| Abstract: | If it is more fundamental to formulate biological expression in terms of electromagnetic fields, does this also imply that living things are especially sensitive to the external electromagnetic environment? Specifically, we examine possible genomic effects due to reversals of the geomagnetic field. To maintain sensitivity following a reversal, the Wiltschko hypothesis for the avian magnetic compass can be subsumed under an NB imprinting paradigm, where N is the horizontal vector pointing to magnetic north and B the geomagnetic field vector. Even with a compass that is invariant under reversals, there are nevertheless potential difficulties due to discontinuities in the magnitude of the field during the transition between one chron and the next. Indeed, transitions may be one reason for other-than-magnetic avian auxiliary compasses. Additional problems may also arise during transitions because of high rates of change in B. However, the largest reported dB/dt (Steens Mountain event) is estimated at 1 /u.T/day, seemingly too small to induce significant Faraday current density. Reversals may have also helped determine the nature of the interaction mechanism between GMF and living systems. Mechanisms based on fixed magnetic moments may not be capable of adapting to the reversal process. A better case can be made for an ion cyclotron resonance interaction. Direct involvement in the cell-signaling activities of biological ions would provide such flexibility, and also point to a broader role for the GMF in modulating CNS function than merely to provide orientation. |
