The first life on Earth may have begun in puddles and ponds, not oceans


A new study from mit has shown that the ancient ponds (or large puddles) can provide a suitable environment for breeding the first forms of life on Earth — it is the ponds, not oceans as previously thought. According to scientists, shallow water with a depth of about 10 centimeters, can contain a high concentration of what scientists believe was a key ingredient for the emergence of life on Earth: nitrogen.

How life first appeared on Earth?

In a shallow reservoir of nitrogen in the form of nitrogen oxides would have a good chance to accumulate in sufficient quantity for reaction with other compounds and the creation of the first living organisms. In a much deeper oceans nitrogen would be more difficult to establish a significant presence, catalyzing life.

“Our General message is that if you think that the origin of life required fixed nitrogen, as many think, then life would be extremely difficult to emerge in the ocean,” says lead author Sukrit a Ranjan, a postdoc Department of Earth Sciences, atmosphere and planetary science at the Massachusetts Institute of technology. “It would be much easier to appear in the pond”.

The Ranjan and his colleagues published the results of their work in the journal Geochemistry, Geophysics, Geosystems.

By the way, if you wonder how did the research of the emergence of life on Earth — we recommend our longed in six parts:

Part one: how to make a cage?

Part two: the split in the ranks of scientists

Part three: the search for the first Replicator

Part four: the energy of the protons

Part five: so how is it to create the jail?

Part six: the Grand unification

To break the link

If primitive life really arose as a result of key reactions involving nitrogen, according to the scientists, this could happen in two ways. The first hypothesis involves the deep ocean, where nitrogen in the form of nitrous oxide could react with carbon dioxide released from hydrothermal vents, with the formation of the first molecular building blocks of life.

The second hypothesis on the origin of life, based on nitrogen, includes RNA — RNA, or a molecule that helps to encode our genetic information. In its primitive form the RNA was probably free-floating molecule. Some scientists believe that when in contact with nitrous oxides RNA could chemically to form a first molecular chain of life. This process of formation of RNA could occur either in the oceans or in shallow lakes and ponds.

Nitrogen oxides were probably deposited in water bodies, including oceans and ponds, as remnants of the decay of nitrogen in the Earth’s atmosphere. Atmospheric nitrogen consists of two nitrogen molecules related to the strong triple bond, which can destroy only extremely energetically powerful event — lightning.

“Lightning is similar to the explosion of a very powerful bomb,” says Ranjan. “It produces enough energy to break the triple bond in our atmospheric gaseous nitrogen to produce nitrous oxides, which can then get into the water”.

Scientists believe that the early atmosphere could be enough lightning to produce an abundance of nitrogen oxides that contribute to the origin of life in the ocean. The Ranjan said that scientists have assumed that the stock of nitrogen oxides were relatively stable after the introduction of compounds in the oceans.

But a new study he identifies two significant “discharge funnel” — that is, effects that could destroy a significant portion of the nitrogen oxides, particularly in the oceans. He and his colleagues reviewed the scientific literature and found that nitrogen oxides in water can be destroyed in the interaction with UV light of the sun, and also with the dissolved iron released from the primitive ocean species.

The Ranjan said that as ultraviolet radiation and dissolved iron could destroy a significant portion of the nitrogen oxides in the ocean, sending connections back to the atmosphere as gaseous nitrogen.

“We have shown that if you consider these two new craters, which no one thought before, the concentration of nitrogen oxides in the ocean will be reduced 1000 times compared to what people expected before,” says Ranjan.

“Build a Cathedral”

If we talk about the ocean, ultraviolet light and dissolved iron would make nitrogen-containing oxides are much less available for the synthesis of living organisms. However, in the shallow waters of life would be the best chance to stay afloat. Partly because ponds have much smaller volume in which to dissolve the contents. As a result, nitrogen oxides accumulate to much higher concentrations in ponds. Any “funnels” in the UV light and dissolved iron would have a smaller impact on the total concentration of the compound.

The Ranjan said that the smaller the pond, the greater the likelihood that nitric oxide will interact with other molecules, in particular RNA, for catalysis of the first living organisms.

“These ponds could be the depth of 10-100 cm with a surface area of tens of square meters or more,” says Ranjan.

It may seem that it’s a puddle, not a pond — but in this sense: in a deeper environment of nitrous oxides would just be too diluted, which would exclude any involvement in the chemistry of the origin of life. According to the estimates of other groups, about 3.9 billion years ago, shortly before the first signs of life on Earth, all over the world may have been about 500 square kilometers of small lakes and ponds.

“This is very little compared with the number of lakes that we have today,” says Ranjan. “However, for the beginning of life this is enough”.

The debate about whether life originated in pools or oceans continues, but the Ranjan believes that the new research presents compelling evidence in favor of the first.

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