The Laschamp Event evidence shows that the magnetic field of the Earth can change quickly, and just as quickly change back. Other magnetic field evidence shows large increases and polarity changes. Either the magnetic field of the Earth has an unknown mechanism as its cause (not unlikely, since it remains unexplained), or the Earth is sometimes in the presence of an outside magnetic field (perhaps from some kind of massive solar event). Either way, magnetic field fluctuations are just a uniformitarian alibi for events — such as global glaciation — that are caused by brief, unusual events. The Earth’s magnetic field means squat to the Earth’s climate.
[snip] What is remarkable is the speed of the reversal: “The field geometry of reversed polarity, with field lines pointing into the opposite direction when compared to today’s configuration, lasted for only about 440 years, and it was associated with a field strength that was only one quarter of today’s field,” explains Norbert Nowaczyk. “The actual polarity changes lasted only 250 years...” [/snip]
https://www.sciencedaily.com/releases/2012/10/121016084936.htm
” magnetic field fluctuations are just a uniformitarian alibi for events”
Not “just”.
I’m sure they can be! And that there are examples of the backward doing so. But radiation-caused mutation is an established fact. And a huge weakening of the magnetospere would increase mutation.
A strict limit though would be “beneficial” mutations. Very rare. That’s the catch.
I don’t mean to denigrate the study of mating-influenced genetic change, and the myriad factors involved such as climate.
But it’s a fact that radiation can cause it too.
( Though beneficial mutation is a rare result in all but the simplest organisms- it happens.)
Ancient Tree With Record Of Earth's Magnetic Field Reversal In Its Rings Discovered