What set the stage for the emergence of life on early Earth?

There will never be a single answer to that question, but there are many partial answers related to the global forces at play during that period.  Two of those globe-shaping dynamics are the rise of the magnetic fields that protected Earth from hazardous radiation and winds from the Sun and other suns,  and plate tectonics that moved continents and in the process cycled and recycled the compounds needed for life.

A new paper published in the Proceedings of the National Academies of Science (PNAS)  reports from some of the world’s oldest rocks in Western Australia evidence that the Earth’s crust was pushing and pulling in a manner similar to modern plate tectonics at least 3.25 billion years ago.

Additionally, the study provides the earliest proof so far of the planet’s magnetic north and sound poles swapping places — as they have innumerable times since.  What the switching of the poles tells researchers is that there was an active, evolved magnetic field around the Earth from quite early days,.

Together, the authors say, the two findings offer clues into how geological  and electromagnetic changes may have produced an environment more conducive to the emergence of life on Earth.


The early Earth was a hellish place with meteor impact galore and a choking atmosphere.  Yet fairly early in its existence, the Earth developed some of the key geodynamics needed to allow life to emerge.  The earliest evidence that microbial life was presented is dated at 3.7 billion years ago, not that long after the formation of the planet 4.5 billion years ago. (Simone Marchi/SwRI)

According to author Alec Brenner, a doctoral student at Harvard’s Paleomagnetics Lab,  the new research “paints this picture of an early Earth that was already really geodynamically mature. It had a lot of the same sorts of dynamic processes that result in an Earth that has essentially more stable environmental and surface conditions, making it more feasible for life to evolve and develop.”

And speaking specifically of the novel readings of continental movement 3.25 billion years ago, fellow author and Harvard professor Roger Fu said that “finally being able to reliably read these very ancient rocks opens up so many possibilities for observing a time period that often is known more through theory than solid data.”… Read more