MIT has published the results of a new study that looks at how life might have begun first on Earth eons ago. The study has found that early life was more likely to have sprung up in shallow bodies of water, like ponds, than in the ocean. MIT reckons that shallow bodies of water, around 10cm deep, would have held high concentrations of nitrogen, an ingredient key for life on Earth.
According to MIT, in shallow ponds nitrogen in the form of nitrogenous oxides would have a good chance of accumulating enough to react with other compounds and give rise to the first living organisms. In a deeper ocean, the researchers believe that nitrogen would have a harder time establishing a life-catalyzing presence.
There are two leading theories on how nitrogen was required to form early life. One suggests that in the deep ocean nitrogenous oxides could have reacted with carbon dioxide bubbling from hydrothermal vents to form the first building blocks of life. The second theory involves RNA.
In this theory RNA was likely a free-floating molecule and when it contacted nitrogenous oxides, some scientists believe that RNA could have been chemically induced to form the first molecular chains of life. This method could have happened in oceans or shallow lakes and ponds. The team believes that these nitrogenous oxides were likely deposited in bodies of water as remnants of the breakdown of nitrogen in the Earth’s atmosphere.
That breakdown is thought to have happened by an extremely energetic event, such as lightning, that could break the strong molecular bonds of atmospheric nitrogen with two nitrogen molecules. Theories are that there was plenty of lightning in the early atmosphere to produce an abundance of nitrogenous oxides. The team does think that UV light from the sun and dissolved iron from primitive oceanic rocks would have caused much of that nitrogen to go back into the atmosphere, suppressing its presence in the ocean.