Just before the Cambrian explosion. Is it a possible sign of maturity — in the light of so much more information today — that a researcher does not rush to insist that the near disappearance must be the cause of the Cambrian explosion?
Shortly after this time, the Cambrian explosion occurred and complex animals emerged across the planet. “One can speculate — and there have been some speculations — that a weaker magnetic field may have some relationship to these evolutionary events,” Tarduno said. That is because a weaker field might allow more radiation to get through, which could cause DNA damage and higher mutation rates, which in turn, might have lead to more species evolving.
But this is mere speculation, Tarduno said. When Earth’s magnetic field weakens a bit during events such as magnetic reversals (where the north and south poles flip), for instance, there’s no evidence that species are affected, he added.Yasemin Saplakoglu, “Earth’s Magnetic Field Nearly Disappeared 565 Million Years Ago” at LiveScience
It certainly is mere speculation when we consider that, generally speaking, radiation is much more likely to produce damaging mutations than helpful ones. It would be interesting to know if some Ediacaran species disappeared at this point.
Just a few of the alternative plotlines for the causes of the Cambrian explosion: Researchers: Extreme fluctuations in oxygen levels, not gradual rise, sparked Cambrian explosion
Maverick theory: Cambrian animals remade the environment by generating oxygen
Did a low oxygen level delay complex life on Earth?
There was only a small oxygen jump
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Animals didn’t “arise” from oxygenation, they created it, researchers say
Theory on how animals evolved challenged: Some need almost no oxygen
New study: Oxygenic photosynthesis goes back three billion years
Enough O2 long before animals?
Life exploded after slow O2 rise?
So the Cambrian really WAS an explosion then?
Researchers: Cambrian explosion was not an explosion after all (When in doubt, insist that nothing happened.)