Computers are simulating the ancestral versions of the most common protein on Earth, giving scientists an unparalleled look at early life’s development of harnessing energy from the sun and production of oxygen.
These findings could shed light on the evolution of alien life elsewhere in the Universe, researchers said. They recently detailed their findings in the online version of the journal Geobiology.
Photosynthesis , which uses energy from sunlight to create sugars and other carbon-based organic molecules from carbon dioxide gas, has played a major role in Earth’s history. Photosynthesis supports the existence of plants and other photosynthetic organisms across Earth’s lands and seas, which in turn sustains complex webs of animal and other life. It also generates the oxygen gas that has chemically altered the face of the planet. [Early Earth: A Battered, Hellish World with Water Oases for Life]
Although oxygen currently makes up about a fifth of the Earth’s atmosphere, very early in the planet’s history, oxygen was rare. “Our planet has, for much of its history, resembled an altogether alien place,” said Betül Kacar, an evolutionary biologist and astrobiologist at Harvard University.
The first time the element suffused Earth’s atmosphere to a great extent was about 2.5 billion years ago in what is called the Great Oxidation Event. Prior research suggests this jump in oxygen levels was almost certainly due to cyanobacteria — microbes that, like plants, photosynthesize and produce oxygen.
Studying how life evolved in the alien conditions of Earth’s deep past may shed light on “conditions that may more closely align with the temperature or atmospheric compositions of a wide variety of planets outside our Solar System,” Kacar said. In other words, research into early life on Earth could help us understand possible alien life on distant exoplanets.