New models shed light on life's origin
The research reveals clues about the physical and chemical
characteristics of Earth when life is thought to have emerged.

Date:
February 10, 2023
Source:
University of Rochester
Summary:
Researchers from the University of Rochester and the University
of Colorado Boulder used experiments and zircon chemistry to build
more accurate computer models of fluids that act as pathways from
inner Earth to Earth's surface. The models allow researchers to
simulate what metals may have been transported to Earth's surface
when life first emerged, about four billion years ago. The research
has important implications not only for discovering the origins
of life but also in the search for life on other planets.


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FULL STORY ==========================================================================
The first signs of life emerged on Earth in the form of microbes about
four billion years ago. While scientists are still determining exactly
when and how these microbes appeared, it's clear that the emergence
of life is intricately intertwined with the chemical and physical characteristics of early Earth.


==========================================================================
"It is reasonable to suspect that life could have started differently
-- or not at all -- if the early chemical characteristics of our planet
were different," says Dustin Trail, an associate professor of earth and environmental sciences at the University of Rochester.

But what was Earth like billions of years ago, and what characteristics
may have helped life to form? In a paper published in Science, Trail
and Thomas McCollom, a research associate at the University of Colorado Boulder, reveal key information in the quest to find out. The research
has important implications not only for discovering the origins of life
but also in the search for life on other planets.

"We are now at an exciting time in which humankind is searching for
life on other planets and moons, as well as in other planetary systems,"
Trail says.

"But we still do not know how -- or even when, really -- life started on
our own planet. Research like ours helps identify specific conditions and chemical pathways that could have supported the emergence of life, work
which is certain to factor prominently into the search for life outside of
our planet." The importance of metals in the emergence of life Research
into life and its origins typically involves a variety of disciplines
including genomics, the study of genes and their functions; proteomics,
the study of proteins; and an emerging field called metallomics, which
explores the important role of metals in performing cellular functions. As
life evolved, the need for certain metals changed, but Trail and McCollom wanted to determine what metals may have been available when microbes
first appeared billions of years ago.

"When hypotheses are proposed for different origin-of-life scenarios, scientists have generally assumed all metals were available because there weren't studies that provided geologically robust constraints on metal concentrations of fluids for the earliest times of Earth's history,"
Trail says.

To address this shortcoming, Trail and McCollom studied the composition
and characteristics of fluids in the lithosphere -- the outer layer
of Earth that includes the crust and upper mantle -- billions of years
ago. These lithospheric fluids are key pathways to transport dissolved
parts of rocks and minerals between Earth's interior and hydrothermal
pools in its exterior where microbial life could have formed. While
researchers cannot directly measure the metals that existed billions of
years ago, by determining the properties of the fluids, they can infer
what metals -- and the concentrations of the metals - - could feasibly
have been transported between Earth's interior and exterior during the
time when life emerged on the planet.

Clues in billion-year-old minerals Billion-year-old rocks and minerals
are often the only direct sources of information about Earth's earliest history. That's because the rocks and minerals lock in information about
the composition of Earth at the time they are formed.

The researchers conducted high-pressure, high-temperature experiments and applied these results to early-Earth zircons, a robust type of mineral collected at sites in Western Australia, to determine the oxygen pressure, chlorine content, and temperature of lithospheric fluids billions of
years ago.

They then input this information into computer models. The models allowed
them to simulate the properties of the lithospheric fluids, and, in turn, simulate which metals could have travelled through the fluids to reach hydrothermal pools at Earth's surface.

Understanding how life originated The researchers were surprised by
what the model simulations indicated. Many origin-of-life researchers,
for instance, consider copper a likely component in the chemistry that
could have led to life. But Trail and McCollom did not find evidence that copper would have been abundant under the constraints in their analysis.

One metal they did test that may have been available in high
concentrations was manganese. While it is rarely considered in
origin-of-life scenarios, today manganese helps the body form bones and
assists enzymes in breaking down carbohydrates and cholesterol.

"Our research shows that metals like manganese may function as important
links between the 'solid' Earth and emerging biological systems at
Earth's surface," Trail says.

Trail says the research will help scientists studying the origin of life
to input more concrete data into their experiments and models.

"Experiments designed with this information in mind will result in a
better understanding of how life originated."
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========================================================================== Story Source: Materials provided by University_of_Rochester. Original
written by Lindsey Valich. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. Dustin Trail and Thomas M. McCollom. Relatively oxidized fluids fed
Earth's earliest hydrothermal systems. Science, 2023 DOI: 10.1126/
science.adc8751 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230210185150.htm

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