人类的眼睛有磁场感应能力?

Birds and sea turtles can migrate thousands of miles, by reading the Earth’s magnetic cues. But we too might have magnetic sensing abilities—in our eyes. So says a study in the journal Nature Communications. [Lauren Foley, Robert Gegear and Steven Reppert, "Human Cryptochrome Exhibits Light-Dependent Magnetosensitivity"]

Previous studies suggest long-distance migrators—and even fruit flies—pick up magnetic fields with the help of a light-sensitive protein called "cryptochrome." We produce cryptochrome too—without it, our circadian clocks would break. Human cryptochrome doesn't require light to function, though—and it doesn't seem to give us a phenomenal sensitivity to magnetic fields. But can it do more than keep the circadian clock ticking?

To find out, researchers took out fruit flies' usual cryptochrome gene and inserted the human version. And the transgenic flies had no problem navigating a magnetic maze when exposed to light—indicating the human protein can still serve as a light-sensitive magnetic sensor.

We happen to have a lot of cryptochrome in our retinas—ideally situated to receive light. Which suggests we might be able to see magnetic fields in some way. On the other hand, evolution might have just given cryptochrome a new job in new organisms. So don’t throw away your GPS.

—Christopher Intagliata