About the episode
There have been several waves in our planet’s history in which life on Earth suddenly became more complex and diverse. But researchers don’t yet know as much as they would like exactly why this is.
In many cases, it may be a combination of several factors. But for a specific period of time, between 591 and 565 million years ago, researchers believe that may have been largely due to a decline in the strength of Earth’s magnetic field.
Scientists say that this decrease in the magnetic field coincided with an increase in oxygen in the atmosphere and oceans. The latter may have led to the emergence of more complex organisms during that period.
They discovered this by studying minerals in the Earth’s crust, taken from a 591-million-year-old rock formation in Brazil. The crystals they studied contained very small magnetic minerals, and from this we can see even now how strong the magnetic field was millions of years ago.
The minerals showed that 591 million years ago, the magnetic field was about 30 times less strong than today’s magnetic field and the magnetic field that had been around for a few thousand years.
This weakening must have continued for about 26 million years. Exactly the period when the amount of oxygen increased significantly.
What the researchers think happened: The weaker magnetic field allowed more hydrogen to escape from the atmosphere, leading to higher oxygen levels. This is eventually possible for many of the most complex plant and animal species.
Read more about the research here: Evolution: A weak magnetic field may have supported the diversity of life on Earth
