Life on Earth is known to have begun somewhere between 3.7 and 4.5 billion years ago, after meteorites splashed down and eventually launched essential elements into warm little ponds, according to the scientists. The calculations done by the experts suggest that wet and dry cycles bonded basic molecular blocks in the ponds’ nutrient-rich broth into self-replicating RNA molecules, constituting the first genetic code for life on the planet. The researchers base their conclusion on exhaustive research and calculations, using a multi-disciplinary approach.

The available evidence suggests that life began by the time when the Earth was still taking shape, with continents emerging from the ocean and no protective ozone to filter the ultraviolet rays of the Sun.

The model developed by the scientists in order to be able to explain the phenomena that took place during the formation of the Earth, is based on previous finds of high levels of ammonia NH3 and hydrogen cyanide HCN in the discs of gas and dust located around young stars.

The experiments on Earth have showed that these molecules on icy surfaces can be processed into nucleobases after being exposed to UV light. Besides, there is evidence that during the primitive years of the Earth, almost four billion years ago, the planet was bombarded by meteorites with around 2000 kilograms of material containing carbon compounds which arrived per year.

Together with the idea that asteroids brought liquid water that eventually accumulated into oceans when the Earth’s surface was cool enough, thousands of little ponds of water when were planted with the right blend of molecules for life to emerge. RNA polymers formed in the shallow pools that evaporated and refilled periodically, bringing a kick start to a range of chemical reactions that led to more complex molecules.

 

Sources:

https://phys.org/news/2017-10-evidence-life-earth-meteorites-splashed.html

https://www.theregister.co.uk/2017/10/03/warm_ponds_hypothesis_for_life_formation/

http://www.tribuneindia.com/news/science-technology/-meteorites-splashing-into-warm-ponds-sparked-life-on-earth/476714.html