}"pigment"` and `color{Violet}"fats"`.
● Analysis of `color{Violet}"meteorite content"` also revealed similar compounds indicating that `color{Violet}"similar processes"` are occurring elsewhere in space.
● With this `color{Violet}"limited evidence"`, the first part of the conjectured story, i.e., `color{Violet}"chemical evolution"` was more or less accepted.
● We have no idea about how the first `color{Violet}"self replicating"` `color{Violet}"metabolic capsule"` of life arose.
● The first `color{Violet}"non-cellular forms"` of life could have originated `color{Violet}"3 billion years"` back.
● They would have been `color{Violet}"giant molecules"` (RNA, Protein, Polysaccharides, etc.).
● These `color{Violet}"capsules"` reproduced their `color{Violet}"molecules"` perhaps.
● The `color{Violet}"first cellular form"` of life did not possibly originate till about `color{Violet}"2000 million years"` ago.
● These were probably `color{Violet}"single-cells"`.
● All life forms were in `color{Violet}"water environment"` only.
● This version of a `color{Violet}"biogenesis"`, i.e., the first form of life arose slowly through `color{Violet}"evolutionary forces"` from `color{Violet}"non-living molecules"` is accepted by majority.
● However, once formed, how the `color{Violet}"first cellular forms"` of life could have evolved into the `color{Violet}"complex biodiversity"` of today is another fascinating story
● Some scientists believe that life came from `color{Violet}"outer space"`.
● `color{Violet}"Early Greek thinkers"` thought units of life called `color{Violet}"spores"` were transferred to `color{Violet}"different planets"` including earth.
● `color{Brown}"Panspermia"` is still a favourite idea for some astronomers.
● For a long time it was also believed that life came out of `color{Violet}"decaying and rotting matter"` like straw, mud, etc.
● This was the `color{Brown}"theory of spontaneous generation"`.
● `color{Brown}"Louis Pasteur"` by careful experimentation demonstrated that life comes only from `color{Violet}"pre-existing life"`.
● He showed that in `color{Violet}"pre-sterilised flasks"`, life did not come from killed yeast while in another flask `color{Violet}"open to air"`, new living organisms arose from ‘killed yeast’.
● `color{Violet}"Spontaneous generation"` theory was dismissed once and for all. However, this did not answer how the first life form came on earth.
● `color{Brown}"Oparin of Russia"` and `color{Brown}"Haldane of England"` proposed that the first form of life could have come from pre-existing `color{Violet}"non-living organic molecules"` (e.g. RNA, protein, etc.).
● They also theorized that formation of life was preceded by `color{Violet}"chemical evolution"`, i.e., formation of diverse `color{Violet}"organic molecules"` from inorganic constituents.
● The conditions on earth were – `color{Violet}"high temperature"`, `color{Violet}"volcanic storms"`, `color{Violet}"reducing atmosphere"` containing C`H_4`, N`H_3`, etc.
● In 1953, `color{Brown}"S.L. Miller"`, an American scientist created similar conditions in a `color{Violet}"laboratory scale"`.
● He created `color{Violet}"electric discharge"` in a closed flask containing C`H_4`, `H_2`, N`H_3` and water vapour at `color{Violet}"8000 degree C"`.
● He observed formation of `color{Violet}"amino acids"`.
● In similar experiments others observed, formation of `color{Violet}"sugars"`, `color{Violet}"nitrogen bases"`, `color{Violet}"pigment"` and `color{Violet}"fats"`.
● Analysis of `color{Violet}"meteorite content"` also revealed similar compounds indicating that `color{Violet}"similar processes"` are occurring elsewhere in space.
● With this `color{Violet}"limited evidence"`, the first part of the conjectured story, i.e., `color{Violet}"chemical evolution"` was more or less accepted.
● We have no idea about how the first `color{Violet}"self replicating"` `color{Violet}"metabolic capsule"` of life arose.
● The first `color{Violet}"non-cellular forms"` of life could have originated `color{Violet}"3 billion years"` back.
● They would have been `color{Violet}"giant molecules"` (RNA, Protein, Polysaccharides, etc.).
● These `color{Violet}"capsules"` reproduced their `color{Violet}"molecules"` perhaps.
● The `color{Violet}"first cellular form"` of life did not possibly originate till about `color{Violet}"2000 million years"` ago.
● These were probably `color{Violet}"single-cells"`.
● All life forms were in `color{Violet}"water environment"` only.
● This version of a `color{Violet}"biogenesis"`, i.e., the first form of life arose slowly through `color{Violet}"evolutionary forces"` from `color{Violet}"non-living molecules"` is accepted by majority.
● However, once formed, how the `color{Violet}"first cellular forms"` of life could have evolved into the `color{Violet}"complex biodiversity"` of today is another fascinating story