GEOMAGNETIC REVERSALS AND GENOME IMPRINTING

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? Spe cifically, 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 un der an N . B imprinting paradigm, where N is the horizontal vector poi nting to magnetic north and B the geomagnetic field vector. Even with a compass that is invariant under reversals, there are nevertheless po tential difficulties due to discontinuities in the magnitude of the fi eld during the transition between one chron and the next. Indeed, tran sitions may be one reason for other-than-magnetic avian auxiliary comp asses. Additional problems may also arise during transitions because o f high rates of change in B. However, the largest reported dB/dt (Stee ns Mountain event) is estimated at 1 mu T/day, seemingly too small to induce significant Faraday current density. Reversals may have also he lped 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 mad e for an ion cyclotron resonance interaction. Direct involvement in th e cell-signaling activities of biological ions would provide such flex ibility, and also point to a broader role for the GMF in modulating CN S function than merely to provide orientation.