Analysis of rocks taken in South Africa revealed that microfossils of microbial life evolved around hydrothermal vents 3.42 billion years ago. This discovery could help to understand how life first appeared on earth. This could also have implications for exobiology in our search for living things in the solar system.
The development of life occurs in phases in which a structured state of matter, intermediate between the nonliving and the living, gradually emerges. But where did this transformation take place? This question has long been the subject of debate in biology. Did life form in a warm little pond? Or on the ocean floor around a hydrothermal vent? An article published in Scientific progress does not answer the question, but invites us to lean on the second option.
3.42 billion year old microbes
As part of the final work, the team led by prof. Barbara Cavalazzi of the University of Bologna found that micro-fossils prove the existence of life around hydrothermal vents. 3.42 billion years. The remains of this life were isolated from rocks taken from the Barberton green rock belt in South Africa.
“We found evidence of very well-preserved fossil microbes that appear to thrive along the walls of cavities created by hot water from a hydrothermal system several meters below the seafloor.”, the researcher specifies in a press release. “The underground habitat, heated by volcanic activity, may have hosted some of the earliest microbial ecosystems on Earth and this is the oldest example we have found to date.”.
The microfossil filaments found in South Africa are so well preserved that the researchers were able to identify a carbon-rich cell wall and a clear nucleus. The high nickel concentration isolated in these fossils also indicates that prokaryotic archaea, today’s life forms thrive in anoxic (oxygen-free) environments, depending on on methane to stimulate their metabolism.
As old as these fossils are, we know that life on earth may be even older. Molecular clocks show that they actually evolved at least four billion years ago. Fossil the oldest found so far (though disputed in Greenland) they are also 3.77 billion years old.
The study could also have implications in the field of exobiology, potentially increasing our chances of extraterrestrial life. Our eyes then turn to Europe (Jupiter) and Encelade (Saturn), two icy moons that can support hydrothermal activity on its underground seabed.
–
