What is the science of the magnetosphere?
Excuse my ignorance - but the computer models we've seen with respect to the so-called "geodynamo" eddy effects in the various magma layers adjacent to the crust and the inner core are quite complex. When Dr. Glatzmaier's model was wound up and let go, ultimately it did reverse itself without any apparent external stimulus - which would imply a fairly regular flip-flop that would prove out historically. It has not actually been regular.
In the meantime, none of us have ancestors with memories good enough to go back the 700,000-plus years to the last known reversal. Prior to that the reversals (according to Scientific American - April '05 and other sources) occurred more frequently than the 250,000 yr. interval suggested elsewhere here. Now, if Dr. Glatzmaier can model the core reasonably well, has anyone else seen any attempt to model the larger interactive system with the magnetosphere, solar wind, etc. in the event of a reversal?
There should be adequate computing power out there to model such a hypothetical event. Solar/earth physics presupposes an unbroken interactive system from the sun's core to the Earth's core with multiple nuances... very computation heavy but probably doable. Jupiter is a big player in the Earth's magnetosphere (it's been known since the '50's that Jupiter's position can predict whether a solar storm will disrupt Earth electrical/radio transmission for instance) so it's hard to isolate just one or two variables.
Paleological evidence is sketchy... the only thing you can pretend to "know" is what you actually find. Everything you don't find is what you don't know. Humans or human-likes certainly survived pole reversal - although we don't know much "exactly" about that nowadays - there seems to be recent thermoluminescent evidence that Neanderthal, Cro-magnon (and possibly homo sapiens?) overlapped significantly rather than were sequential. [see
http://www.daybreaknuclear.com/bortolot_tl.html]
It's awfully hard to say "exactly" what stresses were put on mammalian (and human) life span, newborn survival rates, food supply, genetics, climate adaptation and the like by the periodic magnetic field collapses and reversals. It would be helpful for people reconstructing species history to have some kind of idea.
Example: if, as a consequence of a "mutation event," epihippus were joined by two other horse-like animals (or multiple other horse-like animals) how closely would we be able... today... to tie that to a pole reversal, or not? Especially if most of the disfunctional/impractical mutations died after one or a few generations? Epihippus might live on... but there also might be one or two other variants of epihippus starting a useful evolutionary line. This DID in fact occur for the next 7 - 10 million years with mesohippus and miohippus, both of which appeared suddenly (stimulated by pole events?) and then split still further, with epihippus failing eventually but multiple divergences co-existing (and competing) at the same time, and with surviving/competing lines ultimately moving to zones of different supportive flora. Does the paleologic record match the "chron" record or not?
I'm neither intending "junk science" wild theory or asking lockstep adherence to Darwinian gradualist evolution. I'd simply curious to know if pole reversals could be one of several important variables impacting species survival and/or evolution, and are we in an actual position to make intelligent judgements on the matter - or do we simply lack evidence one way or the other? I think it might be an unanswered, but not unimportant, question in this age of creationism.
Lack of evidence (at the moment) does not explain everything.
