Human Magnetoreception as a Legacy of Earth's Magnetic Biosphere: Implications For High-Tech Civilizations

In a recent paper (Wang et al. 2019, https://doi.org/10.1523/ENEURO.0483-18.2019), we demonstrated that the human brain receives geomagnetic field information and actively processes it as a sensory modality: small rotations in the field comparable to turning one's head are capable of triggering 1-2 second drops in the amplitude of the brain's alpha-wave pattern (~8-12 Hz), indicating that the brain is both receiving and reacting to the stimulus. Additional experiments tested the 3 most probable biophysical transduction mechanisms and found that only the ferromagnetic hypothesis involving specialized sensory cells with biogenic magnetite, and not electrical induction or a quantum compass (QC), could explain the results. Humans therefore are part of Earth's Magnetic Biosphere, presumably with an evolutionary ancestry of magnetite biomineralization that goes back nearly 3 billion years to the first magnetotactic bacterium. As such, many of the common biophysical properties of the animal geomagnetic sensory system should also be a component of human neurophysiology, including inhibition by radio-frequency electromagnetic fields. Unlike induction or the QC, cells of a magnetite-based sensory organ should be able to be controlled, altered predictably, or even damaged by anthropogenic magnetic fields and radio waves such as those used in MRI and trans-cranial magnetic stimulation (TMS). Thus, the discovery of human magnetoreception brings into clear focus important questions concerning the effect that human control of electromagnetism might be having on migratory and homing animals that use Earth's magnetic field. As all sensory modalities (vision, hearing, taste, touch, smell, etc.) evolve as a result of natural selection improving behavioral responses to external stimuli, the presence of the animal magnetic sense in human neurophysiology argues that it was important for the survival of our not-too-distant ancestors.