Scientists Trace Pigeons' Mysterious Magnetic Sense To Iron-Rich Cells In The Liver

Scientists in Germany said they may have identified the location of the internal compass that helps homing pigeons navigate using Earth's magnetic field. The discovery could help explain one of biology's longest-standing mysteries: how animals detect the planet's magnetic signals. The findings were published in the journal Science. Many animals are known to detect Earth's magnetic field and use it for navigation. These include pigeons, sea turtles, spiny lobsters, moths, mole rats, gray whales, and big brown bats, reported National Geographic.

Researchers believe these animals rely on a hidden biological compass that allows them to orient themselves and carry out long-distance migrations across land, sea, and air. However, scientists have long struggled to understand exactly how animals sense these magnetic cues.

A Century-Old Mystery

Martin Wikelski, a director at the Max Planck Institute of Animal Behaviour in Germany and a co-author of the study, said the sense of magnetism has remained a mystery for about a century.

According to Wikelski, researchers now believe they have found a workable explanation for how the mechanism functions.

For years, scientists debated whether birds detected Earth's magnetic field through their eyes, beaks, or inner ears.

Earth's magnetic field is generated by the movement of liquid iron and nickel deep beneath the planet's surface. The magnetic field extends into space and protects life on Earth from harmful cosmic radiation.

Because the magnetic field passes through an animal's entire body, scientists believed the organ responsible for detecting it could potentially be located anywhere.

The new study suggests that pigeons may house their internal compass in their livers rather than in their eyes, ears, or beaks.

The research began more than a decade ago after Wikelski met immunologist Christian Kurts at a conference. Kurts had been studying macrophages, a type of immune cell that can become sensitive to magnets after consuming old red blood cells and accumulating iron.

The researchers decided to investigate whether these cells could play a role in magnetoreception, the ability to detect magnetic fields.

The team examined several parts of pigeons' bodies, including the eyes, beak, brain, spleen, and liver.

Their analysis revealed large concentrations of iron-rich macrophages in liver tissue. The researchers also found that these immune cells were located close to nerve fibres.

Based on these findings, the scientists believe the pigeons' magnetic sensing system may be linked to these iron-containing immune cells in the liver, offering a possible explanation for how the birds detect Earth's magnetic field and find their way home.