Scientists have long been puzzled by the sudden emergence of complex life on Earth

 

Scientists have long been puzzled by the sudden emergence of complex life on Earth over 500 million years ago. Now, new research suggests that a dramatic weakening of Earth's magnetic field may have played a crucial role in this development.

During the Ediacaran period, which spanned from 635 to 539 million years ago, the first complex animals appeared on the seafloor. These creatures were unlike anything seen before, with strange shapes and sizes. At the same time, the percentage of oxygen in the atmosphere and oceans increased, allowing these early complex life forms to evolve.

Researchers have discovered that Earth's magnetic field, which is generated by the motion of molten iron in the planet's outer core, was significantly weaker during this period than it is today. In fact, the field was 30 times weaker than it is now, according to a study published in the journal Communications Earth & Environment.

This weakening of the magnetic field would have allowed more solar radiation and cosmic rays to reach the Earth's surface, potentially leading to an increase in oxygen levels. The researchers believe that this increase in oxygen may have been a key factor in the emergence of complex life.

The study also sheds light on the formation of Earth's solid inner core. The inner core is thought to have solidified around 565 million years ago, which is relatively recent in geological terms. This solidification would have allowed the magnetic field to recover and strengthen, protecting the Earth from harmful radiation and solar winds.

The research team used geological evidence from rocks in Quebec and Brazil to reconstruct the history of Earth's magnetic field. They found that the field had been weakening over billions of years, but reached a critical point during the Ediacaran period.

The emergence of complex life during this period is associated with a rise in oxygen levels, which would have been necessary to support the evolution of larger, more complex organisms. While photosynthetic organisms such as cyanobacteria are thought to have played a role in increasing oxygen levels, the new research suggests that the weakening of the magnetic field may have also contributed to this process.

The study's findings have implications for our understanding of the evolution of life on Earth and the role of the magnetic field in shaping our planet's history. While the exact mechanisms are still unclear, the research provides a new perspective on the complex interplay between the Earth's magnetic field, atmosphere, and life.