Breaking news

Birds see magnetic fields by using quantum mechanics


Many birds have a sixth sense. No, not seeing dead people: they detect the Earth's magnetic field.

This ability allows them to return to the same places year after year during seasonal migration.

Now scientists are closer to identifying the mechanism our feathered friends use to detect the Earth's magnetic field, involving quantum mechanics in their eyes.

Birds see magnetic fields by using quantum mechanics

Cryptochrome-4: a bird's magnetic sensor

The research team is led by scientists from the University of Oldenburg in Germany and the University of Oxford.

It has been studying a protein known as cryptochrome-4 found in the birds' retinas.

For 20 years, experts have assumed that this protein acts like a bird's magnetic sensor.

It is microscopic compass that points the bird in a specific direction.

The protein is involved in chemical reactions that produce varying amounts of new molecules depending on the direction of the Earth's magnetic field.

The bird's neurons eventually react to the amount of these molecules to redirect the animal.

"But no one can confirm or verify this in the laboratory," said biologist Jingjing Shu of the University of Oldenburg in Germany.

How the protein reacts to magnetic fields

"How animals perceive magnetic fields is a mystery.

We don't know much about it. This is another great Holy Grail in sensory biology."

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

A cryptochrome-4 similar to real birds Crypt-4

The researchers studied the cryptochrome-4 they produce themselves, rather than proteins extracted from real birds.

To make cryptochrome-4, they inserted DNA instructions for protein production into it.

The bacteria read the instructions and made the proteins.

"The protein you get from bacteria is identical to the one found in birds," said biologist Henrik Mouritsen from the University of Oldenburg.

Chemical reactions of bird cryptochrome-4 in a magnetic field

The team observed the protein undergoing chemical reactions inside a test tube placed in magnetic fields about a hundred times stronger from the earth.

By comparing the types of proteins found in different bird species, they discovered that.:

  • Cryptochrome-4 in a migratory European robin is more sensitive to magnetic fields than cryptochrome-4 found in chickens and pigeons, which do not migrate.

In addition, their observations indicated that cryptochrome-4 could stimulate neural activity - and thus communication with the bird's brain - through its chemical reactions.

"The [reaction products] It exists long enough and is produced in sufficient quantities to serve as signaling material," Warrant said.


The team wanted to better understand how the protein activates the birds' neurons.

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

These interactions, which change the shape and structure of the protein, involve the movement of single electrons.

That’s means that we are in the realm of quantum mechanics.

In these reactions, light strikes and distorts the protein, which is made up of a series of molecules folded in on itself.

This distortion causes the electrons in one part of the chain to jump from one bond to another to form a pair of molecules.

These two molecules have an odd number of electrons that pair up - leaving one unpaired electron.

Then the two unpaired electrons in each molecule form a binary, with the quantum spins pointing in opposite directions.

Quantum mechanics comes into play

This is where quantum mechanics comes in.

The spins of the two electrons begin to oscillate, with one electron tilting in the direction so that their spins line up.

Then back again, about a million times a second.

When the electron spins are aligned, they create more feedback reactions for the neurons to respond to than when the spins are opposite.

The time that the electrons spend in alignment or not depends on the direction of the magnetic field.

Thus, the response of a bird's neuron depends on the direction of the magnetic field.

Similar to the way the neurons in our eyes respond to different wavelengths of light and send information to our brains that is interpreted as colors.

It is plausible that the neurons in birds transmit information about magnetic fields - allowing the birds to see the magnetic fields and to navigate them.

Follow us to receive all news