Just as Alice fell down the rabbit hole and found herself in another land with many a strange creature, scientists currently believe that deep below Earth’s surface is another world teeming with miniscule worms and microbes. First, however, let us take a look at the above-ground bacterial world. While the world human population is estimated to be just about six billion or so right now, the world bacteria population is over five million trillion trillion individuals. And that is a statistic from 1998. This number includes the bacteria that exist in the environment and the bacteria that reside inside organisms, such as the Escherichia coli that have taken up residence inside our large intestines. As a review, bacteria are prokaryotic, meaning that unlike eukaryotes, their DNA is not enclosed in a nucleus, and they have no organelles. More than half of the life on Earth is composed of bacteria.
Now, back to these underworld bacteria: Robert Hazen, of the Deep Carbon Observatory, says that these bacteria could be residing in locations about six to twenty miles beneath the Earth’s surface. For example, in China, microbes have been found six kilometers below the Songliao basin. Researchers have also found worms one kilometer below the surface in South Africa. The question then arises about how in the world these organisms could survive in such adverse conditions like being in an environment sans oxygen. Well, the newly found bacteria can survive without oxygen and archaea can depend on ammonia or sulphur for nutrients.
Not only are these creatures found in these subterranean places, but researchers currently speculate that they may be millions of years old, remaining in a non-dividing state for so long that they seem as if they are dead! Such creatures could go millions of years without undergoing division. How incredible–a world seemingly stuck in time. Hazen is also considering an alternative view of how life began, believing that life, rather than springing up on the surface, has subterranean roots due to the evidence that this sort of environment has the components for life: energy, water, and carbon. Hazen even takes this hypothesis so far as to say that it could be possible that life on Earth came from Martian life in that life forms living on asteroids (an environment similar to underground Earth) from Mars could have immigrated to Earth post asteroid collisions. Further research into such a hypothesis could bring about dramatic shifts in the current ideas about the evolution of Earth and its life.
Written by Aishwarya Vishwanath.