#magnetoreception

Dancing turtles have proved for the first time that some animals use Earth's magnetic field to create a personal map of their favorite spots, scientists said Wednesday. Some animals that migrate across the globe – such as birds, salmon, lobsters and sea turtles – are known to navigate using the magnetic field lines that stretch from Earth's north to south pole. Scientists knew the animals used this magnetic information as a compass to establish where they were. Now they increasingly believe the turtles are also able to plot a magnetic map featuring important places such as nesting or feeding spots.

"In winter, lakes and rivers across the country are filled with migratory birds flying in from the north. How do birds keep such precise bearings while flying thousands of kilometers? German scientists have newly found a compass in birds’ ears. It had been known that substances in the retina or beak respond to magnetic fields, but this means they also “hear” direction through the ear.

David Keays, a professor at LMU, and his team in Germany said in Science on the 21st that “experiments confirmed that pigeons detect magnetic fields in the inner ear and send electrical signals to the brain.” The team validated the pigeon experiment results through single-cell RNA decoding and tracing of brain signal pathways.

It has been known that various animals such as migratory birds, turtles, and trout sense the direction and intensity of Earth’s magnetic field to orient themselves, but the exact mechanism has remained unclear. Eric Warrant, a professor at Lund University in Sweden, said, “The ultimate holy grail of sensory biology is to understand magnetoreception,” adding, “This study is the most definitive demonstration of a neural pathway involved in magnetic field processing in animals.”"

I'm losing my mind a little at the thought that magnetoreception could be a result of quantum reactions inside cryptochromes and that even humans have a weak version of it going on in our cells.

Birds, fish and some other creatures can sense Earth’s magnetic field. This ability is known as magnetoreception (mag-NEE-toe-ree-SEP-shun). Many creatures use it navigate. Scientists have long wondered whether humans can do this, too. Now, a study of brain waves suggests people indeed have a “sixth sense” — for magnetism.

In a lab at the California Institute of Technology, in Pasadena, researchers discovered people form a distinct brain-wave pattern when they are exposed to a magnetic field that is equal in strength to Earth's . But the pattern emerges only when the field points and moves in a certain way. The researchers shared their findings online March 18 in eNeuro.

The discovery offers evidence that people respond to Earth’s magnetic field without knowing it. It’s not yet clear how our brains might use this information.

Biophysicist Can Xie’s first impression of the study was, “Wow, I cannot believe it!” Previous tests of magnetic sense in humans have had mixed results. This new result is “probably a big step for the human magnetic sense,” Xie says. He works at Peking University in Beijing, China.

First Neuroscientific Evidence that Humans Have Geomagnetic Sense.  

An international team of neuroscientists and geoscientists from Caltech, the University of Tokyo, Princeton University and Tokyo Institute of Technology has discovered that the human brain can detect Earth-strength magnetic fields.

The Earth is surrounded by a magnetic field, generated by the movement of the planet’s liquid core. At the planetary surface, this magnetic field is fairly weak, about 100 times weaker than that of a refrigerator magnet.

Many migratory (such as birds, turtles, eels and lobsters) and non-migratory (fruit flies, cockroaches, honey bees) animals are equipped with a special sense called magnetoreception that allows them to detect this field to perceive direction, altitude or location.

Although magnetoreception has been well-studied in these creatures, scientists have not yet been able to determine whether humans share this ability.

Dr. Joseph Kirschvink, a geoscientist from Caltech and Tokyo Institute of Technology, Caltech neuroscientist Dr. Shin Shimojo and their colleagues set out to address this long-standing question using electroencephalography (EEG) to record adult participants’ brain activity during magnetic field manipulations.

"When you consider, say, a salmon, or a pigeon, your first thought is probably not “Wow, I bet that guy is great at quantum mechanics” – and yet, that’s precisely what the evidence suggests: that these animals, among others, exploit some of the most advanced science currently understood by humans in their everyday lives – and according to a new paper, they’re doing so in ways that push at the very limits of quantum physics."

"Basically, the performance of a magnetic sensor depends on three things: its volume, sensitivity, and the measurement time. The smaller the result, the more sensitive the magnet.

Sounds simple? Maybe – but these days, we can get pretty darn small. Go too far down in scale, and things start to get a bit wibbly – or, as physicists prefer to call it, quantum."

"So, what does all this have to do with animal senses? Well, biologists have long known that many animals have the ability to sense magnetic fields – it’s how birds find their way home, how foxes find success in hunting, and how dogs know how to go doo-doo. They’re good at it too, to a level that scientists have found almost baffling – the Earth’s magnetic field is extremely weak, all things considered, and yet these critters can tap into it with an uncanny level of accuracy.

That means they must be operating some near-quantum-limit levels of magnetoreception – but just how near has so far remained a mystery."