About the episode
There have been several waves in the history of our planet in which life on Earth suddenly became more complex and varied. But researchers do not yet know as well as they would like what exactly caused this.
In many cases it was probably a combination of several factors. But for a specific time block, between 591 and 565 million years ago, researchers think it could have been largely due to a dip in the strength of the Earth’s magnetic field.
That dip in the magnetic field coincided with an increase in oxygen in the atmosphere and oceans, the scientists say. And the latter probably resulted in much more complex organisms during that period.
They discovered this by studying minerals from the Earth’s crust, taken from a 591-million-year-old rock formation in Brazil. The crystals they studied contain very small magnetic minerals and from this we can see even now how powerful 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 the current magnetic field and that of a few thousand years ago.
This weakness must have lasted 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, which resulted in a higher percentage of oxygen. And ultimately possible for many much more complex plant and animal species.
Read more about the research here: Evolution: Weak magnetic field may have supported diversification of life on Earth
