According to science, life gradually evolved from straightforward non-living (inorganic) molecules to sophisticated organic (living) ones. Chemical reactions defined the early stages of this development. The earliest forms of life on Earth came in the form of prokaryotic organisms as a result of these orderly chemical processes. Single-celled organisms without membrane-bound organelles made up the earliest living forms on the planet. From these primordial, primitive cells, life developed into the incredibly complex forms that we see today.
The Stages of Chemical Evolution
As mentioned, the process of change happened in phases. Things started when non-living molecules found in ancient settings slowly changed to give rise to simple organic substances like amino acids. The components of the ancient environments include elements like hydrogen, ammonia, water, and methane. Surprisingly, oxygen never formed a part of this environment. This implied it became a chemically reducing agent in the chemical reactions that formed life. The main source of energy came from the ultraviolet rays of the sun. This energy played an important part in the chemical reactions. This kind of chemical synthesis would only take place in an atmosphere without oxygen. Photosynthetic cells which became a part of this process helped in the release of oxygen as a by-product. The oxygen formed part of the formation of the ozone layer that henceforth protected the Earth from ultraviolet radiation. This argument would be supported by an experiment by Stanley Miller and Harold Urey in 1957.Formation of Protobionts
The organic compounds that resulted in the early stages would combine to form large units like proteins. Through dehydration, these units would link up and produce polymers. Subsequently, polymer interactions would give rise to Protobionts. Protobionts exercised other properties of living organisms; however, they did not display reproductive characteristics.Reproduction and RNA
In the final stage of evolution, Protobionts developed the ability to reproduce new generations of their kind. They had RNA, which played a vital part in the transmission of characteristics to the next generation. Therefore, through fission, this RNA was passed on to the offspring.Conclusion
In conclusion, while these stages of evolution may seem complex and less convincing, chemical evolution provides evidence of the origin of life from the lifeless inorganic substances.References
Bernd Markert, Stefan Fränzle, Simone Wünschmann. Chemical Evolution: The Biological System of the Elements. New York: Springer, 2015.
Martin J. Van Kranendonk, David W. Deamer andTara Djokic. “Life Springs.” Scientific American (2017).
Rauchfuss, Horst. Chemical Evolution and the Origin of Life. New York: Springer, 2008.
