Billions of years ago, self-replicating systems of molecules became separated from one another by membranes, resulting in the first cells. Over time, evolving cells enriched the living world with an astonishing diversity of new shapes and biochemical innovations, all made possible by compartments. Compartmentalization is how all living systems are organized today from proteins and small molecules sharing space in separate phases to dividing labor and specialized functions within and among cells.
In 2016, astronomers using data from NASA’s Kepler mission, discovered a planet unlike anything in our solar system –a “water world” planetary system orbiting the star Kepler-62 –a five-planet system with two worlds in the habitable zone their surfaces completely covered by an endless global ocean with no land or mountains in sight.
“Utterly Different Worlds Than Earth”
“These are utterly different worlds compared to our own Earth,” said Harvard University astronomer Li Zeng in 2019 about the chances that water worlds are a common feature of the Milky Way, which was heightened by research using computer simulations showing that sub-Neptune-sized planets –planets featuring radii about two to four times that of Earth– are likely to be water worlds. Some of these planets, Zeng observed, have oceans deep enough to exert pressures equivalent to a million times our atmospheric surface pressure. Under those conditions, fluid water gets compressed into high-pres
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Researchers believe land would have been scarce some 3 billion to 4 billion years ago. Alec Brenner/Harvard University
Ancient Earth was a water world
Mar. 9, 2021 , 9:00 AM
Across the ages, sea levels have risen and fallen with temperatures but Earth’s total surface water was always assumed to be constant. Now, evidence is mounting that some 3 billion to 4 billion years ago, the planet’s oceans held nearly twice as much water enough to submerge today’s continents above the peak of Mount Everest. The flood could have primed the engine of plate tectonics and made it more difficult for life to start on land.
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Step into your new, microscopic time machine. Scientists at the University of Colorado Boulder have discovered that a type of single-celled organism living in modern-day oceans may have a lot in common with life forms that existed billions of years ago and that fundamentally transformed the planet.
The new research, which will appear Jan. 6 in the journal
Science Advances, is the latest to probe the lives of what may be nature s hardest working microbes: cyanobacteria.
These single-celled, photosynthetic organisms, also known as blue-green algae, can be found in almost any large body of water today. But more than 2 billion years ago, they took on an extra important role in the history of life on Earth: During a period known as the Great Oxygenation Event, ancient cyanobacteria produced a sudden, and dramatic, surge in oxygen gas.