One of the richest lines of research for those thinking about life beyond Earth has been the world of microscopic creatures that live in especially extreme and hostile environments here. The realm of extremophiles has exploded in roughly the period that exoplanet discoveries have exploded, and both serve to significantly change our view of what’s possible in nature writ large.
I was reminded of this with the publication today of a paper on extreme life in the deep mines of South Africa. This is not a brand new story, but rather significant step forward in a story that has implications galore for the search for life beyond Earth.
The extremophile chronology in South Africa goes like this:
First there was the microbe D. Audaxviator, “the Bold Traveler,” found living in light-less solitude more than two miles down a South African gold mine. Nothing alive had ever been found in rock fractures at that depth before.
Then there was H. Mephisto, the “Worm From Hell,” the first complex, multi-cellular creature (a type of worm) found living at almost equal depths in the same group of mines.
Now the researchers who made both of those discoveries have discovered a “veritable zoo” of multicellular creatures living in the wet rock fissures of the gold and diamond mines of the Witwaterstrand Basin of South Africa, roughly
a mile below the surface.
The earlier discoveries (reports about them were published in 2006 and 2011) had already changed scientists’ understanding of life in the rocky underworld. They had also given encouragement to those convinced that microbes and maybe multi-celled creatures can survive in fissures deep below the surface of Mars and other moons and planets. The latest jackpot carries this shift in thinking further.
“It is very crowded in some places down under,” said Gaetan Borgonie of ELi, a Belgian nonprofit that studies extreme life, and of South Africa’s University of the Free State in Bloemfontein.
Borgonie, lead author of a paper about the “veritable zoo,” said that his discovery in 2011 of a new species of nematode at great depth had been dismissed by some as a “freak find.” But now, he said, “the fact that we have found in two mines, in different water, two ecosystems featuring several types of invertebrates hopefully puts that notion to rest as wrong.”
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