People have been trying to understand how living things know where they're going for more than 100 years.
Daniel Kattnig, a researcher in the chemistry department at Oxford University, works in a lab that studies radical pairs - a phenomenon in which atoms acquire extra electrons that are "entangled"with one another, each affecting the other's motion even though they're separated by space. It's a field of science that is difficult to understand but imagine trying to figure it out with a bird brain.
But according to an increasingly popular theory, birds and other animals use a radical-pair-based compass to "see"the Earth's magnetic field, allowing them to undertake great migrations without getting lost.
It's still unproven, but Kattnig and his colleagues just verified a key component: In a study in the New Journal of Physics, they reported that the timing of these subatomic interactions makes them a good candidate to explain avian navigation.
"We think they are using quantum mechanics to navigate," Kattnig said. "There are still many steps before we can say this for certain."
Previously, scientists have proposed animal compasses based on the sense of smell, memorised landmarks, the direction of the sun, polarisation of light and even the positions of the stars. It's even been suggested that dung beetles plot a path back to their burrows by following the Milky Way.
In the early 1960s, it was demonstrated that magnetism was at the heart of animal navigation.
It's thought light-sensitive proteins called cryptochromes - which have been found in the retinas of birds, butterflies, fruit flies, frogs, humans and other creatures - are at the centre of the mystery. When light strikes the proteins, it creates radical pairs that begin to spin in synchrony. They're entangled in a microsecond chemical reaction.