Birds have a mysterious “quantum sense”. For the first time, scientists saw it in action

Seeing our world through the eyes of a migrating bird would be a rather frightening experience. Something in their visual system allows them to “see” the magnetic field of our planet, a smart quantum physics and biochemistry trick that helps them travel great distances.

Now, for the first time, scientists at the University of Tokyo have directly observed a key reaction believed to be behind the talents of birds and many other creatures to detect the direction of the planet’s poles.

Most importantly, this is evidence that quantum physics directly affects a biochemical reaction in a cell – something we have long speculated but have not seen before.

Using a custom-made microscope sensitive to faint flashes of light, the team observed a culture of human cells containing a special light-sensitive material respond dynamically to changes in a magnetic field.

A cell’s fluorescence darkens when a magnetic field passes over it. (Ikeya and Woodward, CC BY)

The change observed by the researchers in the lab is exactly what one would expect if a quantum-shifted effect was responsible for the illuminating reaction.

“We didn’t change or add anything to these cells,” says biophysicist Jonathan Woodward.

“We believe we have extremely strong evidence that we have observed a purely quantum mechanical process affecting chemical activity at the cellular level.

So how are cells, especially human cells, able to respond to magnetic fields?

While there are several hypotheses, many researchers believe the ability is due to a unique quantum reaction involving photoreceptors called cryptochromes.

Cyrptochromes are found in cells of many species and are involved in the regulation of circadian rhythms. In species of migratory birds, dogs and other species, they are linked to the mysterious ability to detect magnetic fields.

In fact, while most of us can’t see magnetic fields, our own cells definitely contain cryptochromes. And it is proven that even though they are not conscious, humans are still able to detect Earth’s magnetism.

To see the reaction within the cyrptochromes in action, the researchers bathed a culture of human cells containing cryptochromes in blue light, causing them to become weakly fluorescent. As they glowed, the team swept magnetic fields of different frequencies repeatedly across the cells.

They found that, each time the magnetic field passed over the cells, their fluorescence decreased by about 3.5% – enough to show a direct reaction.

So how can a magnetic field affect a photoreceptor?

It all comes down to something called spin – an innate property of electrons.

We already know that the spin is significantly affected by magnetic fields. Arrange electrons the right way around an atom and collect enough of them in one place, and the resulting mass of material can be moved using nothing more than a weak magnetic field like the one surrounding our planet.

This is fine if you want to make a needle for a navigation compass. But with no obvious signs of pieces of magnetically sensitive material inside pigeon skulls, physicists must have thought smaller.

In 1975, a researcher at the Max Planck Institute named Klaus Schulten developed a theory on how magnetic fields could influence chemical reactions.

They were something called a radical pair.

A garden variety radical is an electron in the outer shell of an atom that is not associated with a second electron.

Sometimes these single electrons can adopt a wingman in another atom to form a radical pair. The two remain unpaired, but thanks to a shared history, they’re seen as entangled, which in quantum terms means their spins will eerily match no matter how far apart they are.

Since this correlation cannot be explained by continuous physical connections, it is purely quantum activity, which even Albert Einstein considered “ frightening. ”

In the turmoil of a living cell, their entanglement will be fleeting. But even these briefly correlated spins should last just long enough to make a subtle difference in how their respective parent atoms behave.

In this experiment, when the magnetic field passed over the cells, the corresponding drop in fluorescence suggests that the generation of radical pairs was affected.

An interesting consequence of the research could be how even weak magnetic fields could indirectly affect other biological processes. Although the evidence for magnetism affecting human health is weak, similar experiments could prove to be another avenue of investigation.

“The joy of this research is that the relationship between the spins of two individual electrons can have a major effect on biology,” says Woodward

Of course, birds aren’t the only animal that relies on our magnetosphere for direction. Species of fish, worms, insects and even some mammals have a knack for this. We humans might even be cognitively affected by Earth’s weak magnetic field.

Evolving this ability could have produced a number of very different actions based on different physics.

Having evidence that at least one of these links the weirdness of the quantum world to the behavior of a living being is enough to force us to wonder what other pieces of biology come from the frightening depths of fundamental physics.

This research was published in PNAS.