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Wikenigma - an Encyclopedia of Unknowns Wikenigma - an Encyclopedia of the Unknown

Primordial Soup

In 1953 an iconic set of experiments showed that some of the chemical building blocks of life, such as amino acids, could form spontaneously in the atmospheric conditions thought to prevail on the primordial Earth. This gave rise to the idea that the early oceans were a "primordial soup" from which life somehow emerged.
The idea still holds a great deal of water, but 50 years on the details remain sketchy. It is still unclear, for example, how a primordial soup of simple molecules could give rise to today's system of DNA and proteins. It is a classic chicken-and-egg problem: DNA codes for the proteins that catalyse the chemical reactions that replicate DNA. How could one exist before the other?"

Source : New Scientist Sept. 2004

The first ideas of life having somehow formed from inanimate matter go back as far as Ancient Greece.

The original concept of The Primordial Soup emerged in the 1920s, suggesting that combinations of carbon, hydrogen, water vapour, and ammonia - together with electric discharges from lightningplugin-autotooltip__plain plugin-autotooltip_bigLightning

High powered lightning discharges are happening somewhere on Earth 100 times every second.

A possible mechanism for the very substantial electrical charges within the clouds was put forward in 1978. Following lab-based experiments, it was suggested that the charges arise from the static-electric interactions of graupel (slush) and ice crystals moving within the cloud (due to convection currents caused by widely differing air temperatures) .
- could form amino acids.

There are other considerations though : The same conditions which form the amino acids can also destroy them. And, as the New Scientist article cited above explains, the fact that amino acids can be present doesn't explain the formation of DNA and proteins.

There are currently several dozen other theories regarding how life might have evolved on Earth - none of which has been generally accepted.

See: Wikipedia

An alternative theory called Panspermia suggests that life may have arrived on Earth via comets etc. Traces of amino acids have now been found on comets, meteorites and even in space itself (example ref.) In 2023, it was announced that uracil - one of the base-pair componds of RNA - had been found in a meteorite (ref.).

Nevertheless, the problem still remains as to how life arose, regardless of where it happened.

Also see : Life on Earth (timespan)plugin-autotooltip__plain plugin-autotooltip_bigLife on Earth (timespan)

There is currently no scientific agreement as to how long ago life on Earth evolved. Estimates, based on geological evidence, vary by about 200 million years - from between 3.85 billion years ago (Ga), and 3.65 Ga..

To date, the oldest undisputed fossils appear in rocks from 3.2 Ga, but recent carbon-dating techniques applied to rocks from
and Defining Lifeplugin-autotooltip__plain plugin-autotooltip_bigDefining Life

There isn’t, as yet, any definition of a 'lifeform' which can withstand logical scrutiny.

Exceptions can easily be found for any definition so far presented. For example (from The American Heritage Dictionary of the English Language

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