A group of scientists are looking for clues about the origin of life in a massive chunk of rocks they pulled up from deep below the seafloor.
In the pitch-black waters at the bottom of the Atlantic is a vast array of hydrothermal vents and hot springs that, some scientists hypothesize, offer a similar environment to where life may have blossomed on Earth billions of years ago.
The region is called the Lost City, and it has been a hot spot of scientific interest for decades.
But there was one area of the Lost City that researchers couldn’t access until recently: the deep sub-seafloor rock that supports the city. Hidden within that rock could be organic molecules that hold clues to how life began.
“It sounds crazy to say that, but it’s not wrong,” Susan Q Lang, an associate scientist at the Woods Hole Oceanographic Institute, told Business Insider.
Lang co-led a team last year that drilled deeper into that seabed than ever before and obtained a sample that’s over 4,000 feet long. Here’s how they achieved such a feat and what they’ve found in those rock samples, so far.
The drilling took place from a 470-foot-long research vessel in the Atlantic Ocean.
Not far from the underwater mountain range the Mid-Atlantic Ridge, Lang watched a team of experts drill over a kilometer below the surface on the research vessel JOIDES Resolution.
“They made magic happen,” Lang said. Up to that point, people had only drilled into this type of rock to a depth of about 200 meters (0.12 miles), Lang said.
When Lang and the team surpassed 200 meters they were already extremely excited, but then the drill just kept going.
“Within a day we were at like 275 meters. And then three days later we were at like 500,” Lang said. They kept drilling until they reached a record depth of 1,268 meters.
Researchers obtained a record-breaking sample of mantle rocks.
It’s not the deepest hole ever drilled, but it is the deepest sample of this kind of ocean rock researchers have ever obtained, Lang said.
Lang and the team were after the type of rock that once existed deep within Earth’s mantle — the layer between Earth’s crust and core.
While the drill didn’t go into the mantle itself, the sample contains pieces of it that rose up from deeper in the Earth due to tectonic activity.
The Lost City could hold clues to the origin of life.
The researchers could have drilled just about anywhere on the seafloor, but they chose a site near the Lost City because its conditions may echo the environment present when life started forming.
The Lost City has what are known as carbonate towers made of limestone that stream out fluid between about 59 degrees to 239 degrees Fahrenheit, Lang said.
These fluids have high amounts of hydrogen. “Hydrogen is a really good fuel source, and so microorganisms can use it to fuel their metabolisms,” Lang said.
Perhaps it was crucial to early life forms, too.
If you want to know about Earth’s early days, you need to dig deep.
When life started to form around 4 billion years ago, Earth was oxygen-free. Then the advent of photosynthesis came about, which was great for life on Earth but not so great for Lang’s research.
“Photosynthesis has dramatically altered the surface of Earth by the production of O2, which has remade the types of minerals in rocks,” Lang said.
That’s why, instead of studying carbonate towers and the Lost City’s surface, Lang and her colleagues drilled further down, about a half mile away.
If life debuted in this type of environment, signals to its origins could be locked inside the molecules deep underground, which are unaltered by surficial processes like photosynthesis, Lang said.
Looking for evidence of oxygen-free life
The research team collected an over 4,000-foot core of a dense igneous rock called peridotite.
Because Lang and the team were working with samples that had never been exposed to the surface, it was important to preserve their subsurface conditions.
To do so, the team kept some rocks from being exposed to oxygen.
These samples from the deep give the researchers a better chance of seeing how molecules formed before photosynthesis started on Earth 3.5 billion years ago, Lang said.
Researchers want to grow microorganisms based on the rock samples
While Lang looks for molecular signatures, others on the team are after something else.
Microbiologists want to look at the type and amount of microbes found on the rocks, geologist Johan Lissenberg, another member of the research team, told Reuters. It’s another huge mystery the samples could help solve.
“We know very little about the rock microbes,” Fengping Wang, a geomicrobiologist with the project, told Quanta Magazine earlier this year. “It’s one of the last questions in the deep biosphere: What’s in the hard rocks?”
Researchers are still studying the samples
The pathway to life may have started with hydrogen from a deep-sea vent. It created small organic compounds by mixing with carbon dioxide and water. More reactions led to longer organic acids and then amino acids, according to Lang. Eventually, the first microbes formed.
The research team is focused on the early steps in the process. “We are looking for the presence of a lot of these small organic molecules that we would expect are those first steps,” Lang said.
It’s still the early stages of the search for these molecules, but the researchers published their early results about the mantle’s chemical makeup in the journal Science.
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