Scientists are coming ever closer to understanding the cellular navigation tools that guide birds in their unerring, globe-spanning migrations.

The latest piece of the puzzle is superoxide, an oxygen molecule that may combine with light-sensitive proteins to form an in-eye compass, allowing birds to see Earth’s magnetic field.

“It connects from the subatomic world to a whole bird flying,” said Michael Edidin, an editor of Biphysical Journal, which published the study last week. “That’s exciting!”

The superoxide theory is proposed by Biophysicist Klaus Schulten of the University of Illinois at Urbana-Champaign, lead author of the study and a pioneer in avian magnetoreception. Schulten firsthypothesized in 1978 that some sort of biochemical reaction took place in birds’ eyes, most likely producing electrons whose spin was affected by subtle magnetic gradients.

Reverse-Engineering the Quantum Compass of Birds | Wired Science | Wired.com