Magnetosensation: the unsolved mystery

Magnetosensation, or the magnetic sense, is the ability of organisms to detect the Earth's magnetic field. Behavioral evidence supporting magnetosensation emerged in the latter half of the twentieth century, and it is now recognized as widespread across the animal kingdom. Yet the mechanisms underlying this sense remain poorly understood, with three main hypotheses proposed: magnetite-based detection, radical pair reactions in photosensitive molecules, and electromagnetic induction. This review provides a concise overview of current knowledge on magnetosensation, emphasizing behavioral evidence, sensory mechanisms, and the neural processing of magnetic information. We also discuss findings on magnetosensitivity in humans, highlighting evidence that suggests humans may retain a residual unconscious magnetic sense. We argue that understanding the mystery of magnetosensation has broad implications: it can yield insight into poorly understood biological and health effects of magnetic fields, inform the emerging field of magnetogenetics for remote control of cellular activity, and guide the protection of ecosystems dependent on magnetosensitive species.