Researchers from University of California, Riverside, have discovered the way ancient organisms learned to survive on early Earth: they used a protein that helped them garner energy from sunshine when there was no oxygen.
Times like this were common on Earth before the Great Oxidation some 2.5 billion years ago.
Scientists looked into proteins named rhodopsins that helped early inhabitants of our planet to capture solar energy and feed on it long before the complex process of photosynthesis became available.
There might be a lot more to early Earth lifehacks than the use of rhodopsins, according to the scientific team, and the connection between life and environment can be a perfect key to finding out more about extraterrestrial life.
"Life as we know it is as much an expression of the conditions on our planet as it is of life itself. We resurrected ancient DNA sequences of one molecule, and it allowed us to link to the biology and environment of the past," study lead Betul Kacar, an astrobiologist at the University of Wisconsin-Madison, said.
Modern rhodopsins can absorb light that photosynthetic chlorophyll pigments cannot, but the latter still complements the ancient protein in a way that points to "co-evolution, in that one group of organisms is exploiting light not absorbed by the other", according to the findings.
"The information encoded in life itself may provide novel insights into how our planet has maintained planetary habitability where geologic and stellar inferences fall short," the authors explained.
Which is why, the study continues, the understanding of how early organisms managed to fight for their life in conditions that may now seem alien to us might help scientists find and explore life elsewhere.