Deep beneath the surface of our planet lurks an immense amount of life, with tiny life forms such as ‘zombie’ bacteria amounting to a mass 245 to 385 times greater than the carbon mass of all humans on the surface.
A 10-year international effort to reveal our planet’s secrets found that the ‘deep biosphere’ amounts to 15 to 23 billion tonnes of life – far more than previously believed.
Scientists with the Deep Carbon Observatory drilled 1.5 miles into the seabed, and sampled microbes from mines and boreholes up to three miles deep.
The scientists say that the hitherto unknown microbes deep inside our planet are like a new Galapagos, the islands which helped to inspire Darwin’s theory of evolution.
Two types of microbes – bacteria and archaea – dominate Deep Earth.
This so-called microbial “dark matter” dramatically expands our perspective on the tree of life. Sientists now believe that about 70% of Earth’s bacteria and archaea live in the subsurface
Deep microbes are often very different from their surface cousins, with life cycles on near-geologic timescales, dining in some cases on nothing more than energy from rocks.
The findings have led some experts to question whether life actually began deep beneath the surface, either within the crust, near hydrothermal vents, or in subduction zones, then migrated upwards towards the sun.
Fumio Inagaki, Japan Agency for Marine-Earth Science and Technology says, ‘Even in dark and energetically challenging conditions, intraterrestrial ecosystems have uniquely evolved and persisted over millions of years.
‘Expanding our knowledge of deep life will inspire new insights into planetary habitability, leading us to understand why life emerged on our planet and whether life persists in the Martian subsurface and other celestial bodies.’