Birds Use Quantum Mechanics to See Magnetic Fields, New Research Suggests - Gizmodo

A research team, led by scientists from the University of Oldenburg in Germany and Oxford University, studied a protein known as cryptochrome-4, found in birds’ retinas.

For 20 years, experts hypothesized that this protein served as birds’ magnetic sensor, a microscopic compass that points the bird in a particular direction.

The protein participates in chemical reactions that produce varying quantities of new molecules that depend on the direction of Earth’s magnetic field.

In a step toward confirmation, Xu’s team has now observed, in great detail, how the protein responds to magnetic fields when isolated in a test tube.

Then, the team orchestrated and observed the protein undergoing chemical reactions within a test tube placed in magnetic fields about a hundred times stronger than Earth’s.

Comparing variants of the protein found in different bird species, they found that cryptochrome-4 in the migratory European robin is more sensitive to magnetic fields than the cryptochrome-4 found in chickens and pigeons, which don’t migrate.

In addition, their observations indicated that cryptochrome-4 could plausibly trigger neuron activity—thus communicating with a bird’s brain—through its chemical reactions.

To that end, they simulated the chemical reactions of cryptochrome-4 on a computer.

In this study, Mouritsen’s team relied on a new technique for observing microscopic systems capable of capturing nanosecond-speed changes in the protein to observe the details of the chemical reactions.

However, the study doesn’t conclusively prove that birds use cryptochrome-4 to sense magnetic fields.