The 'alien life' deep underneath us: Researchers find first evidence of life in Earth's mantle under the Atlantic Ocean

Rock samples from an underwater mountain in the Atlantic Ocean could help to explain how early life formed on Earth, or on other planets.

In a 47-day expedition, researchers collected rock samples that reveal signs of life in the mantle of the ocean’s crust.

The mantle rocks, which were collected by an international team using seabed rock drills, could provide clues about the reactions that fuel life in areas without sunlight, and the behaviour of carbon in such a setting.

Rock samples from an underwater mountain, Atlantis Massif, in the Atlantic Ocean could help to explain how early life formed on Earth, or on other planets. In a 47-day expedition, researchers collected rock samples that reveal signs of life in the mantle of the ocean’s crust

The expedition was led by co-chief scientists Dr. Gretchen Früh-Green ETH Zurich, Switzerland and Dr. Beth Orcutt Bigelow Laboratory for Ocean Sciences, US.

Researchers on the study pioneered the use of seabed rock drills from Germany and the UK, equipped with new technologies that allowed them to detect signs of life.

The team set out with the Rock Drill 2 from the British Geological Survey and the MeBo rock drill from MARUM in Bremen, Germany to collect the rock cores from a 4,000-m tall underwater mountain, the Atlantis Massif.

Now, a ‘science party,’ has spent the past two weeks studying the findings at the International Ocean Discovery Project (IODP) at Bremen Core Repository in Bremen, Germany.

The samples from the shallow mantle show signs of life, along with indication of unique carbon cycling and ocean crust movement.

COULD LIFE SURVIVE SO DEEP?

The mantle is composed of rock that is heated to between 500°C and 900°C (932°F-1,652°F), which under huge pressures remains solid.

The boundary between the crust and the mantle has been widely assumed to also be the seismic boundary beneath the oceans.

However, there are some who propose the the seismological boundary may actually be the lowest point at which seawater has seeped into the mantle through cracks into the rock.

This transforms the rock into a material called serpentinite.

This reaction generates methane and hydrogen, which can be used by bacteria living deep inside the Earth's crust for energy.

By examining these rocks collected from the mantle of the ocean’s crust, scientists aim to determine how they end up at the seafloor, and how they react with seawater.

This reaction could provide sustenance for life in the absence of sunlight, and the researchers say this may be how early life developed on Earth.

According to the researchers, this could also reveal the behaviours of carbon, as it is potentially sequestered – or stored – during the reaction between the rocks and seawater, having implications for the climate.

The Earth's crust makes up just a tiny amount of the planet's structure (illustrated), with the boundary between the mantle and the crust thought to be where much of the seismic activity takes place. In a 47-day expedition, researchers collected rock samples that reveal signs of life in the mantle of the ocean’s crust

‘The rocks collected on the expedition provide unique records of deep processes that formed the Atlantis Massif,’ said expedition co-chief scientist Gretchen Früh-Green.

‘We will also gain valuable insight into how these rocks react with circulating seawater at the seafloor during a process we call serpentinization and its consequences for chemical cycles and life.’

The findings reveal the processes by which life exists under extremely harsh conditions, which could help scientists as they continue to look for life on other planets.

‘During drilling, we found evidence for hydrogen and methane in our samples, which microbes can ‘eat’ to grow and form new cells,’ explained Beth Orcutt, co-chief scientist from Bigelow Laboratory.

‘Similar rocks and gases are found on other planets, so by studying how life exists in such harsh conditions deep below the seafloor, we inform the search for life elsewhere in the Universe.’