Blue light and an inclination compass dependent human magnetoreception in geomagnetic food orientation

摘要

Blue light and an inclination compass dependent human magnetoreception in geomagnetic food orientation Magnetic fields, including the Earth’s magnetic field (geomag- netic field, GMF), are known to influence a wide phylogenetic range of creatures with magnetoreception, from bacteria to mammals, as a sensory cue or a physiological modulator. Despite some previous evidence, it is largely accepted that humans cannot sense magnetic fields. Here, we provide novel, compelling evidence that humans sense the GMF to orient their direction toward food, in a light- dependent manner. In a self-rotatory chair experiment, starved men, but not women, significantly oriented toward the modulated magnetic north or east, to which they were previously food- rewarded before the test, without any other helpful cues including sight and sound as their eyes were closed and they were wearing earmuffs. In contrast, unstarved or non-rewarded starved men did not show a notable orientation. Moreover, the geomagnetic food orientation was abolished with a blindfold, suggesting that sensing light is essential for magnetoreceptive behavior. Furthermore, mag- netic orientation was reproduced under blue light (>400 nm) but was not reproduced at a longer wavelength (>500 nm), indicating that blue light is necessary for magnetic orientation. Importantly, inversion of the vertical component of the GMF resulted in ori- entation toward the magnetic south, indicating that orientation is dependent of GMF inclination. The results demonstrated that human male subjects can sense the GMF and use it for magnetic food orientation when starved, and suggest that the eyes are puta- tive magnetoreception organ and an inclination compass underlies the magnetoreceptive behaviors in humans.