New discoveries that change the "origin of life"

Researchers from the University of Cambridge and the University of Cape Town may have found a way to solve the mystery of how phosphorus became an important part of life on Earth, and they have recreated prehistoric seawater
containing phosphorus in their labs.

Their findings, published in the journal Nature Communications, suggest that seawater may be a source of phosphate loss, suggesting that there may be sufficient amounts of seawater to support life
without the need for special environmental conditions.

Professor Nick Tosca of the University of Cambridge, one of the authors of the study, said: "This could really change the way we think about
the environment in which life originally originated.
"

The study, led by Cambridge PhD student Matthew Brady, revealed that if seawater contained a lot of iron, early seawater could have carried 1,000 to 10,000 times
more phosphate than previously thought.

Phosphate is a key component of the DNA and RNA that make up life, although it is one of
the least common elements in the universe relative to its biological significance.
The mineral form of phosphate is also relatively difficult to obtain – it is difficult to dissolve in water for life
.
Scientists have long suspected that phosphorus became part of living things long ago, but it's only recently that they've begun to recognize its role
in directing the synthesis of molecules needed for life on Earth.
"The experiments showed that it made amazing things happen – if there was a lot of phosphate in the solution, chemists could synthesize key biomolecules," said
Tosca, professor of mineralogy and petrology in the University of Cambridge's Department of Earth Sciences.
However, there has been controversy
about the exact environment required to produce phosphate.
According to some studies, phosphorus should actually be less readily available
to life when iron is plentiful.
However, this is controversial because the early Earth's atmosphere was oxygen-deficient and iron should have been widely present
.
They used geochemical modeling to simulate conditions on early Earth to understand how life depended on phosphate and what kind of environment the element would have evolved
.

Brady said: "It's exciting
to see that simple experiments in a bottle can overturn our view of the early Earth's environment.
" In the lab, they synthesized seawater
from the same chemicals thought to have existed in Earth's early history.
They also conducted experiments in an oxygen-starved atmosphere, just like
the ancient Earth.
The team's results suggest that seawater itself may be the main source of
this basic element.
"This doesn't necessarily mean that life on Earth started in seawater," Tosca said, "and it opens up a lot of possibilities for how seawater can provide phosphate to different environments — for example, on lakes, lagoons or coastlines, where waves from seawater may carry phosphate to
land.
" ”

Previously, scientists had proposed a range of methods for producing phosphate, some of which involved special environments, such as acidic volcanic springs or alkaline lakes, and rare minerals
found only in meteorites.

"We have a hunch that iron is key to phosphate solubility, but there is not enough data
," Tosca said.
When the team looked at seawater from sediments deposited in the modern Baltic Sea, they had the idea for
an experiment.
"It's unusual because it's high in phosphate and iron — and we're starting to wonder what's different
about these specific waters.
"

In their experiments, the researchers added varying amounts of iron to a series of synthetic seawater samples and tested how much phosphorus
it could hold before forming crystals and separating the mineral from the liquid.
They then built these data points into a model that could predict how much phosphate ancient seawater could hold
.

Baltic Pore Water provided a set of modern samples that they used to test their models
.
"We can perfectly reproduce this unusual water chemistry," Tosca said
.
From there, they went on to explore the chemical composition
of seawater before any living things appeared.
The results also have implications
for scientists trying to understand the possibilities of life beyond Earth.
Tosca said: "If iron helps put more phosphate in solution, then this may be related
to early Mars.
The evidence for the presence of water on ancient Mars is abundant, including ancient riverbeds and flood sediments
.
We also know that there is a lot of iron on the surface of Mars, and sometimes the atmosphere is deprived of oxygen
.
They simulated the passage of surface water through rocks on the Martian surface, suggesting that iron-rich water may also provide phosphate in this environment
.

"It will be interesting to see how this community uses our results to explore new, alternative pathways for life on Earth and further afield
," Brady said.

References: Marine phosphate availability and the chemical origins of life on Earth