The facts prove it again and again. These transitional periods are very violent events at the surface.
The universe is driven by electrical phenomenon and the magnetic reversal is an intimate part of the relationship between the Sun and the Earth. It is possible that our magnetic field itself is only recharged by these events and without it we'd experience cosmic radiation directly on the planet's surface.
The evidence is that the Neanderthals used to cruise through these events, probably because of their fondness for the underground refuges that they are intimately associated with. This is a big hint to other species that just because you killed the Neanderthals doesn't mean your ideas and evolutionary strategies were superior to theirs. All it means is that you killed the Neanderthals.
When in doubt at how to survive long term as a race people should always ask themselves WWAND? ("What Would A Neanderthal Do?") These people had mastered survival in all conditions for over a million years before Sapiens was even a definable type. They were big on caves and were never far away from the subterrene.