Biological effects of weak magnetic fields: can the radical‐pair mechanism provide a universal explanation?

ABSTRACT The biological effects of weak magnetic fields have long been a subject of scientific inquiry, with increasing evidence supporting their influence on biochemical, physiological, and behavioural processes. This review describes three primary mechanisms of magnetoreception that have been identified in migrating animals: use of magnetite in sensitive cells, sensitive electroreceptors, and spin dynamics in cryptochrome radical pairs. It also critically examines the potential of the radical‐pair mechanism to serve as a universal explanation for the diverse non‐sensory biological effects of weak magnetic fields, including extremely low‐frequency magnetic fields, static magnetic fields, and hypomagnetic conditions. Understanding how weak magnetic fields influence radical‐pair processes could revolutionize our approach to bioelectromagnetic interactions and provide new avenues for development of medical and technological applications. Future research should focus on direct real‐time monitoring of radical‐pair‐mediated biochemical reactions, evaluating the interplay between magnetic fields, light exposure, and temperature, and refining theoretical models to bridge the gap between quantum‐scale interactions and macroscopic biological effects. Addressing these questions will be essential in determining whether the radical‐pair mechanism can serve as a unifying principle in magnetobiology.