I was just talking tonight to somebody on a 2012 forum and the idea was interesting because it dovetails pretty closely with everything else I have been learning about the relationship between the Sun and the Earth.
Here are the premises, all from standard accepted geoscience:
1. Nobody is sure what creates the magnetic field that shields the Earth from cosmic radiation. There are plenty of theories but most of them do not hold up when you do the math. The field just is. Get a couple of beers into a good geologist and they'll admit this to you.
2. Current evidence indicates that magnetic field strength does wax and wane inside a grand series of cycles starting with the 11 year sunspot cycle, the 12000 year larger cycle, the 22000 year cycle that is wrapped around that. Despite how politically correct it is to pretend that big thing you see up in the sky doesn't exist and if it does has no affect on the Earth, the fact is an honest scientist will admit there appears to be a very complex and elaborate relationship between magnetic reversals on the Sun and magnetic reversals here on the Earth.
3. Some scientists have suggested that the Earth's magnetic field is charged exactly like a dynamo inside a DC motor by the alternation of the Sun's magnetic field. It has been posited that this is really the energy source for our protective magnetic field ... we are parasites on the heliosphere we share with the Sun and it's regular flip-flopping. There's just one hole in this theory ... at the levels of energy we know about in recorded history, there doesn't seem to be enough juice to create a field of the strength we see in our planet's magnetic field. Something has to make up the difference somewhere that we don't currently know about for this theory to hold water.
Follow all that? Okay, here come's the slam-dunk.
It is possible that the only thing that makes life possible on this planet are the regular catastrophic magnetic reversals triggered by the Sun to charge up our shield. Without these cyclic catastrophic events, our magnetic field would be too weak to protect us and the surface would be sterilized by cosmic radiation. Nothing but deep underground bacteria could survive. In order to have life at all on this planet ... we need regular magnetic reversals to charge our field.
Interesting stuff, right? Think about this for a while.
In addition to causing regular extinction cycles, these reversals also drive rapid evolutionary change (explaining "the fossil gap" that is a serious hole in evolutionary theory), lay down diamonds and precious metals, create hydrocarbons (oil, coal, shale) and may be the reason you and I are not sitting in a tree somewhere eating fruit and throwing our feces at one another.
When you find a theory that explains a list this long of what were previously "mysterious phenomenon," you either need to find a major flaw in it or overturn your existing paradigm and adopt this one ... which in my opinion is far superior in it's ability to clarify as opposed to obscure the world around us. Accept magnetic reversal as a starting premise and you will find you can answer an awful lot of questions that regular scientists just shrug and give you dumb looks about.