Science

New evidence suggests life on Earth started in shallow ponds, not deep oceans

A new study gives more evidence that life got started in shallow ponds, not the deep ocean
A new study gives more evidence that life got started in shallow ponds, not the deep ocean
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A new study gives more evidence that life got started in shallow ponds, not the deep ocean
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A new study gives more evidence that life got started in shallow ponds, not the deep ocean

Evolution is the generally-accepted explanation for how life on Earth became so complex, but there's one thing it can't explain – how life emerged from non-living matter in the first place. The prevailing hypothesis is that life got started in the ocean, where hydrothermal vents provided just the right chemical reactions. But a new MIT study has found that ancient oceans probably didn't have enough nitrogen – but shallow ponds might have.

Nitrogen is often credited as a key part of the transition from non-life to life. The story goes that when nitrogenous oxides and primitive RNA mixed, the RNA was chemically induced to start forming the first amino acids, which then developed into the first simple organisms. These nitrogenous oxides are thought to have rained down on the surface after lightning strikes split the bonds of nitrogen in the atmosphere.

But according to the new study, nitrogenous oxides likely wouldn't have lasted long enough to reach the deep-sea hydrothermal vents, and ultimately kickstart life. The team found two previously-overlooked factors that break down nitrogenous oxides in water: ultraviolet light from the Sun, and dissolved iron from rocks.

"We showed that if you include these two new sinks that people hadn't thought about before, that suppresses the concentrations of nitrogenous oxides in the ocean by a factor of 1,000, relative to what people calculated before," says Sukrit Ranjan, lead author of the study.

So if the oceans didn't have enough nitrogen in one place, where did life get started? According to the MIT team, shallow ponds are better candidates. Because there's simply less volume for the compounds to be diluted across, higher concentrations of nitrogenous oxides could build up in these ponds, giving them a better chance of interacting with molecules like RNA.

"Our overall message is, if you think the origin of life required fixed nitrogen, as many people do, then it's tough to have the origin of life happen in the ocean," says Ranjan. "It's much easier to have that happen in a pond. These ponds could have been from 10 to 100 cm (3.9 to 39 in) deep, with a surface area of tens of square meters or larger."

The idea that life didn't arise in the deep ocean isn't a complete game-changer – it's been hypothesized many times before that life could have gotten started in shallow ponds or hot springs. The researchers admit that the latest study doesn't resolve the debate, but it does provide an intriguing new piece of evidence to sway the argument towards life emerging from a shallower bowl of primordial soup.

The research was published in the journal Geochemistry, Geophysics, Geosystems.

Source: MIT

9 comments
SimonClarke
3.8 billion years ago the earth was still very hot but some crust had formed, therefore there would have been no oceans, only ponds on top of the thicker crust. Note, life didn't evolve from 3.8 billion years ago until 530 million years ago when it exploded.
RangerJones
Keep searching. It's getting more humorous every time.
F. Tuijn
OF course it did evolve, just not to the stage of multicellular organisms until about 650 million years ago.
bwana4swahili
It is obvious no one knows how life got started on Earth, except for all those taking the bible literally. Personally, I believe in panspermia. But as for how life originated elsewhere in the Universe to allow for panspermia on Earth, the jury is still very much out...
Thinker
Could have, may have, 3.8 billion years ago?, 530 million years ago?. What do you KNOW?? I think it takes a lot of faith to guess at, and even suggest the origin of life in this article. I seems to me you’ll believe anything other than that God created us unique creatures.
Doug Lough
All kinds of theory's out there. Some partially supported by science. Some just educated guesses. My uneducated guess is that life started in multiple areas under multiple conditions, in different time frames. Conditions would be different depending elevation, temperature, availability of nutrients, timing of cohabitating elements and and atoms. (right place at the right time) Thats why we have such a diversity of life. Certain conditions at the bottom of the ocean and the dry deserts would develop different starter-species. but the fundamental process would be the same as there is only so many building blocks available to start with. Then the starter-species would then breed into other species depending on proximity and compatibility.
bullfrog84
I think it's funny people are still debating "which came first". With the right circumstances life will start anywhere. Life begins and ends for new and old organisms big and small all day every day. Our end will come soon enough and it will a blink in the midst of the universe. Get over it as it is our humanity that caused it.
flyerfly
@ RangerJones...you are right it does get more and more funny all the time! But it is sad in a way that those who call science their friend have to use the words "may" ,"could", "suggests" etc. There is no certainty and it changes from year to year. How these people stay employed is the real mystery! Even the weather people get it right more often then them! Like the size of the national debt these "scientists" throw around years with such grand time scales that it boggles the mind. But such fantastic time scales are certainly needed to try and get people to believe something that would otherwise be preposterous.
Martin-tu
Finally, a decent explanation for my shallow personality, it was in my genomes all the time.